water in engine from following sea

[fawcettm]

Hi,

Friends recently were on the Caribbean 1500 and with a large following sea got sea water in their engine through the exhaust, after cleaning and drying and WD40 the got the engine running again, I was wondering what people do to prevent this? Riser hoses? oneway flow values? Sea Cocks on exhaust? We are planning to go off shore and our exhaust outlet is on the starboard side above the waterline but on a good heal I can see this happening to us, Would too much rise hinder exhaust water from leaving the boat and backing up in the engine?

Mark

[mike dryver]

some have shut offs in the exhaust line near the transom or actually where it can be easily got to. your exhaust hose loop should be as high as possible and have a siphon break in it. a quick fix might be to install a flapper on the external flange, the same that were/are used on sport fishers for backing down on fish.

[jrd22]

Our exhaust is in the transom and there is a ball valve so we can close it. The external flappers work well for the occasional wave but will still allow water in if submerged for any length of time.

[Omatako]

A simple solution is a piece of lay-flat hose attached to the exhaust outlet with a hose clamp. When the enigine runs the hose allows the exhaust to function normally - when the water pushes up from astern the hose folds and blocks the pipe.

[imagine2frolic]

Isn't this water a waterlock muffler is for?........i2f

Vetus at Go2marine - Mufflers & Waterlocks

[fawcettm]

Thanks for the info and Ideas! I went to the vetus site as well and they have a whole range of products, the waterlock muffler wont stop water from eventually getting back to the engine from constant water coming into the exhaust but a flapper on the exhaust and the gooseneck will. I guess adding a seacock will make it even better.

Mark

[OldColumbia]

In our Columbia 36 there's a large lazarette aft of the cockpit that allows access to the ballcock/thru hull that's the exhaust outlet in the deadrise between the waterline and the transom. Under way it's usually at or near the h eighth of the stern wave, so closing the ball **** is important, as is remembering to reopen it before starting the engine. Usually within the harbor we don't close it. The transom high loop of the exhaust hose (top just below the gunwale) seems to prevent backflow.
Two Atomic4's seized however from water intrusion from overcranking and poor exhaust design before our last repower.

[Northeaster]

I have a related question on the need for a siphon break on a high loop.

My 30 year old boat has a high loop (with no siphon break), just before the exhaust exits, vertically downward, underneath the transom, which is just above the normal water line. I realize the importance of having siphon breaks when seacock are (or can be when heeled) submerged for periods of time. However, even in bigger seas (coastal cruising only) mine will not stay under - it will be in / out with every crest / trougth.

My 1982 Yanmar 2GM, only has the regular exhaust elbow (not the high riser) and a rubber silencer (not a waterlock muffler), and yet I don't believe it has ever had a problem from following seas.
I read about all of the stuff I should have, but also believe in the "If it ain't broke, don't fix it!!"

[OldColumbia]

Dear Northeaster,

My old Columbia originally had a jacketed exhuat for the A4 that extended to a custom built copper riser system that rose from near the base of the transom to terminate at the thru hull without any seacock or siphon break. After the first of my A4's seized, we replaced the entire exhaust, riser, hose and added a siphon break for the raw water intake as well as adding the high loop at the stern without a siphon break to the ballcock at the thru hull.
The second A4 rusted out internally ( raw sea water cooled) and the same upgraded exhaust was used with the remanufactured Universal 25XP including a siphon break for the "fresh water" side because of it's circuit through the hot water heater. No Problems, except when motoring the exhaust outlet is alternatively submerged when the deadrise is beneath a swell. It seems the exhuast simply blows the water into the seawater and causes some steam if the water is cold.
I agree that if it's raining, it's too late to fix the roof, and if it isn't raining you don't need to.

[roline]

The Cal 9.2 has a 2GM20 with the U riser water injector at the exhaust port. The exhaust hose goes athwart-ship to a plastic Vetus water lift muffler. The exhaust hose then goes to a huge loop just under the transom deck by the rudder shaft for height and then to the exit at the stern of the hull at the overhang. That gives the decending hose a 34" height. No problems encountered to date...