by edelweiss » Sun Sep 02, 2012 3:50 am
I recently tackled this issue. The short answer is there is a small backing plate and to get to it you would have to remove the head liner. We have a 38T hull.
I decided that removing the head liner was not something I was willing to do. So I approached this from the outside of the deck.
I removed the grab rails first by cutting the bronze 1/4 20 bolts with a reciprocating blade ( like the FEIN tool ) This process was rough on the gelcoat raised pad but saved the teak. Next I drilled out the embedded bolt in an "aggressive" fashion. You could say that I was very deliberate. In the process I opened up the hole to about a 3/4 inch diameter. I was very careful about the depth to avoid penetrating the head liner. My goal was to get about 1 3/4 inches deep. After removing the grab rail I found that there were 7 holes for 6 bolts. There was a drilled hole with no bolt in it. This was an obvious construction error and a source of leak as the bedding material aged and failed. I drilled this hole out too. I left these large cavities open to dry for several weeks.
The repair was basically using the epoxy pot method described in the Gudgeon Bros text on using epoxy.
I flushed and cleaned the holes with acetone. After 2 more days of drying I first coated the cavity with straight epoxy and then I filled the cavity with thick reinforced epoxy making and effort to displace some epoxy laterally under the original fiberglass. I left this set up for several weeks. I sanded this down to just below the surface level and replaced the gelcoat using standard white. The color match was excellent and as you know using gelcoat often requires several applications to get a perfectly smooth level surface. Take care to remove the wax with acetone between coats.
Gel coat DOES stick to epoxy providing you are very exacting in your epoxy mixing and you let it cure.
Time to clean up your grab rail while you can take it to the shop and do a great job. Clean up the holes with a drill press and measure the depth that your bolt with require in the wood. This is also a great time to varnish it with happiness because you dont have to tape around the base and stand on your head to do the underside.
I used the grab rail itself as a drilling guide. You will need a willing helper to bend it into position and hold still while you position and drill. Much like placing a jib track. I drilled down 1 1/2 inches, not all the way thru the epoxy, creating a blind hole. Then I used a 1/4 20 long shaft nut tap ( from McMaster-Carr not cheap ) and tapped to the bottom of the hole. I dry fitted the cap rail and admired the position. With a pencil, mark the outline of where the base of the rail sits on the gel coat base. If you do not like it, you can repeat the above steps again.
Bevel the hole in the gelcoat. This is probably not necessary since this is a blind hole but.... just in case and is a very good practice.
My new choice of bedding material is butyl rubber which comes in a long roll of tape. It is about 1/8 inch thick but will compress and ooze out with clamping compression.
Clean the surfaces of the gelcoat and bottom of teak grab rail. Place your butyl on the gelcoat where the base of the rail will sit using the pencil outline as a guide.
You will need a helper for this next step
Begin replacing the the rail with the fittings. I used SS 1/4 20 bolts that would penetrate the tapped base 1 to 1 1/4 inch. Be careful not to cross thread the tapped epoxy. There is a lot a pressure on the bolt laterally as you place each one but since you dry fitted these they should all find a home by levering the rail back and forth slightly until it is centered over the epoxy hole. It can be useful to very slightly over size the bolt hole in the teak so that the bolt moves easily in it.
With all the bolts down, apply compression to the rail by whatever means available. If you have some heavy friends, have them stand on the rail and you gradually tighten the bolts to compress the butyl. It will compress more quickly on a hot day. I did this over several days slowly tightening all the bolts. The result is a very satisfying completely leak proof grabrail. Trim the excess butyl that has oozed out ( save it for some other project )
The only difficulty I found was that it was hard to compress the butyl down so take your time on this.
1980 HC 38T/MKII hybrid