Drilling through Transom to mount new kicker
- Thread starter Wrinkles
- Start date
The transom is likely cored with balsa on that year and model of boat. To insure the long term integrity of the core, you should drill oversize holes, under cut the core in the holes, re-fill with thickened epoxy and then re-drill the holes to the size needed. Thataway Bob has posted a tutorial on the process before. I couldn't find the exact tutorial but here is a tutorial for a somewhat similar project. Of course if it isn't cored, life is a lot similar. For a sealant, Boat Life Caulk would be recommended for your install.Wrinkles":3myhqc33 said:
Just as a note, even if you find your transom is foam cored (rather than balsa or plywood), I would still overdrill/fill/re-drill, myself. Reason is that even though foam shouldn't soak up water, there is still the possibility of it de-bonding from the inner and outer fiberglass skins if water gets in (which it can through tiny voids or etc.). Once that bond is gone you essentially have three separate "transoms," with the two fiberglass ones (skins) being weak and floppy. When all three are are bonded together (the two fiberglass skins and the core material) they are really strong and stiff.
This will likely be shown in the links, but note that you don't have to make the holes through the fiberglass skin(s) as large as the area you plan to overdrill. I usually drill the outer hole that I'm going to "dig from" just large enough to fit the Dremel bit I like to use to "back cut" the coring out from inside (this back cut also gives the epoxy fill a bit of a "lock"), and the other hole in the skin I leave just the size of the fastener (that way I can use it to index where I had/have the fastener).
I like to use the Dremel #115 bit or Dremel sanding drum to dig out the coring (unless it's a really small hole, such as for a #6 screw, in which case I use a dental pick or other means). You can run the shaft of the Dremel right around the rim of the access hole you drilled and then let the bit "over-remove" the coring back past the hole rim.
This is what the #115 looks like:
And here is a sanding drum (there is also a larger diameter one too):
This will likely be shown in the links, but note that you don't have to make the holes through the fiberglass skin(s) as large as the area you plan to overdrill. I usually drill the outer hole that I'm going to "dig from" just large enough to fit the Dremel bit I like to use to "back cut" the coring out from inside (this back cut also gives the epoxy fill a bit of a "lock"), and the other hole in the skin I leave just the size of the fastener (that way I can use it to index where I had/have the fastener).
I like to use the Dremel #115 bit or Dremel sanding drum to dig out the coring (unless it's a really small hole, such as for a #6 screw, in which case I use a dental pick or other means). You can run the shaft of the Dremel right around the rim of the access hole you drilled and then let the bit "over-remove" the coring back past the hole rim.
This is what the #115 looks like:
And here is a sanding drum (there is also a larger diameter one too):