Thru-Hull Drilling - Bit to use?

[Jeffro]

I need to know what type of drill bit to use to drill a 1' hole for a Thru-Hull Intake for an additional ballast pump.I am concerned about chipping the finish. I would assume you would drill it from the outside. I am looking at the WakeMAKERS.com Complete Impeller Pump Ballast Kit.

[lsvboombox]

I need to know what type of drill bit to use to drill a 1' hole for a Thru-Hull Intake for an additional ballast pump.I am concerned about chipping the finish. I would assume you would drill it from the outside. I am looking at the WakeMAKERS.com Complete Impeller Pump Ballast Kit.

Any wood holesaw will work.... tape the outside and drill in reverse( i do the whole hole in reverse)... i would start on the outside then switch to inside and drill about an eighth inch then go back to the outside and. Finish the whole.... this way the inside will not split/splinter when u push thru.....

[lsvboombox]

Chamfer the hole as well... so u dont get chips and stress cracks..

[Jeffro]

Thank you!

[c.rix]

I used a diamond hole saw use for tile to get through the gelcoat then drilled through the rest forward with a regular wood bit much quicker

I figured if it wont chip ceramic tile it shouldn't chip the gelcoat

[maxpower220]

Everything posted above. Use tape on the hull prior to starting, start on the outside. The drill bit will work its way through, then finish from the inside. Start both sides in reverse. Once done, use some sand paper and round (or chamfer) the edges of the gel coat, this will help prevent gel coat cracks. Measure several times, you only get one shot.

[Canuckle Head]

Everything posted above. Use tape on the hull prior to starting, start on the outside. The drill bit will work its way through, then finish from the inside. Start both sides in reverse. Once done, use some sand paper and round (or chamfer) the edges of the gel coat, this will help prevent gel coat cracks. Measure several times, you only get one shot.

This may be a dumb question but how do you know how to match up when you go to drill from the inside? Can you see it?

[moombadaze]

^^^^Pilot hole, much easier to repair than a big 1" hole if its wrong

[Canuckle Head]

^^^^Pilot hole, much easier to repair than a big 1" hole if its wrong

I like that idea much better. Thank you kind sir!

[jmvotto]

I just drilled mine in reverse the whole way thru from the outside.. pretty simple. beer always helps the nerves.... pic in my ballast upgrade thread..