Hi Anne,
I was describing some force transmitted up the tiller, perhaps an oscillation induced by the twin rushes of water off the prop as it spun. I think this is because the prop blades and rudder are not parallel (or prop shaft perpendicular to the rudder, for example) in our Ericson 27 test boat. This allows for a timing discrepancy in the arrival of the pulses of water from the prop blades. The tiller would waddle. It was unnerving. I don't think this would be a problem in a full keel boat, as the rudder axis is usually closer to normal relative to the prop shaft.
Cavitation only occurred under peak output.
The MaxProp is quite a nice piece of engineering, and I'll try a three-blade version when sailing becomes more important then demonstrating an electric drive.
Be Well,
Arby
From: amracel <amracel@stuffandjunk.net>
To: electricboats@yahoogroups.com
Sent: Wednesday, June 27, 2012 7:41 PM
Subject: [Electric Boats] Pulsing Action
Arby (or anyone else with a bit of knowledge), can you explain what you meant by '... a pulsing action against the rudder' with your 2-bladed MaxProp. I've had some issue with some sort of vibration. I've taken care of what appeared to be cavitation, but there's still something else going on. I haven't been sure if I'm noticing it because the electric engine is quieter and vibrates less than my diesel did or if something else is going on. So I'm just curious what your experience was since I also have a 2-bladed MaxProp.
Anne Racel
CAL 2-29
4 Degrees
Anne Racel
CAL 2-29
4 Degrees
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