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[des321]

Hi,
This is my first post after building my first model.
Has anyone built and run the little Mincio?
Any problems with the rubber band drive system?

[Captain Povey]

Hi There, I am in the process of building the Mincio and have already changed the stern so that you can get at the rudder linkage when the stern planking is on. I have also replaced the plastic rudder with a brass one. I have serious doubts about the rubber belt drive and have also posted some stuff on here expressing my concerns without getting any respose so I assume nobody else has experience of it. If you do a search for 'Mincio' you will probably find my posts and pictures. How far have you got? Cheers Graham

[des321]

After a brief test in the bath I took the Mincio to my local boat club where it ran for about 10 mins before the battery was expended. It was rather slow and failed to get up on a plane. Being nervous of the elastic band drive I had fitted an 'O' ring. I put an amp meter in the circuit and it pulled 4 amps running free so I suspected there was a problem. Sure enough last week on its second outing the motor burnt out in the middle of the lake. Friendly club members rescued it for me. I considered fitting a larger motor with a timing belt and cogs but there is barely space for this and it seemed a bit OTT for such a small boat. Another idea was to fit equal size gear wheels to each shaft. But that would require a degree of precision in mounting the motor that may be difficult to achieve.
So I have decided to trust the original design. I have replaced the motor with an identical one. It runs free at just under 1 amp and sounds much better. Weather permitting it will go on the water tomorrow.

[Captain Povey]

Hi des321, Thanks for the update. You are way ahead of me as I have not started the second planking yet. What battery are you using as I need to decide on that too. Any chance you can post some pictures? The company I work for has used O ring belt drives on some of the products they make and they certainly need some power, plus ordinary O rings had a nasty habit of breaking at the join because of the way they were moulded. The O ring form made as a belt was much better. I am also considering gears and the possibility of using the Graupner Multi speed 140 with a different prop tube and brass prop but I need to get hold of one to see if it can be squeezed in. Good luck with the next trial. Cheers Graham.

[Colin Bishop]

O rings can be used for belt drives, I use them myself, but the tension is critical as they don't really stretch. As soon as you start to pull the ring out of its natural shape it starts to bind very quickly and power consumption shoots up. The trick is to apply just enough pressure to avoid slippage.

Colin

[des321]

My little Mincio went back on the water today with the standard rubber band drive as supplied by Mantua. It ran fine in air. As soon as on the water it would only go at a snails pace despite the motor running OK. Obviously the band was slipping. Moments later the band broke, just as I originally thought it would. Thanks to the post about 'O' rings needing to be very carefully adjusted I shall now go back to that solution and find away of building in a small degree of adjustment. Will post the result next week if anyone is interested.

[Captain Povey]

Hi Des 321, Sorry to hear about the latest failure of the 'drive belt'. It so no consolation I know but it confirms my suspicions. Good luck with the O ring. I assume it is 1/16" cross section. I am certainly keen to follow this thread and avoid similar frustration so please keep posting. Although I am about to start the second planking I will not be able to do much next week as I will be out of circulation. Cheers Graham.

[des321]

  After many trials with O rings and fitting a Graupner 400 speed motor the performance was improved but substantially below expectations. The issue was always belt slippage.
I fitted a toothed belt and cog drive system and changed the battery from 6v to 8.4v. The result was dramatic. It now goes like I was expecting, getting up onto a plane. It caused problems of water intake due to the amount of spray created. But I am happy to deal with that.

[Captain Povey]

Hi Des, Thanks for the update and glad to hear it is now working to your expectations. After learning form you I have gone for a direct drive outrunner brushless motor, micro servo, small cirrus radio and Li po battery. I am still rubbing down and varnishing but not long now before I try it out. Thanks for the warning about water ingress I will have to watch it as I expect this little boat to fly. Cheers Graham.

