Rob
The diesel is a recent addition. The boat has been operating on solar/battery combination for about two years now. There are two electric drive units and two independent batteries. The batteries are designed for 2 hours at 4 to 5 knots depending on the cleanliness of the hull. Top speed on battery with clean hulls is 8.5kts but not for very long.
This solar/battery system works well for a day sail getting in and out of marina. Typically the batteries are fully charged by the time the boat is locked up at the marina so it is ready for the next day. The diesel extends the range under motor and operates independently of the batteries and controllers. The DC generator on the diesel is the same unit as the drive motors supplying the two drives connected in series. So the generator is spinning a little more than twice the DC motors. The boat will do 6kts under diesel power.
The proa has a "dash speed" around 15kts. That is with sails up in a good breeze and drives out of the water.
For those who have followed the electric drives on the 18m proa, we have finally found a 4-quadrant brushed DC controller drive that can reverse the drives while coasting forward. This is the web site:
The fellow we contacted there is a sailor and was interested in what we were doing. Much better than our contact at Kelly in China who thought dropping the anchor to stop quickly would be satisfactory. Anyhow the 4QD controller works fine. It is all analog so no fancy computer configuration programs but it works. It is soooo much better being able to slow the boat under power rather than relying on it coasting to a stop. This unit also delivers its nameplate current continuously within its thermal limits. You need to read the Kelly data very carefully as a 500A controller is really a 200A controller. The 500A only works in a traction application for breakout torque when the shaft is not turning - sort of meaningless for a boat motor although could be a handy means to break a shear pin in a prop shaft.
Rick
thanks Rick
interesting way of going about it.
I wonder if taking power off of a battery bank might be better,
You can have the genset cut in at a predetermined load. In that way you can centralise all the power requirements and no particular supply problems to any equipment should be endured. There is sophisticated circuitry for this is already out there for off the grid housing applications, and will automatically run the genset for 20 minutes every 2 weeks just to keep the diesel serviceable and top the batteries off. It would also allow you to plug in the solar panels the boat is sure to get in the future.
just an interesting FYI: In submarine use there is also the capacity to provide genset power + battery bank power for a feature known as the 'dash speed'. The dash speed is an emergency measure to provide absolute max power and it is generally held in the market to be 30 knots submerged for a complete exhaustion of the battery (which is massive) in one hour. This speed is higher than that of surface vessels pursuing the boat as they cannot use underwater detection equipment at such high speed.
Electric machines are fascinating devices :)
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