View Full Version : 2003 Sea Water Cooling
04-15-2009, 04:41 AM
"When I sail my yacht in a race or regatta, I always get calls on the VHF that I have left my sea cocks on the cooling system closed, as a very visible 'steam' vapour comes out of the exhaust. I know this is simply the relatively warm exhaust sea water condensing in the cooler atmosphere, but I wonder why the other directly cooled engines do not exhibit this characteristic. The engine runs fine, has a new thermostat in it, and if anything overcools even on long runs.
I've checked the archives for some comments on this, without success. I've been told to run vinegar through the system to remove the salt. The sacrificial anodes on the cooling system are replaced regularly.
Is the 'steam' engine effect just something one has to live with?
04-15-2009, 04:54 AM
What kind of cooling water intake do You have?
Is it an inboard straight shaft or sail drive?
Maybe the overall cooling water flow is down leading to a warmer than normal exhaust temperature.
When was the waterpump impeller last replaced?
04-17-2009, 03:59 AM
"Thanks guys for the interest.
It is a Volvo sail drive, with the water taken through a strainer and an intercooler for the deep freeze (which is not switched on). Looking at the exhaust outlet, there is not more than a dribble of water coming out but it is regular and has been like that since I replaced the thermostat which had been stuck open and allowed too much water through.
The impeller may be old. I will look at that.
This is obviously not a normal characteristic, so I will investigate further. Maybe I will remove the fridge cooler from the intake. The temp gauge always runs quite cool, about 70 deg C I think.
04-17-2009, 04:29 AM
"First try to hook a hose straight from drive to water pump and see if that 'improves' the water flow.
If still the same, You might have to take down the exhaust bend and check if there is a restriction in the outlet of water.
Even if Your engine does not overheat, Your exhaust hose might be damaged from lack of cooling water. If You on top of all have a Vetus plastic muffler severe trouble might occur."
04-20-2009, 04:45 AM
"This weekend was a bit cooler than usual, with some drizzle in the air, so we produced a lot of 'steam', but the engine runs at the right temperature. I took off all diversions on the cooling water intake, but the throughflow is still the same. The exhaust runs cool, almost cold, and the Vetus box is cool too. All cool!
So I think the steam is just normal.
The only excitement on the 60 mile trip was a collision with a whale, by the yacht in front of me. Scared him right back to port to check out the keel attachment. The whole yacht was lifted out of the water.
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