seacock sizes

[S/V Laura Ellen]

I'm replacing all the seacocks on Laura Ellen (37').
What are the commonly used sizes for:

raw water for the engine
sink drains
cockpit drains
water inlet for sinks (I'm in fresh water)
electric bilge pump outlet
manual bilge pump outlet

[outofthenorm]

Allan, I have the following and they all seem right for the job:

- 3/4 inch ID for engine intake. (4-cyl gas - I'd guess that a bigger engine might need more.)
- 3/4 inch ID sink drain
- 3/4 inch ID head fresh water intake

- 1 inch ID electric bilge pipe outlets (2)
- 1.25 inch ID manual bilge pump (Henderson)
These are sized to maximize the flow from the pumps

No overboard cockpit drain anymore, but they used to be 1.25 inch ID as well.

Hope that helps.

- Norm

[S/V Laura Ellen]

Allan, I have the following and they all seem right for the job:

No overboard cockpit drain anymore, but they used to be 1.25 inch ID as well.

Hope that helps.

- Norm

Thanks for the info.
How did you get around the cockpit drains?

[outofthenorm]

The cockpit sole is exactly at the waterline, so more water came in than went out:eek: . I pulled the thruhulls and filled the holes. Now the cockpit drains into the bilge. My plan (someday) is to raise the sole and re-install - but it's way low on the list. - Norm

[kc8pql]

My boat's 38' on deck. Here's what I have:
raw water for the engine
1 1/4" (depends on the engine)
sink drains
1 1/2" galley, 3/4" head (teed into head intake)
cockpit drains
1 1/2"
water inlet for sinks (I'm in fresh water)
3/4"
electric bilge pump outlet
1 1/4" and 2" (depends on the size of the pumps)
manual bilge pump outlet
1 1/2" (teed into cockpit drain, pump size matters)Humm, can't seem to get rid of these numbers....

[willmarsh3]

I know from first hand experience that the sink drain should be about 3/4 like norm said. I used too small of one at first and had the sink constantly clogging up. I have a 1/2" ID on my 24 hp inboard diesel and it seems to be perfectly adequate. The cockpit has a pair of 2" drains going straight down and out the bottom.

[The Bigfella]

Grantala is 50' on deck and has a variety of fittings

sink drain is 2 1/2"

toilet - and I do mean a houshehold style toilet - WAS a 4" above-water through-hull, with no macerator - just lovely eh?

head - now has 1 1/4" inlet, and 1 1/2" outlet

engines (4-53 Detroits) have IIRC 2" inlets

genset has 3/4" inlet

So - as you can see - you can have a wide variety of sizes. If you have the originals, I'd replace to the same size unless there is a good reason to change. I certainly don't think I need the larger fittings on the head - given that they both have to connect to 1" hose, but its harder to go back to smaller size through-hulls than to go the other way

[Andrew Craig-Bennett]

One more:

Mirelle is 37ft on deck; all seacocks are Blakes and easy to get at:

Engine salt water intake 0.75"

Exhaust seacock (yes, we have one!) 1.5" (small engine!)

Bilge pumps (two, both manual) via Y piece to one 1.5"

Sink drain is 1.5" via diverter valve to cabin bilge pump (this is a really good idea!) and thence to aforementioned seacock.

Cockpit drains 2 x 1.5" (crossed drains, very small footwell, with seats at deck level)

Heads inlet 0.75"

Heads discharge 1.5"

[Concordia...41]

Allan - this is a timely topic as just yesterday, replacing my three existing (engine intake, sink drain, head discharge) and figuring out something for bilge pumps and head intake graduated from the "B List" to the "A List." :D

Can you let me in on whatever you've found for suppliers?

Thanks and see you in Mystic!

- M

[Lew Barrett]

Wilcox Crittendon and Groco both make nice bronze through-hulls.

[Bruce Hooke]

I seem to recall a formula that you could use to figure out how long it would take a certain volume of water to drain out of a cockpit via drains of a given size, and a rule about how long it should take. I am mentioning this in case someone can remember more details of said rule.

I suppose the short version of this rule is that cockpit drains should be BIG and should be sized relative to the volume of the cockpit rather than the overall size of the boat.

[kc8pql]

I suppose the short version of this rule is that cockpit drains should be BIG and should be sized relative to the volume of the cockpit rather than the overall size of the boat.

Exactly! I have four 1 1/2" drains in my smallish cockpit. Even so, it would take a while to drain if I got pooped and it filled. As an example, think about a bathtub. The standard household bathtub drain is 1 1/2". Fill it to he brim and then see how long it takes to drain. Most cockpits are quite a bit larger than a bathtub.

Edited to add: It's worth noting that if conditions are bad enough to fill the cockpit, the boat is probably pitching and rolling so much that most of the water would be sloshed back out before it had time to drain.

[S/V Laura Ellen]

Wilcox Crittendon and Groco both make nice bronze through-hulls.

I'm having trouble finding a source of Wilcox Crittenden sea cocks. Are they still being made, who sells them?

[Mrleft8]

Don't you know that size doesn't matter. Allan? ;)

[Ken Hutchins]

More important than size, make sure you use proper seacock with a flange and a proper backing block, DO NOT depend on a threaded fitting.:)

Many thousands have sunk because of improper seacocks.:eek: :eek:

A seacock must withstand a 500 load test, per USGQ.

[Lew Barrett]

I'm having trouble finding a source of Wilcox Crittenden sea cocks. Are they still being made, who sells them?

Sorry Allan; I just checked the Wilcox catelog and it looks like they've dropped their line of sea cocks. Groco remains a very reliable quality producer as does Buck Algonquin. The Grocos have cast handles, while the Buck's are stamped. Jamestown handles all three lines, and shows Buck and Groco sea cocks in their current on-line catelog.
If I were buying them for myself, I'd just go to Fisheries Supply here in Seattle and grab them off the shelf in whatever size I wanted (and discounted too).

www.fisheriessupply.com

[John B]

bar the cockpit drains, the answer is :the skin fittings match the 'appliances'.