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Old 12-06-2009, 13:51   #1
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One Thru-Hull - Many Uses?

I am about to begin tackling some major refit projects on my Stevens 47 including installing two A/C units, and a new DC powered fridge and freezer unit (leaning toward a pair of keel cooled Frigoboat units) and a watermaker.

My boat already has 9 thru-hulls, 7 of which I replaced last fell. I REALLY would prefer NOT to install additional thru-hulls! But, I know each of the A/C units will need water as will the watermaker. This would mean at least 3 additional thru-hulls. BLAAAAAAAA

But... One of the thru-hulls forward is used for the salt water wash down on deck. I figured I could install a 3 way diverter valve like this:

3-way Diverter Valve

And then use that thru-hull for both the forward deck washdown AND the forward A/C unit. Any issues with that? Would I install this kind of diverter valve in line after the shut off valve attached to the thru-hull? Any suggestions on this or experience?

I figured on doing the same thing in the rear with an thruhull being used now for intake for the salt water foot pumps and such. That one would be shared between the foot pumps, A/C unit and watermaker. I figure these things would likely never run at the same time.

Any other ideas on how to minimize the need for installing additional thruhulls?

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Old 12-06-2009, 14:21   #2
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sea chest? see:

- Google Search
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Old 12-06-2009, 14:38   #3
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The 3 way valves will work fine, a bit of a pain to remember to switch them to the right way though! Make them easy to access. Yes put it after the seacock. If the seacock is low enough, and large enough, you can likely just share it via a T and without the 3 way valve at all. Your A/C probably takes a 1/2 hose? and the Washdown pump about the same hose size. The washdown is intermittant use anyway. They could likely share a 3/4 seacock, but could a 1" for sure I would think.
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Old 12-06-2009, 15:59   #4
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Jedi came with one (!) seacock for intake and three standpipes for discharge (no valves with standpipes). The sinks & showers drain by gravity into a small grey water tank that's in the keel. A floatswitch/pump combo empties it into a standpipe.

This sounded too good to be true and it was: toilets would loose prime often and always when underway etc.

What I ended up doing:

- Installed 3/4" seacock forward with sea strainer and this feeds 16 kBTU airconditioning unit plus deck wash pump.

- Installed 3/4" seacock aft with sea strainer for genset
- Installed 3/4" seacock aft with sea strainer for watermaker

The watermaker is AC so uses the generator to work. I shared a single seacock for the two before but they fight for water so they both have their own now.

- converted fridges/freezer to Frigoboat units with keelcoolers, eliminating salt water feeds.

- converted toilets to fresh water flush versions, eliminating salt water feeds.

This setup with 4 seacocks works flawlessly.

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Old 12-06-2009, 22:04   #5
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The sea chest is the traditional way of dealing with multiple take offs. Generally they were located horizontally after the seacock with whatever No. of valves were required. My choice would be to have only one through hull of say 32mm with a seacock / valve then a vertical pipe upstand finishing above the water line with a removeable cap so you can remove a captive strainer from it without having to pull the boat for maintenance, the various outlets required are valved off it at whatever height suits the application.
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Old 12-06-2009, 22:12   #6
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I vote with the sea chest option. The fewer holes in the bottom of the boat the better.
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Old 13-06-2009, 00:14   #7
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Originally Posted by Tspringer View Post
Any other ideas on how to minimize the need for installing additional thruhulls?
I had the same question a while back so let me refer you to A Smarter Seachest?

You'll notice that both a seachest as well as a manifold are good solutions.


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thru hull

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