Bedding deck hardware is something that all boat owners need to do sooner or later. Either because of leaks, new hardware or maintenance of existing hardware. Recently I found an article that shows how the author and several boat manufactures use Butyl Tape for bedding deck fittings.
First I would like to cover some common errors I and others have found on boats and offer a few tips that we have found that help make a better and longer lasting bedding job.
Remove all the old bedding compound.
Clean, clean and clean some more before applying new bedding compound. Many leaking fittings I have taken apart were not cleaned well and the bedding compound did not stick to the hardware. Remember that stainless steel has oil on it from the factory and gel coat can have release agent or other contaminates on it many years later. A bit of wire brushing (or Bronze Wool or Scotch Brite) will help to clean things up, this should be followed through with a thorough cleaning with a degreaser or adhesive remover. Sometimes when parts are very dirty a vigorous scrubbing with soap and water first is required.
Countersink the holes a bit to remove any sharp edges. This will help to prevent cracking around the holes by removing the sharp edge stress raisers. The countersinking will also leave a small “O” ring type area for the bedding compound to squeeze into and prevents all the bedding compound from being squeezed out when the fasteners are tightened.
Use backing plates on hardware such as stanchions and control fittings for travelers and mooring cleats that can be heavily loaded. One one boat, the factory had put plain washers on the hardware that controlled the traveler, as expected the stress of tacking and jibing flexed the sides of the cockpit (solid fiberglass) and cracked the gel coat which required repairs to the side of the cockpit. After paying an outrageous price for the repairs, I installed large fiberglass backing plates and several years later, no leaks and no damaged fiberglass. When I install backing plates I put either bedding compound or high strength fairing compound (thickened epoxy would also work) under the backing plate so there is no point loading on the rough side of the fiberglass and the backing plate has a nice contact with the surface it clamps to.
Sometimes backing plates are required on the top of the deck also for high load hardware. This is often done for mooring cleats or similar high load conditions.
Large heavy washers are better than the standard washers or fender washers found at most hardware and marine stores. The heavy duty washers are hard to find but make a much more secure mount. Washers can also be cut from fiberglass sheets.
I am a great believer in having solid plugs for every deck penetration if the deck is cored construction, such as Balsa, plywood or foam. The hole in the core material is enlarged and then filled with Epoxy, High Strength Filler or other suitable resin. Pieces of solid fiberglass rod can also be used. The solid plug makes sure that no water gets to the core if the bedding compound fails.
Brown stains around a fastener on the inside of the boat is a very bad sign and indicate a leak at a fastener or hardware. The leak should be addressed before more damage is done and a large amount of wet core needs to be removed and repairs made.
Use lots of bedding compound. Squeeze out is good.
Put a large donut of bedding compound around the fastener where it comes through the hardware, be sure and turn the fastener around a bit to help the bedding compound fill in the threads. A ring of bedding compound under the head of the fasteners is also good.
Dry fit the hardware and put masking tape around the hardware a small distance away from the edge of the hardware, this will make clean-up much easier and keep the bedding compound squeeze out from getting all over the deck. Trust me here – DO NOT omit this step.
C & C and a few other manufactures use the Butyl tape method of bedding hardware, however it is a bit more work than the slop and bolt method used by many companies and yards.
I hope this helps you to maintain your boat in good condition.
UPDATE: I checked with a friend that has a 38 year old “Butyl Tape Boat” and they say the deck joint is still tight and they have a couple of minor drips in other places but the boat is otherwise real dry and they have been on more expensive and newer boats that are not “Butyl Tape Boats” that dripped more below, so the extra bit of effort seems to be working out well.
Thanks for your interest in and support of boating safety.