TRAILER DESIGN

Hi All, I am about to build a new trailer for 1682, a timber boat.
The current one is made from 100mm C purlin, yep C purlin, really, and just wont last a trip down the Newell at Christmas.
What are the pro's and con's of hanging the boat from the beams versus supporting under the hulls. Brett ( Fast Energy) has a removable cradle on his and I am leaning that way.
I can see positive and negative to both but was wondering what everybody else is doing and why. Thanks Alan

The best bet is a trailer that stores the boat on the beams but has hull supports near the front beam for travelling.

When sailing your front beam bolts see mainly sheer forces. and a small amount of tension on the inside bolt. When travelling on the road a boat supported by the front beam will have about 90% of the hull weight on the beam bolts. A quick review of trailer design lit. suggests your boat may experience accelerations up to 3-4G so on a mozzie with a hull around 20kg that puts an 80kg load on the at the beam bolts. Not a big deal for the bolts but in terms of the long term stiffness of you platform not a good thing.

Alan, my understanding of having the boats on the hulls is that when the trailer torques, flexes or bounces, all of this is transmitted through the brittle hulls onto the boat. If the boat is hung the beams suspend the hulls clear of all this and it is absorbed by the beams onto the strengthened parts of the hull.
Mine used to be on the hulls but now a c section surrounds the front beam with a large bolt into the mast step to keep it in place. It still rests on pads aft but the fwd beam has 80% of the weight anyway. I slide it onto the pads, lift it up an inch to slide into the C section and screw down into the mast step.
Also makes it a lot better on your boat if you want to stack 2 boats.

Beam support is the way to go. If the hulls get loose and bounce up and down on their cradles it can damage the hulls, and even beak the seam.

Beam support all the way

EG: http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=266555&page=5

Has anybody seen this suspension or used it. Rubber block instead of springs. Independant suspension . Promises a smoother ride.

http://suspensionenhancements.com.au/axleless.html

Is was really fashionable on power boat trailers about 5 years ago. Then people started having problems and realising they had to order replacement parts from a single source. Leaf spring suspension means if it fucks up in the middle of nowhere you can pull into the local wreckers and find something that will get you home.

If i knew how to post pics i would show you all just finished a beam support trailer double decker with 1 rachet strap to tie them down.

Matt
Matt

Hi Matt. Posting photos: there are some instructions embedded in the following post. Thanks to Pirate.
http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=265520#Post265520
I placed my photos in Photobucket. This location is used extensively by the VMCA. Especially Mick Floyd. I would also like to see your photos so good luck. Post them on the mosquito FB site?

Hi Matt. I am keen to see your efforts.
admin@mtmovers.com.au

Alan

As many would know there are numerous photos of the new trailer on the Mossie FB page.

Beautiful work fellas; obviously the result of a lot of thought and experience trailering Mossies long distances.

I have taken the liberty of posting a couple of photos here.



http://s1.postimg.org/8ayomyxvj/Trailer_1.jpg



http://s15.postimg.org/m79yrv0d7/Trailer_2.jpg

Very nice Greg, love the simplicity of it and the over-center clips to hold the rear frame up. Do you slide the boat on the guards or lift it over them? I have always been worried about dropping the boat on the guards of my old trailer.

Alan

Hi alan

Thanks Greg for posting the photos.
this is the trailer the stone boys have made. Took a lot of thought. This trailer is made so that one rachet strap ties both boats on with no other tieing down.
the bottom boat is self loading. Slide on the back cups and before you wedge it into the front cups rest on the guards, hence the carpet. The hi tention lrleavers took a bit of thought as they clamp the tailgate on the boats with robust hinges.

Matt

Hi Matt, some times the simple things take the most thought.It looks good and also easy to put together. I have been over thinking how I should build this.
What size SHS for the uprights for the beams? I can get 40 x 40 x 4mm for nix so I plan to use that. Also like the adjustable mast post, nice touch.

Alan

Hi Alan
the uprights for the front beam support and rear are 40x40x2. 4mm is way to think and heavy. On my first trailer which i am still using and 40x40x1.5. Its been going for 6 years now and travel everywhere, but i think thing 1.5 is a bit underdone. We are happy with 2mm wall thickness. The base is 3mm wall thinkness,and we uused RHS not SHS, as square sections bend over time over the axel

Matt

I am keen to join the Mosquito Facebook page. I have sent a 'join request'. Can someone add me?

I hope it's OK to join given that I sail a Cobra! I do own a Mosquito, but it is currently just two lonely, heavy old red hulls at Kingy's place!

I really enjoy the discussions on this forum and would like to join in on FB If I can.

Cheers

Matthew