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TONGDEE LONGTAIL CONSTRUCTION

Posted by sean on November 28, 2010 at 9:11 AM Comments comments (3)

TONGDEE LONGTAIL CONSTRUCTION

by Sean Walker

What is normally called traditional boat building is constructing a boat the old fashioned way. Plank boards, and other heavy lumber make this type of a boat much too heavy to transport easily. These boats can be built well and strong. Their lives are spent at sea moored at the seashore, or they are confined to a lake or restricted between waterfalls and dams as they are heavy to transport. They are frequently expensive.

 

Composite hull boat building

 

Composite hull construction opened the door to conveniently travel by boat on rivers, lakes and oceans worldwide. Not only did it make portage and trailer use practical due to its lightweight, it launched the boating industry into a new era.Technology provided the way to build strong lightweight boats at an affordable price.This type of boat building has been going on since the 1940's but it really took off in the 1960's when resins became better. One type of resin first used is called polyester and it is still used today.

 

If one is building a regular size powerboat of fiberglass you start with a mold, a composite core and build it up with fiberglass sheets. These are the boats we see on television with big motors and a steering wheel, a speedboat. Although these boats are not that heavy I wouldn't call them lightweight either. Their props run quite deep in the water so shallow river use is very limited. Just because a boat is made of fiberglass doesn't mean it is light. Some people make small motorboats entirely of fiberglass and mistakenly make the hull too thick and heavy thinking it will be strong. What you then have is a heavy weak fiberglass boat. This idea doesn't work well because you need a core material to add strength.

 

A composite hull is a hull made up of several layers of material. If plywood is used (as it is with our boats), there are usually three plies there. Then there is fiberglass, it may be used in strips over the joints or it may cover the bottom of the hull or the entire boat inside and out. 

 

I design and build boats using a method called tack and tape or stitch and glue. I also build using 3/4 in. stringers, this method results in a lighter boat.  People have been building boats using these methods since the 1950's but it really started to become popular in the 1970's. There are thousands upon thousands of these boats on the water today, worldwide.

 

Plywood sheets are cut into panels that make up the sides, ends and the bottom of the boat. Then these panels are assembled and temporarily held together with wire stiching or pull ties while thickened epoxy or polyester resin (glue) is applied to all the places where the sides join the bottom the ends and all the braces. Then fiberglass strips are applied over these weld-like glue joints. This makes a very strong joint.

 

Now we have what looks like a boat. If you put it in the water though, the plywood would soak up water, weaken and rot. To make the boat waterproof we fully encapsulate it inside and out with resin and paint. The plywood with its weld like glue fillits that are covered with strips of fiberglass cloth and the hard resin coating and paint make the boat a single unit, a composite hull and it is very strong.

 

Many people build these boats for themselves it can be done if you have the skill and willingness to study the methods used. There are many days of measuring, sawing, shaping, gluing, grinding, sanding, fiber glassing, and painting and working with the resins. You need to have a workshop and tools, skill, knowledge and a lot of determination to finish any boat however the experience is priceless.

 

There are many good free and inexpensive designs availiable check the links menu for some ideas.

 

Thanks, Sean Walker

 

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THE LONG TAIL MOTOR

Posted by sean on November 28, 2010 at 9:00 AM Comments comments (21)

THE LONG TAIL MOTOR

by Sean Walker

The Asian long tail set up is by far the best; they were invented here and have been well proven over many decades. They can last years with almost no maintenance. The Western setup isn’t as good and they cost a lot of money. If you want to vacation in Thailand, you can take the important parts home in your luggage. These parts are very inexpensive. However, you can construct the long tail set up for very little money if you are up to the task. The following is a description of a long tail setup. It is not a plan but there are a lot of questions answered so it is helpful. A proper design would be desirable but there are not any available.

 

THE ENGINE MOUNT

 

When building a motor swivel mount a lightweight one is desirable. Make it simple, strong and use as little metal as you can to conserve weight but don’t go too light or it may not be strong. Use ring mounts for the tiller handle to slide into also. It has to move up and down 30 degrees depending on the transom height and left and right at least 60 degrees in each direction.

 

Hands off operation is the goal. This means while under motion if you remove your hands from the tiller the tail does not raise or fall but the boat runs along as desired. If this balance and thrust angle is not achieved it is too tiring to operate the boat, you will struggle to keep the prop at the correct depth and the boat will perform poorly. However, when sometimes going upstream or in rough water or at high speeds, it is still necessary to sometimes pull up on the tiller.

