Twin motor mono

[Old School]

Whenever a twin motor setup on a mono is mentioned the usual outcry is far too much parasitic drag. Odd that a twin screw catamaran is the preferred choice for performance over a single screw layout.

With a twin motor mono how is it that in the same hull a single screw can provide sufficient performance and yet adding another equally propulsive screw is detrimental to performance, supposedly decreasing the overall performance over just a single prop? Is there a bias against a twin screw setup on a mono or is it really not worth the effort?

Would a contra (counter) rotating twin prop setup alleviate prop torque and chine walking? Quite possibly given the vee shape of the transom the hull would run "wet" and this would affect overall performance. Would a double stinger setup or an under hull strut installation be better?

[rol243]

a twin prop mono would be ok for straight line use but when it comes to turns , you will have one prop leaving the water due to the degrees angle of the hull. it is much more common to have 2 x engines / motors set up in-line and running just the single prop, a cat / tunnel hull is good for twin prop drives as the hull sits flat in the water when negotiating turns. a slow scale mono hull / ship is fine for twin prop drives though.

[Old School]

I have not considered the effect cornering would have on the outboard side shaft. Several videos on You-tube show that the twin drive does have performance potential.

[rol243]

yes as said, in a straight line. the real offshore outboard mono hulls fitted with 2 / 3 / 4 outboards do go very well but again mainly in a straight line as this racing is mostly straight ahead with large turns.

[Fluid]

Whenever a twin motor setup on a mono is mentioned the usual outcry is far too much parasitic drag. Odd that a twin screw catamaran is the preferred choice for performance over a single screw layout.

With a twin motor mono how is it that in the same hull a single screw can provide sufficient performance and yet adding another equally propulsive screw is detrimental to performance, supposedly decreasing the overall performance over just a single prop? Is there a bias against a twin screw setup on a mono or is it really not worth the effort?

Would a contra (counter) rotating twin prop setup alleviate prop torque and chine walking? Quite possibly given the vee shape of the transom the hull would run "wet" and this would affect overall performance. Would a double stinger setup or an under hull strut installation be better?

I don’t remember reading “parasitic drag” as a reason to eschew twin drives. For a given size hull with very high power twin drives may work better since it uses significantly smaller props; a single drive may have bad torque reactions with a large single propeller.

The biggest issue raised has been the turning disadvantage mentioned above. But would twin drives reduce chine walk? I don’t know but can make a case either way, drive depth would be the greatest factor just as it is with single drives. There have been a number of twin mono builds in the forums over the past several years, a search may help with some of your questions.


https://forums.offshoreelectrics.com...highlight=Twin

https://forums.offshoreelectrics.com...highlight=Twin

https://forums.offshoreelectrics.com...highlight=Twin

https://forums.offshoreelectrics.com...highlight=Twin


.

[CraigP]

The turning problem on twins is akin to a locked our rear differential in a street/drag car. The inside tire will hop because it’s trying to run the same speed as the outside tire. I just put a Rescue Boat together that has two electric motors dressed up in plastic outboard housings. There is no rudder, it adjusts the prop speeds to effect turns. I found a dual ESC controller used on an Ant Bot, that has very sophisticated “mixing” of the two channel outputs to create a very effective control. I posted that earlier and someone replied that there are sophisticated transmitters with mixing capabilities. Helicopter or drone units have to have this. So it would have to be a 3-channel setup, one for rudder and separate channels for each ESC. The transmitter mixes the esc’s Signals in response to rudder input to slow the speed of the inboard motor. I would think having this type of control would be a big advantage for the twin..

[Old School]

Many thanks gentlemen

[iop65]

A mono will tilt to one side in a corner, one prop will get deeper... the other one less
Not hard to understand that this will disturb the handling in the corner,boat will "fight" against cornering because the inside prop gives the most trust
Cats don't tilt......no problem here

[Old School]

Many thanks

[785boats]

I built a twin drive Wasabi Mono. It cornered ok. Even for a hull with no strakes under the hull.

You can hear one motor revving a bit more in the corner, in the first video, as the outboard prop lifts a bit higher than the inboard prop. But it certainly doesn't lift out of the water. The lean angle is not that great.
Also, that video was probably only the third run of the boat & it was nowhere near dialed in. As you will see from its tendancy to lift the nose into the wind, & the flip.

I made the boat purely because I wanted to try twin drives in a mono.

Is it more efficient or faster than a single setup in the same hull? I wouldn't know. I don't really care. It was just something I wanted to do.

If your passion urges you , I say give it a go.

https://forums.offshoreelectrics.com...ghlight=wasabi

Cheers.

[Old School]

Many thanks. A lot of inspiration there.

[Warrio17]

Anyone try this lately? I am in the middle stages of planning a twin mono boat and am trying to absorb all the info I can on the subject.

[HTVboats]

I believe it is Giovani Guzman (spelling) that has a Q twin mono. Have raced against him in Orlando and it is a force to be reckoned with. Very fast and stable, immaculate setup. DF 39
Mic

[Onyanga]

Hey Warrio17, See your comment from June. Wondering if you got past planning and got up and running on the twin mono. I am building one now, just cause I wanted to, and on here looking for info to avoid making mistakes. I have a Delta Force 41. got a pair of 4074 motors at 1400 kv and two TFL surface drives.