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[Brian60]

Can I have some advice please. Now that my current build is coming to an end I'm already looking at the grp hull I have in storage to rebuild.

It's a AHT hull of 42in length and 10in width and of 14/15 kilo displacement when finished. Using twin kort nozzles the props are 55/60mm 4 blades.

What motors can anyone recommend? I did have twin 545's in it when it was first built, but they never ran so I can't comment but they just looked underpowered compared to the size of the hull.

[Calimero]

Did you ditch the 545 ? If not, I assume they gave sub-par performances as you want to change them ?


Do you already have batteries ? What voltage ?


If you're rebuilding from scratch, why not go with brushless motors. Two nice 500kv motors under 6V.


Whether you go brushed or brushless, I'd really go with two ESCs and keep both rudders independent. Yes that means 4 channels for propulsion only. But it gives tremendous maneuverability (you could even forego the bow thruster).

[boatmadman]

I have an anchor handling tug of similar size and weight, Bourbon Orca, there is a build thread on here.


I used 2 900 size motors on 12v, controlled by action twin esc and mixer and it has more power than it needs, turns in its own length, extremely manoeuvrable.


It has a bow thruster, but I rarely need to use it, and only when I want to move the boat sideways!


Ian

[Brian60]

Thanks for the info guys.

I still have the 545's in fact I have got four of them ( I originally had two hulls) They were never used in anger but I don't want to re-install them if they don't have enough oomph for this size/weight. The plan mentions two decaperm or robbe Navy (which in the haste to build originally turned into 545's because that is all the model shop had! I have no idea of the output of either of those motors so that may be a guide if anyone can match them up with what is available.

I also have two Graupner bow thrusters (from a third hull that got ditched as way too big) These are true propellers in a tube and not the water jet type which seem common nowadays. The plan calls for two at the bow and one at the stern- I'll put them both at the front.
That big hull I had (was a 6 footer) of the Stena Seawell also had two Graupner azimuthing kort nozzles, I even toyed with the  installation of these. But they only have 40mm props and the mechanism that drives them within the hull stands too high to actually fit below stern decking. So looks like they will stay in storage for another 20 years 

[radiojoe]

Hi Brian
My thoughts would be use the 545s geared down a bit, my tug is a similar size and only has one motor and that's a 12volt 540 on a 6 to 1 reduction gear swinging a 70 mm prop, and indications are there is ample power. 

[jarvo]

HI Brian


Have a look at car heater blower motors, bought from a scrap yard, They are cheap, use little power, have huge torque, easy to install, you only need small ESCs 20amp would be fine, swing huge props with ease.


Model motors for models, not miniature ships!!!!!


Give you pause for thought


Mark

[Brian60]

Thanks for the ideas guys, I think I'll go with Joe's idea and recycle the 545's. Jarvo I had thought about car blower motors, but being in Spain trying to lever anything out of a scrapyard is harder than panning for gold in the UK! When they will sell you something you might as well buy it brand new, the prices are practically identical.

Over here a 14 year old Ford Focus still sells for about £5000 yep £ not €