# Cockpit Draining - Below waterline?



## gatorsteven586 (Sep 10, 2014)

I have an Irwin 41 that I'm gradually figuring out, but my most recent finding is that the plumbing from my center cockpit drain goes down into a seacock/thru-hull fitting uneder the waterline at the bottom of my boat. 

I don't quite understand this configuration. The cockpit sits high out of the water, so why not just have the drain lines go directly overboard out the stern, to an above-waterline egress? I could understand if I had a smaller boat with the cockpit floor close to waterline, as the heeling or alot of heavy weight in the back would make the boat more prone to take on water from the outside if the egress dips underwater, but having a thru-hull at the deepest part of the boat for a cockpit drain seems riskier.

Everything I read says to limit the amount of thru-hulls, and I am not understanding the practicality of this one.

In addition, even when my cockpit does drain water, not all of it will go out since the thru-hull is underwater, correct? So I'll have a certain amount of dirty-cabin standing water in my lines no mater what. I could see that maybe if I was underway, the movement across the bottom might suction this water out, but I'm docked right now.

Any comments are appreciated to help me undrestand this configuration. I would like to limit the amount of thru-hulls, and also have a cockpit that completely drains any water it takes on.

Thanks!


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## RichH (Jul 10, 2000)

Any water that goes down that tubing/hosing will empty and the remaining water in the hose be equal to the level of the 'ocean'. What will remain in the hose will be insignificant.


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## Faster (Sep 13, 2005)

Straight out-the-back cockpit drains, without below water through hulls would/do make most sense.

Taken to extremes, today's open cockpits are an extension of that idea.

Most boats, however, have issues with storage interference (lazarettes, propane lockers, steering systems, etc) that would conflict with such drains. in addition, those drains are often relatively flat and can become dirt collectors and breeding grounds for algaes themselves.

We once converted a 'down through the hull' cockpit drains to an out-the back on a former boat.. we went out under the counter, but above the WL. Turned out the sternwave underway, esp when heeled was higher than the cockpit floor aft, and we created a cockpit backflooding issue that hadn't been there when the cockpit drained straight down and through at the front.

So... like so many scenarios.. 'it depends'.


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## Group9 (Oct 3, 2010)

That is a strange way to configure cockpit drains. My Cape Dory 25D was set up like that, too and it only had a manual bilge pump, so I always closed them off when I left, which always resulted in standing water in the cockpit after a rain. But, I figured that was better than than finding nothing but the mast poking up out of the water one day.


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## SVAuspicious (Oct 31, 2006)

gatorsteven586 said:


> I have an Irwin 41 that I'm gradually figuring out, but my most recent finding is that the plumbing from my center cockpit drain goes down into a seacock/thru-hull fitting uneder the waterline at the bottom of my boat.


On center cockpit walkovers you can run the cockpit drains athwartships. That doesn't work with a walk through. You can't go through the transom without hoses at knee level or higher between the engine room and the berth.

The vertical drains on my center cockpit boat have yet to be an issue.


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## Tenoch (Sep 28, 2012)

My H.R. Monsun not only has the cockpit drains going to through hulls straight down below the waterline, but the deck drains also go into the boat and connect to these lines. I heard somewhere (can't remember where) that it is purely cosmetic so that you don't have residual slime and goo running down the outside of the hull. I am NOT a fan of the deck drains going through the boat at all...but what the hell do I know?


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## killarney_sailor (May 4, 2006)

We have cockpit and deck drains going straight down on our centre cockpit Bristol. Perhaps it was the way things were done in the good old days, I am not sure. I do know that I have an incredible number of thruhulls to worry about.


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## jrd22 (Nov 14, 2000)

Our cockpit scuppers exit below waterline and the hoses cross over to the opposite side so that when heeled over the scupper isn't below waterline. I've done the measurements to try and run them out the transom (to eliminate two through hulls) but like Ron we would have water in the cockpit at about 15-20 degrees of heel. I guess I just have to live with them. We did eliminate the deck scuppers that also had through hulls by glassing them over and cutting three oval holes through the side of the hull.


