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JamesMusslewhite

PT Boat - "Devil Boats" - style hulls

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JamesMusslewhite

I decided to start this Thread because of the response on the subject on the "Cargo Tribike for town and farm" thread I posted. There was so much response that I thought it would appeal to many members on the forum. It was hidden in a thread about the topic of tricycles. I have cut and pasted some of my post on the other threads and have combined and re-posted them below.

 

PTs were between 72 and 82 feet in length depending if they were Elco or Higgins models. Only 570 boats were ever built and most were run aground and burned by the US navy after WW2 ended. They were constructed with plywood or slat wood strips hulls and with mahogany inner ribs. I will only be designing on the PT "displacement" hull design which could displace (30-75 tons) at speeds of (35-40 knots). 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 there are two known instances that PTs hulls stayed afloat up to 12 hours after being cut in half. The Japanese called them "Devil Boats" because they said when they thought the sea was to ruff and dangerous for any boat to even be on the water, was when the PTs would attack them.

 

I plan on building two boats using the basic hull design but at only a length of 45-55 foot which should be propelled easy enough with two large block car engines. The waters of many towns on islands around me are often shallow inlets, so this shallow draft is best. I want a boat that handles the shallows and still be operated and safe in rough deep seas; and be able to travel and down Mindanao's coasts, Leyte, Bohol, Cebu, and even Manila if the mood strikes me. I will have them designed for comfort and still have adequate deep cargo hold. two I will start on the first hull construction next spring. I have a 25 foot and a 34 foot pumpboat but frankly they are much too small for what I will need these boats for over the next few years.

 

Instead of the average 80 foot design which I hope later to build commercially, I will keep my boats to the 45-55 foot range, which will be much lighter and easier to navigate in the inlets around these small islands. I prefer also be able to use two smaller 6 cylinder diesel motors because of cheaper cost and operation cost, plus it is far safer than having hundreds of gallons of gasoline on a wooden boat. Running mostly on only 1 engine will help with fuel consumption. Two engines is so one is in reserve in case of an engine failure, engines can be switched over to minimize ware and tear on long trips, and if say Abu Sayaaf, MILF, or NPA wants to race, than both engines and it's displacement hull design means that baby will fly. I plan also to install a Satellite Anti-Theft system, built into the woodwork so it is undetectable just in case it is ever stolen.

 

I may desire later to build as many as I can contract, once I have mastered their hull construction and I will have all the required jigs built. I may want to custom build the interiors to suit customer's specifications. I know I have the skills to build and supervise their construction. I believe there is a potential lucrative market for PT hulled custom cargo, patrol, and pleasure crafts here in the Philippines and surrounding countries.

 

Boat building is exacting but it far less complex. That being said, it requires woodworking skills, and proficiency with tools and blueprint reading. One must understand basic math skills. But one must also enjoy being a perfectionist. If a person loves working with their hands, have patience, and tenacity then you can build a boat. You just have to do things right the first time, which requires one to study and check you steps. The key is designing the ribs so that the hull design is correct and has the appropriate angles.

 

 

hull2-1.jpg

The key is in the design and accuracy of the inner ribs, this must be correct for proper hull shape.

Ribs will be constructed of Mahogany.

 

hull2-20kit.jpg

If the ribs are correct than the hull will have the right dimensions and curvatures.

 

planking7.jpg

The first layer will actually be the hardest step of the two layered Hull design.

 

sideplank2.jpg

The hull will require two layers of slat boards which will give the hull strength.

Quality glues, screw, nails, and fasteners are essential.

 

 

origplank2.jpg

These are original photos of the 82 foot class PT boat. I will be using a 45-55 foot design.

 

 

origplank3.jpg

 

 

 

planked1.jpg

 

The interior can be on unlimited floor plans or designs; pleasure, commercial, cargo, or patrol which depends on the requirements of the customer.

Smaller Hull designs can also be built using plywood and then fiberglass, and even foamed inside plywood inner walls. It is a very versatile low draft hull design. It is just one big adult size wooden boat Model Kit.

