PT-105 at high speed

PT boats were a variety of torpedo-armed fast attack craft used by the United States Navy in World War II to attack larger surface ships. "PT" is the US hull classification symbol for "Patrol Torpedo". The PT boat squadrons were nicknamed "the mosquito fleet". The Japanese called them "Devil Boats".^[1]

The original pre–World War I torpedo boats were designed with "displacement" hulls. They displaced up to 300 tons and the top speed was 25 to 27 kn (29 to 31 mph; 46 to 50 km/h). The PT boats used in World War II were built using the planing-type hull form developed for racing boats. They were much smaller (30–75 tons) and faster (35–40 knots). Both types were designed to strike at larger warships with torpedoes, using relatively high speed to get close, and small size to avoid being spotted and hit by gunfire. They were much less expensive than large warships. PT boats were much faster, smaller, and cheaper than conventional (displacement hull) vessels.

During World War II, American PT boats engaged enemy destroyers and numerous other surface craft, ranging from small boats to large supply ships. PT boats also operated as gunboats against enemy small craft, such as armored barges used by the Japanese forces for inter-island transport.

History[link]

In the late 1930s, the U.S. Navy requested competitive bids for several different concepts of torpedo boats. This competition led to eight prototype boats built to compete in two different classes. The first class was for 55-foot (17 m) boats, and the second class was for 70-foot (21 m) boats. The resulting PT boat designs were the product of a small cadre of respected naval architects and the Navy.

On June 8, 1939, contracts were let to the Fogal Boat Yard, Inc., later known as the Miami Shipbuilding Co., of Miami, Florida, for PT-1 and -2, and to the Fisher Boat Works, Detroit, Michigan, for PT-3 and -4.^[2] These four boats were essentially the Crouch design, modified in some details by the Bureau of Ships. At the same time the Philadelphia Navy Yard began construction of two other designs (PT-7 and PT-8), created by designers at the Navy Yard and the Navy Bureau of Ships.

Henry R. Sutphen of Electric Launch Company (Elco) and his designers (Irwin Chase, Bill Fleming, and Glenville Tremaine) visited the United Kingdom to see British motor torpedo boat designs. While visiting the British Power Boat Company, they purchased a 70-foot (21 m) design (PV70) (later renamed PT-9 during the competition), designed by Hubert Scott-Paine.

PT-9 in June 1940.

Other entries in the competition were three boats built by Andrew Jackson Higgins of Higgins Industries in New Orleans. These boats were PT-5 and PT-6 (built using government-required Sparkman and Stephens design, scaled to an overall length of 81 feet (25 m)) and then PT-6 "Prime" which was redesigned by Higgins personally using his own methods. The final competitor for the contract was Huckins Yacht Corporation, which came up with competing 70-foot (21 m) boat class designs.

The results of the competition found that none of the boats, as built, was up to the necessary performance specifications identified by the Navy.

The Plywood Derby[link]

The Board of Inspection and Survey decided to conduct comparative service tests. The following boats were tested off New London, July 21 to 24, 1941:

• PT-6: 81 ft (25 m) Higgins; 3 Packard 1,200-hp engines.
• PT-8: 81 ft (25 m) Philadelphia Navy Yard; aluminum hull; 2 Allison 2,000-hp engines, 1 Hall-Scott 550-hp engine.
• PT-20: 77 ft (23 m) Elco; 3 Packard 1,200-hp engines; equipped with special propellers; special strengthening added to hull framing and deck.
• PT-26, -30, -31, -33: Same as PT-20, except with standard propellers and without special strengthening.
• PT-69: 72 ft (22 m) Huckins; 4 Packard 1,200-hp engines.
• PT-70: 76 ft (23 m) Higgins; 3 Packard 1,200-hp engines.
• One 70 ft (21 m) boat built for Britain by Higgins; 3 Hall-Scott 900-hp engines.

The test included an open-sea run of 190 miles (310 km) at full throttle, forever after referred to by PT personnel as the "Plywood Derby." The course started around New York Harbor, at Sarah Ledge, then led around the eastern end of Block Island, then around Fire Island Lightship, finishing at Montauk Point Whistling Buoy.

This was a shakedown to see which company would be contracted to build the Navy PT boats. At the completion of the trials, the Navy considered all three designs. The Elco 77-footer (23 m) (PT-20) came in first with an average speed of 39.72 kn (45.71 mph), followed by the Huckins 72-foot (22 m) boat (PT-69) and the Higgins 76-footer (23 m) (PT-70).^[3] the Navy saw the merits of the other two boats and decided to offer all three companies contracts. Elco received the largest share of the contract with contracts for 350 boats, Higgins was awarded contracts for 199 boats, and Huckins was awarded a contract for 18 boats.

The Elco company may have had an advantage owing to their experience in small-boat building, having built 550 80 ft (24 m) sub chasers for the Royal Navy during World War I. Additionally, in 1921, they introduced the famous 26 ft (7.9 m) "Cruisette", (a gasoline cabin cruiser). This success in small-boat building was followed in the 1930s with 30-ft to 57-ft "Veedettes" and "Flattops", which were gasoline-powered boats that set the highest standard in a golden era of boating. This small-boat experience helped Elco obtain a contract for 10 boats based on the 70-foot (21 m) Scott-Paine Model PT boat. These 70 ft (21 m) boats were tested and determined to be too light for open sea work, but Elco got a contract for 24 larger boats based on a lengthened 77 ft (23 m) design.

Elco[link]

The Elco Naval Division boats were the largest in size of the three types of PT boats built for the Navy used during World War II. By war's end, more of the Elco 80 ft (24 m) boats were built than any other type of motor torpedo boat (326 of their 80 ft (24 m) boats were built). The 80 ft (24 m) wooden-hulled craft were classified as boats in comparison with much larger steel-hulled destroyers, but were comparable in size to many wooden sailing ships in history. They had a 20 ft 8 in (6.30 m) beam. Though often said to be made of plywood, they were actually made of two diagonal layered 1 in (25 mm) thick mahogany planks, with a glue-impregnated layer of canvas in between. Holding all this together were thousands of bronze screws and copper rivets. This type of construction made it possible for damage to the wooden hulls of these boats to be easily repaired at the front lines by base force personnel. Five Elco Boats were manufactured in knock-down kit form and sent to Long Beach Boatworks for assembly on the West Coast as part of an experiment and as a proof of concept.