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## krisscross (Feb 22, 2013)

They work fine but unclogging drains like that can be royal PITA.


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## Minnesail (Feb 19, 2013)

I've wondered about that too.

On the new model Catalina 22 the cockpit sole slopes towards the back and and the cockpit drains are just holes through the transom.

My older boat has cockpit drains right in front of the companionway that go straight down to a thru-hull in the bottom of the boat. The cockpit sole slopes down towards the front so water runs toward these drains.

It seems like that adds unnecessary complexity and expense, so I wonder why they did it that way. Tradition?


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## Gary M (May 9, 2006)

My through hulls exit through the hull behind the water line but ahead of the transom. Under way they are likely under water but at the dock they are a couple of inches above it so no worries.


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## scratchee (Mar 2, 2012)

Judging from my own transom, I'm going to concur with an earlier poster that the underwater drains are to keep unsightly streaks and stains from developing.


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## newhaul (Feb 19, 2010)

Group9 said:


> That is a strange way to configure cockpit drains. My Cape Dory 25D was set up like that, too and it only had a manual bilge pump, so I always closed them off when I left, which always resulted in standing water in the cockpit after a rain. But, I figured that was better than than finding nothing but the mast poking up out of the water one day.


That's not really a good idea to close the cockpit drain off saw a boat full of rain water filled the cockpit and spilled over into the cabin wasn't a pretty sight to walk up to also with proper maintance the possibility of a drain line failing is minimal


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## danr620 (Jul 11, 2007)

Guys my clipper marine 21 has the single drain and biggest problem is if leaves block it and then you can have a bathtub! :laugher System works guess I need some sort of strainer.

Dan


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## THEFRENCHA (Jan 26, 2003)

Same boat Same settings
Several bad experience
First a clamp failed underway ...lots of water incoming !
Second There is a fair amount of water that stays in the pipes and hoses 
And mine froze at the dock during winter Hose burst open with seacock open
Again lots of water incoming and boat started to list on its side with about 2 feet of seawater inside 

So I changed the setting Cockpit drains are going directy into bilge and seacock is permanently closed
This winter I plan to have the drain evacuate directly at the stern above exhaust with a back valve as security Very easy to do on the Irwin 41


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## Pegu club (Jun 10, 2012)

Our 1975 B24 has cockpit drains that go straight down thru the hull with no seacocks. The boat was designed this way, we have had the boat going on three years with no issues, and hopefully never will.


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## Group9 (Oct 3, 2010)

newhaul said:


> That's not really a good idea to close the cockpit drain off saw a boat full of rain water filled the cockpit and spilled over into the cabin wasn't a pretty sight to walk up to also with proper maintance the possibility of a drain line failing is minimal


Well, I only lived a couple of blocks from that boat and checked it on the way to work almost every day. I probably wouldn't do it if I lived where it wasn't convenient to check it every day.

According to Boat US, most boats sink at the slip, and most of the time it's due to an open thru hull, and slipped or burst hose. Everything on that Cape Dory was first class. I just don't know why they rigged the drains that way. Probably as someone else suggested, so there wouldn't be water stains on the hull from and above the water line drain.


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## SkywalkerII (Feb 20, 2008)

My 1966 Tartan 27 has two drains that go straight to the bottom, exiting through thru hulls. I replaced the hoses, double clamp them, and forget them. Luckily, in an emergency, they are easily accessible.

SKywalker


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## HR28sailor (Feb 11, 2010)

With the cockpit drains below water level, while the boat is moving a partial vacuum is created and the water is sucked out of the cockpit faster than if it had a static drain. this is the Venturi effect. Myself I like a dry cockpit.....


