twin outboards on deep vhull advice

[MadProps]

could use some advice on prop shaft height before I start drilling the hull to mount motors...
using the setbacks my props on the outboards will be as far back behind the boat as the stock Pursuit prop is sitting with the inboard motor setup so they should be running in somewhat similar conditions as a stock pursuit setup


thanks for looking

[Old School]

Have you seen this video -

https://www.youtube.com/watch?v=N4niaPfuoxo

[MadProps]

I have seen that thanks, but he has his motors so deep and his boat ran slow....I am not sure, I want other opinions

after setup on my stock pursuit I found that an 1/8 variance in prop height can equate to 10mph variance so Im trying to get this setup close as I can before I start drilling

[rol243]

i think the safest method of setting up the twin outboards would be to make up 2 x aluminium plates that can be bolted onto the transom at the selected spacings so you can adjust the motor/s up or down to get the correct prop to water settings. this would look ok and be part of the motor bracket.

[Old School]

I have seen that thanks, but he has his motors so deep and his boat ran slow....I am not sure, I want other opinions......

The builder does state firstly that he is not after a high speed boat and secondly in the final test he did not have a rescue boat so was only running at 50% throttle input to avoid overturning the boat. That said, I believe the video was around three years old and in his subsequent uploads he did not post a further video since on the boat so perhaps it was not as great a success as he planned.

Following on from the suggestion above a complex but workable solution would be a tapped fixed plate to the transom and a slotted adjustable plate affixed to the outboard mount. The degree of adjustment would be limited by the adjustment slots on the moveable mount plate. This in inline with the previous suggestion above.

[MadProps]

I made an adjustable jackplate

[JestDanny]

I tried that motor as a single on a 26" deep vee with some success. I set my ride height and thrust angle like I would set up a tunnel boat, surface drive, center of prop shaft just a fraction above hull bottom. I ran it on 4s2p, I had a few handling issues, chine walk and some porpoising, the boat showed some potential, after several runs trying to get it dialed in I was just getting close and the boat stopped dead in the back stretch. I broke the flex shaft loosing the prop, drive dog, nylon washer, along with the broken shaft. Yes the shaft was greased between runs, 6 /8 months later the thin wet spagatti noodle flex shaft was still not in stock at mfg.'s web site. Now I see the shafts are available but the drive dog and washer are not, no matter that motor was tossed in the trash long ago.

[Steven Vaccaro]

I mounted mine with the prop shafts about even with the lowest part of the V. It runs great UNLESS I knuckle the throttle. Then it lists to one side and sticks like it's glued. I was going to add tabs to help this in the future.

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[CraigP]

Steve, is that with counter rotating props?

[MadProps]

thanks guys will mount them even with bottom of V

Steven do you think it lays over because it needs counter rotating props?

[Steven Vaccaro]

They are counter rotating. I tried them both ways. Similar issues.

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[CraigP]

Another probably stupid question, please bear with me, I’m trying to understand this dynamic. Are the motors in the outboards spinning counter or is the counter rotation created by the lower end unit?

And are the motors mounted vertically or horizontally in the outboard housings?

[Steven Vaccaro]

Another probably stupid question, please bear with me, I’m trying to understand this dynamic. Are the motors in the outboards spinning counter or is the counter rotation created by the lower end unit?

And are the motors mounted vertically or horizontally in the outboard housings?

In most of them that I know of, the motor controls the reversing of the prop. I dont know of any with gears that are doing the work. But thats not to say they arnt out there.

[MadProps]

disappointing to hear......maybe I should mount these motors on a cat if they cant be run properly on a V
thanks for the input
out of curiosity Steven whats speeds are you seeing with 2 of these on a v hull

thanks

[CraigP]

So we can probably rule out prop torque. I know some of those lower units have small trim tabs on the side. Is it possible that one side is skewed relative to the other and you’re getting lift from that when you punch it? The only other thing is that the boat’s side to side weighting is off. In my mono, I run batteries along each side, to put weight there and help stabilize the boat. It’s like a tight rope walker using a balance bar... That’s all I got. I guess trim tabs might be the last resort. I know you know all this.... just thinking out loud..

[CraigP]

Oh I see the pic at the top, no side trims casted in...

