Motor /Controller /Prop upgrade

[Dave Cooper 6Participant @davecooper6]

Hi Ray – thanks for the confidence vote. Despite 'conforming' with all the size /type guidelines, they still don't fit in the post box.

Dave

[Charles OatesParticipant @charlesoates31738]

The system can behave oddly at times, I don't know if that's connected with the method used to re size pictures, I can't think why it should be, but this is quite old software I'm told.

Anyway, why not throw caution to the wind, put them in as best you can and see what happens when you post them.

Chas

[Dave Cooper 6Participant @davecooper6]

[Dave Cooper 6Participant @davecooper6]

[Dave Cooper 6Participant @davecooper6]

[Dave Cooper 6Participant @davecooper6]

Sorry about the photo sizing folks – I tried many times to get it right !

Bow undercut : shows a profile (loosely) as used on RAF craft. Runs aft to the step.

Bow step : shows the shallow 'v' shape of the step which is about 1/3 back from the bow. (Not yet tried in practice just an idea at this stage).

Superstructure : in the early stages of the refurb'. Not sure about mast height yet – they were quite tall though. Turret to be replaced, guns (loosely) twin Bofors. Wheelhouse scale is roughly 1/48 judging by some German artillery figures I have !

Any ideas where I can source a suitable turret ? Will probably test run with the existing motor (350) and prop (30) plus a 1500 MaH LiPo until some experience gained…

Dave

[Dave Cooper 6Participant @davecooper6]

Correction : previous post should have read motor = 380 (current starting point for tests).

Note from the workshop, it's amazing how grey primer shows up all the little inconsistencies !

[ashley needhamParticipant @ashleyneedham69188]

Dave. Now I can see what you mean about the bow step, I am not keen. I think it is too small to be a step proper, even if going fast and is likely just to cause drag.

Personally I would sand this flat OR put a bit of sheet balsa behind it and fair this into the rear section.

The bow undercut looks useful though. Ashley

[Dave Cooper 6Participant @davecooper6]

Hi Ashley – yes, might have to revert to your blue Styrofoam idea. Must brush up on my hydrodynamics !

Dave

[Dave Cooper 6Participant @davecooper6]

[Dave Cooper 6Participant @davecooper6]

[Dave Cooper 6Participant @davecooper6]

[Dave Cooper 6Participant @davecooper6]

Hi folks, progress is slow but steady – a few questions please :-

1. Is it a good idea to run the Rx aerial up a foremast (not yet fitted) to the mainmast and then down to the aft jackstaff ?

2. Second pic shows 'vintage' installation but with modern LiPo (1500 MaH). OK for bath testing I think, but, will probably need an upgrade to drive shaft (2 > 4mm) and replacing the Bob's board with a modern ESC.

3. Final pic – is the waterline red too red…I was thinking maybe a car accessory Red Primer (or similar) may be better ?

Boat will be re-numbered in due course as I've yet to see any RAF launches of this type numbered over 2xxx.

Thanks for any answers /assistance.

Dave

[ashley needhamParticipant @ashleyneedham69188]

Dave. I find in most cases it is sufficient to run the Rx wire around the deck hatch. If this is troublesome, then having a small portion of the wire vertical can help.

Bath test once you have changed the propshaft and vintage Bobs board.

Red oxide paint is the "usual" red colour of choice. It goes much brighter when wet and in the sunlight.

Ashley

[Dave Cooper 6Participant @davecooper6]

Thanks Ashley

Some good tips as usual. Rx wire currently runs around the hull perimeter and seems to be ok.

I did do a quick bath test this morning just to check out forward /reverse etc. Did a bit of re-wiring this afternoon to make it easier to get the battery in and out.

Yes, I'll try the red oxide – Halfords /model shop ?

Dave

[Colin BishopModerator @colinbishop34627]

Halfords red oxide is very good but it is a primer so technically not waterproof. Ideally it should be sealed.

I have recently discovered, along with others, this matt lacquer from Halfords. It gives a lovely finish and appears to be OK for any sort of paint.

**LINK**

Colin

[ashley needhamParticipant @ashleyneedham69188]

I usually just splash some Eze Kote on it. Gives it a semi gloss finish. Under way the red bit will be wet and thus shiny in any event.

Will check out the matt lacquer, very handy.

Ashley

[Dave MilbournParticipant @davemilbourn48782]

I have recently discovered, along with others, this matt lacquer from Halfords. It gives a lovely finish and appears to be OK for any sort of paint.

There's also a Satin version of this which I've used on their Red Oxide with great results.

It does seem to be solvent-based, however, so the usual advice to test it on a small area should be heeded.

