The Offshore Voyaging Reference Site

Great Core Removal Drill Bits

I think pretty much everyone knows that when installing new fittings on a cored boat we should first remove the core before filling the void with thickened epoxy and then re-drilling for the fastener(s).

There are a bunch of different ways to do this, but the set of Alfa Tools Forstner bits I just bought myself, while far from inexpensive, are the quickest, neatest, and generally best way I have found to make a suitable hole in the outer skin, and remove most of the core, without penetrating the inner skin.

Way better and more controllable than a hole saw.

Highly recommended.

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Mathieu Fortin

Forstner bits are a joy to use overall. I haven’t touched my spade bits in ages. Lee valley have a good selection for Canadians out there and shipping is free.

Torsten Hansen

Fiberglass is hard on Forstner bits. If you want them to last, you may want to drill the skin with a whole saw, then switch to the Forstner to remove the core

George Haselton

With correct file &stone these can be sharpened in minutes. Creating more solid waste from an item with only a tiny part (edge) needing a little grind isn’t appropriate

Peter Dunbar

Good idea— but I would rather use the cheapest Harbor Freight bits rather that high quality German ones.

Hugo Janse

I really like to drill the hole in the topdeck with a 8mm or larger bit and then ream out the rest with the dremel bit 115 using the hole as a guide. This leaves some topskin intact fixing the epoxy plug in place.