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Is a seacock needed on a thru-hull going through transom?

Posted: Jul 3rd, '19, 10:44
by ktm_2000
Hi all,

I need a 1 1/2" thru-hull for my live-well drain which will be installed above but close to the waterline. I'm going to try to keep it as high as possible but want to make sure I can drain the livewell with gravity alone so it won't be too far from the water line. I know thru-hulls on the bottom need a seacock so if you hit something and the strainer on the bottom gets ripped off the seacock is bolted to the hull on the inside and remains intact making the hull watertight. The pickup for the livewell/washdown pumps is on the bottom and for that application I had a seacock prior to the renovation and will be putting it back in place.

If I run the drain out the transom, do I need the seacock? or is a ball valve on the inside good enough?

Re: Is a seacock needed on a thru-hull going through transom

Posted: Jul 5th, '19, 08:25
by Ernie Sandoval
This might help?

Image

Re: Is a seacock needed on a thru-hull going through transom

Posted: Jul 5th, '19, 23:12
by Tony Meola
If it is close to the water line, I would put a shutoff in. Better safe than sorry.

Re: Is a seacock needed on a thru-hull going through transom

Posted: Jul 14th, '19, 15:24
by ktm_2000
I was on vacation for a bit and avoided the internet for a week plus, thus no response.

I was planning on a shut-off valve for the drain but didn't think a sea-cock was required.

Re: Is a seacock needed on a thru-hull going through transom

Posted: Jul 14th, '19, 22:48
by Tony Meola
I suggested a seacock just in case a hose springs as leak or comes off. With the thru hole so close to the water line, you want somed way to stop waterr from coming in the thru hull.

Re: Is a seacock needed on a thru-hull going through transom

Posted: Jul 14th, '19, 23:04
by Pete Fallon
Ktm,
My bait well drains were on the transom with ball valves for safety reasons, I used the old fresh water cooling dumps for the bait well fittings they were 1-1/4" brass fittings. I had a macerator pump plumbed into the drains to get rid of the scales and other crap from the two 40 gallon oval wells that were mounted behind each engine box with fitted cushions on top. There were no hoses hanging over the deck sides or getting in the way on deck. Discharge and intake hoses were run under the cockpit soles port and starboard, the intake 1-1/4 sea cock was aft of the fuel tank with a 3000 gph Rule trash pump feeding each live well and the port and starboard side wash down hoses, it also doubled as an extra bilge pump along with the 3 other 2,200 Johnson bilge pumps.
Pete Fallon

Re: Is a seacock needed on a thru-hull going through transom

Posted: Jul 15th, '19, 09:34
by ktm_2000
thank you all for your responses.

Here's what I had for the pick-up side, sea-cock in the old hull drain location.
https://photos.app.goo.gl/vFHqPVWm3LY17qn56

In the past I did a portable tank drained over the side, PITA

Here's my thought on the drains for both livewell and my bilge pumps.
https://photos.app.goo.gl/fErfnBArgTX2hTzk9

I would like to keep all the thru-hull fittings on one line for cosmetic purposes, In the transom area I will close off a portion like the person did on this Bertram 31 https://photos.app.goo.gl/9MaQsYXh9TzXq8d88 to hold all my battery switches, fuel filters, etc. PVC tubes will be put in to route hoses, coming from under deck and extend them @6" above the deck in case water got in there. I will add additional 6" or so rise on the bilge pump hoses so if I were backing down, water shouldn't be able to back through the system.