In gear or N when sailing?

[tunnels]

Originally Posted by TeddyDiver

There's a possibility that a worn impeller allows water to flood the system. Depends thou what's the hight of waterline vs engine (exhaust injection)...

Sorry ! While i lived in Tahiti i befriended a couple that had sailed down from Vancouver , water had got into there motor and so they'd done a reco job while they were there , I said bye and off they went !! A few days later they were back , motor full of water AGAIN !! want the first time and had happened a few times , Motor sailer with motor below water line and exhaust climbing to the back to exit . they were totally bewildered as to how it had happened the sea cock had been opened only for a short time while heading for a lagoon to stay . lots a head scratching . so i had a look and could see anything obvious . I asked if the water pump had ever had the rubber impeller replaced and no it hadnt . The quick removal of the plate and one blade of the impeller was missing and opened the inlet and the out let and had let water pass through and totally fill the exhaust to water level and the water went back into the motor , at one particular point the exhaust and the intake valve are off there seats and so had filled the intake manifold and was flowing out the manifold .

A few weeks later had a simular thing with a completely differant boat where the exhaust muffler was mounted much higher than the motor and the water baffle inside had fractured over time and allow all the water held inside to flow straight DOWN into the motor and was leaking out the intake manifold ,again because on a 6 cylinder there always one set of valves that are partly open and water fills the cylinder and flows into the intake manifold .

REPLACE THAT RUBBER IMPELLER ONCE A YEAR AT LEAST !!! AND CARRY A SPARE ALWAYS !!.

[michael pierzga]

But remember Tunnels, the only way that water can enter is via the exhaust system. On a correct exhaust installation, the sea water exhaust injection dump line is routed above the waterline of the vessel and in the center of the ship with a syphon break. If you completely removed the water pump impeller, the sea water pressure could not rise above waterline and could not enter the engine. On a marine exhaust system its very important to get the componenent geometry , including the inside diameter of the exhaust line overboard, correct. Aqua lift low and water injection with siphon break high. This water injection should always be on a "downward" section of the hot exhaust pipe so that at normal heel angles sea water cant drip water back into the exhaust. Too large an exhaust overboard pipe and the "blow " of the engine might not be powerful enough to completly evacaute the wet exhaust system

[TeddyDiver]

Originally Posted by michael pierzga

On a correct exhaust installation, the sea water exhaust injection dump line is routed above the waterline of the vessel and in the center of the ship with a syphon break.

The problem lies that they also do block up sometimes.. and in that case the impeller is the only thing in the way of the siphoning.

[michael pierzga]

Water cant siphon UPHILL....get the geometry of the exhast system correct and use a syphon break to protect against odd angles and you will never have problems. I use a Vane pump for seawater cooling...water flows right past the Vanes...I have no saltwater in the exhaust problems.

[TeddyDiver]

Originally Posted by michael pierzga

Water cant siphon UPHILL....get the geometry of the exhast system correct and use a syphon break to protect against odd angles and you will never have problems. I use a Vane pump for seawater cooling...water flows right past the Vanes...I have no saltwater in the exhaust problems.

Check up in dictionary or somehere the meaning of "siphon" or look down the toilet how it works . If an antisiphon doesn't work you don't have siphon break.. not so hard fiqure that out right? And another point you seem to miss.. incase of a not functioning or missing antisiphon water does sometimes run uphill when the exhaust cools down.. (thou that's not siphon then)

[michael pierzga]

Prove it too me...please demonstrate . My water injection loop is 1.5 meters above waterline and 20 mm id pipe. Please hold that water column for me. Ive never seen it done. You may have stumbled upon the perpetual motion machine. Free energy...!!!!! Yah

[TeddyDiver]

Originally Posted by michael pierzga

Prove it too me...please demonstrate . My water injection loop is 1.5 meters above waterline and 20 mm id pipe. Please hold that water column for me. Ive never seen it done

I can hold 6 times of that water column above waterline regardless of the pipe diameter.. a bet?

[michael pierzga]

Perpetual motion machine... you can keep a syphon going uphill !!!...let patent it..30, 70.... I get the thirty since you discovered it.

[TeddyDiver]

There's no perpetual in this.. There are two different setups.
One with the water injected in the exhaus considerably higher above the waterline. And those that doesn't (for a reason like no room like in deep sailboat hull sometimes). In the latter case the water pipe only is "looped" higher and in the loop is added an antisiphon valve..

[michael pierzga]

The reason the syphon break and its location in the loop is critical is because many yacht cant use a simple up and down loop. My loop goes up 1.5 meters...then travels 2.5 meters horizontal, then dumps into the exhaust. This 2.5 meter of pipe holds a lot of water. The syphin break is designed so that this water will not fall into the exhaust and possible fill the aqualift past safe level when the engine in turned off. The geometry of the exhaust layout is critical and deserves much thought before built.

[TeddyDiver]

Originally Posted by michael pierzga

My loop goes up 1.5 meters...then travels 2.5 meters horizontal, then dumps into the exhaust. This 2.5 meter of pipe holds a lot of water..

And I can tie my willie but I still have to pee... Sorry about that but you can take your loop on top of the wheelhouse, go around the cockpit three times and it still doesn't make any difference if your siphon break doesn't work. Having engine (or exhaust) installed high enough breaks siphon but that's not the case in all installations. You don't have had any problems so far and propably never will that's normal.. but remember those things (antisiphons) are just valves and they don't allways work..

[michael pierzga]

I carry no valves as a syphon break . Simply a "Tee" in the seawater dump line with a 12mm id tube plumbed into it and vented overboard to break syphon.

[TeddyDiver]

Originally Posted by michael pierzga

I carry no valves as a syphon break . Simply a "Tee" in the seawater dump line with a 12mm id tube plumbed into it and vented overboard to break syphon.

Not recommended to anyone boating in freezing temps..

[michael pierzga]

Dont know...been to the arctic, but in summer. Might deserve thought for winter operation.