Cockpit drains

[coopec]

Currently I have three cockpit drains exiting through the transom (2 X Stbd + fwd Port) from the center cockpit of my 43ft yacht. The aft Port drain I had connected to an underwater skin fitting near the keel. I've decided to use that skin fitting for the raw water intake and using one of these nylon strainers over the skin fitting

View attachment 57794

I can easily exit the fourth cockpit drain through the transom (as the others are) or more easily through the side of the hull. (It is 4 feet from the cockpit floor to the water-line)

• If I do go through the side of the hull do I use a scupper valve?
• If I exit near the water-line or one foot below the cockpit floor it won't make any difference when a large wave washes along the gunwale because the cockpit will tend to fill up anyway.
• If I exit too high then when the yacht is heeling to starboard, the drain could be ineffectual.

My inclination is to exit about 2ft down from the cockpit floor using a scupper valve.

Now, could I have the experts opinion please?

Clive

 

[duncan99210]

What's a scupper valve please?

 

[coopec]

What's a scupper valve please?

View attachment 57795

https://www.google.com.au/#q=scupper+valves+for+boats

Clive

 

[GrahamM376]

Our two (center cockpit) drains run into one 38mm pipe to a normal skin fitting just above the waterline, port side. Cockpit never fills.

 

[Seajet]

It would be a good idea to make the drains closeable, in case of damage aft drastically altering the trim; I know one boat which was saved by closing the cockpit seacocks to avoid further flooding, after being hit in the stern by a steel fishing boat.

 

[LittleSister]

It would be a good idea to make the drains closeable, in case of damage aft drastically altering the trim; I know one boat which was saved by closing the cockpit seacocks to avoid further flooding, after being hit in the stern by a steel fishing boat.

A bit excessive, perhaps? His cockpit floor is 4 feet above the waterline. 4 feet above the waterline would be coming over the cockpit coamings on your boat or mine, regardless of whether any seacocks were open or closed!

 

[Seajet]

I'd suggest still a good idea, and when specifying any boat I'd stipulate closeable drains.

The cockpit in question may be 4' high, but if the boat was damaged at the stern - collision or lobster pot tearing out the propshaft etc - I bet the skipper would be jolly glad to be able to isolate the cockpit !

 

[coopec]

Thanks for your replies.

The aft section of the yacht (I call it the lazarette) is separated from the rest of the yacht by a bulkhead. I worry that it is not ventilated in anyway at this stage. Maybe I could use a mushroom ventilator to keep the yacht watertight in the event of catastrophic damage to the aft section

I was very careful when I laid up the hull to make it as strong as possible so I want to avoid below waterline skin fittings where possible. So far I can see I have to have skin fittings for
1. Raw water inlet
2. Toilet inlets X2
3. Aft toilet outlet
4. Sewage outlet. (gray water outlet is above W/L)
5. Inlet for water de-salinator (planned)

 

[William_H]

Hello Clive. I hope the construction is moving forward and all is going well.
Re cockpit drains I note that from Yachting Australia Racing Rul;es of Sailing Special Regulations part 1 section 3 specifications for cockpit drains are given. This calls for 4 drains for a boat of your size min 20mm diameter equivalent after screens. I would think large right be preferable. Now these standards are not obligatory for you but might give an indication of what is reasonable and of course you might get the urge to do a Bali race.
Sorry I can't find a link to these regs but mostly they are epublished in the "blue Book" Racing rules of sailing if you have any racing friends. good luck olewill

 

[coopec]

William

Thanks for your encouragement as it is a welcome change to some comments I get. And yes, the Bali race has been penciled in. (Expect a call!)

I found the link to the rules you mentioned: thanks.

When in doubt I have been using the American Yachting and Boating Council standards. and David Pascoe (Marine surveyor) requirements. I think it was David Pascoe who said the cockpit must empty within 40(?) seconds. As a consequence I have 4X 40MM drains in the bottom of the cockpit plus one (40MM) above the Port cockpit seat which drains on to the deck. I'm happy with that but I was alarmed when I read.

View attachment 57826

I was going to discharge the main bilge pump into the cockpit so I'll have to work out why I shouldn't do it. Maybe pumping bilge water into a cockpit that is already having trouble discharging the contents through the drains is not very clever?

I found the link to the PDF Yachting Australia Racing Rules.
https://www.google.com.au/#q=yachting+australia+boating+rules+

I think these are the rules you are referring to

View attachment 57827

I'm currently plumbing up the motor fuel, cooling and exhaust systems so I am on a very steep learning curve.

Clive

ADDITIONAL NOTE
I have read twice in the last few days that Rule make up a non return valve for bilge outlets that cause very little resistance. I don't want to use a goose-neck as they cut right back on the discharge rate of the bilge pump. I can't find a picture of a Rule non-return valve but here are some others.

View attachment 57829