Builders' Forum Archives
Posted by Laszlo on Jun 15, 2006
That 16" radius is either wishful thinking or an initial design point, depending on your point of view. While the deck beams start out as 16" (if you buy the kit or are really careful in making your own), the front deck itself will end up as something other than 16" because it gets bent in 2 directions (front/back, left/right) to give that distinctive Chessie shape.
Depending on a lot of factors (exactly where the builder ends up putting the bulkheads and beams relative to each other, how well planing the sheer clamps goes, exactly where on the decks the hatches end up going and the workmanship on the deck beams, bulkheads, hatch frames, doublers, stiffeners and rims), that radius could show quite a bit of individual variation from boat to boat.
The hatch system described in the plans handles a large range of variation, but if you end up with the hatch cover being at the extreme flat end of the range relative to the deck, the dowels, the reduced radius frames, inboard strap anchor points, etc. may be necessary for a tighter fit.
You can check the fit before gluing the frames to the hatch covers, while there's still time to make some adjustments. Just take the hatch frames and hold them up under the deck after the hole has been cut and the doublers and stiffeners installed. If the curves match, you'll be fine. If the center of the frame touches the underside of the doubler and the ends don't, the deck is flatter than the hatch (usually not a problem). If the edges touch and the center doesn't, the hatch is flatter than the deck (potentially a problem).
As long as any gaps are less than half the thickness of the weatherstripping you should be fine no matter what the curves do and you shouldn't have to do anything.
In Response to: Re: Hatches by Chris J. on Jun 14, 2006