futile
I have a 1974 V21. It too had a ton of old caulk under the rub rail. Adding caulk there is futile. To seal the seam, get inside, take off the trim piece that hides the joint, and inspect the seam from there (this is one job you get to lay down on). If there are gaps of 1/8" or more, it's sometimes possible to tighten the nut and pull the two molds together better. Then, use a good quality caulk on the INSIDE. You'll get a much better seal with about 10% of the caulk you'd need outside, and you can SEE where the leaks are if it still leaks. There were some nuts I couldn't get tighter. I ended up back outside pulling the rubber out of the rub rail to expose the heads of the machine screws. I used my Dremel tool to grind off the heads and replaced the screws. The rubber will go back on if you have a second person pull on the bitter end to stretch it, then use a not-too-sharp screwdriver to wedge it back into the aluminum channel. Naturally, the place where my boat needed the most attention was also the most inaccessible: the bow. Where the two molds join, the fit wasn't just right - the deck didn't overlap correctly - so someone cut away the hull until the deck laid on it, the two edges butting each other rather than overlapping. They then hid this little gem of craftsmanship with the rub rail extrusion. Neat, huh? Classic MacGregor construction. Fine...until you try to use the thing and the first wave comes over the bow. Half of it would end up inside. Not a desireable situation. I shudder to think what they're putting out now. With all the ballast tank problems, cracked rudders, and flipped boats the 26X guys are complaining about, I think those things are only safe at the dock. Wait. didn't I read about one that sank right at its dock? Anyway, I really loaded my bow area up with caulk (again, from the inside). There didn't seem to be any other way to deal with the problem, short of removing the deck molding and building up the hull with fiberglass. So far, so good. Of course, there's a catch. You knew there would be, right? The machine screws that held the inside trim in place on my boat were fed from the inside out: the nuts were on the OUTSIDE, hidden under the rubber of the rub rail. I had to break off the trim piece in places (dumb, cause I later took the rub rail out of the channel anyway). It was rotten, anyway, from all the water that had come thru the seams over the years. Just the kind of escalation you expect when you restore an old boat, right? Money? It's only paper, ya know. I could keep going but I won't. Good luck and I hope this has been of some help.
