Avoiding water coming in through exhaust (hydrolock)

[foufou]

My exhaust system has two high loops. One after the muffler going nearly as high as the cockpit seats. The other high loop is the mixing elbow itself. Close to 20" high above the manifold. It would be difficult to get water to back up through such a system

[S/V Alchemy]

Originally Posted by barnakiel

I had the dry kind on an Oyster. Was very quiet but maybe because the boat was a huge beast too.

I am not sure the same term applies but it seems it is far more common for water to get thru the elbow (siphon valve fault) or via a faulty head gasket. (?)

b.

I am going to a "North Sea Exhaust" shortly. Two exhaust lines teed off above the WL to outlets port and starboard. You can chuck the anti-siphon as one exhaust is always in open air. Back pressure is mitigated because you've effectively doubled the area of the exhaust outlet. I ot the idea from Dave Gerr:

Mine will have the "T" sufficiently above the WL (in a box under the lowest pilothouse companionway stair) to make the runs slope to the water on either side. In addition, I will have an inline seacock just below the "T" in order to prevent even the wildest of seas from backfilling the waterlift. Yes, this means I must turn it prior to starting the engine. That means "hang the key on the handle".

Not everone can have this sort of setup or would want to. But it does eliminate through careful design some issues, such as a siphon break, long runs to the transom, the need for goosenecks and mufflers, and the need to bury exhaust runs under aft cabins. It's also proven, as the "North Sea" name suggests. Another trick from the same page is the idea of running fuel vent lines to goose necks (within brass poles, for instance) atop the coach or pilot house instead of just below the toerail. Some ketches do this at the mizzen, but I've never understood why a vent at the topsides on sailboats prone to burying their rails was a good idea. Trawlers also run them out under the overhang of deck houses.

[Three Sisters]

Originally Posted by wingless

The factory installed exhaust on my boat includes both side exhaust outlets and underwater "torpedo" shaped venturi outlets.

Both exhaust designs used both outlet locations.

None of the designs include flappers or anything other than an elevated or convoluted path to prevent the trailing wake hitting the back of the boat from hydrolocking the engines. There was never an issue w/ the lift mufflers used through 1999 and later restored in 2001.



This shows the lower cost log exhaust that Sea Ray used for a short period.




This show the underwater "torpedo" venturi exhaust outlet.




The lowest opening shows the port side exhaust opening.

Well, thanks for the education, having never heard of or seen the underwater venturi installation. And all the exhaust components are a short run with the v-drive. That venturi would have me asking alot of questions. Good on you for having the knowhow and patience to improve the entire system.

[wingless]

Originally Posted by Three Sisters

Well, thanks for the education, having never heard of or seen the underwater venturi installation. And all the exhaust components are a short run with the v-drive. That venturi would have me asking alot of questions. Good on you for having the knowhow and patience to improve the entire system.

Thanks, but the dealership performed the new boat warranty rework from the short-lived log exhaust to the earlier / later revision lift exhaust shown here.

My redesign was to a different part of the system, to permit fresh water flushing, followed by draining my obscenely expensive cast iron parts bone dry after operation.

[Compass790]

Yes I absolutely agree about Yanmar exhaust elbow. Bad design kills a lot of engines but looking at the parts prices maybe Yanmar had a cunning plan???:-) As you say easily fixed with an s.s. elbow

[Three Sisters]

Originally Posted by jsc7

Hydrolock caused by salt water coming into the engine via the tail pipe on inboard engines can be a serious problem, but I do not see too many posts on this sub-forum complaining about that occurring so it must be pretty uncommon.

Typical owner manuals list a range of things that can cause it: drift fishing in heavy seas or in wake-strewn areas, being anchored in heavy seas, backing up over a wake, slowly down or stopping suddenly, an engine shutdown while in motion, hoisting the boat stern high. It would seem to be a lot of opportunity for water to get into the engine, but I don't see the complaints.

I guess the reason why it does not seem to happen much is that the water has to get past a gauntlet of twists and turns and make it through the muffler as well.

Is hydrolock commonly experienced and a constant threat, or something that most boaters with inboard engines don't worry about too much?

If you like reading, this is an informative article. Owner's nightmare included.

BoatUS. com Consumer Protection Bureau

[Three Sisters]

Originally Posted by wingless

Thanks, but the dealership performed the new boat warranty rework from the short-lived log exhaust to the earlier / later revision lift exhaust shown here.

My redesign was to a different part of the system, to permit fresh water flushing, followed by draining my obscenely expensive cast iron parts bone dry after operation.

Would this happen to be the flush valve ?


Smart idea.

[wingless]

Originally Posted by Three Sisters

Would this happen to be the flush valve ?



Smart idea.

