Chain Plate and Deck Fitting Sealants

[Rich Olson]

My boat is fiberglass and the chain plate deck plate is stainless steel. I've seen much damage done by leaking chain plates and want to do everything I can to prevent leaks. I have heard and seen recommendations to use everything including Dolfinite, Silicon, Polysulfides, and Polyurethanes. As far as I can tell, Dolfinite will dry out but it will take several years, silicons are not a good solution unless re-done every year, Polysulfides are recommended but may still be difficult to take apart, and polyurethanes may provide the best seal and will be permanent but may be too difficult if it ever needed to be taken apart. It seems people use what they have always used depending when they got started.At this point I plan to use Boat Life Caulk and have over drilled the holes for the screws and filled with epoxy. Will re-drill holes for screws and bevel top edge to form an "O"ring with the sealant. My questions are:1. Now that there are some de-bonding agents for polyurethanes (I believe that Boat Life has one), do you believe that they work well enough for disassembly to allow the use of a polyurethane for deck fittings and thru hulls?2. Do you believe Polyurethane is a more secure and permanent seal then a Polysulfides like Boat Life Caulk and would now be recommended for almost all applications? 3. How long would you expect the Boat Life Caulk seal to last without leaking on deck fittings and chain plates?3. Should Boat Life Caulk (or other polysulfides) be replaced periodically regardless of observed leaks which you may or may not see happening depending on the conditions under which the leaks occur. If so, how often should it be replaced?4. Does Boat Life make (or plan to) a polyurethane like 3M 5200? 6. Because my deck plate is installed with screws, am I correct that I should just tighten the screws reasonably tight not squeezing out all the sealant under the plate and then just leave the screws alone after the sealant is cured so as not to break the seal on the screw?I've heard good reports about Boat Life Caulk but just want to take advantage of the latest technology if it's an improvement.Thanks, Rich Olson

 

[Grace L. Schmidt]

Chain plate

1. BoatLIFE's Release is an adhesive and sealant remover. It works at the bond between the sealant and the surface. It would be very difficult to get the area down in the chain plate crevice. It would be a bit easier for the deck hardware, but the same difficulty for thru-hulls. With so many other caulking options, I would not suggest using polyurethane for applications of this sort.2.Polyurethanes are definitely permanent and therefore more secure, at least in the short term. Over time, polyurethane continues to harden until a point when it can actually become brittle. Polysulfide, which has excellent adhesion qualities of its own, on the other hand tends to get better with age.3.When applied properly to a well cleaned and prepared surface, Life Calk has been know to last at least 10 years.4. No, BoatLIFE does not make a pure polyurethane. We do make a combination polyurethane/silicone, Life Seal. It gives the best features of each, excellent adhesion, but removable, permanent flexibility and excellent UV resistance, as well as 24 hour cure.5. Tightening the screws is always touchy. Not enough and you have a problem, too much and you squeeze out all the sealant. My recommendation would be to tighten them moderately, stopping before you squeeze out all the sealant. When the sealant is cured, come back and try tightening them again. If you do get a turn or two, I would dab some additional sealant around the edges to fill any gaps you may have created. Now you will have a good gasket underneath and good protection on top.