Installing a Skin Fitting
Submitted by Jackfrost80 on Wed, 2015-10-21 11:28
I am installing a second automatic bilge pump and transducer and the diameter of the through hull fittings are 21mm and 26mm but the hole saw fittings at Bunnings and Masters only come in 20 or 22mm and 25 or 29mm. Is it just a case of cutting through the hull at the smaller diametre and filing it out or are there specialty hole saw bits I can track down?
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randall df223
Posts: 6454
Date Joined: 08/08/11
I reckon the the 22mm saw
I reckon the the 22mm saw would be ok for the smaller fitting as long as you have a good size flange on the fitting and plenty of sika flex. The 29 mm saw is probably getting too big for the larger one though.
Seakem maybe able to give some good advive hole saws
Fish! HARD!
Jackfrost80
Posts: 8156
Date Joined: 07/05/12
Cheers mate, I thought the
Cheers mate, I thought the same with the 22 as it's only the transducer cable cover. Beyond Tools has the 21mm and 27mm bits so looks like I'm sorted. No project is cheap on a boat haha
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makai
Posts: 459
Date Joined: 28/10/08
Holesaws
There is generally so much slop / wobble in holesaws that they cut a larger hole than specified. So the 25mm holesaw will almost certainly cut a hole big enough to fit the 26mm fitting. Maybe try a test hole in some scrap before tackling the hull.
Jackfrost80
Posts: 8156
Date Joined: 07/05/12
Even better mate, the old man
Even better mate, the old man have a set with 25mm
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nightfish
Posts: 327
Date Joined: 18/10/10
Unibit or step drill bit
expensive but may cover those size holes?
sea-kem
Posts: 15040
Date Joined: 30/11/09
Just make sure you drop your
Just make sure you drop your drill speed down and plenty of cutting paste or even grease will do it. That's if it's an ali hull? Makai is right they will generally slop around a bit and give you a bigger Diameter.
Love the West!
Jackfrost80
Posts: 8156
Date Joined: 07/05/12
Glass mate. I intend to tape
Glass mate. I intend to tape the area with blue painters tape and run the hole saw backwards until I get through the gelcoat and then nice and steadily cut through the hull.
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grantarctic1
Posts: 2546
Date Joined: 03/03/11
As above
As said above, better to go the slightly smaller size hole.
Being fibre glass you could then use a half round file to open the hole up a bit if needed .
oz74
Posts: 276
Date Joined: 14/05/12
..
agree- you can always make a hole bigger.....
z00m
Posts: 1086
Date Joined: 10/05/14
You can't fit a 21mm cylinder
You can't fit a 21mm cylinder in a 21mm hole.
Jim
Posts: 1342
Date Joined: 05/05/06
With a hammer anythings
With a hammer anythings possible!
Bend over
Chinbald
Posts: 317
Date Joined: 21/02/09
Just did the exact same job
Fitted a second auto bilge pump and a deck wash pick up to the Reefy, drilled the hole with hole saw, then used a mates high speed electric die grinder with a small cloth wheel, best little tool for the job and recommended for glass work.
thesupervisor
Posts: 1136
Date Joined: 10/06/09
was just about to say die
was just about to say die grinder
Best tool ever
getting the bottom line final answer from a bunch of blokes that use false names and put smiley faces at the end of paragraphs is not the best place in the world to get the information you seek.
thesupervisor
Posts: 1136
Date Joined: 10/06/09
was just about to say die
was just about to say die grinder
Best tool ever
getting the bottom line final answer from a bunch of blokes that use false names and put smiley faces at the end of paragraphs is not the best place in the world to get the information you seek.
sea-kem
Posts: 15040
Date Joined: 30/11/09
Yep, never gets a rest in
Yep, never gets a rest in our workshop. Internal deburring, oversizing etc. Brilliant tool.
Love the West!
Jackfrost80
Posts: 8156
Date Joined: 07/05/12
Cheers guys. Ran some holes
Cheers guys. Ran some holes through practice wood and the 25mm hole saw was too small so ended up getting a 27mm one and it worked a dream.
My advice to anyone drilling through a hull is to get two very strong magnets to locate where the hole will come through as I measured up the exact same spot on the port side as the other bilge outlet on the starboard side and if I'd had gone in there I'd have hit a curved section inside the hull.
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randall df223
Posts: 6454
Date Joined: 08/08/11
Hard drive magnets out of
Hard drive magnets out of old computors work a treat thru 4mm plate ali.
Fish! HARD!