Yes, that is a smart idea.

No, I was unwilling to compromise the existing raw water plumbing layout for a different design, The spacing is very tight, so I designed and fabricated my own parts that maintains the existing plumbing exactly.

Mine has a homemade aluminum raw water cover w/ a garden hose connector, so I remove the standard cover, place this one for the flushing, then stow it away for the next flush cycle. This permits easy flushing of the engines, then easy flushing of the raw water intake to the through hull.

The big issue on my boat was that the dripless seal is cooled by pressurized raw water. The factory layout had that dripless seal raw water takeoff below the waterline, making it impossible to drain my cast iron manifolds after use. There was a constant flow of raw water into the bilge with that layout when attempting to drain those expensive cast iron parts.

Now I have the pressurized raw water feed to the dripless seal connecting above the water line, so I can now drain the cast iron parts bone dry after flushing.

[Three Sisters]

Originally Posted by wingless

Yes, that is a smart idea.

No, I was unwilling to compromise the existing raw water plumbing layout for a different design, The spacing is very tight, so I designed and fabricated my own parts that maintains the existing plumbing exactly.

Mine has a homemade aluminum raw water cover w/ a garden hose connector, so I remove the standard cover, place this one for the flushing, then stow it away for the next flush cycle. This permits easy flushing of the engines, then easy flushing of the raw water intake to the through hull.

The big issue on my boat was that the dripless seal is cooled by pressurized raw water. The factory layout had that dripless seal raw water takeoff below the waterline, making it impossible to drain my cast iron manifolds after use. There was a constant flow of raw water into the bilge with that layout when attempting to drain those expensive cast iron parts.

Now I have the pressurized raw water feed to the dripless seal connecting above the water line, so I can now drain the cast iron parts bone dry after flushing.

I see your point. What you are describing actually is an easier procedure than the flush valve would have been. I like the idea of flushing and draining the manifolds. Mission accomplished.

Now if the OP would only show up once in a while.

[Jim Cate]

Originally Posted by Three Sisters

I see your point. What you are describing actually is an easier procedure than the flush valve would have been. I like the idea of flushing and draining the manifolds. Mission accomplished.

Now if the OP would only show up once in a while.

I wonder if anyone besides me is appalled by the notion of a design that requires such a procedure after each use?

And I ask once more: has anyone ever heard of an engine having water shoved up its exhaust while it is running? Seems so very unlikely to me...

Jim

[wingless]

Originally Posted by Jim Cate

I wonder if anyone besides me is appalled by the notion of a design that requires such a procedure after each use?

At this point being appalled is irrelevant. I have replaced my exhaust over and over and over again, at about $4K in parts each time. That has made me disgusted and sick over the waste, cost and effort.

For me to now have a "solution" that will provide the expected acceptable service life is worth the inconvenience to protect the parts.

[Jim Cate]

Originally Posted by wingless

At this point being appalled is irrelevant. I have replaced my exhaust over and over and over again, at about $4K in parts each time. That has made me disgusted and sick over the waste, cost and effort.

For me to now have a "solution" that will provide the expected acceptable service life is worth the inconvenience to protect the parts.

It may be irrelevant to YOU, but it is not to someone in the process of choosing a boat to buy. Knowledge of such design "features" would certainly influence my decision process.

Jim

[Three Sisters]

Originally Posted by Jim Cate

I wonder if anyone besides me is appalled by the notion of a design that requires such a procedure after each use?
Jim

It's jacketed cast iron, any flush and drain is better than none, wouldn't you say ?

[Jim Cate]

Originally Posted by Three Sisters

It's jacketed cast iron, any flush and drain is better than none, wouldn't you say ?

given that this combination of design and material will fail without flushing, sure, better than none!

But, I believe that other combinations of design and material exist which do not requir this treatment, and that they would be a better choice, at least for me.

I've owned inboard powered yachts for the past 40 years now, and have never once flushed my exhaust cooling system. I have once replaced an OEM exhaust fitting (on a BMW D-35) with a stainless one that I fabricated myself. That one, as well as the other OEM ones, lasted thousands of hours in total. I believe this to be a reasonable expectation for a marine engine. YMMV.

Jim

[contrail]

Originally Posted by UNCIVILIZED

Thoughts on how much a flapper on your exhaust exit helps in preventing this? And who has a "failsafe" ball valve which prevents accidental backfilling due to waves, & or storms? Fail safe being in quotes, since if you forget to open said valve once the engine is running, bad events could ensue.

On my older boat, I installed a ball valve in the exhaust hose. In heavy going, unless under power, I would close that valve, and hang the engine key on the handle to that valve to prevent a brain fade. Was pretty bulletproof....don't know why it's not more common.