Holy cow! I wonder how that happened. I have not read of a similar incident on this website in the 8 years I've been aboard the C36IA. I will be most interested to read Steve Frost's ideas on this, as his engine expertise is about the best one can get, and of course his experience with the Mk I exceeds mine by a truckload.

My first thought is to question the routing of the exhaust hose and the muffler...whether on extreme stbd heel the upper level of the hose was lower than any trapped water within.

Jason and Larry,

I can only speculate that the siphon break did not do its job. I think it is unlikely that even at a high degree of heel that water ran into the exhaust hose though in a following sea this may be possible.

The more likely event I would think is that the siphon break failed and as the engine cooled it created a vacuum and sucked water back into the engine through the water lift muffler.

The vacuum break is mounted high up on the bulkhead just aft of the refer, it should also be high enough to prevent water backflow in a following sea when you are healed as well, weather it was water coming in thru the exhaust outlet or being drawn from the water lift muffler I feel the siphon break is the most likely cause for water in the engine barring an internal coolant leak in the engine such as a head gasket issue.

I just pulled the exhaust hose from my boat. I have been wondering if the hose would flood if heeled over to the rail. Mine is strapped up about 6 in below the toe rail. I feel this is leaving a potential siphon situation. I am thinking of routing the hose to the centerline in the lazerette with a siphon break installed. Any comments would be appreciated.
Mark

Mark,

I do not think the routing of the exhaust hose presents a siphon issue. On my boat the exhuast outlet does occasionaly submerg when heeled, reaching in a following sea. Though the outlet submerges the routing of the hose as it goes up from the hull fitting is usually well above the water line at the transom.

As I had mentioned to you in my response to your query in the ask the experts section, the siphon break is not in the exhaust hose but, in the coolant line between the heat exchanger and the exhuast wye where the cooling raw water is dumped into the exhaust. The loop routes up to near deck level on the bulkhead. If the vent crusts up with salt and fails to open it can create a siphon effect drawing the exhaust water out of the muffler and back into the exhaust elbow. Again as stated im my earlier correspondance a vacuum can develop as the engine cools creating some suction on this line. It actually may be more likely on a port tack when deeply heeled as then the muffler can be above the exhaust manifold and once water starts flowing will continue to syphon until it fills your exhust system and any cylinder that has an open exhuast valve.

You did state you found the syphon break vent crusted up. I would replace the exhaust hose as you already have it removed and it is likely original, replace or clean the syphon break to get the check valve working and leave the routing of the exhaust hose as is as I am sure Mr. Douglas gave it considerable though prior to developing the routing.

Thanks again Steve. Still no luck finding a partial roll of exhaust hose. I don't like the thought of paying $600 for the 50 ft. Anybody up for a snake wrestling match to change your exhaust hose and join me in buying a roll of hose? Mark

Mark,

Just had a look on EBay and there were several listings for Marine Exhaust hose. Saw a listing for 21' of 1'1/4 for $60.
I do not recall exactly what the I.D. of our exhaust hose is but, there were many listings for marine exhaust hose most at around 4-5 dollars per foot or less.

Interesting theory.

You are saying that perhaps the dynamic force generated in the water by 8kts of speed against the clamshell scoop forced the raw water through all that plumbing and then past the impeller into the aqua lift muffler. With no engine exhaust pressure to force it out, the water built up and then came back into the engine through the exhaust manifold.

I suppose that could happen but I have no idea if 8 kts is fast enough and it would seem that the impeller would need to be in horrible shape.

If you decide to close your inlet seacock, you are increasing the time to start the engine in an emergency (well, you could start it without water flow, but that wouldn't last too long). If the time delay is not a concern, I would store the key next to the inlet seacock so that starting it with the seacock closed would be much less likely.

I would keep looking for the root cause and correct that. Good luck.

I did not know any C36 came from the factory with a scoop on the raw water inlet. My C36 and old C30 did not have a scoop. Is this something an owner installed? If the Catalina engineers thought a scoop was something beneficial to a C36 I would think the boat would come from the factory with a scoop installed.

EBAY is a great idea! This web site is a great idea! As I probe the many different subject areas I am amazed at the innovative ideas the folks have come up with for their Catalinas. Thanks- Mark