Seawater thruhull

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rsvpasap
Engineer
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Joined: Fri Dec 13, 2013 2:05 pm
Sailboat: MacGregor 26X
Location: Seattle, WA

Seawater thruhull

Post by rsvpasap »

Every once in awhile, something turns out better than you hoped for. In an attempt to cut down on potable water use, I installed a sea water pump. I couldn't bring myself to put a thruhull below the waterline, so I put it above. I used a Sea Dog garden hose water inlet, a short piece of hose, a couple of strainers and some plastic fittings outside the boat. Inside the boat, I used a 3.0 GPM self priming pump and 1/2 PEX (I've converted all the boat plumbing to PEX, it's so reliable and easy to use.) Now there is pressure seawater to the trigger sprayer in the galley, the cold water tap in the head and a second Sea Dog fitting in the cockpit for a wash down hose. Wash dishes or clothes in seawater (and rinse them in fresh), pressure water for hosing down the cockpit after cleaning fish/shellfish or tracking mud in from the shore, etc. I remove the hose when underway and attach it after setting the anchor. I have cut my potable water usage by more than half.


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Russ
Admiral
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Location: Bozeman, Montana "Luna Azul" 2008 M 70hp Suzi

Re: Seawater thruhull

Post by Russ »

Veeery nice installation. I like the arm that lowers and raises. All the fittings look very professional.
Plumbing it to cabin fixtures is brilliant.

I too, could not bring myself to punch a hole below the waterline for my washdown pump. I have a ghetto version of what you did. I bought a garden hose and connect to the washdown pump at the motor well sort of like where yours is and just toss it over the transom when I want to use it.

I forgot to pull it out when I had the original strainer and the prop destroyed the strainer. So, I attached an RV water filter to the end to filter out as much junk as I could. Just replace it each year.

The ONLY drawback to seawater is that bio junk can grow in the lines if you don't flush them regularly.

Where we really enjoy this is for misting ourselves on hot days. A great way to cool down.



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--Russ
C Buchs
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Sailboat: MacGregor 26X
Location: Camas, WA 98607

Re: Seawater thruhull

Post by C Buchs »

One of my first mods was a wash down pump. Single best way to help keep sand and mud under control.

Mine is installed similar to yours. I like the idea of plumbing it to the sinks inside. My only regret is my pump is too small. I bought the Johnson 2.9 GPM model and it's OK, but bigger would be better.

Jeff
OverEasy
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Re: Seawater thruhull

Post by OverEasy »

Hi Rsvpasap!

Nice work! :)
Great idea of the PEX plumbing. :)
What type of connectors did you use?

I’ve heard similar marine growth issues from several cruisers.
The word was to periodically not only flush with fresh water but to flush with a 10% bleach / water solution and allow it to stand in the plumbing for a while (~30 minutes).

I don’t recall the frequency specifically but something along the lines of once a week and before storage.
They also blow out the lines before storing for any length of time.

Best Regards,
Over Easy
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Starscream
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Sailboat: MacGregor 26X
Location: Montreal, Quebec. 2002 26X - Suzi DF90A

Re: Seawater thruhull

Post by Starscream »

My washdown pump is the manual version. 🪣 bucket.

Nice work.


I've often wondered why boat builders always use thru hulls instead of a system of hoses over the transom. Would be easy to design into the construction of a boat, and much easier to maintain.

I hate the factory thru hulls on our X. A source of constant worry.
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