Raw Water Cooling System Questions

[morgantheship]

I am in the process of repowering my Hunter 27. It currently has a Renault engine which I will be replacing with a Yanmar 2GM engine. Yesterday I disconnected everything from the Renault engine in preparation of pulling it out of the boat. Let me prefice that there are two seacocks. One for inlet water and one (I thought) for outlet water. I noticed that only the inlet water cooling water line was connected to the engine. And the outlet water line ran somewhere else but was not connected to the engine. So I began to wonder what the outlet water line is connected to and what is the purpose of the outlet water line and its seacock?
The Yanmar 2GM engine that I will be installing is also a raw water cooled engine and I am wondering if it also will be connected the same way?
Could someone enlighten me with some understanding as to how this cooling system works and what I might need to pay attention to when installing the Yanmar engine? Thanks.

 

[Nelsonhow]

Raw water cooled engines have only 1 water connection.

Raw water from the ocean is sucked in through a thru hull near the engine (under the waterline). Pulled through the water pump and into the engine water jacket. After the water does it's job injected into the muffler at the back of the engine through the exhaust riser or elbow. The stuff that spits out the back of the boat is the cooing water and exhaust gas.

The other thru hull on the H-27 is the drain for the sink.

 

[morgantheship]

Raw Water Cooling Questions

No one ever told me that the other seacock was the drain for the sink. I feel a bit foolish but I am glad that I am learning more about my boat. To think that when I purchased the boat last May, I was instructed to open both seacocks which my wife and I did religously. I will now have to go down and follow the other seacock line to verify. Thank you.

 

[Manny]

Nelsonhow is correct, the other seacock is for the sink. If you remove both drawers under the sink you will see the hose running all the way up to the drain. If you have gate valves instead of seacocks now would be the time to replace them. My sink had a gate valve and I found when I went to remove it, the valve had corroded to the point of always being open.

Manny