John, regarding, "expect about 3.5 mph max", if the Minn Kota were larger and so moving the boat easily at that speed, then is the full available power not being used because the prop is not matched ? That is, for big Minn Kota's on small boats, would a higher pitch prop deliver more speed ? I realize this could over load the motor, but I have amp meters and can keep an eye on on current.
--- In electricboats@yahoogroups.com, "John" <john.zimmerlee@...> wrote:
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> Though it is more complicated than this . . . the 30 amp motors have 9" props and therefore 63.585 sq inches . . . times two or 127.17 sq inches total. The 55 amp has 11 inch prop or 94.985 sq inches of grip.
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> The 30 lb thrust motors have been recently redesigned to a shorter length and I question their rating and their duarbility. Their motor diameter is just 3.25".
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> The 55 lb thrust has a larger 3.625" diameter and is built stronger.
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> Redundancy is nice to have when offshore, and differential steering might be nice too . . . but I question the single 30's ability to push your boat . . . and would enjoy a good laugh watching you steer the boat while leaning over the stern and twisting handles while coming into port. You may find it more responsive to use the motor(s) in fixed position and steer with your usual rudder.
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> All MinnKota props have a 4" pitch and most are expected to turn about the same RPM. If you put 1 large MinnKota or 20 small ones on your boat . . . expect about 3.5 mph max!
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> The 24 volt motors are more efficient than the 12 volt series. They cost more and will needs 2 batteries in series.
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> John Zimmerlee
> Stream Dancer & Versaboat
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