Model Boat Mayhem

Technical, Techniques, Hints, and Tips => DC Motors (Brushed) and Speed Controllers => Topic started by: destroyer42 on July 16, 2007, 08:31:36 pm

Title: Motors or Props
Post by: destroyer42 on July 16, 2007, 08:31:36 pm

Hi Advice needed?
I have a model slipway Range Safety Craft and I have upgraded the motors to Model Motors Direct 777. Also I have change the props from 40mm 2 blade to 35mm 3 blade clevers all running on 12v. Howerver I still can't get it to plane. Do I need better motors or should I change the props? Advice needed.

Thanks
Destroyer 42

Title: Re: Motors or Props
Post by: DickyD on July 16, 2007, 08:52:57 pm

Hi, Westbournes recommend the Graupner Speed 600-Eco motors and the Tornado TRC4300 9.6v Sub C Nimh battery.
You will often find that you get more speed with a 2 bladed prop.
What type of 12v battery are you using ?

Title: Re: Motors or Props
Post by: FullLeatherJacket on July 16, 2007, 10:07:57 pm

Model Slipway Kawkab PTB - very similar hull to Range Safety. Fitted with Graupner 600 Eco motors running from 8.4v NiMH packs on Robbe 2-bladed nylon props (40mm, I think). How's this for planing?

http://www.modelslipway.com/kawkab/kawkab2.jpg

Remember - it's the "lead" in SLA that gives you the clue....... planing boats don't like weight.

FLJ  8)

Title: Re: Motors or Props
Post by: J.beazley on July 16, 2007, 10:21:11 pm

I agree with FLG, try and use Ni-Mh cells to keep weight down and try her on either 7.2 or 8.4 volts and see how she goes.
If you need more power add a few more cells and go to 9.6 if that doesnt get her out the water something is wrong elsewhere.

Jay

Title: Re: Motors or Props
Post by: Stavros on July 16, 2007, 10:27:09 pm

Go back to the 2 blader first you should see the difference st away,had the same prob wiht a mtb changed to 2 blader majic Stavros

Title: Re: Motors or Props
Post by: meridian on July 16, 2007, 10:42:08 pm

I have recently completed a Model Slipway Range Safety Craft and have used two Graupner Speed 600 Eco motors each powered by its own 7-cell 8.4v 2400mAh Ni-Cd pack. It planes beautifully at just about scale speed. I don't have photographs of it in action at the moment but will try and take some this weekend and post them on this forum. As a matter of interest I adapted the kit as an MOD Police Launch and I am very pleased with it. Pictures of it appear in the gallery section of Model Slipway's website.

meridian.

Title: Re: Motors or Props
Post by: destroyer42 on July 17, 2007, 07:47:39 pm

Hi DickyD I'm using 2 6v 4ah wired together to give 12v.
I have a couple of spare Graupner Eco 600 motors. I'll try them. Just got to get a couple of ni-cads 9.6v and put the original 40mm 2 blade props back. I'll let you know the outcome this weekend.
Many thanks.

Title: Re: Motors or Props
Post by: DickyD on July 17, 2007, 07:54:57 pm

Hi there, for batteries try:

 http://www.component-shop.co.uk/index.html 

Very cheap and excellent service

Title: Re: Motors or Props
Post by: Shipmate60 on July 18, 2007, 06:29:15 am

I made the original model of this craft.
I ran her on 2 x 545's and a 6 volt 10 Ah battery with 3 blade fast props from Prop Shop, she was reasonably fast but would last for well over an hour.
She is now in Beale Park Museum.
The original boats werent that fast.
Original engines were MAN medium speed diesels, these were changed for Rolls Royce Diesels, then finally Volvo Pentas (with a prop change to 4 blades).
On the last installation these boats struggled to make 21 knots.
The Police boats were powered by Ford Sabre Turbocharged engines which were a bit quicker, but didnt like running slowly, then being opened up. This tended to blow the turbo.
There are also some Customs boats based on this hull with Cummings Engines (I think) which did perform well.
The hull isnt a fully planing hull, but a semi-displacement hull with spray rails, Trim tabs were fitted to keep the bow down as they did have a tendancy to lift, but not actually plane.
But I must admit they do look good on the plane.

Bob