Trailer Advice

I'm having a custom aluminum trailer built. Torsion Axle, 20.5 x 8.5 tyres, all LED lighting. Just wondering if anyone thinks there is something that should be added before the fabricator gets going on it. I gave him the go ahead yesterday and he will probably start on it early next week. The frame is all 3" x 4" aluminum square tubing, the tounge being 1/4" wall, and the rest being 3/16" wall. I'm using a cut off from a comptip installation for the mast crutch. That should be cool. I'm also using composite decking that will be filling all of the open space inside of the frame. It will be recessed down about an 1/8".

It's a little over-engineered (=heavy) if you ask me.

Just the frame members you have there are over 220 lbs. Add your decking and the suspension and you've got a trailer that weighs over 500 lbs before you even put a sailbox on it.

I think the wall thickness of Trailex trailer extrusions is less than 1/8", but they've also got the slots in them that increases the moment of interia significantly.

Originally I was going to use 2"x4" square tubing, but up'd the the size because I couldn't find any lights that were small enough and be flush mounted. I could find plenty that were surface mount, but that isn't what I wanted.

I like things that don't break.

Very cool Karl.

Ive been wanting to design a trailer myself for a while, but never got the push. Would it be ok with you, if I get a copy of the blue prints sent via email? I can computer-rize them for you if you want.

I would design it such that you could put a removable rear mast support that is attached to the trailer (as oppopsed to resting the mast the rear beam of the boat). Just personal preference.

I love this site. Good reading

http://www.acatsnw.com/trailer/trailers.html#Final%20Design

Jonathan Grant

Karl, since you like big stuff, how's that for a regatta "buggy"?

I had something similar built rather than going with the Trailex - too many of the light aluminum trailers are not rated for double-stacks, and even the ones that are only have a capacity of around 1,000-pounds. Two F18s and gear push that limit.

Here's my custom trailer without the double-stack:


You can see the double-stack set up in the video from the first day of the F18 Championships on AdventureOnline.TV. All the double-stack stuff comes off and hangs on the fence behind my trailer. The frame is aluminum I-beams with a galvanized tongue.

I thought about doing the decking, too, but changed my mind - I did design in a tall fore and aft mast stand, a trax rack, and an extra-long tongue (who doesn't need one of those?) for trailering behind a motorhome. Drew the design on a napkin, took it to a trailer place in Jacksonville - the whole rig cost less than the double-stack Trailex and has a 2,500-pound capacity.

You won't be sorry building something to meet your specific needs, especially if you travel with the boat.

Oh, and a cautionary note - make sure you measure the sail box(es) you intend to use before your design is final. My crossbars were about 6-inches too far apart, so I had to move the front one back a little. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

And make sure your design includes a moveable axle so you can fine-tune tongue weight. <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

A couple things come to mind:

- 1/4" wall tubing seems extremly heavy given the application. I think most trailers would be in the 1/8" to maybe 3/16" range. I would look at other trailers for a basis of design.

- It looks like all the tubes are on the same plane, i.e. nothing sits on top of anything else. Is that correct? Then, based on your sketch, your front crossbar is actually two pieces. Is that correct?

- One thing that sticks out to me as being "not good" is where you bring the A-frame in to the front crossbar. Personally, I would have that connection be directly in line with the longitudinal beam, that way you resist bending of the front cross bar.

sm

SRM-

1/4 wall is overkill. Definately. Didn't cost too much more in weight, or dollars, so I figured why not.

Front crossbar is two pieces. I figured this would be better than breaking up the tounge. I think I may add a piece underneath to help carry the load, or perhaps just plate it.

The A-frame part was a question for me too. I can't explain why I want it this way. There really is no really good reason for it. But I like it? <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" /> My thinking may have been to get wires to the front marker lights slightly easier, and to add a little more space for whatever. Perhaps a brace running forward under the decking, inline with the side rails, would be sufficient?

The beams of the trailer are further apart than the beams on the boat. I'm thinking that if I want to add a double stack, or rear mast support I will be able to slide the boat forward a few inches and go straight up with it. For a double stack set up I planned on two legs with a crossbar on top. Make them easily removable with pins, and a bar going front to back to tie it all together.

-Spellcheck is destroying my capacity to spell- <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

I suspect that based on the size of rectangular tubing that you have chosen, you could weld the pieces together in about any configuration and you'd be ok. Just looking at that A-frame, to me, it doesn't look right.

As one other poster said, you should make sure your brackets allow you to move the axle to balance the tongue weight.

And also, I assume you have chosen the axel/springs you plan to use. Make sure your frame rails are spaced properly to accept the axel.

sm

Stronger is better with ali. I have seen three boat trailers flag and bend because of not being "over-engineered". Why not indeed.

If you have fenders, make sure they are strong enough for your 2 biggest friends to stand on or one to fall on.

Leave gaps in your decking for the rain to drain through.

Weld at least 2, one on each side, 2x2 ID tubes to the rear crossbeam. These will serve as sockets for mast supports and things you havn't even thought of yet.

With the light front mast support, think about what you are going to stand on when you need to reach high.

It looks great.

With a liberal guess on what the weight will be the whole mess should weigh in around 1200 lbs. Trailer should be about 680 lbs, boat weighs 340, cattrax weigh about 30 lbs? Plus a little extra for gear. A few things I need to figure out is where the wings are going, where the cattrax are going, and the spin pole is going. For a half hour drive I don't mind the Cattrax sitting on the hulls, but I wouldn't go cross country like this.

In one of these posts, welding was mentioned as a means of construction. I would really try to avoid welding and see if you can have all the connections designed for thru bolting with gusset plates. I would really worry about the welds (or material around the welds) cracking over time. I think in the end you will have a trailer that lasts longer if you avoid the welding.

Otherwise, I like the design and have actually drawn up something very similar. Just haven't had a chance to get it built yet...

TB

Ditto that - Aluminum welds don't handle fatigue very well because it really affects the heat treating of the material. That front cross beam area really sees a lot of cyclical stress there. That being said, the 1/4" wall tubing is probably healthy enough to survive it - but I would still try to avoid structural welds in those high flex areas.

I also think you will find that the axle is too far to the rear too.

Welding alloy is problematic because it ruins the heat temper of the material...thus is losses about half it's strength.

My all alloy tilt trailer for Tornado is completely bolt-up. Made of 2x3x1/8 except for tongue which is 4x4. I also use a Torflex axle. Word of advice, don't finalize the axle location until you've loaded up the trailer with boat/gear/box. You will want to fine tune the axle point to achive 10-20% tongue weight.

Mike.

I don't think that welding is an issue as long as it is done right. You may want to weld a plate over and/or under the joins in the A. Here is a design that I built that was welded..Actually the A was bent and then plate were welded over the top. The crossbeams that hold the boat are bolted under the frame via U bolts. This allows you to put your sail box inside the frame, not on top.. More clearance for the dolphin striker.

Picked her up today and wired all the lights. What a flippin pain. I'll try and post pics as soon as I can. It looks sweet.