Raw water manifold for safety?

[unbusted67]

Are there any production boats that use a raw water manifold instead of multiple through hulls to distribute raw water throughout the boat? Doesn’t this seem like a better option safety wise than drilling multiple hills in ones hull?

[billknny]

You keep asking these good questions, and I have the same answer.

My Amel 53 has three thruhulls below the level waterline. One serves the forward head toilet and anchor wash down. One the engine, genset, water maker, and ac pumps, and one the aft head toilet. All sink drains go to a common sump and are pumped overboard

Other boats of the same size I have seen with 18 (!) underwater thruhulls. That’s crazy.

[Red Sky]

The Caliber 47 has one.

[DanaTucker]

My Paceship has three. AC, head and heat exchanger for the motor. In theory, your question may have something to do with the amount of water flow for each point it is needed. Think of a sprinkler system for your yard. The more sprinkler heads you have, the larger the manifold needs to be to supply them. That is why most of them are broken down into zones. Just a thought.

[Dsanduril]

Pretty much all of the Dashew designs, power and sail. Jedi can give you the specifics about his Sundeer.

[Lepke]

Ships and big boats have a vertical pipe in the engine room for a common raw water intake. Each water need is tapped into the main water induction pipe with a shut off valve. Some have an additional pipe for water exit.

[slug]

Originally Posted by unbusted67

Are there any production boats that use a raw water manifold instead of multiple through hulls to distribute raw water throughout the boat? Doesn’t this seem like a better option safety wise than drilling multiple hills in ones hull?

Sure. A Raw water manifold , with discharge thru a single , above waterline thru Hull , is common

Pictured is the bilge intake manifold

You also need a discharge manifold

[tkeithlu]

That was one of my prime reasons for rejecting common trawlers as not seaworthy. I have two through hulls - water in and sewage out, and the sewage one stays locked down. The intake requires lots of hose snaking around the engine room for the engine, genset, and watermaker.

It appeared to me that most manufacturers simply put a through hull wherever they needed water, even under engines where you'd never get to them in time if one popped.

By reversing the position of the inlet valve handle, I made it so that pulling a wire in the main salon above the engine room closes the raw water intake.

Good for you for seeking fewer through hulls.

[slug]

Originally Posted by tkeithlu

That was one of my prime reasons for rejecting common trawlers as not seaworthy. I have two through hulls - water in and sewage out, and the sewage one stays locked down. The intake requires lots of hose snaking around the engine room for the engine, genset, and watermaker.

It appeared to me that most manufacturers simply put a through hull wherever they needed water, even under engines where you'd never get to them in time if one popped.

By reversing the position of the inlet valve handle, I made it so that pulling a wire in the main salon above the engine room closes the raw water intake.

Good for you for seeking fewer through hulls.

Sea water intakes that operate while in the Harbour such as air con handle a lot of water and are prone to clogging... weeds plastic bags....

Best practice is to keep seawater service to engines and generators separate

Watermakers need clean water .... keep the intake upstream of waste discharge

[sailcrazy]

Best I've seen was called a "seachest". It was a quite large diameter tube served by a single big seacock, and had multiple access points (ea with a valve around it and vertically. The one I saw was open at the top, so waterlevels, debris, flow rates, etc could easily be handled/watched/seeviced. I always thought a removable top on it would have been better, for safety, but this one was open.

[Cheechako]

I think a manifold COULD provide for a small addition of safety, but I think most of the time it degrades safety. Why? because often it is hung right off a thru hull fitting and is heavy made of SS or Bronze. A thru hull fitting is very thin at the root of the thread (worst possible place due to sharp stress risers) If you suspend weight off of it that makes it worse.
I once eliminated 3 or 4 thru hulls and made a manifold. By the time I was complete with extra hoses under floor, fittings/Tee, multiple under waterline clamps I felt much less secure,. A good seacock and fitting well maintained is a nearly fail proof device. Just my 2 cents.
A good manifold mounted to the hull would be better. But still requires a lot of extra hose running around to the location of the end device.

[Dsanduril]

^^^

Yes, this is the question I have every time this question comes up. What is the risk of failure of the 30 feet of pipe/hose running through the hull vs. the risk of failure of a through-hull connected to the consumer by 3’ of hose?

Would love to see some real statistics.

[AKA-None]

Consider also that a sea chest will typically entail a larger hole in the hull to feed all that stuff.

[Cheechako]

Originally Posted by Dsanduril

^^^

Yes, this is the question I have every time this question comes up. What is the risk of failure of the 30 feet of pipe/hose running through the hull vs. the risk of failure of a through-hull connected to the consumer by 3’ of hose?

Would love to see some real statistics.

Either well done is OK I suppose. But there is also the problem with fittings fitting hose well. I have been amazed some times that a wire wound stiff hose can be pulled right off a metal fitting even if double clamped. Other times no way can you get it off.
No real standardization in fitting barb sizes.
Or the opposite problem: hose is so tight you have to lube it and put it in hot water to get it on the fitting. Next thing you see is brand new hose is cracking at the fitting!
I replaced all the thick rubber asian (?) hose on the boat in my avatar when I rebuilt it. That hose had no wire but was very thick wall... like 3/8" thick!
A) I gave myself tendonitis just trying to get the old hose off.
B) I realized that hose without wire will clamp a lot better/tighter than wire wound.
C) the original hose was in very good shape and would have been fine.

[Simi 60]

60 ft trawler.
1 single through hull for the primary engine
1 single through hull for the genset and deckwash.
That is all.