Thru Hull Fittings

So I'm thinking of starting my integrated ballast project and am going to pick up a through hull fitting. What do I need to think about be for cutting the hole. What is the best way to cut? What do I seal it up with?

1. Location, location location. After I got all my parts for my manifold, I dry fitted everything before drilling anything for proper fit, future pump maintenance, etc. Also, it helps if you drill a small pilot hole before using the hole saw. 2. Through hull hole size. You want to get the right size hole saw for the job obviously. It can even be a bit smaller than your through hull, which you can then file down to the size you need for a snug fit. 3. I used 3m Marine 4000 fast cure sealant.

GL and feel free to pm me if you have anymore questions. I'm sure more peeps will chime in. I just did mine a month or so ago and there's one thing I would've done differently and that is the location of my vents / drains.

Tony

According to Bob Lacovara, THE fiberglass and composite GURU, through hull fittings are the number one source of a failed hull after manufacture defect.

If you don't properly seal the hole, water will eventually seep in between the layers of glass in your hull. Once in, it's game over! The hull will eventually delaminate. Water will weaken the glass in the area over time. If freezing comes in to play, then it will happen a lot faster! Go find your local boat wrecking yard, outdoor boat storage facility, or rv storage place. If you look at the old boats the most common failure is the transom... it has lots of holes in it..

I know a lot of guys have drilled holes all over their boat with no problems, give them time...

I would either suggest glassing in the hull before the 3M Marine 4000 or move up to 5200... Just my opinion though.


Hmmm.

Hmmm... I'm really reconsidering. Thanks Sam! I don't want to ruin my boat. Plus the only place I can put a semi permanent bag is under the deck up forward and it won't even fill all the way. I'm just thinking that drilling and glueing for just one bag may not be worth it.

That is the dumbest response that I have ever read. Do u realize that every single boat in the water has a thru hull to cool the motor?? As long as you seal it properly you should have no problems at all. Just make sure to the area you drill is flat on the bottom. I know like 8 or 9 people that have drilled with no problems to speak of. If thru hull fittings are really that detrimental to hull integrity do u think manufacturers would use them not to mention offer long term hull warranties? Our first boat didn't have factory ballast and we drilled and fitted ourselves no problems in the four year we owned the boat. And my dad enlarged the thru hull on his supra last year no prob and I plan on adding another thru hull to my super air over the winter to allow me to plumb two more sacs in. Just take your time and pick your spot carefully.

Cut and pasted from this site:
http://www.diy-wood-boat.com/Through_Hull.htmlA New Hole?

If you are contemplating adding a through hull fitting you need to plan its position.
So before you start to drill that hole consider;

•Will it be readily accessible from inside.
•Will there be ample room to turn the valve handle.
•Will the new fitting set up any turbulence in front of your depth sounder or speed log impeller.
•Will the hose run from the fitting be a short and straight as possible.
•On the other hand, will that stiff hose be long enough to allow it to be bent for easy fitting and replacement.
Once you have chosen the position drill a pilot hole from the inside so you can be sure that it is centered on a plank and between frames.

Then using a hole-saw to suit the size of the fitting cut the required hole from the outside of the hull.

Using the hole-saw from the outside will give more room to control it and a crisper edge to the outside of the hole.

Once you are sure the hole is the correct size clean it up with sand paper and prime it with paint or varnish.

Use the same sized hole-saw to cut the aperture in a piece of hardwood for a backing plate.

The backing plate wants to be 2 or 3 inches larger than the flange of the seacock and shaped to match the inside curvature of the hull.

The backing plate is to reinforce the hull around the hole and to provide a flat surface for the seacock flange to bed onto.

The backing plate will also want to be primed to prevent rot.

If it is possible to plan for the hole to coincide with a butt block joint between planks, the valve flanges and securing bolts will add to the strength of butt and the butt will do away with the need for a backing plate.

However, the need for a new hole in the hull might possibly be avoided by fitting a tee-connector to an existing inlet or discharge line.



Read more: Through Hull seacocks below the waterline. http://www.diy-wood-boat.com/Through...#ixzz13hwMCNOZ
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Originally Posted by superair502

That is the dumbest response that I have ever read. Do u realize that every single boat in the water has a thru hull to cool the motor?? As long as you seal it properly you should have no problems at all. Just make sure to the area you drill is flat on the bottom. I know like 8 or 9 people that have drilled with no problems to speak of. If thru hull fittings are really that detrimental to hull integrity do u think manufacturers would use them not to mention offer long term hull warranties? Our first boat didn't have factory ballast and we drilled and fitted ourselves no problems in the four year we owned the boat. And my dad enlarged the thru hull on his supra last year no prob and I plan on adding another thru hull to my super air over the winter to allow me to plumb two more sacs in. Just take your time and pick your spot carefully.

Hey GENIUS!

If you could read the entire post you would notice that I said to do it correctly. After talking with THE industry expert not 8 or 9 people, I suggest that after you cut the hole, you seal it with glass/resin so that the sides (the exposed sidewall) of the hole are effectively sealed. This seals them off and stops water from being absorbed through the hole sidewall. What do they do at the factory of most major brands? They either use 5200, epoxy, or resin to seal the hole. They don't just drill holes and add hardware, I've been to the Correct Craft, Sanger, and MB factories and have seen this in person... not told by 8 or 9 people...

Just thinking out loud here, but I wonder how many DIYers "sealed" their through hull side walls prior to using 3m 4000 or 5200. That stuff is bullet proof, right?

Tony