Of seacocks drains and things

[Graham_Wright]

Having wrestled with locations and safety of various sea connections, I thought of leading hoses for engine water, galley inlet and outlet and cockpit drains to sea in a water-tight locker with the hoses then taken above the waterline to their destinations. No seacocks to be used.

If a hose comes adrift, we end up with a locker full of water but a bit of inboard diving can plug that and the boat stays afloat.

Any comments?

 

[cass123]

On large ships, this is called a sea chest, but even the sea chest has
a main sea valve.
Wouldn't go this way if I were you, sounds too risky.

 

[Graham_Wright]

Appreciate the response but why?
Please elucidate.
It seems to me that most leak problems occur with the seacock. A plain hull-through can be almost indestuctible if the mechanical loads are removed from it.

 

[cass123]

Maybe I'm missing something or being overly cautious in my old age,
but it just dosn't sound right.
Your locker will have a head of water on it all the time, not just when a
hose comes adrift. Where would you place your locker to satisfy the
demands of both cockpit drains and onboard services ?. If fitted off the
C/L. would this not bring the galley drain near the W/L. when heeling
to a strong breeze.

Can only say that I certainly wouln't do this, perhaps others will disagree.

 

[boatmike]

On a ship it is normal to have a sea chest. the advantage being that it can be covered with a large grille to keep weed and detritus out and there is a reservior of water always there. The outlets from the sea chest are all valved however and there are just as many valves as you would have if you used seperate skin fittings. The advantage is that the systems are less likely to get blocked and all the valves are conveniently in the same place. Often a compressed air or steam line is routed into the sea chest to purge any blockage.
On a yacht there is nothing to be gained by this approach and all that you would do is end up with more plumbing. In particular, cockpit drains and scuppers should go straight to sea over the side. They don't have to be below the WL at all but must be below the sole plate of course, even when heeled so often are. Grey water outlets like galley sink etc and black water outlets (toilets) should never be led to a sea chest unless you really want to fill your engine up with "Richard the III"s . In short there is a reason for the way things normally are on a yacht. Keep your hose runs short and use good quality bronze skin fittings. And remember only inlets need be below WL. Outlets can be above (although poo is better pumped out below WL for obvious reasons!)

 

[Graham_Wright]

That all makes sense but I have a particular problem with cockpit drains as the boat is centre cockpit with a passge-way that interrupts the obvious route for the port side drain hoses. They have to go straight down to fit in and then the seacock is inaccessible. I can hose them out through the starboard side but to get sufficient fall when heeled, they must be below the waterline. The starboard side cockpit drains are worse in respect of seacock accessibility which will inevitably mean they will be left open. A permanently open seacock is just a skin fitting in disguise.
I would not wish to fit a "sea chest"; a bit too big shippy for my vessel but individual connections to skin fittings spread over a fairly large area all in a watertight locker (glassed in all round) seems a reasonably seamanlike solution. Should any connections fail, the water level in that locker is still reasonable to ferret around in to plug the hole or replace the hose. I have had the frightening experience of giving a seacock a gentle tap to free it at the start of the season to find a considerable fountain of water entering the boat when it broke free. Had SWMBO not been close at hand with a plastic tomato ketchup bottle, a very interesting situation could have developed!

 

[boatmike]

It's only a seaman-like solution if you have sea cocks. You originally said no seacocks to be used. this would be very unwise in my opinion.

 

[Graham_Wright]

Sorry to worry at this but what are the seacocks for?
I will have shut off valves where required e.g. engine water intakes but in a position close to the filters and accessible. But I see no use for them for cockpit drains.
It seems to me that seacocks conventionally protect the hose attached to them which is less vunerable to failure than the seacock supposedly protecting them.
There is at least one boat builder who glasses in sea connections and connects the hose above the waterline via a rigid standpipe. I personally don't like this as, unless it is extremely well protected mechanically, the leverage is sufficient to do considerable damage to the attachment and the hull if inadvertently over-stressed.

 

[boatmike]

The seacocks isolate the seawater connections at the hull. This is not just to protect against a burst pipe it is to ensure that if there is fire (for instance) you can shut off at the hull.What you are missing is that the waterline only remains the waterline if the boat is not damaged. If you do sustain damage you do not want a leak that floods the boat to an extent to be catastrophic. Say, heaven forbid, you hit a rock and water is coming in. Say there is an engine room fire. Would you not like to know that all that plastic pipe does not allow the ingress of further water.?
Bad enough to have to deal with one problem at a time. Shut off sea cocks, deal with damage, put out fire etc.....

 

[cass123]

I certainly must be missing something.

If your locker is to be watertight , how can the water level be reasonable, and how do you plan to be able to ferret about in a watertight locker?.

Hate to think of the gunge that will be "recycled" into your engine cooling intake.

Best of luck anyhow.

 

[Graham_Wright]

Hell! This is becoming a struggle!
I think I am suffering from the problem of being too close to something to be able to adequately describe it to others.
I have a very deep cockpit locker that is watertight up to the cockpit coaming i.e. glassed in to bulkheads all round. Any hole in that below the waterline or from a fitting below the waterline will allow the ingress of water up to the waterline which I accept will be depressed a little by the ingress of said water. This locker is large enough to admit a body kneeling in the bottom albeit with considerable discomfort. The normal waterline is about 300mm above the bottom of the locker (V-shaped). If this locker were flooded, the additional weight of water would cause a rise of maybe 50-100mm. This still allows reaching to any failed connection or through-hull.
My suggestion is to make all the hull connections that need to be under water and those cockpit drains which by reason of the requirements of fall when heeled to individual through-hulls.
I do not intend to use a "sea chest" (which is presumably why you think the engine intake is open to "gunge".
I'm not sure I understand the argument about fire. I suppose the engine water intake hose could melt as it passes throught the engine compartment before reaching the shut-off valve which is next to the filter. Being pedantic, once full, (the engine compartment is watertight to well above the water line as well) the fire would be extinguished!

 

[tugboat]

Ever since boats/ships have had through hull fittings below the waterline it has been considered good design/seamanship to have a valve at the ship's side. On a boat this protects the hose which is perceived to be the weak link. On a ship it protects from the rusting of the internal pipework. Also allows clearing of filters, etc. If a problem develops, shut the valve, deal with the problem, open the valve, Bob's your uncle. Previous poster's comment about fire melting hoses is a very valid comment for most installations. I don't think anyone is saying you can't do what you are suggesting - just that it goes against what most of us consider good design/seamanship. Obviously you know your boat better than we do. If you are happy that it is safe for you and your loved ones and wouldn't put off a purchaser when you come to sell the boat? It would be worth consulting a local surveyor for an opinion. I'm curious to know how you will waterproof the hoses where they pass through the bulkheads to exit this watertight locker en route to engine, etc? If you are going to use bronze bulkhead fittings ( as would be advisable) you might just as well fit seacocks and be done with it.

 

[Graham_Wright]

Thanks for all the advice.
Your last sentence sparked an idea.
On a submarine, cables, pipes etc pass through bulkheads via connectors such as you mention.
I have already explained that I will fit seacocks to engine water feed (of which there are two) and envisaged those in the engine compartment. If instead they replaced the through bulkhead fittings they would be more accessible in panic from the cockpit.
Seavalves fitted elsewhere would have to be in the engine compartment so shutting off in the event of fire would be counterproductive as the access required would admit more air and feed the fire.
The cockpit drains will not be valved at the hull.