Seawater impeller

[sailorboy1]

I opened up my engine seawater pump today for inspection and possible impeller replacement. This is the first time I've opened the unit up and I was surprised to see that the vanes were bent over in two directions as I definitely expected them all be in the same direction. Anyone ever seen this?

[Sailmonkey]

All the time. When the engine shuts down it "rocks" in the last compression stroke before coming to a full rest. The 20ish degrees of counter rotation turn the impeller just enough to move some vanes the other direction.

[sailorboy1]

I kind of suspended that as the cause, but never hurts (too much) to check into.

[a64pilot]

I'm surprised you got the right answer, right out the gate, I would have thought we would hear about Coriolis effect and a few other theories first

[Sailmonkey]

Originally Posted by a64pilot

I'm surprised you got the right answer, right out the gate, I would have thought we would hear about Coriolis effect and a few other theories first

You'll notice right hand vanes do this in the Southern Hemisphere as opposed to the left hand vanes in the northern hemisphere.

[sailorboy1]

On "production" boats vanes go any direction they feel like!

[goat]

Originally Posted by Sailmonkey

You'll notice right hand vanes do this in the Southern Hemisphere as opposed to the left hand vanes in the northern hemisphere.

SB1 is getting closer to the equator.

[Sailmonkey]

Has this thread really died this quietly?!?

I remember the last time the thing with the impeller vanes reversing was posted there were people arguing that the vanes could never be reversed without major mayhem.

Where are the zealots?!?!

[Sun and Moon]

Do the vanes go the same direction on monohulls and catamarans? Or maybe on catamarans they bend backwards, while on monohulls they break?