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## jzk (Feb 25, 2008)

I have to big cockpit drains that go straight aft on the 47.7. If we were to get swamped, most of the water would exit there. But the big wheel is recessed into a well that has a drain straight down through the boat to a below the waterline through hull. This ends up being the main drain, as the water in the cockpit never makes it aft of this well. And, it tends to get clogged often.


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## Seaduction (Oct 24, 2011)

Below waterline scupper drains.... just more places to sink the boat if a leak occurs.


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## capta (Jun 27, 2011)

Seaduction said:


> Below waterline scupper drains.... just more places to sink the boat if a leak occurs.


Why are so many of you terrified by thru hulls? In over 50 years on hundreds of boats, some built in the early 1900's and before, I have never had a thru hull, seacock or hose cause a boat to sink or even cause a major leak,
If y'all can't maintain your seacocks, thru hulls, hoses and hose clamps, I''m sure there are plenty of other things that are also poorly maintained, that are even more likely to sink your boat.


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## mad_machine (Dec 16, 2012)

my sea sprite is 51 years old and it's cockpit drains go straight down to thruhulls. I know it seems weird, but it works. I imagine there is a reason Alberg Designed it that way


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## Chainplate (Aug 18, 2014)

Our boat was given a Lloyd's A1 certification when it was completed and it has two 2.5" thru hulls well below the water line to drain the cockpit. It's very rare that our center cockpit takes a big wave but when it has happened, the water drains very quickly.

Fair winds and calm seas.


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## ReefMagnet (May 8, 2008)

capta said:


> Why are so many of you terrified by thru hulls? In over 50 years on hundreds of boats, some built in the early 1900's and before, I have never had a thru hull, seacock or hose cause a boat to sink or even cause a major leak,
> If y'all can't maintain your seacocks, thru hulls, hoses and hose clamps, I''m sure there are plenty of other things that are also poorly maintained, that are even more likely to sink your boat.


Our boat's cockpit drains lead to a single thru hull fitting in the engine room. When we purchased our boat last year, I progressively went through all the hoses and connections, generally replacing the single worm clamps with two clamps at the below waterline connections. Our cockpit drain hose is almost like exhaust hose - it's a very heavy walled black rubber which may or may not be the age of the boat (30 years). To my shock and awe, I discovered that the single hose clamp attaching the hose to the tail of the valve was clamped too high and that it had missed the tail altogether. It had been this way for many years at least. Needless to say I fixed that issue pronto!


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## bvander66 (Sep 30, 2007)

Majority of ocean going center cockpits will have multiple drains cross connected below deck and going to usually two through hulls. The main reason is to ensue coxkpit drains quickly when you take a wave which fills cockpit. Our boat has 4x1.5" drains going to two 1.5" seacocks. Boat has been on the ocean since 1981 and no problems.


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## SVAuspicious (Oct 31, 2006)

capta said:


> Why are so many of you terrified by thru hulls?


I didn't worry about them at all when I lived aboard full-time. I didn't worry about them the winter we hauled. This winter with the boat in the water but not living aboard I do worry about freezing.


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## capta (Jun 27, 2011)

SVAuspicious said:


> I didn't worry about them at all when I lived aboard full-time. I didn't worry about them the winter we hauled. This winter with the boat in the water but not living aboard I do worry about freezing.


I'd have to agree with you about not giving any thought to thru hull failures when hauled, lol. I've only spent one winter in ice since I was fishing in AK, so I can't speak to that, but I have read with interest about 'winterizing' systems, should I ever choose to go through a winter where it's less than 80 degrees.


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## Group9 (Oct 3, 2010)

capta said:


> Why are so many of you terrified by thru hulls? In over 50 years on hundreds of boats, some built in the early 1900's and before, I have never had a thru hull, seacock or hose cause a boat to sink or even cause a major leak,
> If y'all can't maintain your seacocks, thru hulls, hoses and hose clamps, I''m sure there are plenty of other things that are also poorly maintained, that are even more likely to sink your boat.


Like what?

I'm not terrified of flat tires, and I keep good ones on my truck, and I haven't had a flat in 15 years, but I carry a jack and a spare.

