Polyurethane, polysulfide & ABS transom...
The Mercury Airdeck has an ABS sheathed transom that needs a couple through bolts sealed below the waterline.
Reading about the various sealants polysulfide (3M 5200, 3M 4200 & Life-Calk) are incompatible with ABS (the Polyusulfide attacks the ABS, hardens & cracks). Polyurethane (Life-Seal) is supposedly more aggressive than polysulfide.
Does that leave me with a polyether (3M 4000)? Suggestions?
Also want to put a brass tube through the transom above the waterline for when I want to use the engine bolts (through the tube). 3m 4000 good enough to hold them in place (thinking through bolt, stainless washer, rubber washer, transom) or is an epoxy needed (Marinetex)? Suggestions (photos?).