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Old 14-01-2008, 12:50   #1
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Are you pleased with your cockpit drains?

Hi guys,

I'm putting together the parts for my Triton to rebuild the drain system on the cockpit.

What size through hull fittings, deck fittings and hoses are you guys using? I'd like to overkill this project for heading off shore.

Are there formula/suggestions for the volume of a cockpit to the diameter of the drains?

Thanks

Zach
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Old 14-01-2008, 12:52   #2
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Aloha Zach,
I know we've covered this before. Have you done a search?
JohnL
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Old 14-01-2008, 13:04   #3
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Sorry Zach. I couldn't find the old thread either but I remember there being a formula deriving from filling your cockpit with one following sea and having it drain before the next sea filled your cockpit.
I decided to go with the biggest I could with what I had so I've got one drain in each corner of the cockpit sole 1 1/4 in diameter. If I were to do it again I'd go larger. I believe my cockpit is about the same size as yours even though I have a 42.
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Old 14-01-2008, 14:08   #4
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Cockpit drains? What talk is this? I don't have any. Open transom > cockpit drains
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Old 14-01-2008, 14:27   #5
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Either 2 or 4 drains, at 1-1/2" diameter each, are common.

Paraphrasing ABYC on Cockpit Scuppers
H-4.5.9.1 When filled with water to the fixed sill (bridgedeck or coaming) height, 75 % of the cockpit water volume shall drain in 90 seconds. There shall be no leakage to the hull interior during the test.
H-4.5.9.5 Scuppers and all components must be at least 1” internal diameter.
H-4.5.9.6 If scuppers have strainers, their discharge outlet must be 50-percent larger diameter than the scupper.
H-4.5.10.2 Scupper discharge at or below WL must have a seacock
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Old 14-01-2008, 17:04   #6
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2, 1 1/2 inch cockpit drains aren't enough to quickly drain a cockpit. A cruising veteran Bristol 39 I looked at had 2, 2" drains glassed into the back of the cockpit exiting out the transom in addition to the 'standard' 2, 1 1/2" drains at the front of the cockpit. This boat had been a lot of places including a North Pacific crossing and assume the added drains were the result of experience.

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Peter O.
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Old 14-01-2008, 17:44   #7
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Thanks guys,

I like the thought of transom drains, though they'll add 2 more things to the transom in addition to the outboard and future windvane...

Theres not much room under the cockpit sole for any more drain lines.

Any thoughts on transom trains that start half way up the cockpit? The dainty transom on the triton means the hull goes up more than a few inches before reaching the counter. With 4 people in the cockpit my bilge outlet which is about an inch below the transom
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Old 16-01-2008, 17:43   #8
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Check the ORC Offshore Special Regs for some guidance. I have 2 at 1 1/2 and 2 at 3/4. My cockpit and drains comply size wise to ORC, but I am going to rework the drains to all be 1 1/2. The more the merrier. Part of this due to usually half are uphill and there is still significant water left for the lower drains when the boat is heeled. The other reason is although you can be at risk of loosing small things down the larger drains, they are much less likely to clog. I don't care for screens as they reduce the effective size of the drain. I have seen cross bars to keep the children, keys and small animals from disappearing. They may be OK.
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Old 16-01-2008, 17:56   #9
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As happy as I could be. Four 2 inch scuppers.
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Old 16-01-2008, 21:36   #10
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Quote:
Originally Posted by Weyalan View Post
Cockpit drains? What talk is this? I don't have any. Open transom > cockpit drains
Are you bragging or complaining??

I plan on installing the largest I can find, reasonably. And with screens. I spend a lot of time flushing out the dirt and moss.
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Old 16-01-2008, 21:42   #11
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BTW Cockpit drains are one of the main things that sinks boats at the dock in wet and/or cold climates. They either freeze and brake or get plugged then start filling the boat.

See thread....... What Sinks Sailboats (wood excluded) Survey
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Old 20-01-2008, 19:56   #12
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Ugh... got unlogged and the board ate my post when I hit send.

...

I lost my notebook which contained all the part numbers and measurements of Pylasteki. Nevertheless, the existing drains are 1 1/2 inches or larger. I'll be adding two more of the same size, inboard of the two existing ones. In order to make the hoses easier to change I'm thinking seacock placement would be ideal somewhere around where the engine stringers were.

Do you guys have any thoughts on bilge pumps being plumbed into cockpit drains... or any experience using the Henderson March V diaphragm pump as a the pump accessible from the helm? My piston pump died yesterday, and isn't in a spot where one can steer and bail at the same time...

I think a grate of some sort is a good idea, I had a heck of a time removing the starboard hose... there was a snap shackle wedged inside the hose, sitting on top of the seacock. Was a moment which had me wondering why a hose would not submit to the bending in one spot only... I'd hate to find something stuck blocking the valve!
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Old 20-01-2008, 22:12   #13
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(thats looking down onto the engine bed through the open cockpit floor hatch) (( the thing with all the inlets is the pumps manifold two manual for the two bilge sumps two electric for the same and sink and shower tank pumps, manifold exits out through cockpit drains)) (((the boat has no other through holes)))

I have two 3 1/2 inch in the cockpit floor and two 2 inch at the back of the seats in the boat that iam building. I was amazed at how slowly the cockpit drains on my ferro boat with two 1 1/2 drains. A lot of extra weight with one good wave....

((((Henderson pumps are great very easy to fix, very easy to open and clear if blocked. Excelent cockpit pump (last man standing pump) ))))
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Old 21-01-2008, 02:43   #14
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Excerpted from ABYC H-4 ~ Cockpits and Scuppers:

4.5.9.1
When filled with water to the fixed sill height, and with weathertight hatches sealed to the height of the sill, 75% of the cockpit water volume shall drain in 90 seconds. There shall be no leakage to the hull interior during the test.

4.5.9.2
The minimum requirements for the drainage system shall be calculated using either of the following
formulas:

4.5.9.2.1
A = 0.385 x (Vc Root h)
where
A = minimum total area of all drains - square inches
Vc = total amount of water that can be contained in cockpit with the drains closed - cubic inches
h = cockpit depth - feet

or

4.5.9.2.2
Dn = 0.7 x [Vc (n x root h)]
where
Dn = minimum diameter of each drain, in inches
Vc = total amount of water that can be contained in cockpit with the drains closed, in cubic feet
h = cockpit depth - feet
n = number of drains in cockpit
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Old 21-01-2008, 04:13   #15
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Bigger is better here, ain't it? And of course it depends on the volume of your cockpit. Shiva has two, which are 2" . The well is about 29"x51"x18" with seating all around to about 98"x63"x15"... about 70+ cu ft .

If we got the whole cockpit filled it would add 2 tons! OUCH.

Go big... live to tell about it!
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