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Old 06-24-2013, 03:56 PM   #25
Brooksie's Avatar
City: Cape Cod, MA
Country: USA
Vessel Name: Island Seeker
Vessel Model: Willard 36 Sedan
Join Date: Oct 2007
Posts: 986
Originally Posted by FF View Post
That 20% + difference is the Holey Grail for the electric propulsion folks.

All their schemes and big bucks complexity are geared to capturing that 20% and eventually using it.

I would prefer to use a cruising prop, no complexity , or the 2 speed gear box and have no huge expensive heavy battery sets to drag out and down the dock.

A ZF 2 speed gearbox is OTS and should last the life of the boat , unlike a batt set.
I read the articles by Caulder in ProBoat re: electric propulsion. My letter in this month's issue says it all.

Re: ZF, I contacted them and they had no interest in using their 2 speed gearbox in that manner and would not even comment on my application. They said, as I recall, their gearbox is only to shifted "up" under load not "down" which is what I was proposing to them. Also it seemed that the ratios were all wrong. What I was proposing was starting off in "High" gear and running up to cruise speed at which point the engine would be fully loaded (or nearly so) then downshifting to "low" gear to continue up to flank speed. They dismissed the idea offhand... Their loss
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