DM

Edited By Dave Milbourn on 01/09/2019 10:40:19

[Dave Cooper 6Participant @davecooper6]

The bright red that has been applied so far does seem to be durable and waterproof. I think I may leave this on until I get around to the prop /driveshaft upgrade.

Thanks for the painting tips all. I'll get some red oxide and lacquer and experiment with some scrap wood in the meantime – Dave yours looks very slick I must say…

Dave C

[Dave Cooper 6Participant @davecooper6]

Well folks, the first run of the little RAF launch took place this morning on the upper reaches of the river Avon.

I must say it looked a treat in the early morning sunshine ducking in and out of the various overhangs on the river…

Trim-wise, it was a little bow-heavy to start with but, when 3/4 to full power was applied she came up nicely onto the 'step' (I know Ashley had his doubts about this..) and, rode bows just clear. It may need a little 'church roof' in the stern just to assist slow speed running.

I think the hull can handle a little more power – at the moment I have a 380 /385s motor with a 3-blade prop running a 2mm shaft / 7.4v Lipo and a Bob's Board.

Suggestions welcome for the next upgrade: eg 2-blade racing prop /3mm inner shaft (any bigger and I'll have to change the outer as well – rather not !). Also, the Bob's Board may be sapping a little power and there did seem to be a slight power hesitation when crossing back over the wake ?

Thanks to all for the help so far…I think it will be a nice cruising yacht next with an auxiliary motor /folding prop' combo and much bigger so that I can get my poor old fingers inside.

I have a few nice videos of this morning's runs taken by my wife on her smart phone – are we able to upload /link from the forum ???

Dave C

[ashley needhamParticipant @ashleyneedham69188]

Well done Dave. Ashley's doubts are still there and I didn't say it would not work, just that it would increase drag so a performance boost may be had by….

Not sure how you could fit a 3mm shaft if you have a 2mm already (without reading all the posts!!),

Prop choice is far greater for the standard 4mm shaft size, so that's what I would go for, and an S35 two blade plastic prop will do you. The easiest way to a bit more power would be to fit a 480 motor (J Perkins do one) which is the same diameter as a 380/400 and shares the same mounting holes, but is longer and a bit more powerful.

The "modern" alternative would be to go brushless but would mean a new motor AND a new esc. Personally a 4mm shaft, 35mm prop and 480 is the easy choice. Please replace the Bobs board with a Mtronics 20A ESC, which will do ok.

Should be able to upload the link.

Ashley

[Dave Cooper 6Participant @davecooper6]

Hi Ashley

The boat does accelerate very quickly once 'up-on-the-plane' – probably near to what my reactions can keep up with at present !

In terms of the upgrade, (thanks for the tech' on this by the way), the shaft outer is 6mm diameter – hence, I felt I could safely drill out the bobbins at either end plus, the stern-end of the "Huco" coupling to take a 3mm inner. I'm wondering if 4mm would be pushing the clearances a bit ?. The boat is nice and water-tight now so, I'd rather not start to rip the insides out.

So, then, a motor upgrade, 3mm shaft (if I can find a suitable prop) and, possibly an ESC to replace the BB could be in order. The real essence of the project – as inherited from my son and his friend – is for a 'pocket money', fun-scale little boat. I think if I turn it into a 'cheque book project' the fun element will disappear…

Thanks again for your help,

Dave

[Ray Wood 3Participant @raywood3]

Hi Guys,

This little boat is far too small to start talking brushless, the hull shape isn't designed for mach 2 speeds try more volts up to 9.6v if you can get the battery in ? Dave you said it looked a treat ! Mission accomplished ?

Bob's board is 30 year old technology and takes Quite a lot of space.

Regards Ray

[Malcolm FraryParticipant @malcolmfrary95515]

Apart from the space taken, there are two main downsides to Bobs boards. One is that they need a very good match to the motor to give control. Either next to nothing until at full power, or everything all at once as soon as the wiper is off-normal. The other is that at everything but full speed, they waste battery power.

Electonic ones take up less space and offer good control with a wide range of motors with good efficiency at all speeds. A "maybe" downside is that most cause the motor to whine oe whistle to a greater or lesser degree.

When needed, a Bobs board can be serviced. The downside of that is that it will need servicing from time to time.

Electronic one don't, which is just as well because most are sealed for life.

[Ray Wood 3Participant @raywood3]

Hi Dave,

Yes an ESC with BEC like the Mtronics 15A will allow you to do away with the radio battery and the servo operating the Bob's board so it should be a win – win situation?? or you could leave it as it is and move onto the next project.

Once I've completed a motor boat and run it a couple of times I lose interest in it very quickly, where as a sailing boat in my view is much more fun long term

Regards Ray

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