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View Full Version : Thru-Hull Drilling - Bit to use?



Jeffro
03-13-2011, 07:17 PM
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
03-13-2011, 08:27 PM
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
03-13-2011, 08:30 PM
Chamfer the hole as well... so u dont get chips and stress cracks..

Jeffro
03-13-2011, 10:10 PM
Thank you!

c.rix
03-17-2011, 05:46 PM
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
03-17-2011, 09:48 PM
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
03-18-2011, 03:09 PM
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
03-18-2011, 03:23 PM
^^^^Pilot hole, much easier to repair than a big 1" hole if its wrong

Canuckle Head
03-18-2011, 03:39 PM
^^^^Pilot hole, much easier to repair than a big 1" hole if its wrong

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

jmvotto
03-18-2011, 04:28 PM
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..

maxpower220
03-18-2011, 06:21 PM
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?

A standard hole saw has a drill bit on which you attach the hole saw teeth. The drill bit is used to center your hole, it also protudes further out than the saw. The drill bit will penetrate the inside surface well before the hole is complete. You simple go to the inside of the boat and place the drill bit in the hole and start sawing.

Canuckle Head
03-18-2011, 06:53 PM
A standard hole saw has a drill bit on which you attach the hole saw teeth. The drill bit is used to center your hole, it also protudes further out than the saw. The drill bit will penetrate the inside surface well before the hole is complete. You simple go to the inside of the boat and place the drill bit in the hole and start sawing.

Doh! Forgot about that part......

mmandley
03-19-2011, 09:49 AM
Look in my upgraded thread listed in my sig if you want to see a 2 beer job to calm the nerves lol. The hole i put in the nose of my boat i could put my hand threw it. No going back when its that big.

tazz3069
04-02-2011, 07:16 PM
Do not use a regular hole saw. It will chip the gel coat. Goto Home Depot and get a 1" Diamond hole saw. It cuts like a hot knife through butter. I use this when I cut my holes for my new ballast system.

Gottop69
06-16-2011, 11:55 AM
bringing back old post.. Do you need to epoxy the hole or just use rubber gaskets to help seal the raw fiberglass

lsvboombox
06-16-2011, 12:03 PM
bringing back old post.. Do you need to epoxy the hole or just use rubber gaskets to help seal the raw fiberglass

sealing the inside of the hole can only help but 3m 4200 or 5200(just about permenant) between the fitting and hull would be fine

Gottop69
06-17-2011, 09:27 AM
ok so no need to seal hole with epoxy?

lsvboombox
06-17-2011, 09:30 AM
ok so no need to seal hole with epoxy?

not a requirement...... just overkill(i am into to overkill)

jmvotto
06-17-2011, 10:12 AM
Don't really see a reason to use expoxy or sealant on the thru hulls, they don't do it at the mfg level. if you ever change them out it will be a B&tch to get them out using the 3m 4200 or 5200. MY .02 They shouled be well above the water line so splahing and rain water should not seep in.

lsvboombox
06-17-2011, 10:46 AM
Don't really see a reason to use expoxy or sealant on the thru hulls, they don't do it at the mfg level. if you ever change them out it will be a B&tch to get them out using the 3m 4200 or 5200. MY .02 They shouled be well above the water line so splahing and rain water should not seep in.

oh yes... for some reason I am thinking of a thru hull fitting under the waterline.... above the waterline I still used 4200..

Gottop69
06-17-2011, 11:38 AM
I am talking below water line

bergermaister
06-17-2011, 03:12 PM
Well if you're REALLY loaded down with ballast on the surf side they may be dragging through the water! I just did new thru hulls right under the rub rail on each side towards the front of my rear compartments and added a little 4200 just to make sure.