Cutting 4" holes in fiberglass seat bases.

[kaneboats]

drilling the holes is literally a process that takes multiple sessions of drilling over a day or days

If drilling anything takes a long time your bit or hole saw is either the incorrect one (e.g., wood bit on metal) or it's toast. A new hole saw will pay for itself in saved time and likely save your drill(s) too.

[trayson]

If drilling anything takes a long time your bit or hole saw is either the incorrect one (e.g., wood bit on metal) or it's toast. A new hole saw will pay for itself in saved time and likely save your drill(s) too.

So, since most bits are billed as either metal or wood, then where does fiberglass fit in?

[MLA]

You just need a general use bit, just a quality commercial grade bit and arbor. Those cheap bits are not sharp to start with and dull quick. The arbor wears out along with the double-D slot in the hole bit.

[trayson]

You just need a general use bit, just a quality commercial grade bit and arbor. Those cheap bits are not sharp to start with and dull quick. The arbor wears out along with the double-D slot in the hole bit.

Would this be good enough?

http://www.amazon.com/DEWALT-D180064.../dp/B00005LEZR

[jstenger]

Yes, that is a good quality bit. You will also need the arbor for it.

[gregski]

A toothed hole saw is the wrong tool for the job. Yes, I know that basically everyone here has used them for fiberglass with success but that doesn't make it the right tool. You want some variety of a grit/grind blade. If I were you, I would buy this carbide grit saw: http://www.amazon.com/Lenox-Tools-29...ide+hole+saw+4. I used a similar Lenox carbide grit saw in a 1-1/8" size for my through hulls and it was a breeze. No "run it in reverse" tricks required since it is the right tool - the description even says it's for "fiberglass, ceramic tile, laminates, and other abrasive materials".

[MLA]

If you dont mind waiting and willing to mail order, then get the carbide bit. If you need to finish the job, you can walk into your box store and get

http://www.lowes.com/pd_348118-28303...d=3361258&pl=1

http://www.lowes.com/pd_300697-28303...d=3358054&pl=1

[gregski]

...or a dremel with a rotozip bit. That's what I used to cut a large deck plate hole in the center locker. It worked well. Even a jig saw would probably be better than a 4" wood hole saw.

[ian ashton]

I drilled mine with my 18v Ryobi, took about 30 seconds. I think you need a better hole saw.

[MLA]

...or a dremel with a rotozip bit. That's what I used to cut a large deck plate hole in the center locker. It worked well. Even a jig saw would probably be better than a 4" wood hole saw.

Actually no. The problem with a jig saw is you have the base of the saw riding along the finished gelcoat surface. Even if you tape it off, the vibration from the saw is going to tear the tape and mare the gel. The other issue with a jig, is having room to swing the body of the saw as you make your cuts, not to mention drilling a pilot hole for the blade. Two if its not a round hole.

Rotozip type tools will make fast work of fiberglass for sure, but you have to be super careful to not let them get away from you and color outside the lines if you will. I wont use them for round holes if I can use hole saw. The rotozips work for square or rectangle holes or off shaped holes. Even then, a 10" sub hole will typically kill a bit and on occasions, break one. I havent used my Roto in about 2 years now, moved on to a better tool.