 

The first two 45-55 foot boats will probably take me closer to a year to construct. Mostly because I will be doing most of the work myself, so I can work out all the complexities and processes necessary to build and rotate the hull during construction. I also may choose to first build a small 30 foot design first just because of the lighter weight, less expense, and ease of building. I also could build the smaller boat designs in pairs and sell the smaller design boats to a broader market. The building and selling of several smaller pleasure boats would finance the larger hull designs. I would use high grade woods, quality glues, paints, lacquers, and building materials. Quality craftsmanship will be what I will be striving for, and will be the key to having success selling these boats. There maybe a good market in the Philippines; but there is also Malaysia, Hong Kong, Taiwan, Vietnam, Korea, Japan, and China among others.

 

Cost and sell price will be dictated by the wood types, interiors, and motors. I really want to build high end, superior quality boats.

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Alan S

If you look at the history of small attack craft, you will find that Fairey Marine, Vospers, Thornecroft, and many other British makers produced models, and much of the US work was based upon their original designs.

 

Fairmile were a major designer and the origin of many designs, and later, their designs were copied (and updated) by Viking-Watercraft, who eventually became part of Vosper-Thornecraft).

 

They built models as short as 45ft, which were widely used as Pilot vessels, harbour defence craft, police launches, and for commercial use.

 

It just so happens that I have sets of plans for most of their models, having done a stint on contract with them.

 

Comparing the basics with your design, the major difference is that theirs were mainly fibreglass construction, which has some advantages.

(Although personally, I would go for a steel hull in Philippine waters.)

 

Good idea though, and I would certainly be interested in seeing how it progresses.

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JamesMusslewhite

If you look at the history of small attack craft, you will find that Fairey Marine, Vospers, Thornecroft, and many other British makers produced models, and much of the US work was based upon their original designs.

 

Fairmile were a major designer and the origin of many designs, and later, their designs were copied (and updated) by Viking-Watercraft, who eventually became part of Vosper-Thornecraft).

 

They built models as short as 45ft, which were widely used as Pilot vessels, harbour defence craft, police launches, and for commercial use.

 

It just so happens that I have sets of plans for most of their models, having done a stint on contract with them.

 

Comparing the basics with your design, the major difference is that theirs were mainly fibreglass construction, which has some advantages.

(Although personally, I would go for a steel hull in Philippine waters.)

 

Good idea though, and I would certainly be interested in seeing how it progresses.

 

Correct, the Elco designers visited the United Kingdom to see British motor torpedo boat designs. While visiting the British Power Boat Company they purchased a 70-foot design PT70 designed by Hubert Scott-Paine. It was the PT70 design that had the most influence on Elco's overall design. Elco built 326 of their 80-foot boats; Higgins produced 199 78-foot boats; and Huckins received the smallest contract and built 78 foot boats, none of which saw combat.

During World War II, the Vosper Boat Company of Great Britain arranged for several boatyards in the U.S. to build British-designed 146 70-foot (21 m) boats and were exported to Allied powers such as Canada, England, 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. They were constructed by Annapolis Boat Yards and Miami Shipbuilding Company.

 

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.

 

Hubert Scott-Paine the famous British aircraft and boat designer and record-breaking power boat racer designed the British Power Boat 70-footer (later named PT9), as a template for American production under licence. PT9 was taken by the SS President Roosevelt to Elco

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Alan S

James, I was taught navigation and boat handling in a Fairmile MGB, owned by an uncle who bought it shortly after the war for

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JamesMusslewhite

James, I was taught navigation and boat handling in a Fairmile MGB, owned by an uncle who bought it shortly after the war for

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D_D
Cost and sell price will be dictated by the wood types, interiors, and motors.

 

 

 

What is the average cost ?

 

From low end to high end ?

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JamesMusslewhite
Cost and sell price will be dictated by the wood types, interiors, and motors.

 

 

 

What is the average cost ?

 

From low end to high end ?

 

I honestly do not know yet. I have to work up an accurate list of all materials, then work out 1" mahogany wood slats, ribs, beams, exterior plywood, motors, gearboxes, shafts, propellers, cabling, hardware, wiring, tubing, nails, screw, rivets, cloth, glue, lacquers, paint, and other items I can not even think about right now; and then there is labor cost. I have never pencil whipped this project before, and will not know the total cost until completion. After the first one, they should be easier to build with unnecessary steps and mistakes streamlined out of the process. which will lower their overall expense.

