Nige. What size of huntsman is this?? loads of chaps must have built this model in the past and not so past, so one would thin k that their would be plethora of replies on this subject, but there again..

You presumable have shafts fitted, and they are metric?

Ashley

NLL. If you dont want to mess about too much, I would leave the setup as a single shaft, much easier and cheaper to power than a twin.

I was going to suggest two 600`s but on reflection this may be a bit underpowered, depending on the type of 600 (there are half a dozen varieties out there).

For a single shaft something meaty would be required, the Graupner 700 or similar types find favour with others, running 12v or more. For planing you will want a fairly powerful beast

My MFA Fantome is of a similar size and has a good performance from a pair of MFA800 motors (total about 140 watts) on 12v Nimh pack. Performance would be sparkling if I dropped a pair of 850`s in, straight swap. See picture, this is on a 12v Gel battery, goes a lot better with a Nimh battery of 1/3 the weight!

You could go brushless,but there does not appear to be a lot of expertise out there for this sort of situation. They are mostly used for very fast applications, hydros etc, or where small size is critical, neither of which apply to your boat..it only needs to be reasonably fast and there is not a significant lack of room…

Brushless motors are specified by their rev/volt figure, and then what sort of current they could be expected to draw. For a, say, 40mm prop I dont suppose you would want to rev above (and I am talking off the top of my head here) say 15,000 RPM, and so one might calculate the motor spec from this, but only if you have decided on the battery voltage first.

Ashley

My advice would be one single Speed 900 running on 18-24v with a 3-blade 50mm prop. Setting up a Huntsman with twin shafts isn't as easy as you might imagine. Don't even think about using sealed lead-acid batteries – they are far too heavy.
Incidentally it's 40 years this month since I first put pencil to paper for this kit. I have to say that it's not dated anything like as much as its designer!
Dave M

Hmm… 40 years ago, I would have thought that 30 yards of best rubber band and a home made 70mm prop is what the designer had in mind?

Nige,, .

I might suggest that there is no RIGHT choice of motor/battery/prop combination,and if there are more posters, they no doubt will offer any number of variations on the theme of motor choice.All valid, all offering some advantage of other.

I rather fancy the wallet approach in this matter (being tight), and unless you are bent on the very best performance possible then Daves approach may be the best especially as you already have only the one shaft fitted.. Bog standard sort of motor, nothing fancy , and a 24v Nimh pack (or whatever) , results guaranted.

And that is not to say anybody elses suggestions are worse, or better for that matter.

Dave, would one want water cooling with this setup??

Ashley

Thank you for the various comments, you old geezers.
The original did have IC power, Paul – one of the first HP61F R/C Marine motors in the UK, and probably the first with Schneurle porting and that magic 1BHP figure. I originally fitted the aero silencer but good ole Len Hooley of Ripmax had just commissioned a batch of proper brass marine silencers and so one of those was substituted. The 47" model was powerful enough to haul John Rudd and I around in tow in a 12' dinghy. Happy days.
Ash
Never mind rubber bands., m'lad! Water-cooling may be necessary for the motors if you run them on 24v+.

Dave M

Not in the experience of a few customers who run such set-ups. A few turns of brake-pipe coiled around the motor seem to be enough, with the usual scoop and outlet connected with silicon tubing etc.The Speed 900 is a very efficient brushed motor and on 24v does not draw a huge current as long as you choose the right prop.
I would have suggested an X50 or X55 2-blade racing prop but Alan 'Barzo' Barwick's experience with a 3-bladed type is very interesting. I also originally fitted a 2-blade plastic prop to my prototype Shamrock and, against my (then) better judgement, replaced it at Prop Shop's suggestion with a 3-blade scale type. The model was just as quick, sat better in the water and ran for over twice as long on the same pack. QED.

Dave M

Dave, that is very interesting, I have been told by more than one persons that the X series of props, although fine for most fast applications, is inefficient at slow speeds and so eats the amps, and I am guessing a Huntsman (or whatever) spends perhaps more time cruising past the admirers or going at half throttle..rather than a performance boat which would be run almost flat out everywhere (as it would be a bit boring otherwise!).

Certainly, there was no performance difference on the Fantome when I changed to 3 blade brass..although possibly the 800 motors dont spin x props fast enough to start with.On the other hand, my victorian topedo boat & TBD run just as well with brass props as small X or S pitch ones, and they both use speed 400`s wich are revvy little things.

I think that flat out, and on a "fast" hull you need an X prop, but other than that, a "normal" one will suffice.?

Ashley

Hello

I have just started building a Huntsman 31, does anyone know where i can get a plan for the location of the battery and engine