Current location for King Malu

Sunday 18 November 2012

Stress test the electric drive

In the morning we took King Malu over the the wet dock, tied her up with mooring lines and tried the new motor. The aim of this was two fold - firstly to test in controlled environment and secondly to produce a torque graph for the motor when attached to the propellor.

Now for a real sea trial - that was where we headed in the afternoon!

Rob was keen to stress test the motor; but we were concerned that because the cutlass bearing needs replacement, we didn't want to stress the drive shaft too much. We have noticed a little knocking from the movement in the drive shaft from the cutlass bearing wear.

We compromised and took the motor up to 2,500 RPM (maximum is 4,000 RPM) and to our delight found we could got a measured 6.3 knots on a relatively calm sea. This is with the old 2 folding blade propellor, so we are hoping for great things in the new year with the Axiom 3 blade propellor, when we will also have replaced the cutlass bearing.

At that RPM the motor was showing 38C and the controller 36C, so we are very pleased - it shows we have solved the cooling problem for motor and controller. Admittedly it's winter and not summer, but even still, it shows we have the temperature under control.

This is the last day of tests with Rob and Simone, they return to Italy this evening.

See all posts about PropEL Electric Drive.

Saturday 17 November 2012

Rob and Simone over from Italy

Rob and Simone came over from Italy today for two days. We are doing sea trials with them on the new electric drive. We already know that it's way better than the mark 1, so we're really looking forward to this.

See all posts about PropEL Electric Drive.

Thursday 15 November 2012

Power Transfer Switch

Very early on we bought a commercial Automatic Power Transfer Switch. It went wrong twice and we sent it back to the manufacturer. When it went wrong a third time we decided enough was enough and I designed and built our own.

There are significant differences between the Malu Marine designed unit the the original one that we bought.

1) We use contactors rather than heavy duty relays. These are what shore based Power Transfer Switches for generators use. They are much heavier duty than the relays

2) We use electrical interlocking of the contactors rather than software interlocking. Yes, it's safer!

3) We use 12 volt relays to control the contactors so we can have remote control of the system without exposing the 220 volt mains.

Installed and worked first time!

Wednesday 14 November 2012

'Table' on steering column

Some time ago we built a marine ply 'table' attached to the steering pedestal. We finished painting this and then fitted the test throttle for the new electric drive. Funny how a 'lick of paint' can sharpen up something that was otherwise not. Now we're just waiting for the new motor to arrive to test it!

The last month has been a time of designing and building and testing and aligning the motor. No photos... well, there are photos but we're not publishing them! It's all very encouraging to see the new electric drive coming ready for the sea trials. Rob and Simone are here next week and the trials begin in earnest.