Aboard my O'Day 25 I have recently plumbed the raw water intake line from the engine to an unused manual head intake ball valve (I have been using a port-a-potti so was not in use), I am interested in returning to a manual flush toilet and holding tank (already installed). In your opinion would sharing a single intake between the engine and the head be a problem? The original engine (Volvo 10 hp) raw water intake is an old gate valve and I will someday replace this with a ball type valve, but for the time being was going to put in a tee or y adapter to supply fresh water for the 2 purposes. Any concerns. Thank you. Don
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Yes, two concerns.
I know Peggy will have an answer but I currently have my engine water plumbed to two uses. The difference is that I use two valves and never open both at the same time. You would definitely require a check-valve in the head hose to prevent the engine from pulling the water out of the head(maybe the holding tank?). Then I question whether you could flush with the engine running. You would be pumping against a waterpump turning 2000+ rpm, who wins this one? I vote for a separate thru-hull.
I know Peggy will have an answer but I currently have my engine water plumbed to two uses. The difference is that I use two valves and never open both at the same time. You would definitely require a check-valve in the head hose to prevent the engine from pulling the water out of the head(maybe the holding tank?). Then I question whether you could flush with the engine running. You would be pumping against a waterpump turning 2000+ rpm, who wins this one? I vote for a separate thru-hull.
Never seen it.
Dec. 6, 2000 Dear Don, Ed has hit the nail on the head, so to speak. The fact that you never see a head plumbed to an engine inlet hose is a pretty good clue that the problems mentioned by Ed are real and not imagined. Your diesel is not meant to be used as a macerator pump, which is what it would be turned into if plumbed to the head inlet. Frankly I have had check valves held open by debris, so I would not consider that a possible solution. I don't even want to think about the clean up. You must have the boat out of the water by this time any way, so why not buy it a new through hull fitting for Christmas? Brian Pickton @ BeneteauOwners.net Aboard the Legend, Rodney Bay St. Lucia
Dec. 6, 2000 Dear Don, Ed has hit the nail on the head, so to speak. The fact that you never see a head plumbed to an engine inlet hose is a pretty good clue that the problems mentioned by Ed are real and not imagined. Your diesel is not meant to be used as a macerator pump, which is what it would be turned into if plumbed to the head inlet. Frankly I have had check valves held open by debris, so I would not consider that a possible solution. I don't even want to think about the clean up. You must have the boat out of the water by this time any way, so why not buy it a new through hull fitting for Christmas? Brian Pickton @ BeneteauOwners.net Aboard the Legend, Rodney Bay St. Lucia
Thru hull size
Hey Don, I like the concept but I think several factors have to be considered. First, most head inlet thru hulls are 1/2" diameter, this is barely, if even enough water flow for the engine to use at cruising speed. Second, I agree with Ed- the head is not going to out pump the engine. I'm thinking that a large thru hull (1-1/2") feeding a plentum chamber (8" to 12" of 3" PVC pipe capped) below the waterline then routed to the engine and head from the chamber might give better results. I do agree the fewer holes in the bottom the better. Keep us informed on this. PM
Hey Don, I like the concept but I think several factors have to be considered. First, most head inlet thru hulls are 1/2" diameter, this is barely, if even enough water flow for the engine to use at cruising speed. Second, I agree with Ed- the head is not going to out pump the engine. I'm thinking that a large thru hull (1-1/2") feeding a plentum chamber (8" to 12" of 3" PVC pipe capped) below the waterline then routed to the engine and head from the chamber might give better results. I do agree the fewer holes in the bottom the better. Keep us informed on this. PM
DON'T DO IT!
In my experience every system must be on it's own. In my former boat I shared the bilgepump outlet with the head-basin-outlet. And one of my guests washed her hands out on the sea. (And forgot to close the valve). The result was LOTS of water into the boat through the bilgepump (backwards), So - just don't do it. Allow your different systems to have a safe and robust design and functionality. I admit that it's no fun drilling another hole in the boat - but if you think hard, there's no differens if the two holes are inside. Toomas
In my experience every system must be on it's own. In my former boat I shared the bilgepump outlet with the head-basin-outlet. And one of my guests washed her hands out on the sea. (And forgot to close the valve). The result was LOTS of water into the boat through the bilgepump (backwards), So - just don't do it. Allow your different systems to have a safe and robust design and functionality. I admit that it's no fun drilling another hole in the boat - but if you think hard, there's no differens if the two holes are inside. Toomas
Very bad idea--for two reasons
1. Flushing the head while motoring will pulling cooling water away from your engine, which can overheat the engine. 2. The head intake seacock should always remain closed while underway to prevent the bowl from overflowing do to the ram water effect. Although ram water isn't likely to be a problem while motoring, the likelihood that you'll forget to open the seacock when you head up to start the engine and drop sail is VERY high.
