Good book on boat trailer building

I'm looking for a gook book on boat trailer building.

I have the Glen-L one but I want more informations on structure and design.

 

G'day JF

I asked a question about boat design and didn't get much of a response as I think there are boutbuilders here not trailer builders.

Maybe why they call it the "Bout Builders Forum."

Boat trailers are not built very well because boat manufacturers want to spend all their available resourses on the boat because that's what people buy.

I see it all the time, boat owners struggling to put their boats on their trailers when simple additional features would make the job easier.

I will have to build a new one soon so I am about to start the design.

Don't forget to get a copy of your local trailer laws as Glen-l may not comply in another country.

Gotta go
Poida

 

Structurix is a simple easy to use FEA program that can calculate what size steel members are needed. Runs great on Mac OS X.

I used it and a CAD program to design my trailer. The steel is cut, but I have had not the time to weld it.

 

I need to build this trailer for a deep-V boat with outboards.

I want to use rollers to support boat and I'm looking for diagram for structure and rules of thumbs for steel size.

 

A good sourse for "what works" is as many trailer supply catalogues as you can aquire. I always go to as many boat shows as possible and see what is new in the trailers under the boats. The new "bent" aluminium I-bean frames are a good example. Knowing as much as possible about tongue weight, joint fatigue, weld pattern weak points, and tongue length ratios that make turning & backing easier will come from asking questions at repair shops and hanging out at boat ramps. I learn a lot by observing people trying position and launch/load their boats & the time spent doing it. With permission, examine empty trailers and their bunks & rollers at the ramps.
A boat ain't worth a damn if you can't take it AND bring it back. Trailers are much more important to a plesant outing that people give them credit. Many "boat/motor" failures can be traced back to bad trailering.
I don't know of a book specific to building boat trailers. Basic welding practices, metal fatigue and geomtry books will be valuble basic books to go along with your keen observations, pictures and journal of answers to your questions of others. Then you write the definitive book. Good luck.

 

I would jave thought that the local authorities where you licence the trailer would have to see that the trailer has been built to engineering specifications. I doubt that the declaration that you have read a book about it would suffice.

Unless you are going to do what I am doing replacing a trailer with an existing one and swapping the plates.

Incidently I have a "Vee" hull and an inboard motor. Because the prop needs clearance from the road the hull is higher than a standard boat with outboards. At ramps I had a problem, when I reversed down the ramp the boat was too high and wouldn't come off.

That is the reason that the last owner sold it to me although I didn't think it would be as bad as it was.

Easy fixed I lengthened the draw bar.

Now problem number 2 although the length of the draw bar is legal I have to give corners a wide berth as the trailer will take a short cut across the kerb.

This is not as bad as problem number 3. When I get home parking it is a pain. I have 3 trees across my verge the front yard is fairly small and there is not enough room to manouver it with the long draw bar. Wasn't too bad before.

So I am looking at the feasibility of designing a boat trailer where the wheels, axles and boat are winched up and down the trailer frame.

This will eliminate rollers which take up more space than pads.

So ther ewill be 3 positions for the trailer.

1. When launching and retrieving the wheels complete with the boat pads and boat are winched to the back end of the trailer.

2. When transporting the boat is winched to the mid position. This evens out the difference between the trailer wanting to cut corners when cornering and the distance that the end of the trailer will swing out at the rear. In this position the trailer wheels etc will be locked into position and the boat tied down to the trailer frame.

3. When manouvering in tight situations the boat is winched up as far behind the vehicle as possible.

Also when my boat is on the trailer the water doesn't drain out properly so I would like to incorporate a jacking device at the front so the boat is stored sloping back to drain.

I haven't started drawing yet so it may not all be possible.

Just a seed in my head.

 

Most (maybe all) states in the US require no engineering specs. It has to meet width rules and hitch coupling strength specs as well as light & reflector rules. If licening for the first time as a self made or homebuilt trailer, ALL reciepts for ALL parts used to build the trailer must be saved & presented at the tag office. Some states require that a ID number be stamped into the tonque.

 

Poida: consider a trailer that "lays" down to launch/load. I had a BIG pontoon boat that had a sweet tandem axel trailer that would fold up under the boat. A seperate winch would pull (or relax) the axel assembly accordingly in relation to the main frame. 2 big garage door springs acted to provide the initial pull from center, to get the start-off. The weight of the boat then helprd them to lay down. The winch pulled everything back up under, back to center. Then it pinned for safety while towing. NEVER a hangup!
It was made by "hoosier trailers in Indiana.
http://www.hoosiertrailer.com/classic.asp
I could even sit my boat down on 4 old tires at home & pull the trailer out for maintainence.
As for long tongues (drawbar), I have a bud that sails a trailerable sailboat. His issues of launch & load sound similar to yours. His trailer has a telescoping tongue. 1 section slides into the other to make towing/ tracking better, then extends at the ramp to gain depth without undue imersion of his truck.

 

Yeah thanks Ted

Those suggestions are something I have contemplated but not suitable for my application.

 

Poida, what you need is a tongue extension. There are three basic types, one is a telescoping thing (tube in a tube) with a hitch pin to secure it in each position (extended or retracted), the second is a clam shell kind of thing. This one has a "U" shaped extension and is also secured with hitch pins. I don't like this one much, just looks like a problem waiting to happen. The third one is two separate tongues, one short, one longer. The short one is the used to drive and maneuver around with. The long one is put on at the ramp (after removing the short one) and gets the boat far enough back to be in deep water. Both are complete tongues, hitch, chains, the whole lot. They can be attached with hitch pins as well. I launch a 27' inboard with a bunch of draft and have a 5' extension, but is permanently mounted, as I don't have the maneuvering issues you have, but do require the deep draft to float her off with out parking my truck in waist deep water doing it. I now have water about half way up my rear truck tires, with the front tires well clear, though I do have to step out of the cab into an inch or so of water by the front door.

 

Thanks Par

Telescoping draw bar I feel is not going to be the answer here although it was my original thought.

Replacable draw bar sections is good but I would only use that if I can't figure out another way mainly due to the time factor in changing from one to the other.

I also want to get away from hollow section because of rust issues. They always rust from the inside out due to problems in washing down.

I started doing some drawings today should know soon if what I want to do is feasable.