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Old 05-12-2012, 09:58   #31
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Re: Cockpit Drains

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Originally Posted by Matt sachs View Post
My cockpit has 2- 3.75 inch steel steel pipes straight down thru the hull. I worry about young kids and small pets falling in....

You're right. Its very hard to get small pets and kids to fall in drains that small. I suggest littering the area around the cockpit drain with candy and cat food to encourage high traffic in the area and increase your chances.

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Old 05-12-2012, 11:14   #32
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Re: Cockpit Drains

Hi - well your on the right path. Instead of thinking 'cockpit drains', think 'engine exhaust'. Power boats, sportfishers, etc have the much larger size thru hull fittings for the engine exhausts thru the transom. They usually bolt in place. If you are going to have them totally underwater, you may be able to carefully cut off some of the excess 'lip' and use bronze bolts (not stainless) to secure them to the hull.

They also use fire proof fiberglass tubing - which is removable - for long exhaust runs instead of hose. Usually keeps the cost down, and the fiberglass tubes usually last a very long time.

For my "long" run - which was about 24" with a 45-degree angle fitting in it, I used schedule 80 PVC tubing. To make the run flexible, water tight and removable, I used short sections of "wireless" exhaust hose with marine sealant applied to the overlap section - and double hose clamps.

The two short lengths of 'connecting hose' give a slight amount of flexibity - and I mean slight. But it's enough to give all the parts some amount of give.

I really hate exhaust hose with wire in it - I think it should be outlawed. The encased steel coil eventually rusts, expands and either breaks thru to the exterior of the hose - or worse yet, breaks into the interior of the hose. When I bought my boat I found that this had happened - exterior of hose looked good while the interior was totally collasped in places.

If you need the wire to prevent collaspe of the hose to make a real sharp turn, re-route the hose for a gentler turn or use angled fittings. Wireless hose can make a turn, just not sharp.
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Old 05-12-2012, 11:53   #33
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Re: Cockpit Drains

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Hi - well your on the right path. Instead of thinking 'cockpit drains', think 'engine exhaust'. Power boats, sportfishers, etc have the much larger size thru hull fittings for the engine exhausts thru the transom. They usually bolt in place. If you are going to have them totally underwater, you may be able to carefully cut off some of the excess 'lip' and use bronze bolts (not stainless) to secure them to the hull.
Hi Doug:

There is the missing link in my thinking - exhaust parts, thank you. I only have about a 2 foot run and would be quite happy with 4 inch exhaust host at $15/foot.

I think the only remaining issue is how far above WL is necessary for a safe thru hull with no seacock? My electric bilge pump has a seacock, but my manual whale pump does not and they both appear to be 6 inches or so above WL, through the hull bottom, not transom.

Cheers,

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Old 05-12-2012, 11:53   #34
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Re: Cockpit Drains

Anyone ever tried filling their cockpit with water (at least the footwell) to see how much the boat settles?

I did put 3" drains from the back of the cockpit well to the stern on one boat. I used large exhaust hose as i was concerned about rigid tube breaking free with boat flex... creating a worse problem than a big cockpit. I have not been in a severe storm offshore, but rapid cockpit draining would be generally be pretty low on my list of concerns...
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Old 05-12-2012, 12:06   #35
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Re: Cockpit Drains

I haven't put the engine in the boat yet but eventually. I tried using a PVC pip for a steam box for bending a piece of oak trim and the tube softened and bent. You're saying that the water/exhaust is not hot enough to soften the PVC? I like the idea in concept. I'd have to PM with you for more details.
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Old 05-12-2012, 12:28   #36
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Re: Cockpit Drains

