The displacement of the 22' Marshall cat (fiberglass) is 5500 so 5000 for a wooden cat doesn't seem particularly off base.
eric SV Meander
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Your boat at 5000 pounds seems a little heavy for a 22ft cat boat. To push her, think in terms of watts (power). The Torqeedo 2.0 is a 2000w motor. Our numbers for you boat with a well placed and balanced propeller indicates 2kW is a little light, the 4.0 would be a better fit. A 5kW (it will be a 48v system) inboard would be the best fit.
Speed & Power in calm waters:
Kts Watts
3.0 480
3.8 960
4.8 1920
5.5 2880
6.5 4800
Hull speed 6.29
The 2kW in best conditions will give you 75%of hull speed and in poor conditions significantly less.
Regarding battery they are not all alike and to compare one group 31 to another group 31 should be like for like. With batteries a key number to look at the number of cycles for the depth of discharge (DOD). We believe a minimum cycle of 300 DOD of 80% to be appropriate traction batteries for use as marine propulsion. Lifeline AGM batteries are the standard for you to compare lead acid batteries. Your needs and skill should dictate what is the best motor and battery for you, not what cost less.
Mike
Electric Yachts of Southern California
Speed & Power in calm waters:
Kts Watts
3.0 480
3.8 960
4.8 1920
5.5 2880
6.5 4800
Hull speed 6.29
The 2kW in best conditions will give you 75%of hull speed and in poor conditions significantly less.
Regarding battery they are not all alike and to compare one group 31 to another group 31 should be like for like. With batteries a key number to look at the number of cycles for the depth of discharge (DOD). We believe a minimum cycle of 300 DOD of 80% to be appropriate traction batteries for use as marine propulsion. Lifeline AGM batteries are the standard for you to compare lead acid batteries. Your needs and skill should dictate what is the best motor and battery for you, not what cost less.
Mike
Electric Yachts of Southern California
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