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**Geoff S.** · 21-04-2008, 12:51

My Quandry of the Week:

After peeling, reglassing and refairing, my hull is a complete blank canvas, and I'm free to put new thru-hulls for everything wherever they seem to make the most sense. We're installing ac units (one under the forward cabin bunk, and one aft in the lazarette), and I'm faced with the choice of putting their raw water discharge thru-hulls below the waterline with all its associated sink-the-boat issues...or about 12" above the waterline, which causes the boat to sound like it has a bladder infection all night; could be an auditory nuisance to my neighbours at anchor. Of course, when I'm using them at night, they'll be running off the generator, and while the gennie lives in the engine room and as such the running noise shouldn't be much of an issue for my fellow cruisers, it will have it's own discharge...so maybe the cooling discharge is a moot point?

What are any pros and cons of the two configs that come to mind?

Thankee,
Geoff

**knottybuoyz** · 21-04-2008, 13:56

Hey Geoff

Thought you had already sailed off into the sunset! Got more pics of the boat project?

Can't you locate the AC discharges closer to the waterline? I've seen them just above or in the bootstripe and that lowers the angle the stream hits the water. Seems to be a lot quieter that way. Anti-siphon loops would fix any problems with sinking the boat via the AC discharge eh?

Rick

btrayfors · 21-04-2008, 14:16

I agree with Rick. I put mine just above the bootstripe and, in addition to the loop, I installed shutoff ball valves (belt and suspenders logic!). Works great, and doesn't make a lot of noise.

Bill

Latitude9.5 · 21-04-2008, 14:32

I thought about my install for quite a while, what I did was above the waterline, but it's at a part in the hull where it's angled directly at the water, it's makes hardly any noise at all. At our marina there are a lot of them that make a lot of noise, everyone just lives with it, i honestly can't hear even the loudest ones inside the boat.

**Hud3** · 21-04-2008, 14:38

Geoff,

Just make sure you install the water intake thru-hulls on the opposite side of the keel from the head discharge!!!

And opposite the A/C discharges, too, to prevent recirculation.

Course you probably already thought of that!

drew.ward · 21-04-2008, 16:04

What about using the same simple technique used to quell noise on building downspouts?

Simply attach a piece of rope to the inside of the pipe at some point and let that run out your through hull and down to the waterline.

Because water is hydrophilic to itself, it will cling to the rope and silently flow down into the water. This way you can have your through-hulls as high as you like.

Latitude9.5 · 21-04-2008, 16:09

Mine comes out with a vengence, not a trickle.

**Geoff S.** · 21-04-2008, 17:06

Good thoughts, all. I was thinking that, even at the proposed 12" above the waterline, it would still be underwater when heeling, so the above-water safety argument is kind of moot. Bootstripe seems like a good place.

Come to think of it, every time I'm in a "quiet" anchorage, I can't hear the water discharges over the wind generators!

AnchorageGuy · 21-04-2008, 17:41

Forget at anchor, we have seen marinas with floating docks make the owners turn off the AC units because they hosed the docks down when the discharge is up high.

**Alan Wheeler** · 22-04-2008, 00:06

I doubt the other residents would be all that concerned. I would think you and the others on board would be more concerned with the water noise. And then, there is nothing like the gentle sound of running water to put you to sleep.

cooper · 22-04-2008, 02:04

....and nothing like the continuous drone of a small engine running a generator all night to keep you awake.....

Sandero · 22-04-2008, 03:17

How about this for an odd suggestion: get some elbows fabricate that you can slip into the thru hull from the outside when you are at anchor which conduct the water to below the water line? I know this would look weird and require you set this up at anchor, but it would suppress any noise WHEN you want to. This might even work with hose that you can shove into the thru hull. You can make it work!