Adding above water line thru hull….

NYSail

.
Jan 6, 2006
3,145
Beneteau 423 Mt. Sinai, NY
Hello all…..
Im buying my wife a new secondary bildge pump for Xmas and want it to have its own discharge hose. Currently my beneteau has two factory installed pumps that work in tandem. Have two issues: 1- the pumps are inadequate for the boat and 2- the two hoses combine into a similar sized hose and exist the boat through one fitting. My feelings are that the two pumps get restricted when going into the similar hose it pumping maximum water.
Anyway, want to remove one of these pumps and run a single hose out and then add a high capacity pump with its own float and thru hull fitting.
question: what is the best way to cut the hole through the gel coat without making a mess? Thought I would use a hole saw with a long enough pilot bit and score the outside gelcoat drilling slowly in reverse. Then once down enough, finish the job going through the fiberglass.

Love any advice.

Greg
s/v Souleil
 
Jan 4, 2006
7,266
Hunter 310 West Vancouver, B.C.
Then once down enough, finish the job going through the fiberglass.
Sounds like you've got one dull hole saw. Mind you, all it takes is one or two cuts through the glass fibre and it's pretty well shot. Even if you do have a bit of chipping on the new hole, it will be covered by the thru-hull mushroom head or have I missed something here ?

If you're having problems with the hull not having enough thickness to hold the pilot bit steady, hot glue a small piece of 3/4" plywood (no solid wood) behind the hole for a more solid hold on the pilot drill.
 
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Jan 11, 2014
12,960
Sabre 362 113 Fair Haven, NY
Predrill the pilot hole. Cover the area to be drilled with blue masking tape. Use a good quality bimetal hole saw. If you use a mushroom type fitting the mushroom will cover any small chips.
 

NYSail

.
Jan 6, 2006
3,145
Beneteau 423 Mt. Sinai, NY
Sounds like you've got one dull hole saw. Mind you, all it takes is one or two cuts through the glass fibre and it's pretty well shot. Even if you do have a bit of chipping on the new hole, it will be covered by the thru-hull mushroom head or have I missed something here ?

If you're having problems with the hull not having enough thickness to hold the pilot bit steady, hot glue a small piece of 3/4" plywood (no solid wood) behind the hole for a more solid hold on the pilot drill.
The hole saw is plenty sharp.... Just never cut through gelcoat and don't want to do something stupid and find that it cracks off in sheets...... Hull is very thick
 

NYSail

.
Jan 6, 2006
3,145
Beneteau 423 Mt. Sinai, NY
Predrill the pilot hole. Cover the area to be drilled with blue masking tape. Use a good quality bimetal hole saw. If you use a mushroom type fitting the mushroom will cover any small chips.
Like the tape idea.... thanks
 
Jun 2, 2004
3,554
Hunter 23.5 Fort Walton Yacht Club, Florida
Run the hole saw in reverse first to get through the gelcoat.

If accessible drill about two thirds of the way from the outside in then from the inside out and you will not get the tearout as you push through the last part of the hole.

Most important is to let the bit do the work no need to push the bit through.
 
Jan 11, 2014
12,960
Sabre 362 113 Fair Haven, NY
Im buying my wife a new secondary bildge pump for Xmas
This in my estimation is a perfectly viable Christmas gift. For you young ones, there comes a point in your life when you and your significant other are very difficult to shop for, cause, if you want it you buy it. Thus, it takes great creativity to choose a gift that is meaningful and appreciated.

A few years ago I gave my wife an eWincher for Christmas. It is one of her all time favorite gifts, to be honest she was not wowed on Christmas Day, however, once the boat was back in the water and we were cruising, she adored it.

This year she's receiving a Wichard Gyb'Easy. Thanks to a super deal from Landfall Navigation. Again, she won't appreciate it until we are sailing down wind, and then she'll love me for the thoughtfulness.

To satisfy her until we get a chance to use the Gym' Easy, she will receive an ample supply of Puna Chocolate. This is one of the finest chocolates we have found. The beans are grown and processed on the island of Hawai'i on small organic farms. Once in a while she will share a piece, if I'm good. :biggrin:
 
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NYSail

.
Jan 6, 2006
3,145
Beneteau 423 Mt. Sinai, NY
Pure romance of a sailing couple. The control lines I got for her stocking are the icing on the cake. I’m hoping for a fresh water pump and 6’ of fuel line….. a guy can only dream.

