Swapping to next test motor

Today's task was to swap motors for the next test build.

First task of the day was to remove all connections and make the PropEL drive train ready to take out of the engine room. King Malu is 39 ft long and the engine room is significantly more than a locker but also much less than a room. There is no way I can stand up in it, and when the motor is in, can just about get round all four sides.

Admittedly the PropEL drive train is very much smaller and lighter than the original diesel engine, but sometimes there are still contortions needed to get to some parts.

We then attack ropes and gently pull the motor out into the saloon. We've done this many times and it does get easier each time, but it's still not something one looks forward to.

From the saloon we use a halyard from one of the masts and hoist into the cockpit. Tim and Jacob are carefully making sure that the motor doesn't damage any of the teak in the saloon.

Compared to moving a diesel engine, the PropEL drive train is a breeze... but still heavy. It's a powerful motor so inevitably not light.

The new motor is then hoisted aboard. We started trying to attach numbers to each version, but this one is simply known as the 'blue motor'. Maybe colour coding each version is the way to go!

The motor is water cooled, so we removed the hose attachments from the previous version and then reattached to the blue motor.

Finally it's time for Tim and Daniel to lift the motor, now attached to the front plate of the PropEL drive train back into the rest of the frame and then... back into the engine room.

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More testing

Today we ran the motor for about 4 hours  - running it between 1,000 and 1,500 RPM. We were careful not to push it too much as we still didn't have the small gear wheel locked in place. When we get it drilled and tapped, and also extra washers made for the large gear (the side cheeks are different on the large gear, so we need extra washers for both front and back) we'll do further tests pushing it harder. For these tests the motor was running at about 34C and the controller at about 30C.

One thing that took longer yesterday and Friday to install was the new relay PCB. There were a number is reasons:

I found that that Curtis controller uses positive common for the PWM drives (undocumented) which is somewhat strange and meant all the relays initially didn't work because the diodes were all the wrong way round!

Second problem was that the automotive relays behaved differently from the new PCB relays - the automotive didn't worry about the PWM but the PCB ones just buzzed and didn't make contact. Researching this online I found that the automotive ones worked more by luck than judgement and all relays should have a capacitor across them when connected to PWM to smooth out the pulses. I have it now working! In the process found that the Curtis controller doesn't like highly capacitive loads - which is also undocumented.

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Final sail with Daniel and Becky

This was the last day for a sail with Daniel (my son) and Becky (his wife) before they returned to the UK, so we were really looking forward to it. Our aim was to sail to Cape Pyla or Greco. We didn't quite get there as the wind was very very light.

We started with our large asymmetric foresail. When I say light winds I mean about 5-6 knots, yet the sail allowed us to move at just over 2 knots. Obviously at that speed we're not going to make Pyla or Greco!

Lunch was our traditional shipboard fare for a day sail: fried Halloumi, pittas and tomatoes. Somehow they always taste better out on the water.

We got back just before 5pm. All in all a very enjoyable day sailing.

Short test sail with new Electric Drive

Just a quick out from the marina and back to test the latest build of the PropEL electric drive train.

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PCBs. flow meters and components

Today the PCBs, flow meters and parts for the HUI arrived.  The screen printing on the interconnect board is on the wrong side. The IDC terminals are not standard components for the PCB CAD system and ended up being left-right reversed, but this otherwise works well. I look forward to seeing how much neater all the wiring becomes using this system.

The relay board looks good - for next version I shall make the polyfuse holes slightly larger, but that is only change I think. The three relays will be (1) changeover control for pumps (2) internal fresh water pump (3) 12v control for 96v. This should neaten everything up a lot inside the box.

The water sensor needs thinking about mounting. Because the PropEL drive train is a sealed box I had assumed no condensation, but Tim mentioned 'What if there is condensation on the sensor?' We'll play around with this and try to find optimal mounting.

I fitted a new RS232 board to the onboard computer over the weekend, but Windows refused to recognise it without extra drivers. I intended installing today, but the rain was too heavy so didn't actually go down to King Malu.

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Ready for the next build...

Tim and I stripped the motor ready to remove to swap with the blue motor. Tim then flew to London for meetings and will be back late Friday. Saturday/Sunday we will swap to the blue motor. 

I am slightly concerned about the gear wheels - I remember we used 3.2:1 as the ratio and I think the small gear was somewhere between the two small ones we have. Getting the right ratio is a significant part of providing thrust where we need in on PropEL... to the proellor!

If all goes well we should know early next week if the blue motor is performing better under load. Assuming that the blue motor does what we hope, then next few weeks will be extensive testing on the water.

We're still waiting on the new PCBs from the USA for the relay board. They were dispatched from USA yesterday, I believe, so should be here soon. I have brought back the extra components for them so when the PCBs arrive can test them.