New to this forum, but not new to boats, in fact I have had more boats in the last thirty years than I care to admit to, I'm sure there is a cure for this illness but I'm too frightened to speak with my GP. Background, retired Airline pilot and Precision engineer, interest in water craft started in the 60's with small hovercraft and slowed down to displacement mode in the early 80's. I have been developing Stirling cycle engines over a similar period with little success until recently when I completed a 100watt engine which I fitted in a motorised 5mtr catamaran. The performance is just about tolerable when everything is going well but this time of year with the weed well developed, any trace on the propellor kills what little performace there is available.
Bright idea! I have two 125 Ahr batteries, in my Dutch barge, which sit there slowly discharging as the Barge rarely goes out, will buy a dc motor and a PWM controller and replace the SE in the catamaran. Wonderfull, power at the turn of a knob, astern at the flick of a switch, almost perfect but for the bl***y weed. Fortunately I came across a excellent thread on another forum with a wealth of knowledge on 'efficient electric boats', you will all be aware of this but for me it made hours of enjoyable reading. I noticed in this thread a folding propellor design which looked as though it would shed weed, so I spent last weekend making a version of this idea and hope to try it later this week when balancing is complete.
The only other aspect of my electric motor conversion, which is not yet to my likeing, is the noise from the PWM controller. It is an inexpensive, Thailand produced box of tricks, with the facility to vary the frequency (still trying to get my brain cell around this aspect of the controller) and some reducton in 'hum' can be achieved with the frequency set at its lowest setting. Is this due to the purchase price, typical of PWM controllers or am I doing something wrong?
Your advice would be most welcome.
p.s. I tried to attache some pictures of the folding prop but 'file size too big'! will try again soon.