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Post by peterboat on Mar 22, 2019 17:30:17 GMT
Electric motors have a completely different power curve to IC engines. I'd say larger diameter and reduced pitch. Buy another prop keep the existing one in case of a return to diesel in future. The power curve is irrelevant - that virtually Maximum torque is available from rest makes no odds to the propeller - Tony Dunkley has nailed that bit of the problem. peterboat you need some reduction, 1:1 has its limitations on smaller boats (like our Elysians) but are employed because often there physically isn't the space to swing a larger prop with a reduction gearbox. Acceptable performance can be had using a 1:1 ratio without taxing the engine too much. On your big boat the opposite is true, a finely pitched 19" prop on a 1:1 ratio will be awful, no shove, no stopping, it may well spin up ok (rule of thumb is +/- 1" on a given diameter prop is worth -/+ 200 rpm) but it will be bloody terrible to get your boat along the water. as Tony suggests You can do the reduction with belts and pulleys, no need for a gert big gearbox in between, you can reverse the motor direction electrically - something not so easy done on an IC engine! Gearing will double my torque at 2 to 1 but the motor beyond a certain RPM starts loosing efficiency with back emf becoming a problem, I am hopefully fitting a smaller prop next week and see what that does? The direct drive is very elegant has no need for trust bearings and if it can be made to give me the right cruising speed will work fine, outright speed is not what I am after, cold motor low wattage and silence is key
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Post by bargemast on Mar 22, 2019 18:29:20 GMT
The power curve is irrelevant - that virtually Maximum torque is available from rest makes no odds to the propeller - Tony Dunkley has nailed that bit of the problem. peterboat you need some reduction, 1:1 has its limitations on smaller boats (like our Elysians) but are employed because often there physically isn't the space to swing a larger prop with a reduction gearbox. Acceptable performance can be had using a 1:1 ratio without taxing the engine too much. On your big boat the opposite is true, a finely pitched 19" prop on a 1:1 ratio will be awful, no shove, no stopping, it may well spin up ok (rule of thumb is +/- 1" on a given diameter prop is worth -/+ 200 rpm) but it will be bloody terrible to get your boat along the water. as Tony suggests You can do the reduction with belts and pulleys, no need for a gert big gearbox in between, you can reverse the motor direction electrically - something not so easy done on an IC engine! Gearing will double my torque at 2 to 1 but the motor beyond a certain RPM starts loosing efficiency with back emf becoming a problem, I am hopefully fitting a smaller prop next week and see what that does? The direct drive is very elegant has no need for trust bearings and if it can be made to give me the right cruising speed will work fine, outright speed is not what I am after, cold motor low wattage and silence is key I guess that you're not going to offer your service to pull waterskiers along then Peter.
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Post by peterboat on Mar 23, 2019 12:33:33 GMT
So I acquired a prop today a 16 x 14 and will have some fun getting it put on for a trial, if it does the job I will fit it properly if not one of the two will be modded to suit the job. It has a couple of dinks in it and needs a polish but I am sure it will do the job whether its the right job remains to be seen
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Post by bargemast on Mar 23, 2019 14:10:55 GMT
So I acquired a prop today a 16 x 14 and will have some fun getting it put on for a trial, if it does the job I will fit it properly if not one of the two will be modded to suit the job. It has a couple of dinks in it and needs a polish but I am sure it will do the job whether its the right job remains to be seen Let's hope that this one will do the right job, or at least be close enough to what you really need. Peter.
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Post by peterboat on Mar 23, 2019 15:57:43 GMT
So I acquired a prop today a 16 x 14 and will have some fun getting it put on for a trial, if it does the job I will fit it properly if not one of the two will be modded to suit the job. It has a couple of dinks in it and needs a polish but I am sure it will do the job whether its the right job remains to be seen Let's hope that this one will do the right job, or at least be close enough to what you really need. Peter. Today as I was removing the splitpin and nut to remove the prop I was wondering about my sanity to be honest, but this stuff keeps me agile and fit so I will keep on going until its done, also it will make someone elses conversion an easier job when they can read what I have done and why
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Post by bargemast on Mar 23, 2019 17:32:37 GMT
Let's hope that this one will do the right job, or at least be close enough to what you really need. Peter. Today as I was removing the splitpin and nut to remove the prop I was wondering about my sanity to be honest, but this stuff keeps me agile and fit so I will keep on going until its done, also it will make someone elses conversion an easier job when they can read what I have done and why Maybe that's the sort of thing that I should try to do to hopefully get agile and fit again. I don't have to wonder about my sanity, as I know that that is something of the past, and there's nothing left. Peter.
