Question regarding Air Conditioner Install

[OReely]

My personal opinion on this is to never install a fitting like the one Osprey showed in his post. I always install proper seacocks on below waterline installations.

The fitting Osprey showed only allows for a ball valve to be mounted on top of the fitting. Two problems with this. First, the threads on the fitting shown don't match and engage properly with ball valve fittings. The through hull fitting is a straight threaded fitting and ball valves are tapered pipe threads. This combo only allows for 2-3 threads worth of engagement. Second, if the through hull were to suffer a failure, then you would have an open hole to the ocean. Yes, you could carry an emergency plug and a mallet but do you really want to be rummaging around for things when water is pouring into the boat.

The best method is to use a bronze, flanged seacock that is bolted to the bottom of the boat. The wall thickness of the seacock is many times that of a through hull fitting and, in combination with the bolts, provides a vastly superior solution. The bottom of the seacock has straight threads and can provide a 1/2" or more of thread engagement with the through hull fitting. If there is ever a problem with the system, you can easily just turn the valve handle to shut off the water.

With the seacock arrangement, you lose the built in scoop but this can be easily overcome by adding an externally mounted scoop (http://gator49.hostgator.com/~zeromyst/ecatalog/product_info.php?cPath=219_151&products_id=230) or you can cut a slight groove in the forward face of the through hull fitting to turn it into a scoop of sorts. Something like the fitting in the link below. http://www.groco.net/08-fittings/images/hsth.jpg I've done this many times and if you cut the groove about 1/2" wide and 1/4" deep, it will feed water to the pump while running.

[Chisox]

My personal opinion on this is to never install a fitting like the one Osprey showed in his post. I always install proper seacocks on below waterline installations.

The fitting Osprey showed only allows for a ball valve to be mounted on top of the fitting. Two problems with this. First, the threads on the fitting shown don't match and engage properly with ball valve fittings. The through hull fitting is a straight threaded fitting and ball valves are tapered pipe threads. This combo only allows for 2-3 threads worth of engagement. Second, if the through hull were to suffer a failure, then you would have an open hole to the ocean. Yes, you could carry an emergency plug and a mallet but do you really want to be rummaging around for things when water is pouring into the boat.

The best method is to use a bronze, flanged seacock that is bolted to the bottom of the boat. The wall thickness of the seacock is many times that of a through hull fitting and, in combination with the bolts, provides a vastly superior solution. The bottom of the seacock has straight threads and can provide a 1/2" or more of thread engagement with the through hull fitting. If there is ever a problem with the system, you can easily just turn the valve handle to shut off the water.

With the seacock arrangement, you lose the built in scoop but this can be easily overcome by adding an externally mounted scoop (http://gator49.hostgator.com/~zeromyst/ecatalog/product_info.php?cPath=219_151&products_id=230) or you can cut a slight groove in the forward face of the through hull fitting to turn it into a scoop of sorts. Something like the fitting in the link below. http://www.groco.net/08-fittings/images/hsth.jpg I've done this many times and if you cut the groove about 1/2" wide and 1/4" deep, it will feed water to the pump while running.

O'Reely, you are correct in the use of a true seacock in this application, as well as washdown pickups, generator pickups, etc. In defense I will say virtually every production builder uses the old high speed pick-up/shut-off valve type of install, where you have straight threads on the pickup and tapered threads on the valve. Not a good combination. But in the production world, that's how it's done. When I was at Stamas, that's how we did the engine mains as well, but 2" pickups and valves. Much better chance of leaking there.

Is the way I described the "proper" way to do it? No. Is that how it's done at the production level? Yes. And most of it has to do with cost...

I'm glad you are able to do it the "correct" way. Good advice.