Trailer bunks damaging bottom paint

T

timflan

New member
I've just had Two Lucky Fish's hull repainted. You can read about it over on Navagear:
http://www.navagear.com/2008/11/two-lucky-fish-on-the-hard/
http://www.navagear.com/2008/11/two-lucky-fish-haulout-photo-album/

I would like to modify the inner right-angle surface of the trailer bunks, particularly farther forward, to mitigate some excessive rubbing that damages the bottom paint. I think the photos demonstrate what's happening pretty well.

At a boat ramp, when the boat is run up onto the trailer, the first points of contact are the hull surface near the bow (where it's still got a V-shaped cross-section) and the inner edge of the carpetted, wood trailer bunks.

Starboard side, looking aft:
img-8950.jpg


Port side, looking aft:
img-89631.jpg


Trailer, looking forward:
img-8966.jpg


Trailer, looking forward:
img-8965.jpg


Notice how the carpet has been worn away on this edge. That's handy, as it provides a very clear indication where the problem is.

I'm thinking of radiusing that bunk edge, and applying some sort of slippery coating, either a fabric or a sheet of low-friction plastic like Delrin. Any ideas?

Thanks!
 
King Trailers uses a product called Slick Bunks that is a slick polypropolyne cover instead of carpet. It would probably prevent the damage to the paint.
 
Does water cover your fenders? Perhaps you need to back in farther (but not too far)! Just a thought as my boat floats up to within a foot of the winch.
 
Timflan,

Looks like your brackets for your bunks can be adjusted so the bunks can be turned to be more flat against your hull. If that does not do the trick, you could install 2 x 4 instead of 2 x 6. I would not try to round off the edges of the bunk, better to adjust the angle of the bunks to match your hull.

The use of slick bunks will help tremendously over carpet bunks. You could add them to the forward four feet or so of your bunks, with carpet on the aft half. No need to have them the full length because your boat does not slide across them during launch or retrieval. I like them because they attach to the bunk with screws on the sides. I have seen people use Teflon or delrin slicks on top of bunks with countersunk screws, but I would worry about the screws backing out and gouging the hull.

You can view the modifications I made to my trailer and check out the slick bunks I installed.
 
Has anyone ever had a problem with, or been concerned that they would have, sand or grit collect on the slick material. I keep thinking it might get ground in or collect there and cause premature wear on the gelcoat.
 
I have the slick bunks, they came with my 1993 CD 16. I have seen no damage to the hull. They are very slick. It's easy to push the boat around on the trailer to reposition it as needed. When the slick bunks are wet you can push the boat off the trailer on level ground so be sure everything is strapped down before you move.

Kevin
 
Tim,
I have an EZ Loader with what looks like the same bunk system. I haven't had the same wear pattern on my bunks that you do. I suspect that the bolts under bunk are not allowing the bunks to pivot, hence all the wear on the inside edges. On my trailer the pivot bolts are just loose enough to allow the bunks to tip inward slightly as the bow makes contact-this also allows the bunk to find its best fit with the bottom as the boat settles on the trailer.
 
Timflan-

The boat is obviously riding on the inside ends of the bunks only. Bad Boy is 100% right to suggest you try to adjust the entire bunk to contact the curvature of the hull evenly. See if the bunks can be rotated down and inward to accomodate the boat's shape better and spread out the load.

It could also be that the 2 x8's or 2 x 10's or whatever the bunks are made of are simply either too stiff or too limp to spread out the load, hence the load is being taken at the ends where the vertical metal supports are. Which one it is will depend on how you see the hull being supported by the bunks and the curvature of the hull. Too limp bunks would take all the load above the vertical metal supports, too stiff might take all the load at the ends or at the middle of the bunks, depending on how the hull curvature fits the stiff bunk.


But I bet your problem is mostly that the bunks are simply turned too flat (horizontal), and need to be angled down and inward to match the hull.

Another strategy would be to line the bunks with closed cell foam plastic/rubber that wouldn't absorb water before covering them with carpet or slick plastic. The softness of the foam would help match the contour of the hull better than a hard piece of wood and carpet alone.

One cavet / warning:

Solid plastic covering on bunks can trap water against the hull and force water through bottom paint or even through some other types of paint, though not usually the epoxy used as a barrier coat. Water forced behind one layer or more of paint like this can cause blisters/ bubbles to form, and separate the paint from the hull. We found this out in sailboats, and were fortunate enough to switch back to plain carpet and the water behind the blisters evaporated and they flattened out, leaving no permanent damage. Live and learn!

If you re-carpet the bunks, use Monel staples rather than stainless or plain galvanized steel.

Carpet designed for this use and bought from a marine source will far outlast carpet remnants bought from a carpet dealer.

Joe. :teeth :thup
 
I don't know, I may be totally seeing this totally wrong, but to me it looks like the rub areas are way out toward the outer edges of the bottom and would wost likely be made by your outside bunks, not the center bunks you've pictured.

At any rate, I bought some nice 2x6 slicks from Champion Trailer that you could add right over your old carpeting and they're rounded on the ends so there are no sharp corners. You can see them as photo 3 in the untitled nested album. They just screw on with provided SS screws.

Chris
 
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