Deck Framing

It's a great day indeed when you remove the molds. But don't, be in too great a hurry; a few things need doing before you break them loose.

I assume that you've been properly cautious, with ties across from sheer to sheer in the middle third of the hull (to prevent spreading) and braces between frames below the future location of the sheer clamp in the ends of the vessel, wrhere she'll try to come together. You should mark a true, pure line, representing the underside of the covering board, identical port and starboard, on the sheerstrake, with due allowance for the crown of the deck. The sheer marks on the molds will help you get this right. Dress off the sheerstrakes to this line.

Be sure to run a pencil line down the inside of the planking, along the business edge of each mold. If you haven't yet followed my instructions in Chapter 11,1 wish you'd roll a strand of cotton into the topside seams, and even do some smoothing above the turn of the bilge, to calm the visitors, but I'm afraid this is too much to expect—so go ahead and yank the molds out. As soon as you've finished gawking at the vastness of that hold, we'll consider the problems of the deck frames.

In its simplest form, the deck frame consists of beams extending from side to side of the vessel, usually spaced about the same distance apart as the hull frames—with various openings left for houses, hatches, cockpits—and damned well fastened at both ends to resist the weight of years and boarding seas. This end fastening has taken various forms through the centuries, ranging from spruce-root lashings, hanging knees fastened to frame heads, mor-tise-and-tenon joints through the sheerstrake, to the system most of us now use, which I will describe here.

The sheer clamp

The first move is to fit and fasten a timber to the insides of the frames, with its top edge below the top of the sheerstrake by the depth of the beams, and extending from the stem to the transom. This is a simple enough proposition, with only two inherent pitfalls.

You'll notice the first problem (as I finally did about the third time around) when you lay your concave beam mold across the hull from sheer to sheer and mark on the inside of the frame for the top edge of the sheer clamp at that frame. If the vessel has tumblehome, plumb, or even slightly flaring topsides, that mark must be, below your mold, much less than the depth of the beam. The beam must hit the inboard edge of the clamp. In the forward sections,

Square-edged clamp timber set to the height of the underside of the deckbeam without correction

Sheer Clamp Boat

where the topsides very likely flare decidedly outward and the beams are short, the opposite effect occurs: the inboard edge of the clamp is higher than the outboard and must be notched to get full-width contact with the bottom of the beam. Figure 13-1 shows this effect better than I can describe it.

The second problem crops up in the forward part of the vessel. It's very likely that the flare of the topsides will demand a humped-up curve, which you mav have noticed when you

/ * t fitted the sheerstrakes. Since the clamp is to be a 1 Vs- by 41/2-inch timber, you are not likely to get this curve by edge-setting. Perhaps you'll have to steam it, or even saw it to shape; maybe you'll split it (horizontally, of course) with a saw cut, back to the point where the timber straightens out and starts curving in the other direction (see Figure 13-2a). The latter scheme works fine, and never mind what people say. By the time you bolt the beams to the split clamp vertically and bolt the frames horizontally

every foot or so, it'll be plenty strong.

Cut the forward end of the sheer clamp to bear snugly against the back of the stem, make the scarf cut (2 feet long, horizontal cut; see Figure 13-2b) at the after end, slide it forward on top of your temporary cross-braces, and haul it out to the frames with all the clamps you can muster. You'll be happy you fastened the sheerstrake with screws, because vou can

now back them out and replace them with V»-inch galvanized carriage bolts. Up, down, up, down—counterbore the bolt holes to set the heads l/2 inch into the sheerstrake (fill the holes flush to the planking with polyester putty if you're going to paint the hull).

Assuming you can't get stock long enough to make a one-piece clamp, cut a matching scarf on the after piece and spring it to the marks. Lock the scarf together, lay the after end out over the transom, and cut it to bear tightly against the transom frame. Bolt the clamp to the frames as above, and put four vertical bolts through the scarf.

Don't worry when the croakers say, "She'll hog, sure'n hell, 'thout that clamp's one piece!" Just you wait until we get a shelf into her.

Amount of correction, upward, required

Block representing clamp timber

Block representing deckbeam

Final mark, upper edge of clamp (if left square)

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