How to install an underwater thru hull

I had to add a thru hull for my air conditioner water intake. As most of you know, brass or bronze is out of the question without isolation. I researched and a company makes a composite plastic that equals or outperforms brass, called Marelon by Forespar. Forespar sells direct, the marine stores that carried only thru hull and valves they did not carry the seacock valve. I installed a 93 series valve with an anti-venturi design.

http://www.forespar.com/

http://www.forespar.com/...bleOfContents2009.shtml


Marelon® is a proprietary formulation of polymar composite compounds using DuPont resins and additives to produce a superior marine-grade product.
• For use above and below the waterline
• Precision molded plumbing systems
• Complete freedom from corrosion
• U.L. and A.B.Y.C. approved
• Forespar "93" series valves and thru-hull fittings meet all design criteria and exceed all mechanical property requirements specified by the International Standards Organization


1- Pick location, clear trailer (if used), back enough form the bow so it will not come out of water, away form beams, ect..
2- Drill hole to proper size
(Hint on using hole saw: Drill pilot hole, replace pilot drill in hole saw with 1/4" pin. It will not wobble as much and make a cleaner cut)
3- Sand off bilge undercoat (to insure good bond to bedding agent)
4- Fabricate spacer, Hull thickness 3/16 the thru hull runs out of threads (I made mine out of 1/4" aluminum plate)
5- Cut off excess threads off thru hull
6- Fabricate tool or purchase one to tighten thru hull
7- Check fit dry
8- Prime any bare metal with suitable primer
9- Coat hull, spacer both sides, thru hull and sea cock with sealer 3M 5200 or similar.
10- Tighten to specs
11- Let dry for 3M 5200 7 days

If anyone want to use my tool, You can use it just pay for the shipping. I made a tool for 1 1/2" and 3/4" thu hulls.

Robert,

I second that motion

Norm,
Bigs Live On

Very nice job Robert

My boat already has three water pickups -- one for each engine and one for the head. Just wondering, is there a reason not to use an existing pickup? I am thinking about air conditioning (a$ $oon a$ I $olve a few problem$) and I was going to tee off of an existing pickup (after the ball valve), probably the head, in place of making a new hole in the hull.

The a/c has a saltwater circulating pump, and I can see that it might not want to compete with an engine for water, but I would think that the head would be fine. Anyone have experience with this?

When I had my Trojan F36 I did this. Tee'd off the head through hull for the A/C feed. ALWAYS ALWAYS ALWAYS Had an issue with it. Everytime you would flush the head the A/C pump would loose its prime and shut down. I think the through hull fitting was too small to feed BOTH at the same time. I eventually added another through hull when the boat was pulled.

Per A/C mfg and Raritan, sharing a water pickup is fine. I did not have a thru hull for the head or an A/C why I added one for the new A/C and head.