OK I'm installing my drystacks from EMI and guess what the holes dont line up very well,so I need to open them up, I've been using a barrel sander on a drill is there a better way? I think a sawzall is a little over the top....

Dyno,

I did a 3" to 4" holes for a friend. I put a piece of wood inside transom with a block of wood on it though the old hole. Then I was able to use that to center a hole saw.

If you go that route mask up the glass real good and start cutting with the drill in reverse until you are through the gell coat.

Try one of the drill rotary rasps. The glass will kill the bit, but it should last long enough to finish the job. The longer the bit is, and the greater the diameter, the better it will work. The length to keep you from accidentally pulling out (!) and the diameter to give a smoother cut.

Good question,i need to open up my existing holes from 4" to 5". The best idea ive had so far is to put a old smallblock 350 4" dia piston in the hole with a centering hole in the piston and use a 5 inch holesaw. Is there a better way?Smitty

Smitty,

I think that would work well, in the above mentioned method I used, I forgot to mention that I fixed the inside wood to the transom with two small screws to hold every thing solid. Caulked them up after of course.

Rotary rasp on a air powered die grinder.

How about a jigsaw? A few layers of painter's tape around the hole will keep the base from marring the glass. I tried to cut out holes/slots for new pop-up cleats with a roto-zip, and it was taking way too much time. The jigsaw with a wood blade did the job in a few minutes.

Brian

Thanks for all the input I may take a shot at it with the rasp and my die grinder..

An OSO member once suggested doubling up the holesaws.
Put a 4" inside a 5" and use the 4" for the pilot.
Similar to your idea.

I used a piece of plastic.. had it cut to just fit the 4" hole, then cut it to 4 1/2".. Worked pretty good. But the wood plug screwed in from the back by a cross brace would be the ticket.. You can offset the new hole to make up for the missalignment. Then glass in the open part and sand it smooth.

Of course you have to pop for the bigger hole saw, but hey.. that 4.5" saw has seen a good bit of use.. Next will be the 5".. on the new motor..

Dick