Higgins[link]

Higgins produced 199 78 ft (24 m) boats. The Higgins boats, built by Higgins Industries in New Orleans, Louisiana, were 78 ft (24 m) boats of the PT-71 or PT-235 or PT-625 classes. The Higgins boats had the same beam, full load displacement, engine, generators, shaft power, trial speed, armament, and crew accommodation as the 80 ft (24 m) Elco boats. Many Higgins boats were sent to the Soviet Union and Great Britain at the beginning of the war, so many of the lower-numbered squadrons in the U.S. Navy were made up exclusively of Elcos. The first Higgins boats for the U.S. Navy were used in the Battle for the Aleutian Islands (Attu and Kiska) as part of Squadron 13 and 16, and others (RON15 and RON22) in the Mediterranean against the Germans. They were also used during the D-Day landings on 6 June 1944. A somewhat odd footnote is that even though only half as many Higgins boats were produced, far more survive (seven hulls, 3 of which have been restored to their World War II configuration), than of the more numerous Elco boats, thus seemingly demonstrating the superior construction of the Higgins boat. Of the remaining Elco boats only three hulls (one restored) are known to exist at this time.

Huckins Yacht Corporation[link]

Frank Pembroke Huckins and his innovative Quadraconic hull helped convince the Navy Board of Inspection and Survey to accept the PT designs. After proving that the planing hull was faster, and it provided a platform for the armament requirements of a war boat, the navy awarded Huckins Yacht Corporation a PT design contract in 1941 for a total of 18 boats.

Huckins built two squadrons of PT boats during World War II. A total of 18 78-foot (24 m) boats for squadrons 14 and 26 were commissioned in early 1943. They were assigned to specific outposts in the Panama Canal Zone, Miami, Florida, the Hawaiian Sea Frontier at Pearl Harbor, in the Central Pacific, and a training center in Melville, Rhode Island.

Huckins licensed the use of the Quadraconic hull in PT boat construction. Huckins also granted permission for Elco, Higgins and the Philadelphia Navy Yard to use their patented laminated keel, which increased hull strength. Although neither Elco nor Higgins ever chose to use the Huckins design on their boats, rather choosing to use designs of their own.

The handcrafted Huckins PT, was produced at a speed of one per month. The Elco boats made the best showing with Elco edging the Huckins in light and heavy loaded speed tests (45.3 kn (52.1 mph) versus 43.8 kn (50.4 mph)),^[4] however the Huckins had a tighter turning circle (Huckins 336-P/368-S yards in diameter compared to Elco 432-P/382-S yards in diameter) and pounding factor (Elco pounded 61% more than Huckins). The Elco 77 ft (23 m) was considered acceptable for future construction provided changes were made to reduce pounding in a seaway, and also strengthen the structure in a manner acceptable to the Bureau of Ships.

Vosper and other types of PT boats[link]

During World War II, the Vosper Boat Company of Great Britain arranged for several boatyards in the U.S. to build British-designed 70 ft (21 m) motor torpedo boats under license to help the war effort. 146, armed with 18 in (460 mm) torpedoes, were built for Lend Lease, exported to Allied powers such as Canada, Britain, Norway, and the Soviet Union. They were never used by the U.S. Navy, and only about 50 were used by the Royal Navy, and most were passed to other countries.

In addition, the Canadian Power Boat Company produced five Scott-Paine designed PTs for the U.S., which were also sent as Lend Lease to the UK.

Construction[link]

With accommodation for three officers and 14 enlisted men, the crew varied from 12 to 17, depending upon the number and type of weapons installed. Full-load displacement late in the war was 56 tons.

The hull shape of a PT boat was similar to the "planing hull" found in pleasure boats of the time (and still in use today): a sharp V at the bow softening to a flat bottom at the stern. PT boats were intended to plane at higher speeds, just like pleasure boats. The Elco and Higgins companies both used lightweight techniques of hull construction which included two layers of double diagonal mahogany planking utilizing a glue impregnated cloth layer between inner and outer planks. These planks were held together by thousands of copper rivets and bronze screws. The overall result was an extremely light and strong hull, yet it could be easily repaired from battle damage at the front lines.

As a testament to the strength of this type of construction, several PT boats withstood catastrophic battle damage and still remained afloat. For example, the forward half of future President John F. Kennedy's PT-109 (Elco) stayed afloat for 12 hours after she was cut in half by the Japanese destroyer Amagiri. PT-323 (Elco) was cut in half by a kamikaze aircraft on December 10, 1944 off Leyte, yet remained floating for several hours. Another was PT-308 (Higgins), had her stern sheared off by a collision with PT-304 during a night mission in the Mediterranean on 9 March 1945 and yet returned to base for repairs. PT-167 (Elco) was holed through the bow off New Georgia on August 10, 1943, by a torpedo which failed to detonate; the boat remained in action and was repaired the next day.

In 1943, an inquiry was held by the Navy to discuss planing, hull design, and fuel consumption issues, but no major modifications were made before the end of the war. (Wooden Boat Forum) During the war, both Elco and Higgins came up with stepped hull designs which achieved significant increases in top speed, ("ElcoPlane" & "Higgins Hellcat") but the Navy rejected them for full production due to their increased fuel consumption and other considerations.

Armament[link]

The primary anti-ship armament was two to four Mark 8 torpedoes, which weighed 2,600 pounds (1,179 kg) and contained a 466-pound (211 kg) TNT warhead. These torpedoes were launched by Mark 18 21-inch (530 mm) steel torpedo tubes. Mark 8 torpedoes had a range of 16,000 yards (14,630 m) at 36 knots (41 mph). These torpedoes and tubes were replaced in mid-1943 by four lightweight 22.5-inch-diameter (570 mm) Mark 13 torpedos, which weighed 2,216 pounds (1,005 kg) and contained a 600-pound (270 kg) Torpex filled warhead. These torpedoes were carried on lightweight Mark 1 roll-off style torpedo launching racks. The Mk13 torpedo had a range of 6,300 yards (5,800 m) and a speed of 33.5 knots (38.6 mph).

PT boats were also well armed with numerous automatic weapons. Common to all US PT boats were the two twin M2 .50 cal (12.7 mm) machine guns. Early PT boats (Elco PT20 through PT44) mounted Dewandre plexiglas enclosed hydraulically operated rotating turrets.[2] Almost immediately after the attack on Pearl Harbor, the Dewandre turrets were replaced on the entire PT boat fleet with open ring twin mounts. The ring mount was designed by both Elco and Bell, and designated Mark 17 Twin 50 caliber aircraft mount.[3] Part of the Mark 17 Mod 1 and Mod 2 ring mount consisted of the Bell Mark 9 twin cradle. [4] [5]

Another automatic weapon commonly mounted on PT boats was the 20 mm Oerlikon cannon. On early series of boats, this cannon was mounted on the stern. Later in the war, several more of these 20 mm cannons were added amidships and on the forward deck.

