Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 16-04-2014, 21:48   #1
Registered User

Join Date: Sep 2011
Posts: 49
Cockpit Drain Above or Below Waterline?

Hopefully this is the right forum for this question. I've got an Endeavour 37, which we plan to do an extended cruise on. I'm struggling with the large number of large below water thru-hulls. There are seven 3/4 to 1.5 inch thru hulls plus 2 small chain locker drains all below the water line. Here's my question:
The cockpit drains are 1.5 inche dia. and drain to thru-hulls approximately 2 feet below the water line. The cockpit floor is approximately 21 inches above the waterline. Can I move the drains to an above the water line discharge maybe 15 inches below the drain, and 6 inches above the waterline. Perhaps by putting a check valve on them to keep a wave from pushing water up into the cockpit.
The other question is: Do sink drains need to be 1.25 inch diameter. It's seems odd to have a tiny head sink, draining into a giant 1.25 inch thru-hull. Do people have smaller drain lines? Any advice here would be greatly appreciated. Paul

Paul Mazza is offline   Reply With Quote
Old 17-04-2014, 00:26   #2
Registered User
Reefmagnet's Avatar

Join Date: May 2008
Location: puɐןsuǝǝnb 'ʎɐʞɔɐɯ
Boat: Nantucket Island 33
Posts: 2,644
Re: Cockpit drain above or below waterline?

Cockpit drains draining below the water line are a funny thing. My current boat has the same set up as yours and I discovered not long after buying it that the single hose clamp clamping the hose to the thruhull had missed the nipple altogether. Goodness knows how long it had been like that for, but the hose had never popped off, so in a way that kind of instills some confidence that the drains will remain intact.

Now back to your question, water would enter the cockpit regardless of outlet height. It is a function of cockpit floor height above the waterline. This also means heeled waterline as well. If the "fall" between the drain and outlet is not enough though, you may have problems with draining in a seaway as the water will slosh back into the cockpit before it escapes the drain plumbing. Seas can also enter the drain if they rise higher than the floor with the boat's motion, but I guess rubber flap valves could be used to prevent this.

Your sink drain through hull only needs to suit the size of the drain. My washbasin drain in 3/4" which drains a bit slow, but at least you cant loose your wedding ring down it. Perhaps the larger through hull has been repurposed from a previous function e.g. toilet outlet.

No one like lots of underwater through hulls, but plenty of boats have them. If you maintain them I really can't see why they would need to be repositioned. I personally wouldn't be bothered to move mine.

Reefmagnet is online now   Reply With Quote
Old 17-04-2014, 04:38   #3
Senior Cruiser
bletso's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Louisville, KY
Boat: Globe, cutter/ketch,38
Posts: 387
Re: Cockpit drain above or below waterline?

Of the four I had on Vigah, one was below the WL. I have attached pics of the SS coupling I cut off after I moved the drain above the WL. BTW, the clamp was broken and that was why I disconnected it. It was also in my way trying to get into the engine compartment. I also never figured out why the drains were crossed. stbd drains drain on the port side, etc.

Over time, I have removed three excess seacocks located below the WL. Be honest, how often will you actually remove the hose to check the barb fitting? Granted, the barb should not have been SS on the brass seacock, but the boat was manufactured that way. Visual of the clamps, certainly.
Attached Thumbnails
Click image for larger version

Name:	drain1.jpg
Views:	101
Size:	283.6 KB
ID:	79499   Click image for larger version

Name:	drain2.jpg
Views:	107
Size:	259.3 KB
ID:	79500  

__________________ Boats don't like being neglected, but then neither do significant others!
bletso is offline   Reply With Quote
Old 17-04-2014, 05:01   #4
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 11,594
Re: Cockpit drain above or below waterline?

I'll bet they were crossed on the theory that the downhill drain would of course be the primary drain and attaching it to the uphill through hull would have that through hull out of the water. Probably slowed draining though as there was less drop
a64pilot is offline   Reply With Quote
Old 17-04-2014, 10:36   #5
Registered User
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,215
Re: Cockpit Drain Above or Below Waterline?

Leave your cockpit drains alone.
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Old 17-04-2014, 10:43   #6

Join Date: Feb 2013
Location: Boat is on the Rio Dulce
Boat: Seafarer36c
Posts: 3,584
Re: Cockpit Drain Above or Below Waterline?

Originally Posted by Terra Nova View Post
Leave your cockpit drains alone.
The cockpit drain thing was figured out a long time ago. About the only thing left to argue is should they cross below deck.

Guy is offline   Reply With Quote

cockpit, water

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Relocating Cockpit Drains to Above the Waterline. endoftheroad Plumbing Systems and Fixtures 8 04-01-2014 23:14
Seacocks for above the waterline? Saltyhog Construction, Maintenance & Refit 8 29-08-2013 13:08
Blisters above waterline anjolain Monohull Sailboats 14 10-04-2012 11:57
Ablative Above Waterline Paint ? karma Construction, Maintenance & Refit 4 14-10-2010 00:46
teeeeny tiny blisters--above waterline defever Powered Boats 7 25-09-2008 07:06

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 01:28.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.