Being sure something isn't going to happen because it hasn't happened yet, isn't really a plan so much as it is a hope and a prayer.

http://www.sailnet.com/forums/general-discussion-sailing-related/178402-boat-sank-dock.html


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## capta (Jun 27, 2011)

Group9 said:


> Like what?
> 
> I'm not terrified of flat tires, and I keep good ones on my truck, and I haven't had a flat in 15 years, but I carry a jack and a spare.
> http://www.sailnet.com/forums/general-discussion-sailing-related/178402-boat-sank-dock.html


OMG, you haven't put solid rubber tires on your truck yet? Why not, then you wouldn't even have to carry the spare and jack? Even better take off the tires and run on skids. What's your point?


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## Group9 (Oct 3, 2010)

capta said:


> OMG, you haven't put solid rubber tires on your truck yet? Why not, then you wouldn't even have to carry the spare and jack? Even better take off the tires and run on skids. What's your point?


The opposite of yours, I believe.


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## casey1999 (Oct 18, 2010)

I was also looking at a way to get rid of my two cockpit drain seacocks that are below the water line (each drain runs to a seacock located on the opposite side of center-line of the boat). Since the boat does have a stern wave that rises up at the stern end of the boat, I decided against trying to relocate, as this stern wave may cause flooding in the cockpit. Too many unknowns with changing the original S&S design- they must have had a reason to do what they did.

Cockpit drain hose is the green hoses in the attached pic.


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## HR28sailor (Feb 11, 2010)

Relocating drains aft would get the hoses out of the way when working on the engine. I know wrenching on an engine in a tight spot is hassle enough without hoses in the way. I think back flooding would occur with your drains if a pressure wave was pushing water in. like a following sea situation. As your stern wave is moving across the opening of the drain, you will still have the benefit of the venturi effect pulling water out of the cockpit. Which will drain much faster than just letting gravity do it. just my two cents....


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## casey1999 (Oct 18, 2010)

HR28sailor said:


> Relocating drains aft would get the hoses out of the way when working on the engine. I know wrenching on an engine in a tight spot is hassle enough without hoses in the way. I think back flooding would occur with your drains if a pressure wave was pushing water in. like a following sea situation. As your stern wave is moving across the opening of the drain, you will still have the benefit of the venturi effect pulling water out of the cockpit. Which will drain much faster than just letting gravity do it. just my two cents....


I think it depends on the engine configuration. I know with my S&S34 in order to run the two cockpit drains aft I would need to use some straight pipe, since hose would sag and create a low spot in the drain line. I figured I would need to support this straight pipe in some way and the two pipes would run right over the engine- now I have created a real pain to work on the engine. I also would have created 4 more hose connected joints and a run of fixed pipe- this would create more areas of potential boat flooding leaks- or leaks to drip on the engine.


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## smurphny (Feb 20, 2009)

My '67 A35 has its cockpit drains going straight down vertically. They are approx. 1 1/2" molded-in solid fiberglass tubes that were done in the original layup. They are strong as the dickens and also have corks attached with string as do the other similar standpipes for sinks. As they drain extremely fast, I would guess the reason for this config. is to avoid any bends which would be created going horizontally.


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## christian.hess (Sep 18, 2013)

my islander 36 goes straight down too...however they could be bigger drain holes up top


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## HR28sailor (Feb 11, 2010)

I see your point. joints have the potential to leak and the hose runs would be longer and drain time would be increased not good so should be avoided. Faster the better. That's why designers put the drains below the waterline. water is sucked out faster. smart they were free pumping. They would also need to be secured so they don't move. Alas, every sailboat has compromises of one sort or another.


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## irwin37 (Nov 26, 2013)

Try this again.... I have an Irwin 37 CC with drains that go to below the waterline. Only way it will work as the cockpit floor is at shoulder height in the aft state room. Drains would have to run right through the state room. There is also a walk through on the port side precluding any drain through there.


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