My 1975 SeaCraft 25' Seafari rebuild thread

[flyingfrizzle]

Got going on the transom core. I got 2- 3/4" sheets of Douglas fir marine grade ab ply from home depo for $80 each. Wanted to use Coosa to save weight but man that stuff is high. To get it I had to buy a minimum of like 10 sheets to get a good price or pay higher price and high shipping on just the 2 sheets. I decided in interest of time (wanting to work over the holidays while I.had off) to go with wood. To me wood is the best transom material anyhow but just hate to make the rear any heavier than needed. Deep vee ride better with more weight just got to get enough forward to get the balance right. I used the skin from the inside of the hull to get a pattern marked on the ply. Once I got that marked I took a pice of scrap and traced the hull bottom of the vdr and marked it on the ply for an exact tight fit. Got both pieces tried out, then scuffed the inside face of them with 80 grit to get the smoothness off the ply and to make it absorb the resin better. I used thinned infusion vinyl ester and applied a good hot coat of resin to the wood face so it could absorb in. Styriene will thin resin better than acidtone and works best. Infusion resin is thin to start with but wood absorb resin better when really dry and when the resin is super thin. I cut two layers of 1708 and two 1700 cloth for the inner core between the two plys. The 1708 will get applied to the wood csm side mating to the ply. That will hold more resin for the wood to absorb and fill any flaws in the wood better. I dug threw the stack so i got two nice sheets so it was flaw free mainly as ab grade is anyhow. I almost wished I got the Douglas fir exterior ac grade ply at $40 a sheet (half the cost). I told myself the ab marine would be better even tho they are basically the same thing. Back to lay up schedule, 1708 to the wood csm side touching the face then a layer of 1700 biaxel second 1700 biaxel then 1708 facing opposite the first so csm is up to lay the outer ply sheet on that way the csm touched the face of that second sheet. I applied each layer one at the time rolling each out well to get any air out between layers. Applied the top sheet down after it soaked up plenty of thinned resin. I did this on a 38-40 degree night with my shop cold. This gave me plenty of working time to lay everything up without the resin kicking off. It took 3-4 hours to do everything and once I had it clamped together and weight on top of it I shut the doors, fired up the heat and set it to 90 degrees. Once the heat climbed the resin started to kick. Baked it all night for 10 hours and removed the clamps and then trimmed the edges. This gave me a 3/16 or better lament between my plys. Supper strong and flat. Now I. Will hot coat the sides edges of the plys and outside that will face the rear of the boats original transom skin. It will get just one layer of 1708 due to the outer boat skin is already 3/8" thick. Once I get it hot coated I will lay csm strips 2) 1.5" & 1) 4 " strips around the edges just to seal them against water asorbshion then drop the 1708 layer on the back of the ply face. Once that sets flip it and lay an layer of 1708 on the other side. This will seal the core 100% and as long as no screws go in it there shouldn't never get water in it to rot it out. Once cured it will get scuffed with 80 grit and bonded in the hull to the rear skin with thicken epoxy and several layers added to the front tabbing it in to the hull sides.