Yes, that prop is just a smidge foul:-). BTW, if you click on 'Rich-Text Editor' before you post the it shows the address as a link.
eric SV Meander
--- In electricboats@yahoogroups.com, Mike <biankablog@...> wrote:
>
> Julian:
>
> Here are the results from a test I did in the fall of 2011. As you will see from the last photo the prop was not as pristine as it could have been. My boat is 30 feet has an 11 foot beam and weighs 8 tons.Â
> http://biankablog.blogspot.com/2011/12/notes-of-electric-sailor-tests-from.html
>
> I'm hoping to do another test this spring when the boat has a clean bottom and prop.
>
> Capt, Mike
> http://biankablog.blogspot.com
>
>
>
>
> ________________________________
> From: Julian Webb <julian.proto@...>
> To: electricboats@yahoogroups.com
> Sent: Sunday, March 24, 2013 9:48 AM
> Subject: [Electric Boats] does anyone have current real world performance figures please
>
>
> Â
> Hi All
>
> - Does anyone have actual real-world speed figures for an electric drive vessel they have built or been on please?
>
> - Just simple overall "she's 6 ton, 38', and my 10KW electric pod pushes her along at 4 knots comfortably" will be great thanks.
>
> -Â That's the short story/request on how you make me sleep better tonight with some examples of figures, and you don't have to know the whole gory story to help me feel better, but if you want to know the logic/story behind my plea, read on:
>
> - I am just finishing a Diesel/Electric canal cruiser and it has gotten down to the props.
>
> Her specs are: Built 1964 - 32' w/l - 35' o/a - 11' beam - 4' draft - displacement hull - 9 ton.
> She had 2 x 45 HP Fordson Diesels, original and never overhauled, running through 2:1 V drives that pushed her along at 8 knots cruising and 11 knots top speed spinning 2 x 23" props, borrowed, mismatched and both LH!
>
> - I thought I had it all figured, read Lynch and others on rule of thumb "electric drive can be 1/3 the HP/KW of an ICE and still be close to the same performance" but now I'm meeting doubt and silence at every turn!
>
> - I have installed 2 x 11KW/15HP 6 pole 1000RPM @ 110Nm and of course can use 2:1 reduction and get 500RPM @200Nm (including losses) which I would have thought would be enough to push the old girl down a quiet canal at 6 knots?
>
> 1) I emailed 8 prop "makers" (from Italy to the USA) and when they saw the words "electric drive" most ran for cover.
>
> 2) 4 bothered to answer and in the end only 1 would guesstimate any thrust but even he has steadfastly refused to estimate boat speed, despite the fact that I have given him (and them all) figures, displacement etc and even a primitive hull plot.
>
> - After MUCH pushing (although I couldn't do it too hard or maybe scare him off completely) I found out that although they say the software they use has provision for calculating props for an electric motor, they work on HP or KW and the torque is "included in the power figures" as it were an IC engine.
>
> - When I said to them I can reduce speed 2:1 and double the torque they say they can't take that into consideration and it's based on HP/KW so the whole thing is looking shakey to me! HELP - HELP - HELP!
>
> All input kindly received, Cheers, Julian
>
> --
>
> www.proto.eu.com ltdÂ
>
> unit 9 Somerton Industrial Estate, Belfast, BT3 9JP, U.K.
> Phone;Â (+44)Â 02895 811251Â - Â Mobile; Â (+44) 07427 696 796 Â - Â Fax;Â (+44) 0871 9898296
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