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Best way to plug a screw hole on mast top?

windblown

Member III
I’m replacing the bracket for my wind transducer, and it will leave two old screw holes on the top of the mast partially exposed. What’s the best way to fill the holes before mounting the new bracket to avoid leaks in the future? I‘ve considered: 1. put the old screws in, and use a rotary cutter to trim the tops to create a flat surface; 2. Countersink the old holes and put new flat top screws in; 3. use Bondo or some kind of filler. If I go with either screw option, I assume I’d use tef-gel for stainless steel screws going into aluminum, yes?
Thanks, in advance, for your advice.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Several older screw holes in our spar are filled (flush) with thickened epoxy. No change to those subtle little circles in over 20 years. Seems to be a good solution.
 

windblown

Member III
Several older screw holes in our spar are filled (flush) with thickened epoxy. No change to those subtle little circles in over 20 years. Seems to be a good solution.
Thank you, Loren. Good tip. I haven’t done much work (any) with thickened epoxy yet, but it’s definitely in my future this season. Do I need to worry a bit about epoxy dripping through to the halyard sheaves below (inside the top of the mast), before it sets?
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Thank you, Loren. Good tip. I haven’t done much work (any) with thickened epoxy yet, but it’s definitely in my future this season. Do I need to worry a bit about epoxy dripping through to the halyard sheaves below (inside the top of the mast), before it sets?
Ours are in the side wall of the spar, so I do take your point. Hmmmm.... need a way to "back up" that hole.
Even if you drill and tap, the swarf would fall down somewhere ----- but then you could thread in an aluminum bolt and either leave a pan head exposed or cut it flush. Just try to avoid removing any of the old anodized surface as much as possible.
BTW, in the past I have easily threaded a quarter inch aluminum rod for a different project; easy with my old tap n die set. Use oil, it's a soft metal.
 

windblown

Member III
Ours are in the side wall of the spar, so I do take your point. Hmmmm.... need a way to "back up" that hole.
Even if you drill and tap, the swarf would fall down somewhere ----- but then you could thread in an aluminum bolt and either leave a pan head exposed or cut it flush. Just try to avoid removing any of the old anodized surface as much as possible.
BTW, in the past I have easily threaded a quarter inch aluminum rod for a different project; easy with my old tap n die set. Use oil, it's a soft metal.
So the advantage of the aluminum rod would be to avoid future deterioration due to corosion between different metals?I would thread the rod, screw it in with thread lock, and cut it off?
 

toddster

Curator of Broken Parts
Blogs Author
No extensive research, but I plugged old mast holes with a dab of JB Weld. I guess the same result as thickened epoxy. I’d pretty much forgotten they were ever there.
 

gabriel

Live free or die hard
if the new bracket is covering the old holes and flush against the mast, a small ball of butyl over the holes might be one idea.
 

Rocinante33

Contributing Partner
No extensive research, but I plugged old mast holes with a dab of JB Weld. I guess the same result as thickened epoxy. I’d pretty much forgotten they were ever there.
J-B Weld is super easy to use and its pretty thick so I don't think I would worry about drips inside. Don't be too heavy handed and Just "shmear" some in the hole and forget it. You may want to wipe it out before hand with a bit of acetone so it will be clean and stick well.
 

Sailingfun

Member III
J-B weld will do the trick. If you prefer add a screw, don't forget add a touch of tef gel in order to avoid corrosion and harsh comment from arm chair captains ;)
 

Tom Metzger

Sustaining Partner
What’s the best way to fill the holes before mounting the new bracket to avoid leaks in the future?
OK, I'm new at this boating stuff, but with all of the openings at the top of the mast what is the matter with a couple of new open screw holes? I suspect there may be other problems if this is a sinking concern.

It's hard to believe that I used to have hopes of sailing on this boat.
 

windblown

Member III
OK, I'm new at this boating stuff, but with all of the openings at the top of the mast what is the matter with a couple of new open screw holes? I suspect there may be other problems if this is a sinking concern.

It's hard to believe that I used to have hopes of sailing on this boat.
I see your point.
 

RCsailfast

E35-3 Illinois
Prepped the mast today and sparingly used black life caulk to seal holes. It had worked well in past holes I don’t plan to use again, but can be easily removed if needed. Still working on removing silicone sealant used all over the boat. That stuff should be outlawed,
 
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