Twin Props

[RickDV]

OK, so last week I mentioned that my show ski team has a custom MC with twin props. I was able to get a picture of them tonight and have permission from the owner to post a picture. He did not want me to give details and specs on the design since he is still working on patents...so don't ask for details :-(

RickDV

[SKI*MC]

He did that himself, or MC did that?

[RickDV]

He did that himself, or MC did that?

He designed and built it himself.

[6ballsisall]

WOW!!!

That is SWEET!! I wont ask details but can I ask is that a MC hull or did he design the hull too??? This is used for show skiing right?

[SKI*MC]

Wow!!!!!!!

[RickDV]

WOW!!!

That is SWEET!! I wont ask details but can I ask is that a MC hull or did he design the hull too??? This is used for show skiing right?

The hull design is all MC. Here is a different view...

[stevo137]

Does it add any top end?

[RickDV]

Does it add any top end?

What it does do is gives us more power to get lots of skiers off the dock at one time. The boat has pulled as many as 22 skiers on one pull. We routinely pull 14-16 skiers in our shows.

[stevo137]

What it does do is gives us more power to get lots of skiers off the dock at one time. The boat has pulled as many as 22 skiers on one pull. We routinely pull 14-16 skiers in our shows.
I don't think that I would want a full throttle up with that baby!

[Crash]

"Wow"...er that's already been said..."Wowzie"

That's cool, great ingenuity!! Good luck on the patent(s)...they take forever.

[6ballsisall]

Rick that thing is AWESOME!! You got my mind thinkin about how everything works like the exhaust, two rear ports, 4 banks, hmm.... 3 rudders in rear, all operational? Things that make you go hmmm..... I guess

I like how its called "Pull Star"

[stevo137]

Rick that thing is AWESOME!! You got my mind thinkin about how everything works like the exhaust, two rear ports, 4 banks, hmm.... 3 rudders in rear, all operational? Things that make you go hmmm..... I guess

I like how its called "Pull Star"
J, I'm sure you'll have it figured out by morning! :rolleyes:

[ski_king]

I see it is a 98 with hydro rails added. Maybe Farmer should take a good look, 3 rudders will make it turn.

All kidding aside, that is a sweet setup. I would love to see a inboard view.

[prostar205]

Where did he get the transmission to run 2 props from one single engine output shaft? I'm making the assumption that whoever owns, designed and build this setup, did not add a second engine.

I have a buddy that races 1/4 mile Nitro burning drag boats. He has a Kieth Black 502 putting out over 5,000 hp and had a special transmission build that would allow two counter-rotating prop from a single engine. He is leading the points race for the championship this year.

Neat stuff you have there!!!!

[ski_king]

......two counter-rotating prop from a single engine.........
Good eye! I didn't catch the props were counter-rotating.

[ryanbush]

Where did he get the transmission to run 2 props from one single engine output shaft? I'm making the assumption that whoever owns, designed and build this setup, did not add a second engine.

I have a buddy that races 1/4 mile Nitro burning drag boats. He has a Kieth Black 502 putting out over 5,000 hp and had a special transmission build that would allow two counter-rotating prop from a single engine. He is leading the points race for the championship this year.

Neat stuff you have there!!!!

I Would really like to see the specs on that engine. 5,000hp is almost impossible with under 16 cylinders. that must be a huge chunk of change

[JDK]

5,000hp is almost impossible with under 16 cylinders. that must be a huge chunk of change

A huge chunk of change, yes. Almost impossible, no.
Nitro burning dragsters and funny cars routinely pump out this kind of power.

[6ballsisall]

Theres a local guy with a a hemi powered (not the new hemi, the real hemi) funny car. He has shown me dyno #'s for it that exceed 5k hp. It's blown and supercharged.

[MYMC]

The other prop is chain driven...no need for a second engine or transmission. Every major inboard manufactuer has played with this idea for years.