[des321]

Hi Graham,
That's a very interesting drive system you are going for.
Something you might want to consider if the boat speed is really fast, is the steering. First time out with my improved performance I very nearly turned it over on my first turn. The full-size boats of this design were never super fast I believe. Something like 30 knots maybe. So scale speed (multiply by square root of the scale) gives us about 7 knots. I reckon I am getting close to that. I suspect it would be quite difficult to control at speeds significantly more than this. Let me know when you get it on the water.
Good luck
Des

[Captain Povey]

Thanks for warning Des I will proceed with caution. It would be a shame after all the hard work for it to sink on its first outing. Cheers Graham.

[Captain Povey]

Hello all, Well at last the little Mincio is finished. It has been in the bath and seems to be ok for the big test on Sunday. Unfortunately the first flexible drive proved to be a bit too stiff for the propshaft so I rumaged through my son's old technical Lego and found a very neat universal  joint. It had to be worked on a bit but I am hopeful it will do the job. What do you think Bradders? Cheers Graham.

[Captain Povey]

Hi All, Well here are some pictures of this little boat performing. After the initial successful runs with a sister ship it became very unreliable stopping in mid pond several times. Fortunately for me a sub was on hand to nudge it in. Once back on dry land and resetting everything it seemed to be ok. Friendly advice from fellow club members included 'those cirrus radios are no good', is the aerial long enough (loss of range) etc etc. Other suggestions were that the radio battery @4.8v and 300ma was too small to power the speed controller for the brushless motor and the servo hence shutting down the radio and stopping the speed controller. Back home it seemed ok so a few things here to sort out. Including was somebody else on my frequency or was there interference from the county hall offices and their radios. Anyway it provided some fun and entertainment for all. Cheers, Graham.

[barriew]

You may be right about the radio battery. I've tried one of those in my Deans Fireboat with a brushed motor, and got a few glitches and very short life. If I could find my 'regular' sized pack I would use that

Barrie

[andyn]

I've got a pair of 7.4v 700mah li-po's that are free to you if you can charge them  / fit them in etc

I think they are bit down on power though, old age...

The wash is very impressive

[Captain Povey]

Thanks for the offer of batteries Andyn but I think they will be too big and there is very little room in this little boat. Yes the wash is the result of a high forward speed and a tendency for the bow to go down not up. Possibly because the prop shaft angle is quite steep so I suppose it has a tendency to lift the stern. If I can get more weight at the stern it might help but I don't think these little runarounds were ever designed to get up very high. Cheers Graham.

[andyn]

It isn't a planing hull, and propshaft is far too deep, problem solved

Batteries are 12 x 50 x 28 mm

[Captain Povey]

Thanks for the battery sizes Andy I will have measure up and get back to you later. Cheers Graham

[des321]

Congratulations on a fine looking model. Interesting it doesn't get onto a plane. Mine  does once it goes fast enough. Perhaps you need to look at the balancing. You are getting an enormous amount of water spray, just as I did. I reduced this considerably by fitting strips of wood at the bow that mirror the long ones at the stern.
Do you have a problem with water getting into the boat? I have to tape all the hatches down which spoils the appearance and takes quite a few minutes everytime I run it.

[Captain Povey]

Hi Des231, Thanks for your words of encouragement. I am certainly thinking of shifting some weight to the stern and a club member suggested some bow strips as you have done to keep the spray down. Yes it did get water in the bow and stern compartments so I will be thinking about trying to seal it better next time. I have now moved the aerial and run it down the starboard side away from the speed controller and then up the flag pole at the rear which I made from a stainless steel tube. In the garden the range seemed to improve so that may go some way to curing the cutting out problem. The next test will be with the prop in water to test it under load and see if the radio battery is too small. Cheers graham.

[andyn]

Seal the hatches with Sellotape Diamond Tape. It's clear (hence the 'diamond' bit), stays on when wet, and comes off easily when you want it to.

[dougal99]

Can you still get Diamond tape or has it been renamed? I use it and have a roll, but I was told at Wicksteed that it wasn't in production any more, at least not under the Diamond name. Any info please?

[andyn]

Still in production...

http://www.phoenixmp.com/acatalog/Tapes.html

'Fast' electric boys buy them by the houseload...