Forward of the chart house of some early Elco 77-foot (23 m) boats (PT20 through PT44) were twin .30 cal (7.62 mm) Lewis machine guns on pedestal mounts. Beginning in mid 1943, some boats were fitted with one or two .30 cal Browning machine guns on the forward torpedo racks on pedestal mounts.

Occasionally, some front line PT boats received ad hoc up-fits at forward bases, where they mounted such weapons as 37mm aircraft cannons, rocket launchers, or mortars. When these weapons were found to be successful, they were incorporated onto the PT boats as original armament. One such field modification was made to Kennedy's PT-109 which was equipped with a single-shot Army M3 37mm anti-tank gun that her crew had commandeered; they removed the wheels and lashed it to 2x8 timbers placed on the bow only one night before she was lost. The larger punch of the 37mm round was desirable, but the crews looked for something that could fire faster than the single shot army anti-tank weapon. Their answer was found in the 37mm Oldsmobile M4 aircraft automatic cannon cannibalized from crashed P-39 Airacobra fighter planes on Henderson Field, Guadalcanal. After having demonstrated its value on board PT boats, the M4 (and later M9) cannon was installed at the factory. The M4/M9 37mm auto cannon had a relatively high rate of fire (125 rounds per minute) and large magazine (30 rounds). These features made it highly desirable due to the PT boat's ever-increasing requirement for increased firepower to deal effectively with the Japanese daihatsu barges, which were largely immune to torpedoes due to their shallow draft. By the war's end, most PTs had these weapons.

The culmination of larger bore cannons resulted in the installation of the 40mm Bofors gun[6] on the aft deck. Starting in mid-1943, the installation of this gun had an immediate positive effect on the firepower available from a PT boat. The Bofors cannon had a firing rate of 120 rounds/min (using 4 round clips) and had a range of 5,420 yards (4,960 m). This gun was served by a crew of 4 men, and was used against aircraft targets, as well as shore bombardment or enemy surface craft.

Towards the end of the war, beginning in 1945, PTs received two eight-cell Mark 50 rocket launchers,[7] launching 5 in (130 mm) spin-stabilized flat trajectory Mark 7 and/or Mark 10 Rockets [8] with a range of 11,000 yards (10,000 m). These 16 rockets plus 16 reloads gave them as much firepower as a destroyer's 5 in (130 mm) guns. By war's end, the PT boat had more "firepower-per-ton" than any other vessel in the U.S. Navy.

PT boats also commonly carried between two and eight U.S. Navy Mark 6 depth charges in roll-off stern racks. Additionally, a few PT boats were equipped to carry Naval Mines launched from mine racks, but these were not in common usage.

Although not a weapon, U.S. Navy PTs also were fitted with Raytheon SO radar, which had about a 17 nm range. Having radar gave Navy PTs a distinct advantage in intercepting enemy supply barges and ships at night.

Engines[link]

All U.S. PT boats were powered by three 12-cylinder gasoline-fueled engines. These engines were built by the Packard Motor Car Company, and were a modified design of the 3A-2500 V-12 liquid-cooled aircraft engine. The 3A-2500 was an improved version of the 2A engine used on the Huff-Daland XB-1 Liberty bomber of World War I vintage. Packard modified them for marine use in PTs, hence the "M" designation instead of "A". (i.e., 3A-2500 then 3M-2500). The three successive versions of these engines were designated as 3M-2500, 4M-2500, and 5M-2500, each of which had slight improvements over the previous version. Their aircraft roots gave them many features of aircraft engines, such as superchargers, intercoolers, dual magnetos, two spark plugs per cylinder, and so on. Packard built the Rolls-Royce Merlin aero engine under license alongside the 4M-2500, but with the exception of the PT-9 prototype boat brought from England for Elco to examine and copy, the Merlin was never used in PTs. The 4M-2500s initially generated 1200 hp (895 kW) each, together roughly the same power as a Boeing B-17 bomber. They were subsequently upgraded in stages to 1500-hp (1,150 kW) each, for a designed speed of 41 knots (76 km/h (47 mph)). The final engine version, the Packard 5M-2500, (late 1945) had a larger supercharger, aftercooler, and power output of 1850 Hp. This much power could push the fully loaded boats at 45 to 50 knots. However, using the older 4M-2500 engines, increases in the weight of the boats due to more weaponry offset the potential increase in top speed. Fuel consumption of these engines was phenomenal; a PT boat carried 3,000 gallons (11,360 liters) of 100 octane avgas. A normal patrol for these boats would last a maximum of 12 hours. The consumption rate for each engine at a cruising speed of 23 knots was about 66 gallons (250 l) per hour (200 gallons [760 l] per hour for all 3 engines). However, at top speed, consumption increased to 166 gallons (628 l) per hour per engine (or 500 gallons [1,890 l] per hour for all 3 engines). Navy acceptance trials for every boat required it be able to demonstrate ability to achieve design speed of 41+ knots. Going at this speed, the 3,000 gallons of fuel would be used in only about 6 hours. Wartime conditions such as hull fouling and engine wear could sometimes cause the boats top speed to be degraded until maintenance could be performed.

Service[link]

Originally conceived as anti-ship weapons, PT boats were publicly credited with sinking several Japanese warships during the period between December 1941 and the fall of the Philippines in May 1942. Attacking at night, PT crews may have sometimes failed to note a possible torpedo failure. Although the American Mark 8 torpedo did have problems with porpoising and circular runs, it could and did have success against common classes of targets. The Mark 3 and Mark 4 exploders were not subject to the same problems as the Mark 6 exploders on U.S. submarines' Mark 14 torpedoes. Introduction of the Mark 13 torpedo to PT boats in mid-1943 all but eliminated the early problems that PT boats had with their obsolete Mark 8s.

An 80-foot (24 m) Elco PT boat on patrol off the coast of New Guinea, 1943

PTs would usually attack under the cover of night. The cockpits of PT boats were protected against small arms fire and splinters by armor plate. Direct hits from Japanese guns could and did result in catastrophic gasoline explosions with near-total crew loss. They feared attack by Japanese seaplanes, which were hard to detect even with radar, but which could easily spot the phosphorescent wake left by PT propellers. Bombing attacks killed and wounded crews even with near misses. There are several recorded instances of PT boats trading fire with friendly aircraft, a situation also familiar to U.S. submariners. Several PT boats were lost due to "friendly fire" from both Allied aircraft and destroyers.