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I haven't put the engine in the boat yet but eventually. I tried using a PVC pip for a steam box for bending a piece of oak trim and the tube softened and bent. You're saying that the water/exhaust is not hot enough to soften the PVC? I like the idea in concept. I'd have to PM with you for more details.
I had some failures of Sched 80 large pipe in industrial applications carrying cooling water. Wet Engine exhaust is pretty cool though usually. But what if your impellor goes south and the heat catches the PVC on fire? I would use Fiberglass for a long run, but in the end, one long exhaust hose will have less clamps, fittings etc. Neat and clean....less likely to rattle.... and maybe expensive! then again 10 ft at $15 a foot might not be that bad... it's boat bucks!
It's easy to make your own Fiberglass tubing though. Just lay it up on a cardboard tube of ~ the right diameter and soak it in water after curing to decompose the cardboard. To make the ends neat and clean you can use a hole saw on smaller diameters..... the inside of the hole saw cuts the outside of the layup/tube to a machined surface. Hope you can visualize that. Or you can just grind it carefully.
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Old 05-12-2012, 13:56   #37
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Re: Cockpit Drains

Cheechako ... obviously you haven't read the first post and seen my pictures. Fiberglass tubes is where this thread started. That's exactly how I made mine. I formed them over postal mailing tubes painted with PVA. After cure I just soaked out the cardboard. The only thing hard about the project was rolling out the glass and resin so there weren't any lumps. The tubes were easy to work with. I even cut tube angles on my radial arm saw, rotating each taper, and glued them together with carpenters glue to make 90 bends at the end.
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Old 05-12-2012, 14:40   #38
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Re: Cockpit Drains

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Cheechako ... obviously you haven't read the first post and seen my pictures. Fiberglass tubes is where this thread started. That's exactly how I made mine. I formed them over postal mailing tubes painted with PVA. After cure I just soaked out the cardboard. The only thing hard about the project was rolling out the glass and resin so there weren't any lumps. The tubes were easy to work with. I even cut tube angles on my radial arm saw, rotating each taper, and glued them together with carpenters glue to make 90 bends at the end.
I must have not read it or it's been too long. I was responding to the "side trip" regarding exhaust though......I would have no problem with PVC for cockpit drains.With rubber hose in the link somwhere anyway.
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Old 05-12-2012, 15:22   #39
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Re: Cockpit Drains

Hi - just so everyone knows, I would NOT - as in never - use PVC or any type of plastic tubing for carry exhaust gases.

I have seen the special fiberglass tubing/rubber connecting hoses after a complete cooling water failure on a 440-cid engine in a sportfisher. The rubber exhaust hose connecting pieces (about 10" long) caught on fire and burned through, while the fiberglass tube survived.

My 'big' drain's exit is usually just above the waterline below the transom and the entrance is always above the waterline on the rear cockpit bulkead. The exit thru hull has about 4" of threads come up inside the boat, so from the normal waterline to the end of the treads is about 8".

The big drain has no shut off valve - it is just an open tube.

I have had one big knock-down off shore (ie. masthead in the water) when the boat slid off of an 18-ft wave. When the boat stopped at the bottom of the wave is when the cockpit filled with water (and the MOB gear was washed overboard and the canvas dodger and framework damaged).

I looked at the cockpit as soon as the boat righted - checking for damage - and the water level was about 4-inches from the top of the cockpit coaming. I also checked (moon lit night) for a following wave and luckily there wasn't a second one. The stern was definitely down and a second wave could have caused a lot more problems.

A lot of things were happening at once (turning on the 2 Rule 3600 Rule bilge pumps and doing a quick check for any obvious damage below), but my guess is that by about the 3-minute mark from the cockpit being full it was empty

I checked that the engine was still on it's mounts and in place, then went out and started the diesel so there would be power, checked the rudder stuffing box to make sure it was OK, checked the steering and checked the rig. When I went out, the cockpit was again dry.

Luckily everything was OK and I was REALLY happy that I had taken the time to install the big drains.
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Old 05-12-2012, 19:57   #40
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Re: Cockpit Drains

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My 'big' drain's exit is usually just above the waterline below the transom and the entrance is always above the waterline on the rear cockpit bulkead. The exit thru hull has about 4" of threads come up inside the boat, so from the normal waterline to the end of the treads is about 8".