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Post by JohnV on Mar 24, 2019 12:21:27 GMT
Today as I was removing the splitpin and nut to remove the prop I was wondering about my sanity to be honest, but this stuff keeps me agile and fit so I will keep on going until its done, also it will make someone elses conversion an easier job when they can read what I have done and why Maybe that's the sort of thing that I should try to do to hopefully get agile and fit again. I don't have to wonder about my sanity, as I know that that is something of the past, and there's nothing left. Peter. I've got that Tee shirt as well Peter ..... You get it immediately you buy an old boat to do up
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Post by peterboat on Mar 28, 2019 20:14:48 GMT
Well the new prop gave me 100 rpm extra in forward and maybe 130 rpm in reverse, so today I modded the original prop down to 16 inches, so it is 16 x 10 or so? Given that some of the blade was removed it might be 9 inch pitch? which fits in very well with the prop site which thinks 16.3 x 8.2 is the right thing, so fingers crossed for the magic 1650 rpm when its fitted tomorrow.
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Post by Deleted on Mar 28, 2019 20:49:32 GMT
Hopefully it will work. I still think larger diameter and smaller pitch personally but that would mean a third prop...
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Post by peterboat on Mar 29, 2019 19:00:28 GMT
Well my butchered prop gave me 1200 rpm, but I suspect the batteries are now a little flat, so I will charge them up and see how it goes
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Post by peterboat on Apr 16, 2019 12:42:09 GMT
So today we had a 1.5 hour run in the boat we averaged 3 mph, had two turnings around, and a couple of bursts of full throttle. I chose a non sunny day so I could get an idea of range on batteries, it loos like after the 1.5 hours I had used 15% of my batteries up, I only charge my LifePo4s batteries to 80% and will take them down to 20% so I suspect I have about a 5 hour range on batteries alone, bring in the solar and I think 8 hours is achievable in the sun without any problems.
In the end I have butchered adjusted my prop to 16 x 10 which with the addition of an electric fan means that both the controller and the motor run very cool, so it cant be under any strain, full power seems to get to just over 7mph which is better than I expected.
I have also added Hydraulic steering which was entertaining for the first hour!! On Friday its the big test we are off to Sheffield, so its about a five hour run with a lot of locks, so I will post how much I had left in the batteries at that point, and if I can post a video of the occasion.
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Post by Deleted on Apr 16, 2019 13:51:19 GMT
I for one will be interested to hear how you get on with that. Also interested to see you reduced the pitch of the prop that's what I suspected needed doing
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Post by JohnV on Apr 16, 2019 14:01:12 GMT
7 mph is a quite respectable speed for a canal boat !!! canal boats are hard to judge their design speed, due to the hydrodynamics of the hull resembling that of a house brick. I would have thought that in excess of 7mph is probably very near the best speed against engine power you could expect without a ridiculously large engine/power consuption. To do that on electric and still have a decent range at normal canal speeds is pretty damn good ..... You must be pleased after all your hard work.
edit to add .... that is a higher top speed than I get on Shapfell ..... with a diesel engine !!!
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Post by Deleted on Apr 16, 2019 14:11:36 GMT
I'm not that familiar with peterboat vessel but if I remember right it is something like 57x12ft modern English barge possibly built by Tyler Wilson? So would be reasonable to assume it has a fairly ordinary swim ie similar to that of a narrow boat but on a wider vessel. I find the performance characteristics very encouraging. I guess the problem is that on canals you have to satisfy other people and its not really that convenient to crawl along at 3mph. Would be interesting to see the range at higher speeds. Its a great project, one I would love to have a go at myself but I am loathe to haul the diesel out. Despite being the world no.1 fan of electric I don't think its there yet. Typo edit
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Post by bargemast on Apr 16, 2019 15:34:56 GMT
I'm not that familiar with peterboat vessel but if I remember right it is something like 57x12ft modern English barge possibly built by Tyler Wilson?
So would be reasonable to assume it has a fairly ordinary swim ie similar to that of a narrow boat but on a wider vessel. I find the performance characteristics very encouraging. I guess the problem is that on canals you have to satisfy other people and its not really that convenient to crawl along at 3mph. Would be interesting to see the range at higher speeds. Its a great project, one I would love to have a go at myself but I am loathe to haul the diesel out. Despite being the world no.1 fan of electric I don't think its there yet. Typo edit As far as I remember the electric propulsion is done on a GRP boat that he bought, and from which he removed a BMC 1.5 engine. Peter.
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