1. Flushing the head while motoring will pulling cooling water away from your engine, which can overheat the engine. 2. The head intake seacock should always remain closed while underway to prevent the bowl from overflowing do to the ram water effect. Although ram water isn't likely to be a problem while motoring, the likelihood that you'll forget to open the seacock when you head up to start the engine and drop sail is VERY high.
Ed, Brian...
Ed, head intake hoses are 3/4", not 1/2". While not of earth-shattering importance to this conversation, knowing that can save you some aggrevation should you ever have to a buy hose or a fitting for a head intake. Brian, he's talking about the head intake, not the head discharge. It would take some VERY creative plumbing "turn the engine into a macerator."
Ed, head intake hoses are 3/4", not 1/2". While not of earth-shattering importance to this conversation, knowing that can save you some aggrevation should you ever have to a buy hose or a fitting for a head intake. Brian, he's talking about the head intake, not the head discharge. It would take some VERY creative plumbing "turn the engine into a macerator."
Peggy & Brian
Creative plumbing...YES... but I don't think I want to put that "crap" in my engine!!! JimC
Creative plumbing...YES... but I don't think I want to put that "crap" in my engine!!! JimC
Creative Plumbing
Actually plumbing is one of my unknown (still to discover)skills. Living in century old homes as I have, you have to be creative with your plumbing. The last thing I want to do is turn my boat into a manure spreader. I hear your collective NO's loud and clear. I'll be replacing that old engine gate valve sooner than later. Thanks for the replies. Take care. Don
Actually plumbing is one of my unknown (still to discover)skills. Living in century old homes as I have, you have to be creative with your plumbing. The last thing I want to do is turn my boat into a manure spreader. I hear your collective NO's loud and clear. I'll be replacing that old engine gate valve sooner than later. Thanks for the replies. Take care. Don
Don, read the articles in the Head Mistress forum
Reference LIbrary--on the forum home page. They don't answer every question, but they will give you a basic overview of how your boat's plumbing is supposed to work and how to operate and maintain it. Boat plumbing and house plumbing don't have a lot in common, 'cuz they work on totally different principles, and trying to apply house plumbing "rules" to boat plumbing can create problems instead of solve them.
Reference LIbrary--on the forum home page. They don't answer every question, but they will give you a basic overview of how your boat's plumbing is supposed to work and how to operate and maintain it. Boat plumbing and house plumbing don't have a lot in common, 'cuz they work on totally different principles, and trying to apply house plumbing "rules" to boat plumbing can create problems instead of solve them.
Jim, plumbing the head to draw flush water...
through the same thru-hull that the engine draws its cooling water cannot possibly put waste in the engine. You'd have to plumb the toilet discharge to exit through the same thru-hull. However, there is a company in FL that's trying to resurrect an old--and not very successful--RV waste treatment and disposal system: heat it using the engine exhaust and blow it out the exhaust...the theory being that the heat evaporates all the liquids. kills all the bacteria, and incinerates the solids, reducing them to ash. It does work...but following any RV equipped with one was a gawdawful experience!
through the same thru-hull that the engine draws its cooling water cannot possibly put waste in the engine. You'd have to plumb the toilet discharge to exit through the same thru-hull. However, there is a company in FL that's trying to resurrect an old--and not very successful--RV waste treatment and disposal system: heat it using the engine exhaust and blow it out the exhaust...the theory being that the heat evaporates all the liquids. kills all the bacteria, and incinerates the solids, reducing them to ash. It does work...but following any RV equipped with one was a gawdawful experience!
some thoughts
First of all, anyone who thinks that sharing the head INTAKE can result in waste passing through their engine needs to re-study exactly how a head is plumbed. The only way that could happen would be if there were a VERY defective piston seal, a defective joker, and a closed through-hull, all of which would cause worse problems!!! Second, most engine water pumps have a much smaller flow than commonly supposed....check your shop manual. Third, if instead of using an anti-siphon valve (always prone to blockage and potentially boat-sinking failure), you use a loop with a T leading to a hose with a really high open end (ALWAYS acts to block siphoning), I would doubt that any "ram effect" would cause a problem. However, getting mixed up in your management of when the valve should be open or closed could really ruin your day....you may get it right, but what about guests?
First of all, anyone who thinks that sharing the head INTAKE can result in waste passing through their engine needs to re-study exactly how a head is plumbed. The only way that could happen would be if there were a VERY defective piston seal, a defective joker, and a closed through-hull, all of which would cause worse problems!!! Second, most engine water pumps have a much smaller flow than commonly supposed....check your shop manual. Third, if instead of using an anti-siphon valve (always prone to blockage and potentially boat-sinking failure), you use a loop with a T leading to a hose with a really high open end (ALWAYS acts to block siphoning), I would doubt that any "ram effect" would cause a problem. However, getting mixed up in your management of when the valve should be open or closed could really ruin your day....you may get it right, but what about guests?
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