[Bushwacker]

Masao,

Here's some reference info to give you some idea of what the original layup looked like.

The laminate schedule for the hull listed in the 1969 Boating Magazine article on the 20' Seafari was: 1M +1M + 18R+1M+18R+1M+18R+1M+18R+1M+18R, where 1M = 1 oz. mat and 18R = 18 oz. roving. Another way to think of it is 1 layer of mat and 5 layers of 1801 with the mat side facing the gel coat. Total hull thickness was 0.221" and I think this would apply to the outside of the transom as well as the hull, since it was layed up at the same time. That works out to about 0.040" per layer of 1801 if you figure the gel coat thickness and first layer of mat was about 0.021". It doesn't say what the laminate schedule was for the inside of the transom was. We used 3 layers 1708 on the inside of the transom on Skip & Carla's 21, and I think we got about 1/16" (0.0625") per layer. so the 8 oz mat must make that stuff a little thicker than 1801.

After Don Herman installed the bracket on my boat, I drilled a 1.5" hole in my original transom to install an overflow for the under-seat bait well, since the original baitwell inlet/outlet was covered up by the flotation tub on the Hermco bracket. I kept the plug from that hole and just took a look at it with a vernier caliper, so here's what I came up with thickness for each layer:

The outer skin thickness of this core, including the gel coat, measures about 0.25". There were two layers of 3/4" plywood (which were totally dry - confirming Don's comment that it was the driest transom he had ever seen in a 34 year-old boat!), and then the inside layer of glass appeared to be about 0.190" thick, or maybe 5 layers of 1801. (Makes technical sense to me that Moesly would specify the same laminate schedule on each side of the transom core from an engineering perspective.) There is then a layer of about 0.190" of Potter putty and then the baitwell glass, which I think is chopper gun layup, that is about 0.110" thick. Hope this helps! Denny