Thanks for your helpful advice here and elsewhere. I plan to order some of your butyl soon, before I begin to reinstall my deck hardware. I will pot all holes with epoxy and countersink before applying the butyl.
One question about your experience with the genny track on your own boat. You've had great success at keeping the water out, even though the holes were not countersunk (and evidently not potted with epoxy). Good butyl alone has done the job. The genny track on my boat, at some point before I owned it, allowed water to enter at several points. The evidence for this is that several of the screws are rusty below deck. The amount of water must have been minimal, because there is no evidence of core rot anywhere. The genny track is the only piece of hardware that I've not removed, but I think it would be smart to go ahead and remove it and rebed it with butyl. The only thing is this - I really want to avoid having to pot every single one of the blasted holes beneath the genny track. The hardware for this track is overkill to the max. There are 40 screws (in double rows on each side of the boat). Thus there are 80 total holes that I would have to pot. Do you know of anyone in my situation who's been able to get away with rebedding the genny track with your good butyl alone?
Thanks for any advice in this,
Ericson 25, #226, Oystercatcher
#1 Most genny tracks are concave on the bottom to hold a certain thickness of sealant. This "sort of" takes the place of a countersunk hole. I still prefer to countersink. If your genny track is flat based then you definitely want to countersink.
#2 Why on early ANY builder would run a genny track through cored material is beyond me..... Doh'!!!!
It is a crappy job but ideally potting the holes is the best method.
#3 The butyl will work fine alone the potting is only there as a back up in case you goof up or 30 years later you get a leak... But still a genny track through a cored deck is cost cutting 101....
#4 On the other hand its a 25 footer and your time in potting 80 holes might exceed the value of the job, so just re-bed and go sailing.....