The big drain has no shut off valve - it is just an open tube.
Thank you for the added description of your drain infrastructure and it's relationship to the WL.

I guess the next step is to estimate where my WL will drop to if I have 2000 odd litres of water in my cockpit in a 5000 Kg vessel. As long as the hose is intact the distance above WL to cockpit floor is something like 18 or 24 inches, but if the lower through hull fails, I'd want a few inches there, the question is how few. Not a clean estimation as the boat will be tipping aft as the water load is very unbalancing. Sticking my finger in the air, I'd say I am about 75% sure 4 inches is inadequate and 75% sure 12 inches is adequate. I'll see if I can come up with something that is more than a WAG.

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Old 06-12-2012, 00:29   #41
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Re: Cockpit Drains

I'm having a little trouble understanding this obsession with cockpit drains for several reasons:

1) Our boat (Caliber 40) was pooped in a serious tidal overfall with huge standing waves - cockpit was full to overflowing the seats - continued sailing with no change in trim or buoyancy that I could detect. The three stock/standard 1.5" drains emptied the cockpit in short order while I tried to steer around the worst of the 10' + waves. I noticed no change in the helm responsiveness.

The wave that got us was big enough and put enough water into the boat that we found several inches of salt water in our sauce pans on the 2nd shelve up in the cupboard under the galley sink. All of that water just drained into the bilge where my three bilge pumps quickly discharged it.

This event occurred in the north Sea of Cortez (Gulf of California) about a mile offshore.

2) My brothers boat (Tartan 42) was pooped in a full gale with 12' breaking square waves where the water went from hundreds of fathoms to less than 10 fathoms and there was a 2 knot current opposing the waves. The stock Tartan cockpit drains quickly drained the cockpit. I was hand steering and again we felt no change in the boat handling or steering. Our bigger concern was not over running the next wave as we surfed at 12 knots down each wave. This occurred in the eastern entrance to the Straits of Juan de Fuca between the Olympic Peninsula (Washington State) and Vancouver Island, Canada.

It never occurred to us in either event to be concerned about the speed at which the cockpits drained.

Additionally - I've done a fair number of blue water miles in many boats from 40 to 65 feet and have done several days and many nights of down wind sailing in more than gales and more than 12' breaking seas and I can never remember being concerned about getting pooped or having breaking waves enter the cockpit.

I've spent several enjoyable nights sitting in our cockpit in 45+ knots and pretty big breaking seas as our Sailormat windvane drove us downwind at about 150 degrees apparent and just marveled at how, each and every time, the stern would rise and the breaking sea would rush on by.

Several hundred miles east of the US Carolinas we did 430 miles in 48 hours in a big light fast CRUISER all of it downwind with spinnaker or big genoa on a pole. The swell was enormous with an occasional breaker - never once had reason to think about water in the cockpit.

Attached picture during a 250 NM crossing from the Baja Peninsula to Banderas Bay on the Mexican Mainland in 40+ knots and biggish breaking seas for about 10 hours. Cockpit stayed bone dry and the autopilot steered every inch of the way. We stayed above 7.3 knots with only a 90% jib up.

Maybe I've been naive for several decades of ocean sailing and didn't realize the danger those stock drains posed.
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Old 06-12-2012, 01:09   #42
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Re: Cockpit Drains

Fantastic photo Tacoma! Where was it taken? Any more wave pics?
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Old 06-12-2012, 01:16   #43
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Quote:
Originally Posted by TacomaSailor View Post
I'm having a little trouble understanding this obsession with cockpit drains for several reasons:

1) Our boat (Caliber 40) was pooped in a serious tidal overfall with huge standing waves - cockpit was full to overflowing the seats - continued sailing with no change in trim or buoyancy that I could detect. The three stock/standard 1.5" drains emptied the cockpit in short order while I tried to steer around the worst of the 10' + waves. I noticed no change in the helm responsiveness.

