Builders' Forum Archives
Re: mea culpa
Posted by LeeG on Jun 25, 2004
another way to skin a cat. I was finding that the rounded edge of top mounted 4mm ply hatches were getting dinged a lot as they sat up high and exposed so I tried different methods of making the edge tougher,,,applying thinned epoxy with a small amount of cabosil to hot wood, wrapping 4oz glass over the edge, laying a bead of thickened epoxy along the edge. If the edge grain plywood isn't sealed well and gets a thin seal coat then dinged into the wood then it sucks up water easily giving a stain under the varnish. Your method of a doubled edge makes sense to provide a big rounded edge but also for making the 4mm edge stiffer. Brandon Nelson who did the Baja trip in his CH18 used half round dowels on the top to increase the down force, I suppose it stiffened the edge if they were glued in the right place. Ironically when the simple box shaped hatches for the Cape Charles were replaced with the CNC cut ribs the stress riser at the cantilevered edge went from the perimeter of the boxed hatch former,,to three 6mm wide edges,,with a tighter deck bend than the Cape Charles. There were a couple old 3mm Cape Charles hatches that held up better than the 4mm Chesapeake hatches that didn't have adequate fillets at the ends of the ribs. All this is going for the extra 10%,,but for those folks using their kayaks in the 10% use that requires 100% reliability 100% of the time it's not unreasonable.
In Response to: Re: mea culpa by Tony Calvert on Jun 25, 2004