I have just purchased and 1978 Mariah. The boat has a 2 cylinder raw water cooleYanmar engine. The previous owner, whom I respect very much as a sailor due to his experience, has moved the raw water intake for the engine from the seacock next to the engine to the seacock under the galley sink. He did this because he said that the seacock next to the engine allowed to much air to get into the water that was supposed to be cooling the engine because of the hull design. This gentleman has over 40 years of sailing experience, he has crossed the Atlantic 3 times, has saile in the north Atlantic, raced to Bermuda and the Bahamas, and owned the boat for over 16 years. I am real tempted to put the "plumbing" back to the original design, but because of the previous owners experience and knowledge, I have some hesitantcy (spelling?) to do this. Have anyother owners out there had this problem/experience with too much air in the cooling water when using the seacock next to the engine for the raw water intake to the engine? Charles M Riley Outward Bound
Engine raw water seacock
- Thread starter criley
- Start date
- Status
I did for different reasons
Charles - On my '78 YSM12 Yanmar - I had an issue with air entering the system and it would happen after sailing on a starbourd tack only....the seacock would I guess be positioned in a way that would let air in. I knew this because if I closed the seacock immidiately after motoring it would work fine (that gets tiresome as you could imagine how you end up motoring several times even while day sailing). The problem though was not the design, seacock or way I sailed - the problem was with the old and worn waterpump. A bit of air would enter the system via the seacock and then the pump would not be able to re-prime itself due to an air-leak I assume at the pump cover plate. I replaced the pump and the problem was solved. I was told by Yanmar that the cover-plate on old pumps often gets worn-down to a point where it is no longer water-tight or able to re-prime itself. Your set-up me be using a seacok that is deeper and aft of the keel and its keeping more water pressure at rest on the inlet hose and pump which is fine. If it works then leave it alone. I assume the sink drain is then plumbed to the old engine seacock - correct? I would not T them off the same seacock. Rob
Charles - On my '78 YSM12 Yanmar - I had an issue with air entering the system and it would happen after sailing on a starbourd tack only....the seacock would I guess be positioned in a way that would let air in. I knew this because if I closed the seacock immidiately after motoring it would work fine (that gets tiresome as you could imagine how you end up motoring several times even while day sailing). The problem though was not the design, seacock or way I sailed - the problem was with the old and worn waterpump. A bit of air would enter the system via the seacock and then the pump would not be able to re-prime itself due to an air-leak I assume at the pump cover plate. I replaced the pump and the problem was solved. I was told by Yanmar that the cover-plate on old pumps often gets worn-down to a point where it is no longer water-tight or able to re-prime itself. Your set-up me be using a seacok that is deeper and aft of the keel and its keeping more water pressure at rest on the inlet hose and pump which is fine. If it works then leave it alone. I assume the sink drain is then plumbed to the old engine seacock - correct? I would not T them off the same seacock. Rob
The only way that I can see the posibility
of pulling air into the cooling water from the thru-hull is if the boat were heeled so far as to expose the thru-hull to free air. If you have that much wind you don't need the engine. My water pump is well below the waterline but the filter is mounted high so that if may be serviced without problems. If the gasket on the filter is bad then it may let air into the system. If the thru-hull is close to the centerline of the boat it can't find air. I would look for the problem else where in the system.
of pulling air into the cooling water from the thru-hull is if the boat were heeled so far as to expose the thru-hull to free air. If you have that much wind you don't need the engine. My water pump is well below the waterline but the filter is mounted high so that if may be serviced without problems. If the gasket on the filter is bad then it may let air into the system. If the thru-hull is close to the centerline of the boat it can't find air. I would look for the problem else where in the system.
yahoo group
We have a yahoo group for Mariah owners. There is a forum for these questions on the site as well as a place to post photos of your Mariah or look at some of the other Mariah's out there. You may want to post your concern there. I've owned a mariah for 3 years now and live on board full time with my wife and dog. We have never had any problems with air in the raw water intake. MY thoughts are, even if air got in there, its a positive flow pump that will prime the air out and run it through the engine and cooling system. I'm with Ross in saying if you're heeled over that much, you dont need an engine. I have a 35 horse, 3 cyl yanmar in my 78 mariah. Mike
We have a yahoo group for Mariah owners. There is a forum for these questions on the site as well as a place to post photos of your Mariah or look at some of the other Mariah's out there. You may want to post your concern there. I've owned a mariah for 3 years now and live on board full time with my wife and dog. We have never had any problems with air in the raw water intake. MY thoughts are, even if air got in there, its a positive flow pump that will prime the air out and run it through the engine and cooling system. I'm with Ross in saying if you're heeled over that much, you dont need an engine. I have a 35 horse, 3 cyl yanmar in my 78 mariah. Mike
agree with rob
I definitely agree with Rob. If the seacock is used by the engine and sink, it may not draw enough vacuum to give the engine enough water. My boat must have been re-powered or perhaps the origional owner asked for a larger engine. I have a yanmar 3HM35 in my boat. Wish you guys would post these kinds of discussions on my yahoo group. You can also post photos of your boats and projects there. The group hasnt gotten a lot of traffic. Perhaps we just need to get the word out. http://groups.yahoo.com/group/Mariah31/ Mike S/V Shakabrah '78 Pacific Seacraft Mariah 31
I definitely agree with Rob. If the seacock is used by the engine and sink, it may not draw enough vacuum to give the engine enough water. My boat must have been re-powered or perhaps the origional owner asked for a larger engine. I have a yanmar 3HM35 in my boat. Wish you guys would post these kinds of discussions on my yahoo group. You can also post photos of your boats and projects there. The group hasnt gotten a lot of traffic. Perhaps we just need to get the word out. http://groups.yahoo.com/group/Mariah31/ Mike S/V Shakabrah '78 Pacific Seacraft Mariah 31
- Status