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Old 18-01-2025, 11:06   #1
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Join Date: Jan 2025
Location: Bend, OR
Boat: Ericson 23-2
Posts: 8
cockpit drain

Hi All, I was hoping to get some thoughts on my idea for draining my cockpit.



Current situation: one 3/4" drain at bottom center aft cockpit connected via about 5 ft of hose to thru-hull in bottom of the boat. This hosing has sink drain T-ing into it at the thru hull.



I read Gord May's post from a while back. I estimate my current setup could drain 75% of my cockpit in roughly 9 hours.


Plan:


1.Delete thru-hull altogether (on a 23 ft boat I don't really drain much in the sink beside brushing my teeth and occasional cup of water.



2. Add three transom scuppers at aft cockpit. Directly through the cockpit transome - so no drain tubing. Thinking two at just above the waterline, then another maybe halfway up the transom. Thinking putting some sort of flaps or one-way valves on these. Have to calculate size, but thinking something like each hole would be somewhere around 2-3" in size. Certainly that would drain infinitely faster than current setup.


I'm not going for a blue water boat, but I do plan to solo cruise in the NW and (secretly) have aspirations of doing the R2AK at some point in the future (don't tell my wife).



Questions:


1. Does this general idea seem reasonable?
2. Are there off-the-shelf valve or flap products made for this purpose?
3. Would you put the scuppers right at the waterline? 1-2" above it?

4. Any other thoughts or considerations to think about before drilling through my beautiful transom?



Thanks for all your thoughts


-Peter
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Old 18-01-2025, 11:34   #2
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Location: Michigan
Boat: Columbia 9.6, Hunter Cherubini 37, Jeanneau 57
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Re: cockpit drain

I'd leave the original and simply add 2 more drains as you describe. Do remember when the boat is heeling, any drains can also let water back into the cockpit, keep them as high off the waterline as you can while still being downhill for the water to drain. Don't worry about check valves as dirt and debris can easily clog things up or prevent intended function anyway. The drains on my Columbia are over a foot off the waterline, but when I really get going, I still get a wet foot. As far as size is concerned, a 1" to 1.5" is more than enough for a 23' boat cockpit.
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Old 18-01-2025, 15:44   #3
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Boat: Ericson 23-2
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Re: cockpit drain

Yeah, even though the boat is small, the cockpit is actually relatively large. I calculated it at 329 gallons (roughly 7' long x 5' w x 26" deep minus lockers).



If you are going for 75% drainage in 90 seconds. you need to drain 246 gallons in 90s or 164 gallons per minute. Searching flow rate from plumbing data for passive gravity flow I'm coming up with a flow rate for a 1.5" pipe is 35 gpm. So I wound need 5 of those 1.5" drains.


If I up it to 2" opening then three drains should suffice. Rough math of course. Like I said, I think the current drain with all the tubing length and small diameter opening gets me like 0.5 gpm. It's super slow.
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Old 18-01-2025, 15:59   #4
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Re: cockpit drain

I don’t know your boat, but I do respect the need for a cockpit to remain dry when the boat is heeled, and to drain quickly when swamped. Without additional info, I would dedicate your current ¾” seacock to the galley sink, and install two seacocks for the cockpit. It doesn’t matter if you are sailing a bitty or huge boat, a swamped cockpit means you may get swamped again by the next wave or two, so get the water out ASAP!! IMO, 1.5” is a comfortable drain size. Put one (or two) drain/s on each side of your cockpit, then install two thruhulls, one on port and one on stbd. The port drain/s get connected to the stbd thruhull, and the stbd drain/s to the port thruhull. That way when you are on one tack, the cockpit will drain AND not fill up on the leeward side from the high water on that side. My boat is bigger than yours, but your cockpit may be bigger than mine. Look at other (cruising) boats and do some research.
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