 

The mount must be balanced out weight and thrust wise to facilitate the tail riding in the water at the desired depth. It is very important the tail be about seven feet long (about 2 meters), and the engine be as low as possible. A short shaft will cause too much of a shaft angle between the engine and the water. You want the shafts angle not to be very steep. A nearly parallel attitude would be ideal but the shaft would be very long and the engine very close to the water. A good compromise will suffice. Mount the engine as low as possible. If your transom is high make a longer shaft.

 

When the shaft is fairly close to parallel to the boats attitude the turning and the power distribution is good because the thrust travels from the prop straight up the shaft to the pivot pin and then pushes the boat straight forward. If the shaft is at a steep angle the thrust power will not be used effectively. This is not like an outboard motor where the angle can be considered trim. When the angle is great the thrust pushes forward and the tiller handle pivots down, then you must pull up on the tiller or the prop will rise out of the water. However, you don’t need to understand this now, just keep the shaft long and mount the engine as low as possible.

 

You will need to find the balance point where there is the right amount of weight at the propeller. To find this fulcrum point, place the engine attached to its mount plate on a low table that simulates the engines height when it is mounted on the boat. Next place a piece of angle iron under the engine that simulates the pivot pin balance place. Then place a weight scale under the tail at the propeller. Move the angle iron balance point back and forth until the scale reads 6 Kilos (13 lbs). This is the point where engine pivots up and down so drill three or more pairs of holes into the mount so you can move the engine back and forth from this pivot point to fine-tune the balance after you test the boat. Be advised, heavier and more powerful engines require more weight at the tail than 6 Kilos, if need be drill more holes.

 

THE HUB

 

You will need a welder, pipe and some plate steel to make the hub. The hub bolts onto the engine and has a ball bearing inside it that rolls the shaft. Use an appropriate size pipe and an engine mount plate to bolt the hub to the engine. Drill two holes for the grease can or automotive type grease fittings. Small construction engines 5-13 hp. rotate at a maximum of about 3,600 rpm. Use a high quality bearing that suits your engines rpm.

 

THE SHAFT

 

As far as the shaft goes: the outer tube is often made of galvanized water pipe and has an inside drive shaft of medium steel running on five wood or plastic bushings. The newer set- ups use plastic bushings. The bushings are held in place in the outer tube with ordinary threaded metal screws and the shaft turns inside the bushings. The female threads are in the pipe and the screws protrude into the bushings only a little bit. The bushings should be fitted tightly into the tube housing. It is a very simple set up and the bushings can last years. The galvanized sleeve and inner shaft slides into the hub and is clamped down. The inner shaft slides into a slotted keyway inside the hub. Then there are grease fittings that lube the bearing, cool the unit and help keep water out. There is a steel tail rudder. It helps steer the boat and it curves around and stops just below the prop protecting it from damage. My 13 Hp. engine uses an eight and a half inch two blade prop that is quite weed friendly. Avoid too big of a prop, if you can’t reach the engines top rpm. your prop is too big for that boat and or that engine.

 

THE ENGINE MOUNT CLAMP

 

The engine mount, pivot pin and the mount that is clamped to the boat. Suffice it to say that the clamp must be attached onto the boat as securely as possible and it provides the sleeve bushing that the pivot pin on the engine mount slides into, it resembles a vise. Make it strong as it supports the engine, it doesn’t have to be too heavy duty, unless the engine is say 20 hp. or more.

 

The transoms on many of my boats are slanted at an angle. This is to facilitate having the engine on a transom farther forward and it provides a flotation chamber. A boats bow may rise too much and the boat may become off balance due to too much engine weight aft and there is the pilot’s weight to consider too. Good weight distribution in short long tails are a plus. If you want better performance mount the engine forward. This is not necessarily a hard thing to do. It may be as easy as attaching an engine mount plank 18 inches inboard from the transom.

 

My boats are usually 12 feet long and weigh 50 kilos (130 pounds). If a boat is longer than 12 feet or somewhat bow heavy, mounting the engine a foot or more forward of the transom may not be a necessity. If you already have a boat with a regular transom, it will likely work but it may be good to keep ballast cargo forward. If your boat has an outward angled transom for an outboard set up you will have to weld the motor clamp and pivot pin to a different angle than  on my setup.

 

Asian long tails don’t plane, however my long tails do. The Asian boats are long, very heavy and canoe like. I designed mine for shallow water (2 in. draft), portability and speed. At high speeds my boats are hardly in the water. I have developed a type of boat and application; the long tail hydroplane.

 

My eight foot boat will plane with one person aboard using a 5.5 Hp. engine but the boat, engine and prop are a precisely matched unit. Generally speaking with a long tail set up you won’t get enough power to plane a boat using less than eight horse power. The boat will have to be a good flat bottom performance hull too. Something like a small 50 Kilo. (130 lb.) 12 by 4 foot Garvy. The best engine I have found is a 13 hp. Honda GX 360. I tried a much bigger engine but the weight cancelled out the additional power and the performance was similar to the 13hp engine. The best small boat I make the Nitwing is a true hydroplane. It is five feet wide at the transom and ten feet long, the rear transom is only 8 ½ in high.

