MacGregorSailors.com

speaking for the M only,there is nothing special about the locations of the cross bunks from an structural point of veiw,but for longitudnal bunks there is some points you can use location wise that a little extra strength can be had.U have a hull with an average thickness of 1/4 to 3/8 of an inch with an inner ballast tank system glassed to it so if you use these attaching points there will be some additional stiffness at those locations.your bunks need to be shorter as in 5-6feet in length as it is harder to conform to the hull curveature with 10-12 footlong bunks

Sorry, it must be me but I cannot seem to locate the thread I started a few days back...
Anyways, here are the pictures of the new trailer, looking for aadvice on modding the bunks, thanks. Where does one get material for bunks? I mean brackets and bunk covers... Home Depot? Or trailer specific shops?


https://picasaweb.google.com/gerloczyek/NEWMACTRAILER

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Your trailer is much diffrent than mine.
For you have a steel box frame were mine is aluminum I frame. You don't have a forward bunk support. The Axels are streight instead of U shape for shallow launch.
The winch appears to low etc.
Do you have pictures with boat on trailer?
Dave

vitger wrote:Sorry, it must be me but I cannot seem to locate the thread I started a few days back...
Anyways, here are the pictures of the new trailer, looking for aadvice on modding the bunks, thanks. Where does one get material for bunks? I mean brackets and bunk covers... Home Depot? Or trailer specific shops?


https://picasaweb.google.com/gerloczyek/NEWMACTRAILER

Bunk material: Treated lumber with carpet fastened with monel staples (hardware store). Carpet from Bass Pro Shops or West Marine.

I have a stock trailer for my 26X, and I rebuilt/replaced the old bunks a few years ago when I repainted the trailer. I had a tough time removing the old bunks, which were bolted to the trailer frame. Most of the bolts sheared off. I don't know if the wood in the original bunks was treated or not, but some pieces were showing signs of rot. When I rebuilt them, I opted to not use wood, treated or otherwise. Instead, I used some of that composite plastic wood which is used for stringers on outside decks and benches. It's the stuff made from recycled plastics. It cuts like wood, and holds staples just fine, and it will never rot. The original bolts were not stainless (that's why they were impossible to undo.) I redid them with stainless bolts. Instead of regular nuts, I found some stainless nuts with prongs on the underside. They're designed to not slip when the bolt is turned. I countersunk a hole larger than the nut in the plastic bunk material and then tapped the nuts into place. This arrangement allows me to undo and remove the bunks in the future by simply putting wrench to the bolt head. Since the nut can't slip, they should be easy to unbolt. I used the original carpet covers for patterns and cut out new carpet covers from short knap outdoor carpet material. I've been very happy with this rebuild.

Dave, I already raised the whinch to the maximum height allowed by the winchpost. It is close to, but still slightly lower than the stock one. Will try to put boat on trailer next weekend and take some pictures.

Mike, thanks for the bunk material tips.

For what it's worth, even though the bunks of the original are in a vee configuration, they all only contact the hull in 6 places, and those patches aren't very big. If your longitudinal bunks contact the hull in the same places, it likely won't make much difference which way they run. The unsupported span of the longitudinal bunks will have extremely low stiffness, and won't support much of the boat's weight, so the almost all of the weight will be taken by the bunks where the hard supports are at the ends. Match those locations and elevations, and you have the same thing, except for the missing small vee in the front.

Something to think about, at least.

Thats why I like the long 3x10 inch stringers as they support at least 6 ft of the hull at the strongest point both sides.
I just made up 3x12 inch guide supports on both sides of trailer so the boat always go on trailer even and I can go deeper in the water so I don't have to crank in winch much.This guide support is located between wheels and there is no thru bolting or drilling holes in frame. I will post pictures when I fiberglass the blocks and put on the carpet . This also supports the boat from going sideways on trailer in bumps or big bumps were boat air borns from trailer on Big Pot holes.
You can forget about trying to center boat while pulling out in rough waves as it is automatic.
Dave

tkanzler wrote:For what it's worth, even though the bunks of the original are in a vee configuration, they all only contact the hull in 6 places, and those patches aren't very big. If your longitudinal bunks contact the hull in the same places, it likely won't make much difference which way they run. The unsupported span of the longitudinal bunks will have extremely low stiffness, and won't support much of the boat's weight, so the almost all of the weight will be taken by the bunks where the hard supports are at the ends. Match those locations and elevations, and you have the same thing, except for the missing small vee in the front.

Something to think about, at least.

It just occured to me to check on Karavan trailers website and sure enough, they have a ton of accessories, amongs them brackets and bunk supports. Now what to pick? I am a bit overwhelmed by the amount of choices...

http://www.karavantrailers.com/site_upl ... ks-PDF.pdf

I'd love to see some of you guys' setup, if you have longitudinal running bunks.

Cheers,
Balazs

What you need, IMO, are the locations of the contact patches between hull and bunks, and the angles. I'd survey mine for you, but the boat is on it, and probably will be for a while yet.

Perhaps the next best thing would be to put the boat on it (in all likelihood, it won't sit well), and adjust what you have to hit the spots. Have to jack it up, of course. Looks like a lot of adjustability in that trailer, including the axle locations, which will be really nice for getting the tongue weight right. I keep mine low, but I have two axles like yours, so no instability towing with a Honda Odyssey.

I think you should put some priority on adding goal posts, as it'll be a bear trying to get the boat in the right spot when it's drifting or blowing sideways. Which it will. Lots of freeboard on these boats. In your case, I'd add a second pair forward of the axles. I'm going to try a bridle on mine, between the goalposts in the rear and the small vee at the bow, as it's cheap and easy to try. In your case, without the vee at the winch, extra goal posts are probably easiest, and they just bolt or clamp on.

There are loads of different types from loads of different sources.

http://www.westmarine.com/webapp/wcs/st ... sNum=50816

http://www.westmarine.com/webapp/wcs/st ... sNum=50816

http://www.easternmarine.com/fulton-50- ... gb150-0100