Dear MikeThe hull speed is a threshold where physic calculations change (planning, hydrofoils, wings….)Do you go shopping with a dragster reaching the takeoff speed?
Do you design a lunar shuttle reaching the threshold of the speed light?
Sorry!!! I got time today!!!
This note is for Gennario about his installation. You state this as the performance for your boat:"I can get to 5 knots with 56 Amps – max throttle - I don't do that often. I usually like running at 3 knots at 10-15 Amps."You may want to check your calibration on your monitor or controller. Not know what system component you have, I do not know how that may be done. But at 56 amps at 48v that is 2688w or about 3.6hp. That is not reasonable to push the Catalina 30 at that speed wt that power. and likely your display data is off. The 10kW motor at 48v will have up to 200amps at full power. It should take about 80amps (5+hp) to get the Catalina 30 to 5kts in calm seas and with no current. At full power you should get to hull speed of over 6kts.Mike - Electric Yacht Pacific
On Thursday, August 30, 2018, 11:25:52 AM GMT+12, James Lambden james@electroprop.com [electricboats] <electricboats@yahoogroups..com> wrote:
Gennario,
Those are fantastic results for a Catalina 30.
What kind of propeller and what reduction ratio and what gear reduction if any are you using? You are experiencing the same type of efficiency we get at Electroprop. How was the test conducted? We do the average of two runs in opposite directions to average affects of wind and current that we experience in Santa Barbara.
It takes about half of that to achieve 5 knots or about 55 amps at 48 volts.
Every component that is inside an Electroprop was selected with efficiency being the first requirement. Electroprop's are a bit heavier than belt drives …perhaps 40 lbs heavier, but they are fully enclosed with no exposed wiring and ultra efficient. The Sailor, which is the most common drive for a replacement motor weighs in at 132 lbs.
If your data is correct, then the Electroprop and other similarly efficient systems have ranges of 2 to 3 times or more than the competition. Peukerts exponent has quite a big effect on 200 amp hour batteries driving at 200 amps.
Theres an art to building an electric drive for high efficiency. Congratulations on getting it right the first time. That is quite an accomplishment.
Cheers,
James
James Lambden
The Electric Propeller Company
625C East Haley Street,
Santa Barbara, CA
93103
805 455 8444
james@electroprop.com
www.electroprop.com
The Electric Propeller Company
625C East Haley Street,
Santa Barbara, CA
93103
805 455 8444
james@electroprop.com
www.electroprop.com
On Aug 29, 2018, at 8:20 AM, mike@electricyachtssocal.com [electricboats] wrote:
This note is for Gennario about his installation. You state this as the performance for your boat:"I can get to 5 knots with 56 Amps – max throttle - I don't do that often. I usually like running at 3 knots at 10-15 Amps."You may want to check your calibration on your monitor or controller. Not know what system component you have, I do not know how that may be done. But at 56 amps at 48v that is 2688w or about 3.6hp. That is not reasonable to push the Catalina 30 at that speed wt that power. and likely your display data is off. The 10kW motor at 48v will have up to 200amps at full power. It should take about 80amps (5+hp) to get the Catalina 30 to 5kts in calm seas and with no current. At full power you should get to hull speed of over 6kts.Mike - Electric Yacht Pacific
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Posted by: Berlouin Fred <berlouin@yahoo.com>
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