Thru hull fittings

dutch123 · Posted: Tue May 12, 2009 10:32 am Post subject: Thru hull fittings

Can someone give me advice on drilling the hull for a thru hull fitting please. Obiously this makes me a little nervous and i'm wondering if there is another option. Use is for a wash down pump that is currently plumbed into the 20 gal fresh water tank. Is it possible to mount an intake under the swim grid to avoid drilling the hull? What is the norm? thats for the help. Rolling Eyes

Rob & Karen · Posted: Tue May 12, 2009 10:46 am Post subject:

I have a washdown pump in the cockpit, and I too was reluctant to drill a hole in the hull. I ran the intake hose through the rubber boot into the splash well where it stays when not in use. When I want to use the pump, I hang the hose over the transom into the water next to the motor. Hope this helps.

Rob

Jack in Alaska · Posted: Tue May 12, 2009 1:06 pm Post subject: Thru hull fitting location

Dutch123,

Drilling a hole in the bottom of ones boat just goes against all common sense but.............if you route the tubing from the fitting up higher than the waterline it will not allow uncontrolled water flow into your boat.
My water intake for the wash down and the live well, factory installed, is in the bottom and tubing routed as explained.

Good luck and thanks for the "hello" when we passed through last month.

Jack

matt_unique · Posted: Tue May 12, 2009 2:14 pm Post subject: Wash down

As a Tomcat owner with a raw water wash down I envy the fact that you guys have one plumbed to your fresh tank. It would sure make things easier for me where I presently keep Napoleon on a mooring. You could connect to your rinse port on your engine (if equipped) for a fresh water rinse no matter where you are.

Good luck with your project. If you drill through any coring you of course want to make sure you overdrill/undercut/etc.

thataway · Posted: Tue May 12, 2009 3:57 pm Post subject:

The proper way is to use a hole saw, a fraction of an inch larger than the diameter of the bronze threaded thru hull fitting. You under cut the core back by about 1/4". Use a coat hanger, allen wrench, or Dremel tool. Fill this under cut with epoxy so that it gives both support and keeps water from the core. Put sealant (4200 would be good) under the outer part of the fitting (strainer)--and then make a "backing block" under the inner nut. Use the nut to tighten down on the sealant.

You can run a tube over board. I used a diaphragm pump and put the intake tube over board. This was my choice on a 22.

Ted Osborne · Posted: Tue May 12, 2009 7:23 pm Post subject:

Dutch123. I don't like the idea of a thru hull if you don't have to do it. We have the pump under the gunnel and just toss the intake overboard.

416rigby · Posted: Tue May 12, 2009 7:42 pm Post subject:

Our boat came with a thru hull for a livewell pump and I can't wait to get rid of the bloody thing. I just don't like holes below the waterline with a hull that is cored. I'll be taking care of it sometime this year. I like the "throw the intake over the side when you want to use it" school of thought.

Rick

Fairbanks Fisher · Posted: Tue May 12, 2009 9:01 pm Post subject:

I've got a factory installed raw water washdown system. I went out and took a couple of pictures of the thru hull fitting from inside and out and posted them in my photo album in case you might be interested.

Good luck.

Chuck S · Posted: Wed May 13, 2009 7:35 am Post subject:

We had thru-hulls on our sailboats for the engine coolant, depthsounder, and speedos. Sailboat hulls rarely allow transom mounted things like this. A big Allen wrench on a drill will carve out the hull core and this resultant space needs to be filled with a good epoxy intended for this purpose.

20+ years with the San Juan 28 and these fittings and not a single issue with the thru hulls. Hole preparation is vital, this ain't a one-day project.

-- Chuck

matt_unique · Posted: Wed May 13, 2009 10:29 am Post subject: Interesting

Captains Cat · Posted: Wed May 13, 2009 12:30 pm Post subject:

Matt, I thought about that too when I saw the pix. Could be though that it's just an indentation for the bilge water to collect and is still cored. Hopefully, the first time someone drills through it, they'll let us all know! Thumbs Up

Charlie

Bad Boy · Posted: Wed May 13, 2009 1:56 pm Post subject:

From the various fiberglass projects I have done on my boat and the experience Thataway documented on his fiberglass repairs, I would not assume the factory followed proper procedures for installing any hatch or thru-hull. It takes a lot of time to properly bed a thru-hull as explained in many forums here and factory does not want to and I am inclined to say, from my experience, the factory does not follow the procedures to protect cored hulls.

With that said, I like water intakes through thru-hulls. When properly located, you can use the system while underway. The location of the bait pump intake the factory installed on my boat was too high. It only works when the boat is fully stopped. Once we got underway, the thru-hull was out of the water and the bait pump starved for water. It didn't take long for the bait to die. This is one of several examples where I scratched my head wondering why a boat manufacturer missed this.

As Chuck S said, thru-hulls are not an issue, when properly installed. There are multi-million dollar boats with multiple thru-hulls. Once you install one properly, you will never again hesitate to do so.

George

matt_unique · Posted: Wed May 13, 2009 2:36 pm Post subject: Sealing

thataway · Posted: Wed May 13, 2009 6:40 pm Post subject:

The part on the STB hull on the tom cat is solid glass. A transducer will shoot thru it.

Fairbanks Fisher · Posted: Thu May 14, 2009 12:38 am Post subject:

Using a solid tool handle and tapping on the adjacent hull area and the indented area did not give any indication of density change therefore I would assume a normal cored hull in that area as well.

As an aside, I took a close look at the transom drain thru hull and it appears to have exposed core (see photo added to album). I will be taking out the transom drain fitting, undercutting and sealing the core with epoxy before reinstalling the fitting and I will more than likely remove the raw water thru hull fitting and, if it is not sealed, will undercut and epoxy that as well. Any other thru hull will be gone over the same way (chain locker drain hole). Better safe than sorry. I really like the boat and want to keep it in as good shape as possible.

By the way, I think the reason the chain locker drain is above the bottom of the locker is because the outer clam shell fitting can't go any lower without hull contour interference. Mine is also about an inch from the bottom of the locker.