Any twin Jolly Motors hit the water yet ?

[G Doggett]

I very interested to know if any twin motor Jolly Cats have hit the water yet, and if so how do they perform.
For the time being I have given up on mine until I can figure out a cure for the major porpoising problem.
Have moved the batteries back and forth all over the place, angled the drives down and tried several sets of props, rotating inwards and outwards.
Nothing so far makes any appreciable difference.
Graham.

[crazzy maxx]

what is your center of gravity????

[obrien]

Is the hull straight, or does it have a bit of a rocker to it?

[G Doggett]

Hi Guys
Hull is dead straight and I have tried c/g everywhere from 25 - 50% ( even put two full coke cans up in the bows on one attempt ), but it still handles like a demented porpoise.
The hull is beautifully made with razer sharp edges on the running surfaces and is a real credit to Joseph but at the moment unfortunately it has been relegated to a static display scale model.
The pictures below show the position and angle of the drives which according to my research should be about right.
I feel that if I angle the drives down any further ( as has been suggested) I am compensating for a problem somewhere else, a bit like running extreme down settings on trim tabs.
If I could locate some 40mm lifting props I would give them a try.
On other possible explanation is that the weight of 24 cells it too much for this hull and that that mass sitting in the centre of the hull is causing or contributing to the porpoising. I plan to switch to lipos next year so might have to wait till then to prove this.
Naturally I am very keen to hear from anyone who has run one of these as a twin set up.
Graham.

[crazzy maxx]

those props are mostlikly the reason...
deffintly try some lifters!
if not get trim tabs.
and if u can get a goo day to run set the trim at 0+ 0-

[ReddyWatts]

This hull is designed to run on the rear pads at WOT. Your prop shafts are angled down. The boat is trying to lift the front and the props are forcing it back down causing it to porpoise. IMO I would try lifting the props up higher to allow the hull to lift the bow at WOT. I would not use lifting props.

[G Doggett]

Hi Reddy
When I first ran the boat I had the struts level with the running pads as I figured that was where they should be, but it porpoised real bad.
Joseph suggested I angle them down to cure this but it hasn't really made any difference.
Thanks for the interest and input.
Graham.

[ReddyWatts]

What is your top speed? IMO it needs to be running atleast forty at WOT for the lift to have enough effect and stop it the porpoising.

I would have raised the props 1-2 degrees instead of lowering them. You want it to lift and hold the front of the hull out of the water at WOT.

[Avanti]

sweet looking boat

I agree with readywatts I would lift the drives up, and get some good props. I have not had any good results from composite props

[G Doggett]

OK , I will lift the drives up as my next experiment.
Unfortunately this will involve modifying the mounting plates as I hadn't figured on running these above zero trim.
I can get a pair of ABC H1516 3 blade props in counter rotating at my LHS, do you know if these are lifting props as they appear to be cleaver style.
They are pretty expensive so I dont want to buy them if they wont work.
By the way I have tried a pair of Octura X442s without success.
Still waiting with interest to hear from anyone who has set up this cool boat with twins.
Graham.

[obrien]

you might try the octura V9xx series. those will give transom lift. A cleaver style propeller should provide the boat with transom lift.

[Eyekandyboats]

lifting prop will not help you here!
just now the struts up above 0 and see how it works

The weight of 24 cell night also be causing it But i doubt that.