Trailer to properly support the boat.

[Proa42]

I've been working on a lapstrake (earlier post) and now that I have the info on the scary stuff. Bending and replacing frames is going well. Now, I have to start thinking about the day she goes to water. Since it was trailer life that nearly killed her, I need to make the trailer more "lapstrake friendly". I want the hull to take some its own weight so it doesn't start to sag again (got it pretty fair, I think).

Anyone have suggestions on trailer engineering. 19', round bilge, lapstrake with long keel, and wine glass stern.

[PAR]

You don't want the trailer supports to hold up any potions of the planking if you can help it. What you want is the boat to rest on her keel and be prevented from flopping over onto her flanks with bunks or my preference are support stands. The worst thing you can do to wooden planking is push against it hard in localized areas, like bunks or supports. Never use rollers on planks either, again the same reason, point loading in a very small area, which will pop butt blocks, fasteners, clenches, etc. I can guarantee it.

If your planking is well fastened, the deck tight and well attached, the keel solid and not permitted to hog (well supported), then the turn of the bilge will resist sagging for some time. A few well placed, turn of the bilge support stands can keep them from drooping to a degree, but if drooping becomes and issue, it's not the trailer, it's something else, like loose fasteners.

The images show a trailer about to slide under a 26' lapstrake powerboat I've restored. This is why it's missing fenders, guides, forward supports, etc. If you look closely the bunks are beveled to fit the rolling deadrise in the bottom. Two of the four bilge support stands are installed. Most importantly, you'll notice the bunks seem close together. That's because this is a single screw boat and the beds are on 24" centers (pretty much a standard). This is where you want the bunks, because the keel can't hold up the boat in the aft potions of the hull. The skeg, shaft, strut and rudder prevent under keel support, so the next hard point that will not crush frames and planking are the engine bed stringers. The stands are home made and simply pivoting pads that let the bilge rest comfortably, without a hard edge pushing into the planking.

[hoytedow]

If bunks touch planking, make sure it is wher planks are backed by frame members. More bunks are better.

[PAR]

Since the frames are perpendicular to the planking seams, it stands to reason that bunks will hit many. The bunks above bridged 20 of the 44 frames in the boat.

As mentioned, the bunks should land directly below the engine bed stringers, which is a single screw or outboard powered boat will be 24" apart. Multiple bunks will not be any more effective then the two under the engine beds.

The real key is to insure there aren't any hard edges pressing against the planking, between frame bays or stringers. This is how you distort planking and pop things loose.

[Proa42]

Thanks again.

I almost made a serious mistake. I've located bolster/bunk brackets on line. I'll be installing them outboard on the turn.

One thing more: Excuse my ignorance, but there is a piece of wood just below the turn of the bilge, on the bottom. It runs parallel to the keel through the broadest section of the boat only, not stem to stern. Is this a bilge stringer? approx. 1 1/4" x 1 1/4"

[PAR]

In one of your exterior photos, there appears to be a log (hunk of wood) on the planking. If this is what you're talking about, it's a rub rail of some sort. If it's inside the boat and attached to the frames, it's a stringer.

You boat is light enough to tolerate bunks at the bilge turn, but again they just keep the boat from flopping over onto her flanks and don't push up into the planking. The weight is born by keel rollers.

Your trailer doesn't appear to have enough keel rollers, especially along the forward sections. You'll probably have to make up some brackets to hold rollers, but it's not particularly difficult.