Initially, only a few boats were issued primitive radar sets. Later in the war, as more PTs were fitted with dependable radar, they developed superior night-fighting tactics and used them to locate and destroy many enemy targets. During the Guadalcanal and Solomon Island campaigns in 1942–1943, the PT boats of Squadron (RON) 2, 3, 5 and 6 would lie in wait to ambush a target from torpedo range (generally about 1,000 yards (910 m)). During some of these nighttime attacks, the PT boats' position may have been given away by a flash of light caused by grease inside the black-powder-actuated Mark XIII torpedo tubes catching fire during the launching sequence. In order to avoid return fire by the enemy ships, the PT boat could deploy a smoke screen using stern-mounted generators as they escaped and evaded the enemy ships. The enemy forces would use searchlights or seaplane-dropped flares to locate the fleeing PT boat, illuminating them for destruction by their heavy-caliber guns. Sometimes PT boats used depth charges as a last-ditch confusion weapon to scare off pursuing destroyers. They could adjust the depth charge setting to go off at 100 feet (30 m), and by the time it exploded the pursuing destroyer would be right above the explosion. Starting in mid-1943 and thereafter, the old black powder actuated Mk13 Torpedo tubes loaded with Mark 8 torpedoes were removed and replaced with a newer style of torpedo launcher. The new Mark 1 "Roll-off" Torpedo launcher rack (which was loaded with an improved Mark 13 aerial torpedo) effectively eliminated the problem of a flash of light giving away the position of the PT boat as a result of burning grease. The new launcher did not use any form of explosive to launch the torpedo, and it was about 1,000 pounds (450 kg) less weight than the old tube style launchers.

During the war, a few PT boats were modified to become a "PT Gunboat". In the PT Gunboat, the torpedoes were all removed and replaced with more and heavier guns. These versions mounted extra armor, though tests showed this was not very effective.

The effectiveness of PT boats in the Solomon Islands campaign, where there were numerous engagements between PTs and capital ships as well as against Japanese shipborne resupply efforts dubbed "The Tokyo Express" in "the Slot", was substantially undermined by defective Mark 8 torpedoes. The Japanese were initially cautious when operating their capital ships in areas known to have PT boats, since they knew how dangerous their own Type 93s were, and assumed the Americans had equally lethal weapons. The PT boats at Guadalcanal were given credit for several sinkings and successes against the vaunted Tokyo Express. In several engagements, the mere presence of PTs was sufficient to disrupt heavily escorted Japanese resupply activities at Guadalcanal. Afterwards, the PT mission in the Solomon Islands was deemed a success.

Throughout World War II, PTs operated in the southern, western, and northern Pacific, as well as in the Mediterranean Sea and the English Channel. Some served during the Battle of Normandy. During the D-Day invasion, PTs patrolled the "Mason Line", forming a barrier against the German S-boats attacking the Allied landing forces. They also performed lifesaving and anti-shipping mine destruction missions during the invasion.

Perhaps the most effective use of PTs was as "barge busters". Since both the Japanese in the New Guinea area and the Germans in the Mediterranean had lost numerous resupply vessels to Allied air power during daylight hours, each attempted to resupply their troop concentrations by using shallow draft barges at night in very shallow waters. The shallow depth meant Allied destroyers were unable to follow them due to the risk of running aground and the barges could be protected by an umbrella of shore batteries. PTs had sufficiently shallow draft to follow them inshore and sink them. The efficiency of the PT boats at sinking the Japanese supply barges was considered^[who?] a key reason why the Japanese had severe food, ammunition, and replacement problems during the New Guinea and Solomon Island Campaigns, and made the PT boats prime targets for enemy aircraft. The use of PT boat torpedoes was ineffective against these sometimes heavily armed barges, since the minimum depth setting of the torpedo was about ten feet (3 m) and the barges only drew five (1.5 m).^[5] To accomplish the task, PTs in the Mediterranean and the Pacific (and RN and RCN MTBs in the Med) installed more and heavier guns which were able to sink the barges. One captured Japanese soldier's diary described their fear of PT boats by describing them as "the monster that roars, flaps it wings, and shoots torpedoes in all directions."^[6]

Though their primary mission continued to be attack on surface ships and craft, PT boats were also used effectively to lay mines and smoke screens, coordinate in air-sea rescue operations, rescue shipwreck survivors, destroy Japanese suicide boats, destroy floating mines, and to carry out intelligence or raider operations.

After the war, American military interviews with captured veterans of the Imperial Japanese Navy, supplemented by the available partial Japanese war records, were unable to verify that all the PT boat sinking claims were valid. Like many other victory claims by all parties involved (aircraft pilots, surface ships, submarines) this unclear verification was due in part to the Japanese military's policies of destroying military records.

Supply[link]

Although they did have a small refrigerator on board, PT boats lacked the larger capacity refrigerators of larger ships to store meat, milk, butter, and eggs, so crews depended on the ingenuity of their cook, who might also be quartermaster and signalman, and what he could do with sandwiches, Spam, Vienna sausage, beans, and orange marmalade^{[citation needed]}. PT boat squadrons were supported by either PT boat tenders or PT boat bases which supplied the boat crews with hot meals cooked aboard the larger command's facilities. The PT boat crews were usually located at the end of the supply chain, and as a result, they became proficient at finding "alternative means" of meeting their needs. PT boat crews would often beg, borrow, or barter with nearby ships or military units for supplies. At the front lines, it was not uncommon to see crewmen fish by aiming rifles or tossing grenades into the water near the boat.

PT gunboats[link]

In the Solomon Islands in 1943, three 77-foot (23 m) PT boats, PT-59, PT-60, and PT-61, were converted into "PT gunboats" by stripping them of all original armament except the two twin .50 cal (12.7 mm) gun mounts, then adding two 40mm and four twin .50 cal (12.7 mm) mounts. Lieutenant John F. Kennedy was the first commanding officer of PT-59 after its conversion. On November 2, 1943, PT-59 participated in the rescue of 40 to 50 Marines from Choiseul Island and a foundering landing craft (LCP(R)) which was under fire from Japanese soldiers on the beach.^[7]

In 1944, several Higgins 78-foot (24 m) boats ( PT222, PT-283, PT-284, PT-285, and PT-282) were converted, releasing PT-59, PT-60, and PT-61 for transfer back home to the Motor Torpedo Boat Squadron Training Command (MTBSTC) school in Melville, Rhode Island for use in training in hull repair techniques.

