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[Colin Bishop]

I am currently building a modified version of Vic Smeed's classic Silver Mist motor yacht plan to the original size (21 inches long). Build log on the MB Website.

I am fitting twin screws for additional realism but as they are quite close together with a decent sized rudder I am not intending to go to the cost and complication of fitting independent control as this is a bit of a budget side project. Motors are RE280 3-6v with 2:1 pulley drive reduction driving 20mm brass props. ESC controlling both motors is a Quicrun 1060.

My initial thought is to fit a small 6v NiMH power pack but as I will be using the Quicrun BEC I am wondering if it might be a belt and braces idea to use a 7.2v pack to give a decent margin for the RX supply and a bit of extra power in hand.  RX is a Radiolink one. I will stick with NiMH as it is consistent with my other models.

I have a 1060 Esc in my Greek fishing boat which is about the same size and this works OK on a Monoperm Super.

Any constructive comments welcome.

Colin

[Abandon Ship]

Hi Colin, even a fully discharged 6v (5 cell) NiMH pack should be 4.5-5.0v which should be sufficient for most if not all radiolink receivers. The user manual of my QR-1060 says 5 cell NiMH minimum so it should be OK but I've only used it with 6 cell.
The interesting question here is what minimum actual voltage the 1060 will continue to operate at. The manual says 5 cell but that could be from 4.5v to 7v depending on charge state.
A 7.2v (6 cell) pack would be safer as long as you can limit the throttle to avoid cooking the motors.

[Colin Bishop]

Yes, those are the lines I was thinking along. The Radiolink TX can be set to limit the throttle throw. I suspect the model will chug along happily at around 4-5 volts when cruising cruising. Gentlemen's motor yachts of the period proceeded with dignity!

There were many variants of the James Silver motor yachts which gives me lots of scope to upgrade the model to near scale by adding detail. There are still a surprising number around although most of them seem to have bee extensively modified.

Colin

[Fred Ellis]

Colin
I used a 6v pack with the 1060, it run for about 5 minutes the stopped, so I only now use 7.2 packs, by using the 7.2 I now run all the lights along with a smoke unit from a tank, and that last me an afternoon sailing.
Fred 

[Colin Bishop]

Fred, yes that's the sort of thing I wondered about. Best to have a couple of volts in hand over the listed minimum. You can't be sure what the electronic tolerances are.

Colin

[roycv]

Hi Colin I love the Silver Mist model, I have a plan printed to give a 26 inch loa hull, I hope to build it but others keep getting ahead of it.  I had overlooked that it might be a 2 prop boat so hope to see your version.
I wonder at choice of motors as I think RE types have plain metal brushes, I like a carbon brush but that is just me.  You could use AA cells for the relatively low discharge rate.
I do have a model which drained the previous battery and then the esc switches off the BEC, so the only way back was minimum power and then the rudder control was restored.  I have since fitted new batteries.
I decided to make my own pack using a mini-welder and bought some lighter cells.  These are 4/5ths sub-C 2800mAh and they work very well with a battery 7.2 volts.  They are lighter and a genuine capacity as indicated and supply just under 2 amps (19 watts) and as speed drops off the BEC still supplies enough to power the rx.
One of the reasons I made my own pack up was to have 2 sets of 3 cells so that the battery could straddle the keel rather than the standard type shape.
Will we see the model in MB Mag?
Regards
Roy 

[Colin Bishop]

Hi Roy,

I chose the motors on the basis of size. They came from Component Shop with a capacitor fitted so hopefully that will cut down electrical noise and the Radio is a decent 2.4Ghz set. The boat won't get a great deal of use on the pond so I'm not really worried about wear either, it is a fun project really, using up stock and items in the workshop.

My thinking is to use Vic’s plan for the basic construction and embellish it to produce a near scale model which is what I did with my Greek Fishing Boat. Vic’s plan was developed from photos which allows plenty of modelling licence in the detail. There were a lot of James Silver boats of similar but not quite the same design so there is plenty of opportunity to tweak the detail, lots of photos online too as many of the boats are still around.

The original Silver vessels were twin screw but Vic’s plan, understandably, has a single prop. On the face of it, fitting twin screws on a small model of this type is overkill plus two ESCs and a mixer would be needed in view of the single rudder. Initially I am not going to bother with independent motor control as the props are close together and I have redesigned the rudder so that it intercepts  the propwash. If I do need a bit more steering effect I can use Paul Freshney's method. He always claimed that a mixer was unnecessary as he simply fitted limit switches on the tiller which cut out the inboard motor when the helm was hard over. Cheap, cheerful and effective as he demonstrated. I'll see how it goes (literally!)

I have also noted the deviations from Vic’s design in respect of providing good access to the hull interior as evidenced by Ray Wood's model.

So! The present intention is to use Vic’s basic construction but modify the upperworks to give better access to the interior and add some extra above deck detail.

Not sure if it will appear as an article in the magazine as Ray has published two excellent articles on his larger version and his 'Minimist' in recent years.

Regards,

Colin