Fast electrics. A beginners guide.

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20 February 2013 at 16:56 #39304
Peter Monk
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@petermonk41031
Had a long association with I/c and traditional submerged drives. Looking for a current (ho ho) guide to electric drive, speed control, flex drives etc. I”m not looking for ultimate speed but need guidance on motor size for hull length and basic things like that.
Regards,
Peter.
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20 February 2013 at 16:56 #3958
Peter Monk
Participant
@petermonk41031
looking for an introduction to electrics.
21 February 2013 at 07:15 #39308
Paul T
Participant
@pault84577
Peter

Your question is similar to the old adage of 'how long is a piece of string' and can only be answered with pages and pages of text.

Perhaps if you tell us the size and type of your model so we might help with accurate information.

Paul
21 February 2013 at 09:35 #39309
ashley needham
Participant
@ashleyneedham69188
Peter. i dont think there is a guide as such..at least, only one explaining the general principles. the best way would be to contact, or pop in to, one of the supplies of fast/offshore powerboat hardware and ask.

Anyone you ask will have their own preference for motors and batteries, styles of drive etc.

I have recently dabbled with a subsurface flexidrive and brushless motor, and it is a bit of a minefield. A shop will be able to give you info on reccomened combinations of motor/drive/batteries/prop for a size boat you specify…and that will be that. Any other combination you fancy and you will be on your own. I would choose a 3/16" flexidrive size as this appears to be the commonest and so the various equipment choices will be the widest, but apart from that ?

Have you seen the size of the Octura prop list !!

Ashley
21 February 2013 at 09:55 #39310
shipwright
Participant
@shipwright
In principle you can calculate the drag of a hull, the thrust of a propeller and match a motor to that requirement. However you will need a degree in marine engineering and a large test tank to validate the results !

Model boaters rely on their own and collective experience. So if you know what model you want to build it is possible that someone has built one before and can let you know what motors, props and batteries they fitted and how well the model performed.

If you need to know what output is available from a specific dc motor then see the link below (Mark Beard's excellent Excel spreadsheets) :

**LINK**

Regards.

Ian
21 February 2013 at 10:03 #39311
Colin Bishop
Moderator
@colinbishop34627
Also, check out the MPBA website: **LINK** as they have Fast Electric sections and a list of clubs, one of which may be near you.

A lsit of UK based Model Boating traders and their main areas of sales was published in the 2012 Winter Special edition of Model Boats. If you are a subscriber you can see it online, if not then back issues are probably available.

Colin
21 February 2013 at 11:48 #39315
David Wooley
Participant
@davidwooley82563
The basic principles of fast electrics remain constant it’s just the technology that changes…

As some might be aware I was deeply involved in the early development of fast electrics and MAP published Radio Control Fast Electric Power Boats which was a culmination of that work and remarkably can still be found on Amazon. Many of the basics related to in that book are just as relevant today as they were back then, hardware and technology aside. I will be the first to admit fast electrics were never a cheap alternative to IC. Even back then to race required a heavy investment in knowledge and hardware. Although many of the best motors where hand built it was not until the likes of the Kroker and Bullet motors and fast rechargeable cells that really transformed performance electrics from a fringe rather geekish part of the hobby to main stream . Before that the only really high performance batteries where silver zinc cells basically missile technology .They were good for only 8 -12 cycles and where kept in a refrigerator before the first charge . In fact the resale value was almost as good as the purchase value. When pure speed was the only game in town these batteries didn’t reach optimum performance until the internal temperature rose to a specific level and guessing that was the trick.

Dave Wooley

Edited By David Wooley on 21/02/2013 11:51:17
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