Notable PT boats[link]

Lieutenant (junior grade) John Kennedy (right) with his PT-109 crew.

Many PT boats became famous during and after World War II:

• PT-41, commanded by Lieutenant John D. Bulkeley, carried General Douglas MacArthur in his escape from Corregidor Island, Philippines. Bulkeley was awarded the Medal of Honor for his operations in the Philippines before rescuing MacArthur. Bulkeley's story inspired the book They Were Expendable, and the movie of the same name. PT-41 was the flagship of Motor Torpedo Boat Squadron Three (RON 3), based in the Philippine Islands 1941–1942 (PT-41, -31, -32, -33, -34, -35).
• Life magazine published an article about the PT boat captains in the battles off Guadalcanal, featuring the exploits of Lieutenants "Stilly" Taylor, Leonard A. Nikoloric, Lester Gamble, and Robert and John Searles; the article mentioned many boats in Squadrons Two and Five (in particular, PT-36, PT-37, PT-39, PT-44, PT-46, PT-48, PT-59, PT-109, PT-115, and PT-123).
• Other PT boats gaining fame during the war were PT-363 and PT-489, the boats used by Lieutenant Commander Murray Preston to rescue a downed aviator in Wasile Bay,^[8] off Halmahera Island, for which Preston was awarded the Medal of Honor.
• PT-109, commanded by future President John F. Kennedy, was made famous through the 1961 book PT 109: John F. Kennedy in World War II by Robert J. Donovan, and the 1963 film based on it.
• PT-59: Commanded by John F. Kennedy after the loss of PT-109
• PT-105: Commanded by Dick Keresey at the time of the loss of PT-109. Keresey wrote a book by the same name.
• "PT-373" Commanded by Lt. Belton A. Copp was the first boat, of a two boat squadron, to enter Manila Harbor in order to "test defenses" since the U.S. retreat in 1942. General McArthur honored Lt. Copp and the crew of PT-373 by using it to carry him back into Manilla Harbor on March 2, 1945.

Remaining WWII PT boats[link]

At the end of the war, almost all surviving U.S. PT boats were disposed of shortly after V-J Day. Hundreds of boats were deliberately stripped of all useful equipment and then dragged up on the beach and burned. This was done to minimize the amount of upkeep the Navy would have to do, since wooden boats require much continuous maintenance, and they were not considered worth the effort. The boats also used a lot of gasoline for their size, making them too expensive to operate for a peacetime navy. Much of this destruction occurred at PT Base 17, on Samar, Philippines, near Bobon Point.

A total of 11 PT boats, and 2 experimental PT boat hulls in various states of repair, survive today in the U.S.:

• PT-48

PT-48 is possibly the last surviving 77-foot (23 m) Elco PT boat. In July 1942, PT-48 (nicknamed "Prep Tom" and "Deuce") was assigned to MTB RON 3. This second Squadron 3 was the first to arrive in the Solomons and saw heavy engagement with the "Tokyo Express". PT 48 was one of the first 4 boats to arrive at Tulagi, on 12 October 1942. On the night of 13/14 October 1942, PT-48 engaged a Japanese destroyer at 200 yards (180 m). This Squadron saw action in the Solomon Islands, Guadalcanal, and Funafuti. PT-48 is today in need of major restoration, after having been cut down to 59 feet (18 m) and used as a dinner cruise boat. Because of this boat's extensive combat history, having survived 22 months in the combat zone at Guadalcanal (more time in combat than any other surviving PT boat), a preservation group, “Fleet Obsolete” of Kingston, New York, acquired and transported it to Rondout Creek in 2008 for eventual repair.^{[citation needed]}

Lt jg Raymond O. Sopher was the captain of both PT-48 and PT-60. (citation: Marti J. Sopher, Ph.D., Madison, WI 5/31/12)

• PT-305

PT-305 ("Half Hitch","Barfly", "USS Sudden Jerk") is a Higgins 78-foot (24 m) boat, assigned during the war to RON22, and saw action against the Germans in the Mediterranean Sea. Squadron 22 was operating with the British Coastal Forces, and saw action along the northwest cost of Italy and southern coast of France. In June 1945 the squadron was shipped to the U.S. for refitting and transfer to the Pacific, but the war ended while still in New York. The PT-305 was cut down to 65 feet (20 m) for use as an oyster seed boat in Crisfield, Maryland. PT-305 was acquired by the Defenders of America Naval Museum (DOANM), and then sold in May 2007 to the National World War II Museum in New Orleans. PT-305 is undergoing restoration (as of 2012) to become a permanent display in the new expansion of the museum. [9]. (video and website of PT 305 restoration [10])

• PT-309

A 78-foot (24 m) Higgins, PT-309 ("Oh Frankie!") was assigned during the war to RON22, and saw action against the Germans in the Mediterranean Sea. The squadron was operating under the British Coastal Forces, and saw action along the northwest cost of Italy and southern coast of France. In April 1945 the squadron was shipped to the U.S. for refitting and transfer to the Pacific, but the war ended while still in New York. Coincidentally, the PT-309 ("Oh Frankie!"), was named in honor of Frank Sinatra, with whom the boats' Commanding Officer met at a nightclub shortly before MTBRON22 left New York for the Mediterranean Theatre. PT-309 is located at the National Museum of the Pacific War / Admiral Nimitz Museum^[9] in Fredericksburg, Texas, which was restored by the (now defunct) Defenders of America Naval Museum (DOANM). PT-309 is restored (but non-operational) in a static diorama display without engines installed. Her external restoration was completed by the Texas group in 2002, and is to a high standard.^{[citation needed]}

• PT-459

PT-459 ("MAHOGANY MENACE") a Higgins 78-foot (24 m) boat, was assigned to MTBRON 30 on 15 February 1944 under the command of LCDR Robert L. Searles. MTBRON 30 saw action in the English Channel as part of the Invasion of Normandy. In late June 1945 the squadron was shipped to the U.S. for refitting and transfer to the Pacific, but the war ended while still in New York. After the war, the ex-PT459 was cut down to 65 feet (20 m) and highly modified into a sightseeing boat and fishing trawler. She was acquired by Fleet Obsolete in June 2008 and moved to Kingston, New York for possible restoration.^{[citation needed]}

• PT-486

PT-486, an 80-foot (24 m) Elco boat, was place in service on December 2, 1943.^[10] It was used in the training squadron (MTBRON)4 in Melville, Rhode Island during World War II until it was placed out of service January 16, 1946. Along with PT-557, the vessel was purchased from BFM Industries (Brooklyn, NY) by Capt. George C. Sinn of Wildwood Crest, NJ on October 9, 1951 for $1,015.00. The vessel was sold in 1952 to Otto Stocker who operated the "Sightseer" as an excursion vessel from Otten's Harbor in Wildwood, New Jersey. The business was later sold to Capt. Charles Schumann in the 1980s. He named the vessel Schumann's "Big Blue" and ran the business until 2002. Remarkably, the PT486 was sold to the son of the original owner, Capt. Ronald G. Sinn, who is currently restoring the vessel to recreate the World War II appearance of PT-109, for which the PT-486 was renamed.

