Tuesday, May 22, 2012

Hatch Bedding & Deck Hardware

     This post is a bit out of order, but I am trying to catch up on the backlog I created over the winter. During the cold season, I did complete quite a few maintenance tasks, and I'll try to get some of them up here for viewing.

     If you own a boat, you should know that all the hardware mounted on deck needs to be re-bedded periodically. How you decide to schedule the work is up to you, but, since the recommended interval is about 5 years, I recommend that you re-bed 1/5 of your deck hardware each year. That way, it never gets away from you, and it's not such an overwhelming job when the time comes.

     This year, I decided to re-bed all three deck hatches, both deck rails (the stainless rails on deck, between the hatches), and the windlass foot switches. The first step is the easiest - just pull all the screws, and remove the pieces....

The pictures above show the deck coring, after the hatches are removed. It is very important to carefully inspect and evaluate these areas, once they are exposed. Water intrusion will slowly soften and rot the balsa coring, resulting in delamination and subsequent weakening, or failure, of the deck structure. Once you have access, take a screwdriver or pick, and probe the balsa, and see if there are any soft spots. Also, look for any telltale signs of water staining, discoloration, etc. If the coring is clean and dry, you can move on. If it is wet, it must be dried before proceeding further. If it is softened, or rotted, then the damaged sections will have to be removed, and the deck re-cored.

     Fortunately, as you can see, the coring below these hatches is unstained and dry. The factory applies a coat of gray paint as a sealant, but as the years go by, continued deck flexing cracks the paint. To further protect the balsa, I mixed up some West System #105 Epoxy, and applied 2 coats to all the exposed coring, then let it cure for a couple days. However, I did not apply the epoxy until a couple weeks had gone by, after I removed the hatches. That way, any residual moisture in the coring has time to dry out.

     After the epoxy has cured, the next step in preparation is to chamfer all the screw holes in the fiberglass. This is done for two reasons - first, a small chamfer holds a bit of sealant around the fasteners, and allows for a bit of flexure without compromising the seal. Second, the chamfer prevents gel coat cracking when the screws are tightened, and that also improves the seal and deck integrity.

     Now, once the deck and hatches have been cleaned and prepared for installation, I place the hatch in position, ,and start a couple screws to hold it in place. Then, apply tape to the deck, all around the hatch, as shown below:

     Around the corners, I use striping tape, because it can be contoured so easily. Once taped, pull the hatch, apply a large bead of sealant to the deck, and place the hatch back in position. Make sure there is sealant around and in every screw hole. Tighten the screws evenly, then remove any excess sealant, and finally, pull the tape. You should be left with a perfectly sealed component...


  1. Have you ever used butyl rubber tape as a seal? Looking at doing my hatches and windows this year and have been considering using butyl...thoughts?

  2. Butyl tape is an excellent product, for use in a compressive seal application. But, normally, hardware bedded with butyl tape is bolted in place. So, you put the tape under the bolt heads, and under the fitting, lower it into position, and tighten the nuts from inside the boat, WITHOUT TURNING THE BOLT HEADS. Your hatches are held down with screws, and the butyl will squeeze out as the screws are tightened. So, you'd have to mix sealants, and use butyl on the hatch, and sealant on the screws. Doing that, you risk interference between the sealant and butyl. I'd recommend against it in any case where screws, and not bolts, are used to retain the hatch or window. If you have bolts and nuts on the windows, it's great stuff.