The transom is fiberglass, though there is some compression there. Not nearly like other transoms but some. Thus they need tensioning occasionally. If you impact obstacles, they will also stretch the bolts a bit and compress the plate some.
Just snug em up is best, try to not over tighten them, and we dont have a torque spec on the transom bolts. You should not be able to hurt anything, and since glass and all have some travel in it, it is hard to torque properly. BCB
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