[MadProps]

I tried that motor as a single on a 26" deep vee with some success. I set my ride height and thrust angle like I would set up a tunnel boat, surface drive, center of prop shaft just a fraction above hull bottom. I ran it on 4s2p, I had a few handling issues, chine walk and some porpoising, the boat showed some potential, after several runs trying to get it dialed in I was just getting close and the boat stopped dead in the back stretch. I broke the flex shaft loosing the prop, drive dog, nylon washer, along with the broken shaft. Yes the shaft was greased between runs, 6 /8 months later the thin wet spagatti noodle flex shaft was still not in stock at mfg.'s web site. Now I see the shafts are available but the drive dog and washer are not, no matter that motor was tossed in the trash long ago.

my inboard setup Pursuit chine walked and porpoised a bit till I input a little trim tab and now it runs perfect, it runs 60mph no chine walk or porpoising at all , so I was expecting to see the same results and already bought a pair of trim tabs for this project, but Im really disappointed to hear about the laying on its side when pegged and not sure I want to even proceed now without knowing how it will handle or at what speed it will run I was hoping to let the grankids race the 2 Pursuit's and I was going to limit the throttle on the faster inboard Pursuit to match the twins outboards but if they wont handle the same the whole point of matched hulls is now moot

[Steven Vaccaro]

disappointing to hear......maybe I should mount these motors on a cat if they cant be run properly on a V
thanks for the input
out of curiosity Steven whats speeds are you seeing with 2 of these on a v hull

thanks

I wouldnt say its not possible because people have done it. It just takes tinkering with drive heights.

[MadProps]

I wouldnt say its not possible because people have done it. It just takes tinkering with drive heights.

I trust your judgment Steven I will give it a try, what speeds were you seeing with your twin setup? Im hoping 40-50mph with the twins on 4S , is that realistic?

counter rotating ........... inwards or outwards?

and while your in this thread can you recommend a replacement "Upgrade" Leopard motor for these CNC'd outboard Mercs

stock is 2842 2630kv

thanks again

[Steven Vaccaro]

Im running a titan 40 with heavy graupner outboards and proboat 1500kv motors with 4s each. Its only in the 40mph range. the graupner drives are not that efficient.

[fweasel]

Im running a titan 40 with heavy graupner outboards and proboat 1500kv motors with 4s each. Its only in the 40mph range. the graupner drives are not that efficient.

pics?

[Steven Vaccaro]

I can in about 2-3 months. its in storage until spring.

[fweasel]

I aspire to have an offsite storage problem one day.

[Steven Vaccaro]

I aspire to have an offsite storage problem one day.

Im not so sure my wife would agree. when you have enough crap that you have to put it in diff places it means your a hoarder.

[srislash]

Im not so sure my wife would agree. when you have enough crap that you have to put it in diff places it means your a hoarder.

Oh man, I was going to give the Harley it’s own home. Lol

[MadProps]

I got divorced over hiding Camaro's in garages I rented around the city.....in my street drag racing days

I guess the new addition to the house and her mercedes wasnt enough, that could have been new shoe money

[Steven Vaccaro]

Haha

[CraigP]

I got divorced over hiding Camaro's in garages I rented around the city.....in my street drag racing days

I guess the new addition to the house and her mercedes wasnt enough, that could have been new shoe money

The joke may be on the Ex!! Those cars are worth some serious coin! They bring back some great memories...

[rol243]

the same vintage Mustangs are worth more dollars over here.

[RaisedByWolves]

Steve and MadProps.

I found this video and while the quality is horrible, his boat initially has the issue of rolling to the right which he cures mostly it seems by raising the motor height.

:38 is where you can see it violently roll to the right a couple times and if you can stand the kid and wife yapping in the background and the nausea inducing camera work you'll see he got it running fairly well towards the end. Still needs more trim, but at least he didnt kill any ducks.



Im thinking there may be two or three issues combining here causing the exagerated right side roll.

#1: The natural RSR (Right side roll) unloading the port side prop and making that motor suddenly spin faster and consequently give more lift on the outside blade of that prop, the outside blade naturally having more water to begin with.

2: High lift props.

3: ESC's out of sync.

Im not sure if counter rotating in the wrong direction has been covered but that just popped into my head also.



OK, enough with my theorizing, MP what do you think your boat will weigh when finished?