• PT-615

PT-615, an 80-foot (24 m) Elco originally assigned to RON 42, was commissioned after the war ended. PT-615 was returned to Elco after being sold and was heavily modified into a yacht, which was leased to actor Clark Gable. He named the boat Tarbaby VI, and used her through the 1950s. The boat was serviced and stored by Elco. She was sold several times, and moved to Kingston for possible restoration.^{[citation needed]}

• PT-617

PT-617 is an 80-foot (24 m) Elco boat located in Battleship Cove Naval Museum in Massachusetts. She was obtained from the backwaters of Florida and moved to its current location by JM "Boats" Newberry, the founder of PT Boats Inc. "Boats" along with the team at Battleship Cove Museum restored her during 1984-89, inside and out, at a cost of US$1 million. The boat is owned by PT Boats, Inc., a World War II PT veterans organization headquartered in Germantown, Tennessee. The quality of the restoration was extremely high, and the boat is on display inside a weatherproof building, on blocks out of the water. She is available for public viewing, and has portions of her hull cut away to display the cramped interior of the crew's quarters. General visitors are not allowed inside the boat in order to help preserve her historic integrity.^{[citation needed]}

• PT-619

Served in the South Pacific as a downed pilot rescue boat. Now being restored by Randy Cunnigham in Vancouver B.C. http://www.vancouversun.com/news/Video+Restoring+World+patrol+boat/6481775/story.html

• PT-657

PT-657, a Higgins 78-foot (24 m) boat, has been converted into a charter fishing boat. She is located in San Diego, California and is now named Malahini.

• PT-658

Perhaps the best example of a surviving Higgins 78-foot (24 m) boat is PT658, which was completely restored to her original 1945 configuration from 1995 to 2005. PT-658 is now fully functional and afloat, using the three original Packard V12 5M-2500 gas engines. It is the only 100% authentically restored U.S. Navy PT boat actually operational today. PT-658 is located in Portland, Oregon at Navy Operational Support Center Portland's Swan Island Pier. The group wishes to maintain the boat as a living, breathing artifact dedicated to the history of the PT force of the Second World War.^[11]

• PT-728

PT-728, a surviving Vosper boat built under license at the Annapolis Boat Yard in Maryland, was restored by in Key West, Florida. Her deck house was reconfigured to partially resemble an 80-foot (24 m) Elco instead of its original Vosper 70-foot (21 m) configuration. PT-728 was acquired by Fleet Obsolete and moved to Kingston. There PT-728 allows up to 49 tourists the chance to ride on a "PT boat". This boat is the only U.S. Coast Guard regulation-approved PT boat licensed to take passengers for hire, and the only surviving U.S.-built Vosper design. As of Feb 7. 2012, PT-728 is for sale via the Hammacher Schlemmer catalog for $1 million.^[12]PT658 Video

• PT-796

PT-796 ("Tail Ender") is a 78-foot (24 m) Higgins.^[13] After the war ended PT-796 was used in the Key West/Miami area for experimental purposes. She was retired from service in the late 1950s. Shortly after her retirement from service, the PT-796 was used as a float during President John F. Kennedy's inaugural parade to represent PT-109, with the PT-109 hull number painted on the bow, and several of PT-109's surviving crew members manning the boat. Today, PT-796 is located at the Battleship Cove Naval Museum in Fall River, Massachusetts in a Quonset hut-style building, protected from the weather, and up on blocks. The boat is owned by PT Boats, Inc., a World War II PT veterans organization headquartered in Germantown, Tennessee.

Experimental boats[link]

• PT-3

Two of the experimental PT-Boats also still survive, PT-3 (built by Fisher Boat Works) in Pennsylvania and PT-8. PT-3 was a 59-foot (18 m) barrel-back boat that was rejected by the Navy during trials in 1941 after being deemed too short to carry 4 torpedoes.^[14] PT-3 and PT-8 were both part of Squadron 1 (RON 1) during the testing period. After testing was completed in 1941, PT-3 was reclassified into a Small Boat and transferred to Harbor Patrol duties for the duration of the war.^[15]

• PT-8

PT-8 (built at Philadelphia Naval Shipyard) in Louisiana was built entirely from aluminum but did not pass the speed acceptance criteria for use as a PT boat for the U.S. Navy due to its weight. She was reclassified as a harbor patrol boat for the duration of the war.

• UK Vosper

The two Vosper boats in England were built by Vosper itself, and the first is in fairly good condition at Portsmouth. The second UK built boat is in private hands, floating on a canal north of London and being used as a private residence, though it is remarkably intact in its World War II configuration.

Exported PT boats[link]

Ten Higgins boats were delivered in 1948 for use by the Argentine Navy ("Armada Argentina") during the late 1940s up until the late 1970s.^[16] All of these boats are now retired from naval use, with two still in service today as sightseeing boats on Mar del Plata: the Leonardo da Vinci #8 and the Mar de la Plata #9.^[17] The other six boats are in various states of disrepair or sunk or scrapped.

The PT boat design was also exported after the end of the second world war as an unarmed air-sea rescue launch for use by the South African Navy.

Cinema stand-ins for PT boats[link]

The 1963 movie PT-109 used what appears to be five Elco 80-foot (24 m) boats. The engine telegraph shows the Elco name, and the boats resemble Elcos. The boats were converted from Air Force Crash Rescue Boats, due to the unavailability of operational survivors. The 85-foot (26 m) boats were built with only two Packard engines.

The original 1962-66 McHale's Navy TV series used a Vosper boat.

In the 1997 movie McHale's Navy, 63-foot (19 m) Air Sea Rescue boats were used.

Occasionally Vietnam-era PTF boats (Patrol Torpedo Fast) (built at John Trumpy, Annapolis or Nasty class from Norway)^[18] are incorrectly identified as World War II PT boats. Several PTF boats can still be found around the country, including PTF-3 in Florida, PTF-19 in Chesapeake Bay and PTF-26 in California. These should not to be confused with PT boats, as they differ in many key features.

