Skip Barker had an 18' catamaran in the Wye Electric Boat Challenge this year. He was running twin Torq's at 1.7 kw each, lithium batteries, and completed at a recorded speed of 10.82 mph which means he was probably running about 12 mph since recorded speed is based on course divided by elapsed runtime. Track is always longer than course.
On Nov 6, 2015, at 11:05 AM, James Lambden james@electroprop.com [electricboats] <electricboats@yahoogroups.com> wrote:Does anyone have a formula for calculating power consumed by a catamaran of a certain waterline length and displacement?
Can anyone provide some data on Electric Catamarans power consumption at speed?James Lambden
The Electric Propeller Company
625C East Haley Street,
Santa Barbara, CA
93103
805 455 8444
james@electroprop.com
www.electroprop.comI'll mention a few other things.
My AGM pack of 12 batteries weighed in at a bit over 1800 pounds. The LiPo's will reduce that to 520lbs.
I have burned roughly 80 gallons of Dino fuel over the last 6 years. I worry more about the fuel going bad than burning it.
Since a generator is pretty much standard on a larger boat, using it to power the motors for extended runs is not a problem. As a cruising sailboat it's pretty electrical dependent to operate a lot of things on board (my wife expects it) so having the ability to multi task the thing is good. A number of guys here with smaller boats have portable ones for this reason so I would plan on it.
Unless Mike or others know I don't believe there is anything solar that will make the charging of larger banks possible, upcharging to 72V or larger systems, without a large array in series. Then I don't believe there is a controller out there to handle it. I don't want to make my Cat look like a science project so will wait until they figure out how to make solar sails. 8o)
Steve in Solomons MD
We have seen a growing interest in cruising catamaran conversions and they are well suited for electric. Of the size you are looking at, you would reduce the normally three diesel (two motors and a genset) to one diesel and two electric motors. The cost to repower is high because there are two motors but the return to the boat owner is just as high. It takes about twice the power to push a catamaran due to the fact it has significant wetted with two hulls. Often catamarans were overpowered to allow one diesel to drive the boat at the theoretical hull speed. This could be less of an issue but still a good practice. Weight is a big issue with catamarans and you want to keep weight down so we normally see a modest battery pack and the use of a genset to handle greater power storage needs in addition to house needs. Finally the catamaran allows a build out of a larger solar array and can just about triple the effective placement of solar than a monohull without making the boat look like a solar farm.
Good luck with the search.
Mike Electric Yachts of Southern California/Pacific
Posted by: Ned Farinholt <nedfarinholt@comcast.net>
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