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The Sumpners Afloat
Adventures on "Old Nick" – an Ortomarine-built, Vetus powered Electric Serial Hybrid Narrowboat
Can you tell me your propeller size please. We have the same vetus motor with a 13″ prop
It’s 13×9 – 3 bladed. Vetus ran all the calculations and recommended this size. Early electric boats were built with bigger props, the assum[tion being that the larger prop would make better ues of the lower rpm torque and direct coupling of the electric motor. However there are other considerations when dealing with an electric engine viz drag, current consumption and high reverse currents in emergency stop situations. We have found it to be excellent and it seems to be less susceptible to attracting rubbish. In our third season we are confident that Vetus’ calculations seem to be spot on.
Hello
@Kenneth and @Admin
I too have the ELINE-100 with the 13×9 prop. Would you be able to share the input power and RPM that you are getting at PWR and NOR settings? A static/moored test is fine. I am getting less than spec and I want to see whether others are experiencing the same, or whether it is something going on with my set-up. For reference I’m getting:
PWR: 11.3kW, 1400 RPM spec is 13.3kW, 1600 RPM
NOR: 8.8kW, 1300 RPM spec is 11.3kW, 1500 RPM
I’m also getting cavitation from about 750 RPM which gets significantly worse and noisy as the RPM increases. I wonder if this is something you also are experiencing.
Thanks
Hi Steve
O can’t comment yet on the max power I’m getting because personal circumstances have presented us from using the boat that much. But I agree with you, the noise above about 800RPM is significant and perhaps annoying. It takes away from the joy of silent cruising.
Hi Steve,
I will need to dig out our original test figures but generally all of our cruising is done in Eco mode and we very rarely cruise at more than 800 RPM to conserver power and enjoy silent boating. Above 800 RPM the cavitation noise becomes more noticeable (normally masked on traditional boats by the noise of the diesel engine) and we are comparing notes with other serial hybrid boats to see if prop size affects the noise level.
What it probably needs is a new look at hull design for optimum electric propulsion efficiency.
Best regards
Paul
Hi Steve,
Here is a table of Old Nick’s performance that we measured just after launch…
RPM—-Volts—-Amps—-MPH
500—-50.1—–10.9—-1.9
750—-49.6—–31.1—-2.8
1000—48.9—–71.4—-3.7
1250—47.7—–141.0—4.4
Interestingly, our boat, still 2 months off being launched, has a Lynch Swordfish motor, serial electric but will have a 18×12 propeller, in line with what Lynch recommended (we went down to see them last weekend). Presumably it will maximise torque at lower revs and, I would imagine, be quieter with less cavitation? However, I envisage more trips down the weedhatch! One tip they did give was to reach cruising speed and then back off on the power setting as it was wasting torque which could be utilised at a later point. Hope that makes sense? Only time will tell. Roll on September when we’ll be launched.
Richard
I met someone else with that exact configuration and they said it was working well. So, I think you will be fine.
Steve
Richard
Out of interest, which Lynch motor are you putting in? The 16 or the 20?
Steve
It’s the 16kW
Hi Steve, did you manage to fit and test the 15″ prop over the weekend? Ken
Kenneth
It wasn’t fitted until Monday. I’m going to run some more tests this week and will post the results.
Initial impression is that the cavitation at low speed is reduced but at the expense of top speed.
Steve
Ken
Unfortunately the 15×9 is not an answer for me. While it has had some beneficial impact on low speed cavitation noise it has resulted in a notable reduction in maximum RPM and power and a consequent reduction in top speed.
You can contact me directly on stevemull@hotmail.com and I can give you more details. I’d also be interested to hear more about your experience.
@paul likewise if you want to talk directly.
Steve
Thanks Paul. I’d be really interested to see what props other hybrid builders use. I personally don’t think the 13″ prop makes most efficient use of the motor. Increasing the revs doesn’t lead to a proportional increase in speed, just noise. I’m really tempted to change mine, just to see… Ken
Ken
Vetus have sent me a 15×9 prop which I will try this weekend. I’ll let you know the results after.
While it might well ease the cavitation issue I fear that it will further reduce RPM and power but we’ll see.
Steve
Thanks very much Steve, much appreciated. Ken
Thanks Steve.
Steve, I will contact you directly thanks. Just from me on this thread though, I think the problem with the Vetus 10kw motor is it’s designed and tested for smaller and lighter craft. Even their own spec suggests it’s not really meant for boats our size and weight. I’m not convinced we’ll find a prop to make things any better. My concern remains being able to safely navigate rivers with a flow of around 3mph against us, or even behind us. Ken
We’ve been using this prop for three seasons and we are perfectly happy with it. We have done the Severn, Avon, Soar and Thames from Lechlade to London and back. We always pay attention to the navigation status before venturing out and have had no issues. We go everywhere on Eco mode apart from once on the Severn, when it was on amber falling and there was quite a flow on. It is a different cruising experience than with a diesel engine. I’m not sure that we would have ventured out on a lively river, even in a diesel boat! How long have you been cruising? I genuinely think you’ll get used to it with time.