should not be cementlike
The sealant should be flexible if your arrangement is similar to my 1980 Hunter 33. The chainplate covers are screwed directly to the deck. I do not know what the original factory goop was, but it was flexible. Eventually it leaked. I have used Sikaflex, silicone, combinations of the two, etc. etc. etc. and they have all worked for AWHILE. Just recently, I came up with a new idea. Using some of that epoxy that comes in a stick and is easily molded, I fashioned a raised rim on the deck and outside the edge of each cover. These rims, rectangular in shape and sloped up from the deck so as to be fair, are about 1/4 inch high and about 1/8 of an inch outside the covers. I then cleaned out all the old material (very important, and actually, I did this first) and then filled the entire area within the rim with 5200, right to and a bit above the top. Then, I screwed the plate down to about the level of the rim. 5200 comes out between the rim and the cover and also between the chainplate and the cover. I had masked all of this area and then smoothed the excess 5200 down using a screwdriver blade. When I removed the masking tape, there is no mess. The final result is a rim of the epoxy surrounding a 1/4 in bed of 5200 on which the cover sits. In theory, there should be plenty of adhesion and flexibility. The rim is not structural. Should I need to remove the plates, I can work a knife or piano wire under the covers to break them loose, and use a bit of heat. Frankly, I don't plan on moving them for a long time. The only reason I ever had for removing them in the past was when they leaked, so if I have solved that, I am not going to move anything. So far, the system has worked very well, but it hasn't been long enough yet to know the long term outcome. I have had plently of water over the decks, already, however, so I am very optimistic. You don't want to hear about my earlier versions that led to this!!! But the simple answer is remove all the old stuff and use something flexible and adhesive.
