Re: [electricboats] Electric Drive Installation - Some Data

Impressive, Dan !

From 2 to 3 blade prop, that's the way ! The J is a nice prop.

When your hull is clean, you could try to tune the pitch, when testing at your preferred speed.

This could optimize the power use.

Please post us, if you find that the change to pitch has a noticeable effect.

To make your chart tip-top, maybe you could incorporate your motor RPM in the tests.

We know that you run 3:1, then the prop rpm is easily calculated.

What is the distance between your prop blade tip to the hull, when fitted with this 18" prop ?

Some say 15% of prop diameter is good, others don't.

If you think the water pump is noisy, maybe the pump rpm could be electronically controlled ?

No need to run at full speed, when just a little cooling is required. Saves power too.

I see, that you didn't chose a spherical double roller bearing, like the SKF 22207E (for radial and axial loads).

If you face any trouble with your ball bearing (noise or wear), you can always change it.

How is the torque feeling with this electric motor, compared to the diesel ?

I guess it's giving a real push now, from zero !

Carsten

On Saturday, 24 July 2021, 11:52:16 GMT+8, Dan Pfeiffer <dan@pfeiffer.net> wrote:

For coolant I went with the recommended 50/50 glycol/water.   The system took apr. 2 liters total after I got a lot of air out of it. 

The big filter to the right in the photo is the raw water strainer.   Water in from seacock at lower right, to strainer, to pump, to vented loop, to heat exchager, then back overboard.  The intake is oversized for this application so I have extra capacity for a future diesel genset. 

The coupler is a standard flange unit (Buck Algonquin 50mc004150)  that I modified by machining off the boss and machining in a counter bore to fit the boss on the coupler on the prop shaft. 

The thrust bearing is a 5207-2RS double roller angular contact ball bearing with 2 rubber seals.   Like this:
https://thebigbearingstore.com/5207-2rs-5207-zz-radial-ball-bearing-35x72x27/

It is set in an aluminum housing that I made.  There is a shoulder on the shaft that transfers the forward thust load to the bearing from the aft side and a threaded collar on the forward side  that handles reverse loads.   The shaft is stainless steel.  There is a pilot bearing on the front end of the shaft.  My runout measured on the order of .001".

I turned the cooling on at about 55 or 60C.  I never tried to feel the motor case to see how hot it was. 

Motor temp sensor is in the windings and is read by the Sevcon controller. 

the 18" prop is standard on the boat.  Original was 2 blade fixed 18, I don't recall the pitch.   The feather prop I have is a 3-blade J-Prop and I have the prop pitch set at the #9 index which corresponds to a pitch setting of 13.5".  That's all a bit nebulous and the flat blades of the feathering prop don't behave like a curved fixed prop.  I took the setting I had used with my diesel and 2:1 reduction and picked wahat I thought would be right for the 3:1 reduction of my belt drive (motor RPM is 2400 like the Volvo diesel was).  So I am running the prop at 2/3 the speed I was with the diesel.  Seems lie a good match so far.  I might try setting #10 to verify things.  I can change the prop pitch setting i the water by diving on the prop. 

 

I'll get some clean bottom data as soon as the proper weather opportunity comes for me to clean the bottom. 

Dan

On 2021-07-23 9:18 pm, Carsten via groups.io wrote:

 

Great job, Dan !

 

Man, now you make me ask questions !

 

Did you solve your coolant type issue, and what was the outcome ?

 

What is the big filter for ?

 

What final solution do you have for the coupling/thrust bearing ?

 

What was the temperature of the motor itself (the housing) before the cooling turned on, handwarm or hot to feel ?

And where is your temp sensor located on the motor ?

Is the 18" prop bigger than standard for this boat ?

What is the final pitch (if you adjusted) ?

2 or 3-blade ?

 

If you get a chance for a dip, a completely clean hull will provide better comparison data.

I'm so exited, as your setup will be almost similar to mine.

 

Cheers to your work !

Carsten

 

 

On Saturday, 24 July 2021, 03:11:24 GMT+8, Dan Pfeiffer <dan@pfeiffer.net> wrote:

 

 

I have my electric drive running and I have some data.  I still have some details to sort out and there are some anomalies in the data but it's a start. 

See attached for details. 

Dan Pfeiffer