Ha……
 

NYSail

.
Jan 6, 2006
3,145
Beneteau 423 Mt. Sinai, NY
This in my estimation is a perfectly viable Christmas gift. For you young ones, there comes a point in your life when you and your significant other are very difficult to shop for, cause, if you want it you buy it. Thus, it takes great creativity to choose a gift that is meaningful and appreciated.

A few years ago I gave my wife an eWincher for Christmas. It is one of her all time favorite gifts, to be honest she was not wowed on Christmas Day, however, once the boat was back in the water and we were cruising, she adored it.

This year she's receiving a Wichard Gyb'Easy. Thanks to a super deal from Landfall Navigation. Again, she won't appreciate it until we are sailing down wind, and then she'll love me for the thoughtfulness.

To satisfy her until we get a chance to use the Gym' Easy, she will receive an ample supply of Puna Chocolate. This is one of the finest chocolates we have found. The beans are grown and processed on the island of Hawai'i on small organic farms. Once in a while she will share a piece, if I'm good. :biggrin:
A gyb-easy…… you romantic fool you! I got chills.
 
Jan 4, 2006
7,266
Hunter 310 West Vancouver, B.C.
The hole saw is plenty sharp.... Just never cut through gelcoat
Then you're ready to go. The thick hull will give your pilot plenty of guidance. Hint: don't pre-drill the pilot hole as you want the pilot hole as snug as can be. The hole saw will be your guide when the teeth start cutting. If the teeth don't want to follow the first pilot hole, #$%@#^& because now you've got a loose pilot hole.

The coverage of the area to be cut with masking tape (as per @dlochner ) renders the job completely fail-proof.

I put in a 3" vent hole through a FG enclosure for an engine compartment cooling fan and just took it real slow and easy. Not a blemish anywhere on either the internal or external edges of the hole. The hole was above the hull without a lot of thickness for guidance.
 
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Mar 26, 2011
3,718
Corsair F-24 MK I Deale, MD
The tape is not needed if you just start easy. It's not a big twist drill. But whatever.

Keep the saw wet as you cut. This will save time and save the saw. A spray bottle will do.
 
Jan 11, 2014
12,960
Sabre 362 113 Fair Haven, NY
Hint: don't pre-drill the pilot hole as you want the pilot hole as snug as can be.
Drill a smaller hole first. Most hole saws use a ¼" pilot, drill a 3/16" pilot. The pilot bit may wander before the hole saw bites in. The smaller pilot hole helps to prevent that while allowing a snug fit for the pilot drill.
 
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jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,149
CAL 35 Cruiser #21 moored EVERETT WA
I have put several holes through the old gelcoat on my 1974 boat. If it was going to shatter it would have. I measured the location both inside and out. (if you have a stripe you want to either miss the stripe or put the hole inside the strip. Half in half out looks bad.)

I have used a pilot bit and not. The Pilot bit helps. You want to use the masking tape (I did). I also grooved the gelcoat by running the drill in reverse at a slow to moderate speed. This created a track through the gelcoat without splits. I Dry fitted the external mushroom, then marked the tape with a sharpie. I then used a razor blade to cut the outline of the through hull mushroom. Pulled the tape where the mushroom fits to the hull. When I then fit and caulked the through hull to the hull, the area under the mushroom was adhered to the hull and the area outside the mushroom was not gooed up with over run caulk. It was on the extra tape and when I pealed the tape up it left the hull clean.

A great DIY job... If in doubt just have a friend standing by to encourage you to "DRILL IT". And a beer :beer:to reward you for taking action putting a hole in your boat.:yikes:
 
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Sep 17, 2012
110
Morgan 383 Fairhaven, NY
+1 on running the hole saw in reverse. It minimizes chipping of gel coat. File a slight countersink on the circumference edge to relieve sharp edges and hold a "bead" of caulk.
 
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NYSail

.
Jan 6, 2006
3,145
Beneteau 423 Mt. Sinai, NY
Thanks for all the good input. Simple enough job, but as I said, never cut into gel coat (on purpose) and didn’t want to make a stupid mistake that others had experienced.

Greg
s/v Souleil
 
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Jan 19, 2010
12,565
Hobie 16 & Rhodes 22 Skeeter Charleston
If accessible drill about two thirds of the way from the outside in then from the inside out and you will not get the tearout as you push through the last part of the hole.
Most important is to let the bit do the work no need to push the bit through.
:plus: This approach works from either direction. I usually start from the inside so that I can get the nipple just where I want it on the inside of the boat for the hose exit location.
 
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