 

That is why I want to build a 30 foot unit first. Easy to handle, less expense, and a good guide to develop a reasonable cost assessment. I know I will be able to build it with the highest of quality craftsmanship at the lowest expense to complete. I am though sure that well hand crafted solid mahogany hulled crafts should sell for a nice sum. I just do not know yet what that sum is.

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Headshot

Are you going to use tongue and groove joints on the sides of those slats? That would increase the strength of the hull considerably. Then, if you run a bead of waterproof glue in each joint before tapping them together, you will essentially create solid panels.

 

I would still love to see the ferry captains reactions when you make your torpedo runs on them. Are you going to power these boats using Jacuzzi type (jet boat) engines? That could be one hell of a fast boat if you do.

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broden

each boat should come with a captains hat

 

whiteskipperhat-375.jpg

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JamesMusslewhite

each boat should come with a captains hat

 

whiteskipperhat-375.jpg

Untill I wrap my head around all the logistics and expenses of such a project, my captain,s cap will have "DUNCE" embroidered on it. :evan_iliadis:

Edited by JamesMusslewhite

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JamesMusslewhite

Are you going to use tongue and groove joints on the sides of those slats? That would increase the strength of the hull considerably. Then, if you run a bead of waterproof glue in each joint before tapping them together, you will essentially create solid panels.

 

I would still love to see the ferry captains reactions when you make your torpedo runs on them. Are you going to power these boats using Jacuzzi type (jet boat) engines? That could be one hell of a fast boat if you do.

 

I had thought about that, but I wonder if the mahogany slates being only 1 inch in thickness, if it would actually cause unforeseen problems with wood spiting, slats lining up properly, or having trouble getting joints to join properly; where odd bends or stress points are encountered, due to the curves designed in the hull. It might be possible on the outer layer, being that there is a smooth and solid surface to property bend, allign and tap the tongue and grooved slats together.

 

My torpedo runs would involve running broadside and lobbing San Miguel beers with my trusty state-of-the-art launching arm.

 

I have toyed with the idea of a water jet propulsion system for the smaller hull design. Similar to that used in jet boat design. no bottom mounted propeller and shaft would be nice in shallow inlets. Even an inboard-outboard system. I am still working on a low profile rudder system though. They still have to steer properly, this one has me still stumped a little. :evan_iliadis:

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alkonost45
I am still working on a low profile rudder system though. They still have to steer properly, this one has me still stumped a little.

 

Assuming you are going for a twin rudder system, you toe the trailing edges in by about 5 degees. That considerably improves the steerability of the boat.

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JamesMusslewhite
I am still working on a low profile rudder system though. They still have to steer properly, this one has me still stumped a little.

 

Assuming you are going for a twin rudder system, you toe the trailing edges in by about 5 degees. That considerably improves the steerability of the boat.

Twin rudders would seem to be best. Thanks for 5 degree toe-in advice. I will defiantly research that suggestion.

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JamesMusslewhite

Anyone that has URLs to good boat building websites or any solid advice, please post them on this thread. I am presently trying to gather all the best information on all proper techniques used in the different processes involved, from initial designing, construction, propulsion, wiring and rigging, to applying the glues and finishing. Any assistance from members would be greatly appreciated; because they will allow me to avoid complications, missed steps, mistakes, added expenses, and to do the best job possible. Thanks

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Ozepete

Anyone that has URLs to good boat building websites or any solid advice, please post them on this thread. I am presently trying to gather all the best information on all proper techniques used in the different processes involved, from initial designing, construction, propulsion, wiring and rigging, to applying the glues and finishing. Any assistance from members would be greatly appreciated; because they will allow me to avoid complications, missed steps, mistakes, added expenses, and to do the best job possible. Thanks

 

 

James, have you checked out this wooden boat builders forum? http://forum.woodenboat.com/forumdisplay.php?1-Building-Repair

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