 

A very important factor here is the proper size and pitch propeller. Matching the prop to the engine may be hard to get right outside of Asia where the set up is made. I would make friends with the owner of a boat yard and try out his used small outboard engine props to see what works.

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THE TONGDEE BOATS AND HOVERCRAFT

Posted by sean on November 27, 2010 at 1:05 AM Comments comments (1)

THE TONGDEE BOATS AND HOVERCRAFT

By Sean Walker

What are we about? We are about sport boats. First off let me describe what our boats are used for. All out boats are for shallow rivers and lakes and most of all fun. When we say shallow rivers we mean 6 in. of water, sometimes less. We are always experimenting with ways to make our boats perform better and be even more fun to use.

 

The long tail facilitates shallow water use but the boat must be of a design that will handle shallow water too. Our boats are real performers, so much so that their use is limited only by the amount of water needed to allow the propeller enough depth to drive the boat.

Jet skis and jet boats often make this shallow water claim but unfortunately they need the intake for the water jet pump to be under water and if the water is shallow it will defiantly scoop up debris from the river bottom that will severely damage the pump impeller. The only other boats that can operate in water this shallow are Airboats and Hovercraft, we build them too.

We usually build small boats. Our 11 ½ -foot boat has a maximum capacity of three people. The Nitwing handles two persons and is 10 feet long. Our mini boat, the 8 foot Ruranit is a single person boat; it can be called a PWC (personal water craft). So our boats can go in shallower water than a jet ski but not as fast or nearly as heavy. They are a fraction of the cost of the Jet Ski to build and very inexpensive to operate too. They easily fit in a pickup truck with a single person doing the lifting.

 

Personal goals of the designer

 

Well, here is where I write what it is that drives me to design and build these boats. As I have said elsewhere, everyone needs to play, have fun, thrills, and have a exhilarating experience. Everyone should have something similar in their lives to be happy about. It is something that turns you on so to speak, an escape from boredom.

 

More years ago than I care to mention I was one of the few people who opened up the Golden Triangle of Thailand and other areas to motorcycle riding. At that time there were few highways but mostly back roads in poor condition. The degree of difficulty made for an exciting time but those days are gone now that anyone can travel here by road easily.

 

I had to find new adventures and more remote jungle areas so I began boating. I soon found out that the Thai long tail boats were too heavy to transport to the many areas that I have now explored with my light weight boats. I was also able to improve on the shallow water use as well. I am not saying Thai long tails perform poorly they don't, they are slower work boats. Mine are much faster and have enabled me to further my life's adventure, the exploration of the jungles of Thailand. I saw the challenges, developed building criteria and went for it. My success is that I am having a lot of fun. 

 

I have been designing, building and using my boats for a long time now and I have made great strides in doing what no one else here seems to be doing. Going fast economically and going where no one else can, in very shallow water. Transportation for me is in my pickup.

They dont transport boats much here in Thailand boats are confined to a given area on a river or lake. Thai long tails dont easily fit on a trailer they are too heavy and long. Boats here can be trailered but there arent many launching ramps. There are hardly any places where a trailered boat can be launched without difficulty. My boats are a breeze to launch and use.

 

Speedboats here and indeed everywhere use too much gas. It takes 1,000 - 2,000 B. to travel 80 Kilometers a 2-3 hour run. This amounts to an average cost of 600 B. (18 dollars US) per hour. This is the cost of going fast. With my speedboat you can travel at a slower but similar speed and spend only 170B. (4 dollars per hour US).

 

I admit my boats are usually small, but I like them that way. I could make them bigger but that would cut down on their shallow river use. A maximum size for shallow river use is 14 feet long. I will make bigger boats eventually and you can bet they will not cost much to operate too.

 

Using the boats of my design it is now possible to go quite fast economically, this is facilitated by my engine set up and hydro hull design. I am fast and many times cheaper to operate, and can be easily transported by pick up truck or car top anywhere in the country.

 

If you compare speed wise, a speedboat or a big fast long tail is three to ten times its cost and are gas hogs as previously mentioned. All our boats are very maneuverable sport boats. Our boats use 6.5, 13, and 23hp. engines. Everything I can do to make a boat work well in shallow water and high-speed lake use with small engines will be accomplished. I have developed a new category of boats and my boats are the only ones in it.

 

Now my favorite boat is my catamaran sailboat. Come back and visit for mast and sail making videos. Thanks, Sean

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