Grant, I was somewhat slapdash about the whole thing. I took some basic measurements and made a mock up out of cardboard. The L shape was totally accidental. The cardboard had a natural fold in it there and I thought 'that might be cool' so I went with it. The triangle's measurements are 18" across the top and the sides are 16". The bend is at about a 45 degree angle 3" back from the tip of the triangle. When the cardboard (and then the finished product made from 3/4" marine plywood) is angled back it's 13" from the tip of the triangle to the top of it, right where my index finger is in the photo. It wasn't the most precise fit so I used wood flour thickened poly-resin to fill in the voids and create smooth fillets.
Couple of suggestions:
Use an oval deck pipe fitting. I didn't. I used a round one the guy at WM sold me but forgot to factor in the size of my shackles and reinforced eye splice in the rode to chain connection. I realized that just as I was feeding my anchor line into the finished project.:rolleyes_d: It's fine, I can use that fitting when I do the stern chain locker.
If I did the project again I'd probably cut out the hole in the deck first for ventilation. Working with resin in that enclosed space not fun.
I dry fit the L shaped shelf in and drilled a small pilot hole through the hull for the drain then taped it up. I think the hole is about 25" above the waterline. After I glassed the shelf in I poured about 4 ounces of unthickened resin onto the little bottom part of the triangle which is about parallel with the waterline. This created a self-leveled, glass-smooth surface on the bottom of the shelf which should aid drainage. After the whole thing set up I redrilled the drain hole from the outside a little larger then used a countersink bit inside. As I mentioned I used poly resin, not West Systems so I was very generous with my pours.
Cut the hole in the deck and drill oversized holes for the #10 through bolts. I used an old nut pick to gouge out the balsa core. Mixed up some resin and, using a small brush, work it way back in there to coat the exposed core. Tape off the bolt holes from the bottom and around the inside of the pipe hole. Pour unthickened resin into all of the bolt holes to fill up the void in the deck. Redrill the bolt holes through the solid resin and you shouldn't have any core rot issues in the future. Bed it with 4200 after you masking tape off the fitting and deck.
It's a tight fit with ~200ft. of rode and 30 feet of chain packed in there but it works and I'm glad to have the anchor in a more accessible position.