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Stemhead replacement and broken drill bits

PostPosted: Mon Jul 16, 2012 7:40 am
by ChrisB
My stemhead fitting was seriously deformed during the wild Saturday morning sail through Pensacola bay in the Florida 120. This weekend I finally got around to replacing it. While I was at it, I wanted to perform the reenforcing fix on the "L" bracket that joins the foredeck and the prow by adding two SST bolts through the prow and the bracket. Everything went well until I was drilling the hole for the second bolt and the drill bit snapped off when it cut into the metal of the "L" bracket. Of course, the bit broke off flush with the fiberglass (except for the jagged piece of metal that sliced my finger open when I was stupid enough to run my finger over it). For the time being, I took my dremel tool and ground the burr off the broken bit and covered the bit and hole with sealant. Should I be concerned about leaving the bit entombed in the hull and if so, does anyone have a suggestion as to how to remove the drill bit? Or, in the alternative, should I just keep it sealed and leave it where it is?

PostPosted: Mon Jul 16, 2012 1:15 pm
by GreenLake
Entombed has such a nice ring!

I can't see any huge downsides offhand - other than that you might be determined to complete the job an get a second bolt in there.

PostPosted: Mon Jul 16, 2012 2:27 pm
by ChrisB
I put in the second bolt; just not in my first location choice. I was fortunate enough to have a fairly long "L" bracket and have a relatively easy to see outline off it through the "goop" that holds the bracket to the inside of the prow. I just moved the location of the second bolt.

PostPosted: Mon Jul 16, 2012 2:58 pm
by K.C. Walker
Chris,

The only reason I can think of to extract the drillbit would be corrosion. The rebar that reinforces the cuddy on my 1974 boat has held up amazingly well. So I think your idea of entombment might almost be a permanent solution. Certainly one you may not have to worry about.

PostPosted: Mon Jul 16, 2012 4:30 pm
by GreenLake
To make it really permanent, you might try to get epoxy into all the voids. Depending where on its shaft the bit broke, you may need to drill a tiny pilot hole above it to get epoxy in there to fill the grooves in the drill bit.

A really low viscosity epoxy that is free of solvents would seem ideal for such a purpose. RotFix (or even Clear Coat) from SystemThree would fit the criteria.

The rebar does hold up. Mine is 11 years older than K.C.'s and no issues so far.