Trailer wooden bunks!

[R2]

We recently took the compac off of the trailer and I am in the process of restoring,sanding,painting and replacing the bunks which are split, must be original. The bunks of course have a bow or bend to them and my wife is concerned that new wood will not conform to the countour of the boat, any ideas or comments please.  Thank you., R2

[Pacman]

Your wife is on target with her observation.

Some Com Pac 16s I have seen were supported by 2X4 bumks that hardly bend at all. 

Not the best for the hull because the load is concentrated on contact points.

I recently made new bunks for my Com Pac 16 trailer using 1X4 pressure treated lumber.

1X4s were flexible enough to conform to the shape of the hull while providing excellent support.

If I can figure out how to do it, I'll post a photo.

[Salty19]

After the bunks are dunked a few times they will begin to bend with the shape of the hull.

Remember they don't support weight but keep it from falling over.  Tie down straps will keep the pressure off too.

[JTMeissner]

Well, unless you can find your wood at the store with the right bend in the bin, you will have to make some adjustments that could take some time to finalize.

I replaced the bunks on my trailer last spring, and just used the least expensive pressure treated lumber in the store.  Remember, these are mostly guides and shouldn't take much weight.  I did all the trailer work while the boat was spending the weekend in a slip, so fitting wasn't finished until I pulled the boat out.  The new, straight, boards (old ones were nicely curved into hull profile shape like you observed) did not allow the boat to sit fully with keel on the rollers.  

Two things helped here, maybe three.  I lowered the bunk poles to reduce the pressure, but I had also not completely tightened the bolts on the L-brackets between the poles and the bunks.  This allowed the hull to slightly bend the wood before I cranked down the nuts (slots on the wood side of the bracket).  This keeps the bunk boards in slight compression even without the boat, helping to keep the bend in the wood.

The third thing is that repeated wet/dry cycles will make the boards a little more pliable, so over time you may have to make some slight adjustments.  You're likely to end up with contoured boards before too long.

Finally, it's a ComPac, not exactly known for skimping in the fiberglass build.  While I don't want to warp my hull, I'm willing to take a bit more of a chance than with some big mass product line boat.  Also, I think the bunks sit at about where the berths connect to the hull, probably the points on the side of the boat most able to take external pressure over the length of bunk contact.

-Justin

[skip1930]

No problem. We are talking hull bunks? Not under keel bunks?
The #2 construction grade pinewood 2 x 4's will bend.
What you want to do is set he boat just where you want it on the trailer. Then using a floor jack jack up most fwd and most stern 2"x 2" square steel posts till the bunk board just touch the hull. When the ends are secure, jack up the center till that just touches.
Careful it is possible to the boat clean off the trailer and hang the hull off the hull bunks.
Most hull bunks are carpeted.

skip.