I came to the conclusion that for equivalence electric
should be rated at about 70% of diesel. That is, in my case, about 9 or 10 kw to replace 20hp, this is assuming a shaft speed around 1000 rpm
versus around 1700 for the diesel. I feel this is where the electric
gains its apparent superiority and if diesels could turn much slower the differences would be much smaller.
From the limited data I could collect I feel that most electric instalations may be fine in calmer conditions but when **** hits the fan most are lacking and Frey's ratios are more appropriate.
Given the above and looking at wieghts and costs I could not, for me, justify electric. I went with the lightest option available in diesel being a pair of 20hp Lombardinis.
The cost of established components, eg gen set, is so outlandish that the difference even with astronomical costs for diesel would take to long to recoup.
I wish I had the time and money
to build versions with both to do extensive testing and once and for all establish some concrete evidence to support a true equivalence. I would hope that it would come out in favour of electric but at this point in time the available evidence does not seem to support it. I feel a diesel electric would be the best option at this point in time until batteries such as the valence come in at a respectable price
enabling a substantial bank. I would then switch allegience to a proper hybrid.
Just a thought for your green motion drives. It is a pity that you have not opted for steerable drives as then we could have vectoring thrust which would open the possibilities for some real fun in developing some unique handling on sailing cats, alla the Volvo
Maybe by the time I am ready for my next boat electric may be advanced to the point where I could not resist. Either that or I could get a job as a new technology development person and realy get stuck into exploring the possabilities.