See also[link]

References[link]

Notes[link]

Bibliography[link]

General printed references

• Breuer, William (1987). Devil Boats: The PT War Against Japan. Novato, California, U.S.A.: Presidio Press. ISBN 0-89141-586-6. 
• Robert J. Bulkley, At Close Quarters: PT Boats in the United States Navy (Washington: U.S. Government Printing Office, 1962)
• Victor Chun, American PT Boats in World War II: A Pictorial History (Schiffer Publishing, 1997)
• T. Garth Connelly, Don Greer, Tom Tullis, Joe Sewell, Pt Boats in Action (Warships, No 7) (Squadron/Signal Publications, Inc., 1994)
• David Doyle "Elco 80' PT Boat On Deck" (Squadron/Signal Publications, Inc., 2010)
• Michael Green, PT Boats (Land and Sea) (Capstone Press, 1999)
• Keresey, Dick (2003). PT 105. Annapolis, Maryland, U.S.A.: United States Naval Institute. ISBN 978-1-55750-469-2. 
• Angus Konstam, PT-Boat Squadrons - US Navy Torpedo Boats (Ian Allan Publishing, June 2005)
• An excellent compendium of information about the Elco PT Boats can be found in "Allied Coastal Forces of World War II" Volume II by John Lambert and Al Ross. ISBN 1-55750-035-5. This book has a detailed history of the development of the various Elco boats, with numerous drawings and photos. It also has sections on PT Boat construction, as well as chapters on the Packard engines and typical weaponry used aboard PT Boats.

PT-109 story printed references

• Robert J. Donovan, PT 109: John F. Kennedy in WWII, 40th Anniversary Edition, McGraw Hill (reprint), 2001, ISBN 0-07-137643-7
• Richard Tregaskis, John F. Kennedy and PT-109 (Random House, 1962) OCLC 826062
• Robert D. Ballard, Collision With History: The Search for John F. Kennedy's PT 109 (National Geographic, 2002)
• Haruyoshi Kimmatsu, "The night We sank John Kennedy's PT 109" appeared in Argosy Magazine December 1970, Vol. 371 #6
• Tameichi Hara, Japanese Destroyer Captain (Ballantine Books, 1978) ISBN 0-345-27894-1
• Duane T. Hove, American Warriors: Five Presidents in the Pacific Theater of World War II, Burd Street Press, (2003) ISBN 1-57249-307-0
• James Michener, Tales of the South Pacific, Fawcett Crest Books, (1947) ISBN 0-449-23852-0
• Official Report on Loss of PT 109

External links[link]

• original Elco movie Giant Killers
• www.pt728.com Home of PT 728, a fully restored 72-foot (22 m) Vospor
• An example of daily life aboard a PT boat, recorded in the deck logs
• PT Boat Museum website
• Save the PT Boat USS PT-658 website
• Project video
• PT-617 Photos of the Elco PT boat PT-617 in Fall River, MA
• PT-796 Photos of the Higgins PT Boat PT-796 in Fall River, MA
• PT-235 Photos of life on board a PT boat in the Pacific in World War II by PT Boat Veteran Milt Donadt of PT-235
• Electric Launch Corp records
• Website dedicated to PT Boats
• PC game about PT Boats
• HNSA Ship Page: PT Boats to visit as museums and memorials
• With The Mosquito Fleet, April 1941 one of the earliest large article on PT Boats in the US
• Elco 103 class PT boat resource site

At 17 metres long, the Severn class lifeboats are the largest class of UK lifeboat

A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland (lakes) or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a vessel small enough to be carried aboard another vessel (a ship). Another less restrictive definition is a vessel that can be lifted out of the water. Strictly speaking and uniquely a submarine is a boat as defined by the Royal Navy^{[citation needed]}. Some boats too large for the naval definition include the Great Lakes freighter, riverboat, narrowboat and ferryboat. The term armed boat, used primarily by English speaking naval forces, referred to any boat carrying either a cannon or armed occupants, such as marines^{[citation needed]}.

History[link]

A boat in an Egyptian tomb painting from about 1450 BCE

Babur crossing river Son; folio from an illustrated manuscript of ‘Babur-Namah’, Mughal, Akbar Period, AD 1598

Boats have served as short-distance transportation since early times.^[1] Circumstantial evidence, such as the early settlement of Australia over 40,000 years ago, and findings in Crete dated 130,000 years ago,^[2] suggests that boats have been used since ancient times. The earliest boats have been predicted^[3] to be logboats. The oldest boats to be found by archaeological excavation are logboats from around 7,000–10,000 years ago. The oldest recovered boat in the world is the Pesse canoe; it is a dugout or hollowed tree trunk from a Pinus sylvestris. It was constructed somewhere between 8200 and 7600 B.C. This canoe is exhibited in the Drents Museum in Assen, Netherlands;^[4][5] other very old dugout boats have been recovered.^[6][7][8][9] A 7,000 year-old seagoing boat made from reeds and tar has been found in Kuwait.^[10]

Boats were used between 4000 BCE and 3000 BCE in Sumer,^[1] ancient Egypt^[11] and in the Indian Ocean.^[1]

Boats played a very important part in the commerce between the Indus Valley Civilization and Mesopotamia.^[12] Evidence of varying models of boats has also been discovered in various Indus Valley sites.^[13][14] The Uru wooden big boat made in Beypore a village in south Calicut, Kerala, in southwestern India. These have been used by the Arabs and Greeks since ancient times as trading vessels. This mammoth wooden ship was constructed using teak, without any iron or blueprints which has transportation capacity of 400 tonnes.

The accounts of historians Herodotus, Pliny the Elder, and Strabo suggest that boats were being used for commerce and traveling.^[13]

Types[link]

A tug boat is used for towing or pushing other, larger vessels.

Boats can be categorized into three types:

• Unpowered or human-powered boats. (Unpowered boats include rafts and floats meant for one-way downstream travel. Human-powered boats include canoes, kayaks, gondolas and boats propelled by poles like a punt.)
• Sailing boats, which are boats propelled solely by means of sails.
• Motorboats, which are boats propelled by mechanical means, such as engines.

Parts and terminology[link]

Several key components make up the main structure of most boats. The hull is the main structural component of the boat which actually provides buoyancy for the boat. The roughly horizontal, but chambered structures spanning the hull of the boat are referred to as the deck. In a ship there are often several decks, but a boat is unlikely to have more than one, if any at all. Above the deck are the superstructures. The underside of a deck is the deck head.