The wave that got us was big enough and put enough water into the boat that we found several inches of salt water in our sauce pans on the 2nd shelve up in the cupboard under the galley sink. All of that water just drained into the bilge where my three bilge pumps quickly discharged it.

This event occurred in the north Sea of Cortez (Gulf of California) about a mile offshore.

2) My brothers boat (Tartan 42) was pooped in a full gale with 12' breaking square waves where the water went from hundreds of fathoms to less than 10 fathoms and there was a 2 knot current opposing the waves. The stock Tartan cockpit drains quickly drained the cockpit. I was hand steering and again we felt no change in the boat handling or steering. Our bigger concern was not over running the next wave as we surfed at 12 knots down each wave. This occurred in the eastern entrance to the Straits of Juan de Fuca between the Olympic Peninsula (Washington State) and Vancouver Island, Canada.

It never occurred to us in either event to be concerned about the speed at which the cockpits drained.

Additionally - I've done a fair number of blue water miles in many boats from 40 to 65 feet and have done several days and many nights of down wind sailing in more than gales and more than 12' breaking seas and I can never remember being concerned about getting pooped or having breaking waves enter the cockpit.

I've spent several enjoyable nights sitting in our cockpit in 45+ knots and pretty big breaking seas as our Sailormat windvane drove us downwind at about 150 degrees apparent and just marveled at how, each and every time, the stern would rise and the breaking sea would rush on by.

Several hundred miles east of the US Carolinas we did 430 miles in 48 hours in a big light fast CRUISER all of it downwind with spinnaker or big genoa on a pole. The swell was enormous with an occasional breaker - never once had reason to think about water in the cockpit.

Attached picture during a 250 NM crossing from the Baja Peninsula to Banderas Bay on the Mexican Mainland in 40+ knots and biggish breaking seas for about 10 hours. Cockpit stayed bone dry and the autopilot steered every inch of the way. We stayed above 7.3 knots with only a 90% jib up.

Maybe I've been naive for several decades of ocean sailing and didn't realize the danger those stock drains posed.
Thumbs Up. Agreed.

My sailboat was designed by William Crealock, and he is recognized as being pretty knowledgeable about sailboat design, and the needs of each boat. My CM32 aft cabin ketch came 37 years ago with a place for 6.- 1 1\2" drains, but only two were drilled to make life below in the owners cabin more comfortable, or they were proven, to not be needed. In 37 years, no one has seen fit to install the 4 remaining drains. My sailboat was a west coast girl all her life, until I imported her to Nebraska last spring.

It is worse than that, the straight down thruhulls look to be 1 1\4" Drains fast and dependently on wash day, and on sail days, her design seems to keep spray and waves in check. Mind you no 12' seas in Nebraska, but past owners in blue water never had any water cockpit issues.



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The freeboard of my boat is quite high, cannot reach over the side to touch the water, even when healing, contributes to the dry cockpit.
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Old 06-12-2012, 04:02   #44
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In actual practice, in rough sea, the conditions that completely poop a typical cockpit also toss most of the water out a few minutes later. The drains handle the rest.

Then again for some hapless sailors and poorly designed boats the majority of the water goes down the companionway where the pumps might handle it.

Two 1 1/2 inch drains are plenty for the typical cockpit. But larger is indeed better. Except larger drains swallow more boat parts.

A overflow drain out the transom is sometimes a better solution. It can be large while not being such a safety problem during the 99.99% of the time it is high and dry.
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Old 06-12-2012, 04:23   #45
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Re: Cockpit Drains

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No seacocks if they drain above the waterline is a potential problem how? That seems fine.

If the drain for the cockpit terminates below the waterline, seems to me having no seacock is asking for trouble. A prudent person would close all below water thruhulls whenever the boat is slipped unattended.
Hmm... I must be imprudent then.

By the way, how do you keep the rain from filling up your cockpit when the cockpit drain seacocks are closed?
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