Cockpit drain pipes

[JeremyFowler]

Some more advice needed please… Particularly pertaining to New Zealand and potential Cat 1 requirements:
If a cockpit drainage pipe exits above water level are there any regulations that require it to have a seacock? The problem being that I want a largish drainpipe (for rapid draining) and having a large stopcock isn’t practical and will never be closed anyway as the drainage has to happen even when moored.
Thanks kind folks.

[tkeithlu]

The problem here is local regulations, with which I cannot help you. It is plausible that someone somewhere in the world might require a seacock on a cockpit drain, but it makes no sense. A cockpit drain is functionally a scupper, draining a deck area, the cockpit, that is exposed to waves, back to the ocean before the weight of the water can do harm or get into the cabin. Putting a seacock on it sets up the possibility of the seacock being left closed while underway, resulting in a huge weight of water in the cockpit. That would be dangerous.

Crossing the two drains, so that you don't end up with water coming up the drains into the cockpit, is important. beyond that, I would not put seacocks on them, and I would resist any inspector's judgement thart they were needed.

[chris95040]

If the hole in the hull can be below the waterline (normally, or when heeled, when in big seas, etc) I’d want a way to shut it! If not, at least use some high quality reinforced hose that doesn’t have a chance of splitting open on you.

I had some white sanitation hose, not incredibly old, split open when I flexed it once. It wasn’t attached to anything, it’s just something I think about when making choices like this.

[nuku34]

Hello Jeremy,
I live in NZ. Here’s the Cat 1 regs I have found relating to your question:


COCKPIT VOLUME11.05 (K) The maximum volume of all cockpits below lowest coamings shall not exceed six percent loaded water line times maximum beam times freeboard abreast the cockpit (six percent L x B x FA). The cockpit sole must be at least two percent length overall above loaded water line (two percent L above LWL).The maximum volume of all cockpits below lowest coamings shall not exceed nine percent loaded water line times maximum beam times freeboard abreast of the cockpit (nine percent L x B x FA). The cockpit sole must be at least two percent length overall above loaded water line (two percent L above LWL)


and,
For yachts 8.53m length overall and over. Cockpit drains adequate to drain cockpits quickly but with a combined area (after allowance for screens if attached) of not less than the equivalent of four 20mm diameter drains. Yachts built before 1 January 1972 must have drains with a combined area (after allowance for screens if attached) of not less than the equivalent to two 25mm drains. Cockpits must drain at all angles of heel.11.07 (K)For yachts under 8.53m length overall. Cockpit drains adequate to drain cockpits quickly but not less in combined area (after allowance for screens if attached) of the equivalent to two 25mm diameter drains. Cockpits must drain at all angles of heel.11.08 (M) Cockpit drains adequate to drain cockpit quickly. That is with a combined area (after allowance for screens, if attached), of not less than the equivalent of four 20mm diameter drains. Cockpits must drain at all angles of heel


Sea cocks or valves shall be fitted on all through-hull openings with the exception of integral deck scuppers, shaft log, speed indicators, depth finders and the like, however, a means of closing such openings when necessary to do so, shall be provided.


The full PFD of the all categories of regulations:
https://www.yachtingnz.org.nz/sites/...20ONLINE_0.pdf


I think that if your drains‘ outlets are above the waterline at ALL angles of heel, AND they empty the cockpit “quickly”, you probably wouldn’t need seacocks on them. Look closely at the regs though.

If the drains are solid pipe and permenantly attached to the cockpit sole and the hull, you would probably be ok with no seacock even if the drains exited below the waterline.
My steel “Joshua” ketch had 2 large steel pipes welded to cockpit sole and to hull, exiting below the waterline. The yacht passed Cat 1.


On the other hand, my current boat, a balsa core FRP 10m yacht, has seacocks on EVERY hole in the hull including those that exit above the waterline (2 manual bilge pumps). The possibility of a hose coming adrift from a through-hull fitting, or splitting, with no way to shut off the water flow is not something I want to chance. I’ve been in seriously bad weather (cyclone off Ozzie) where even above waterline through hulls were under water for long periods of time.

[flee27]

What would be the definition of "quickly"?

Foster

[tkeithlu]

Running through the posts above is the point that those hoses are a surface to the hull. Water getting past them is inside where you don't want it. Ergo, stainless steel pipe or damned good wire reinforced hose properly connected. Less than that, and seacocks become a poor substitute - under storm conditions, you likely wouldn't realize that you needed to close a seacock until the boat's stability was compromised. If you are going to install seacocks, make sure that you will never need them. And, don't forget that seacocks themselves are a failure point.

[Deep Blue Water]

How about a joker valve in the drain tube?