SEMI SCALE FOAM AND GLASS MODEL OF MY 15FT 1953 SCHOCK US DESIGN DAY SAILER.
Made a sandwich of 4 x 25mm foam sheets on the 5mm ply deck cutout, glued with foam safe contact spray. The area around the cockpit was only glued round the edges, as 2 sheet thicknesses had to be removed later.
The big foam sandwich was shaped by eye with a Surform file when dry, using the laminate lines for reference. The full sized boat had been measured previously, and everything scaled 20%, and lines drawn on the foam as a guide also.
Once I was happy with the shape (checked side to side with cardboard templates) I glassed the hull with epoxy resin and 5 oz cloth. I rolled on a thick layer of resin before the cloth, to help with filling the pores of the foam. Hull had 2 further coats of resin, sanded between coats, then another 2 with fairing powder mixed rolled on, the 2 more thick fairing mixes squeegeed on, (imperfections filled as well). Each coat was sanded back to eventually hide the weave and leave a smooth surface. LOTS of sanding !-orbital sander, finishing sander, block sanding etc and some Surforming of any high spots in the resin.
Next job (yesterday and today) was clamping the hull to the bench for cutting out the cockpit, (clamps go under blocks with cutouts screwed to the bench with a cross bar for the deck, and hull on foam blocks) Cockpit was cut out using a jigsaw with a short medium blade, and finished to the lines by drum sanding and blocking.
The deck and 1st lamination came away as one piece, and the second lamination was cut down to with an extended snapoff knife set to the depth, and then picked out easily in large pieces due to no glue in that area. Cockpit is now 50mm deep, with a nice flat bottom, ready to either epoxy thin ply round or glass it then lay ply. The deck will be glassed eventually as well. Centerboard case top will be routed out to drop a complete case unit through, (as I did with the cat)
Transom is also 5mm ply, epoxied on before glassing, (which links its' edges to the hull, otherwise it would only be a foam strength joint) Next I'll have to knife some epoxy between the laminations on the centerboard case, as they obviously had no glue previously. the whole case will be ply sheeted and braced.
I'll leave painting till last, as the hull will have a lot more done to it yet ) rub rail, coamings etc) This is where it's up to at the moment,- more to follow. See pics of the full size boat, and some of the detail I hope to add to the model. Boat was built in the 80s, took me a year to restore it, (including removing a full width outboard well.)
JB