An enclosed space on a boat is referred to as a cabin. Several structures make up a cabin: the similar but usually lighter structure which spans a raised cabin is a coach-roof. The "floor" of a cabin is properly known as the sole, but is more likely to be called the floor (a floor is properly, a structural member which ties a frame to the keelson and keel). The vertical surfaces dividing the internal space are bulkheads.

The keel is a lengthwise structural member to which the frames are fixed (sometimes referred to as a backbone).

The front (or forward end) of a boat is called the bow. Boats of earlier times often featured a figurehead protruding from the front of the bows. The rear (or aft end) of the boat is called the stern. The right side (facing forward) is starboard and the left side is port.

Building materials[link]

A ship's lifeboat, built of steel, rusting away in the wetlands of Folly Island, South Carolina, United States.

Until the mid 19th century most boats were of all natural materials; primarily wood although reed, bark and animal skins were also used. Early boats include the bound-reed style of boat seen in Ancient Egypt, the birch bark canoe, the animal hide-covered kayak and coracle and the dugout canoe made from a single log. By the mid 19th century, many boats had been built with iron or steel frames but still planked in wood. In 1855 ferro-cement boat construction was patented by the French. They called it Ferciment. This is a system by which a steel or iron wire framework is built in the shape of a boat's hull and covered (trowelled) over with cement. Reinforced with bulkheads and other internal structure, it is strong but heavy, easily repaired, and, if sealed properly, will not leak or corrode. These materials and methods were copied all over the world, and have faded in and out of popularity to the present. As the forests of Britain and Europe continued to be over-harvested to supply the keels of larger wooden boats, and the Bessemer process (patented in 1855) cheapened the cost of steel, steel ships and boats began to be more common. By the 1930s boats built of all steel from frames to plating were seen replacing wooden boats in many industrial uses, even the fishing fleets. Private recreational boats in steel are uncommon. In the mid 20th century aluminium gained popularity. Though much more expensive than steel, there are now aluminium alloys available that will not corrode in salt water, and an aluminium boat built to similar load carrying standards could be built lighter than steel.

A wooden boat operating near shore

Around the mid 1960s, boats made of glass-reinforced plastic, more commonly known as fibreglass, became popular, especially for recreational boats. The United States Coast Guard refers to such boats as 'FRP' (for Fibre Reinforced Plastic) boats.

Fibreglass boats are extremely strong, and do not rust (iron oxide), corrode, or rot. They are, however susceptible to structural degradation from sunlight and extremes in temperature over their lifespan. Fibreglass provides structural strength, especially when long woven strands are laid, sometimes from bow to stern, and then soaked in epoxy or polyester resin to form the hull of the boat. Whether hand laid or built in a mould, FRP boats usually have an outer coating of gelcoat which is a thin solid colored layer of polyester resin that adds no structural strength, but does create a smooth surface which can be buffed to a high shine and also acts as a protective layer against sunlight. FRP structures can be made stiffer with sandwich panels, where the FRP encloses a lightweight core such as balsa or foam. Cored FRP is most often found in decking which helps keep down weight that will be carried above the waterline. The addition of wood makes the cored structure of the boat susceptible to rotting which puts a greater emphasis on not allowing damaged sandwich structures to go unrepaired. Plastic based foam cores are less vulnerable. The phrase 'advanced composites' in FRP construction may indicate the addition of carbon fibre, kevlar(tm) or other similar materials, but it may also indicate other methods designed to introduce less expensive and, by at least one yacht surveyor's eyewitness accounts,^[15] less structurally sound materials.

Cold molding is similar to FRP in as much as it involves the use of epoxy or polyester resins, but the structural component is wood instead of fibreglass. In cold moulding very thin strips of wood are laid over a form or mould in layers. This layer is then coated with resin and another directionally alternating layer is laid on top. In some processes the subsequent layers are stapled or otherwise mechanically fastened to the previous layers, but in other processes the layers are weighted or even vacuum bagged to hold layers together while the resin sets. Layers are built up thus to create the required thickness of hull.

People have even made their own boats or watercraft out of materials such as foam or plastic, but most homebuilts today are built of plywood and either painted or covered in a layer of fibreglass and resin.

Propulsion[link]

The most common means are:

The Wanli Emperor enjoying a boat ride on a river with an entourage of guards and courtiers in this Ming Dynasty Chinese painting.

• human power (rowing, paddling, setting pole and so on.)
• wind power (sailing)
• Motor powered propellers
  • Inboard
    • internal combustion (gasoline, diesel, heavy fuel oil)
    • steam (coal, fuel oil)
  • Inboard/Outboard (sterndrive)
    • gasoline
    • diesel
  • Outboard
    • electric
  • paddle wheel
  • Water jet (personal water craft, jetboat)
  • Air fans (hovercraft, air boat)

Track-driven propulsion[link]

The water caterpillar boat propulsion system (Popular Science Monthly, December 1918, p 68)

An early uncommon means of boat propulsion was referred to as the water caterpillar which is similar in construction to paddles on a conveyor belt and preceded the development of tracked vehicles such as military tanks and earth moving equipment. A series of paddles on chains moved along the bottom of the boat to propel it over the water.^[16]

The first water caterpillar was developed by Desblancs in 1782 and propelled by a steam engine. In the United States the first water caterpillar was patented in 1839 by William Leavenworth of New York.

Buoyancy[link]

A floating boat displaces its weight in water. The material of the boat hull may be denser than water, but if this is the case then it forms only the outer layer. If the boat floats, the mass of the boat (plus contents) as a whole divided by the volume below the waterline is equal to the density of water (1 kg/l). If weight is added to the boat, the volume below the waterline will increase to keep the weight balance equal, and so the boat sinks a little to compensate.

See also[link]

Abora Boat building Cabin cruiser Canoe Dory Flat-bottomed boat Glossary of nautical terms Gondola Halkett boat Inflatable boat Kayak

Launch (boat) Lifeboat (rescue) Lifeboat (shipboard) Log canoe Motorboat Narrowboat Naval architecture Panga (boat) Pirogue Raft Reed boat

Rescue craft Row boat Sailboat Sampan Ship Skiff Super yacht Traditional fishing boats Yacht Ferry Barge

Wikimedia Commons has media related to: Boat Wikiquote has a collection of quotations related to: Boats

References[link]

External links[link]

• PDRacer - The Easiest Sailboat In the World To Build
• Sailboats database: sailboat data sheets all over the world
• University of Washington Libraries Digital Collections -- Freshwater and Marine Image Bank -- Vessels - images of boats and vessels