Professional top fuel teams these days are making over 7500hp. The only limit is getting more fuel into the cylinder. As it is now the cylinder is one the verge of hydro lock on each power stroke. Back in the late 80's early 90's we were making 5000hp and the sport has come a long way since. Interesting fact for you...the old 426 hemi found in Cudas, Roadrunners and such does not make enough power (in stock condition) to even turn over the blower of a modern top fuel engine. They estimate the drag number of the blower assembly somewhere over 550hp at WOT.

[OhioProstar]

Wow...can we get a group buy for the ski teams on the board.

[ryanbush]

The other prop is chain driven...no need for a second engine or transmission. Every major inboard manufactuer has played with this idea for years.

Professional top fuel teams these days are making over 7500hp. The only limit is getting more fuel into the cylinder. As it is now the cylinder is one the verge of hydro lock on each power stroke. Back in the late 80's early 90's we were making 5000hp and the sport has come a long way since. Interesting fact for you...the old 426 hemi found in Cudas, Roadrunners and such does not make enough power (in stock condition) to even turn over the blower of a modern top fuel engine. They estimate the drag number of the blower assembly somewhere over 550hp at WOT.

NHRA Teams also spend clost to 100k an engine, and that engine will be only good for 3-5 passes

[BrianM]

I see it is a 98 with hydro rails added. Maybe Farmer should take a good look, 3 rudders will make it turn.



I noticed that it was a 98 as well. Maybe that second prop and three rudders will help keep it off the bank.

Talk about Positive Pressure Tracking System:eek3:
Get the shampoo. :uglyhamme

[jraben8]

That's amazing... I especially like the license plate... HAA HAA

[6ballsisall]

I am struggling with the idea of a drive chain here. If the props counter rotate how could you do that?? Second, I don't think having a chain running under heavy load at 4k rpms inches away from the hull sounds real comforting to me! :eek:

[east tx skier]

So how well does it ski? Can we see some shots of the wake?

[ski_king]

So how well does it ski? Can we see some shots of the wake?
My guess is a lot of turbulance, it is made for PULLING POWER

[Gofast]

I doubt it is an open chain. Probably a modified Transfer case, or at lease a multi sprocket chain drive with a casing.

my .02 on this.

Really cool set-up, but it double my cost of Prop repairs from floating debris. Yes, with my luck I would hit something with them.

Also, my first post.....

Thansk Rob

[Scot]

This looks like the work of a truely gifted person... along with some tasty buds, beers, and long nights to even begin to think, what if?

[Scot]

This looks like the work of a truely gifted person... along with some tasty buds, beers, and long nights to even begin to think, what if?

unlike me who can't spell :uglyhamme

[MYMC]

NHRA Teams also spend clost to 100k an engine, and that engine will be only good for 3-5 passes
Actually they are rebuilt after each round...pro teams would never take the chance of running it 3-5 times...and I never said it was cheap.

I am struggling with the idea of a drive chain here. If the props counter rotate how could you do that?? Second, I don't think having a chain running under heavy load at 4k rpms inches away from the hull sounds real comforting to me!
The boat I have seen has the engine connected to a "power distribution box" that has chains running out to each prop shaft. Motocycles use chains spining at very high speeds right next to your foot and leg...why worry? :eek3:

[SD190EVO]

[sarcastically] - That thing'll chine-lock and hit the beach so fast it will make your head spin...

No - that is pretty cool - would like to see the rest...

[6ballsisall]

Actually they are rebuilt after each round...pro teams would never take the chance of running it 3-5 times...and I never said it was cheap.


The boat I have seen has the engine connected to a "power distribution box" that has chains running out to each prop shaft. Motocycles use chains spining at very high speeds right next to your foot and leg...why worry? :eek3:


Your just full of answers!!

But good point about the motorcycle hadn't thought of that. However, I wouldn't think that a motorcycle would be under that kind of load like a boat would plus the thought of a rusting chain......eeks!!

This boat surely is an engineering marvel. I bet that boat has incredible "bite" in the water!! I'd think it would take a pretty hefty engine (if it's one) to turn both of those props and pull that many skiers up.

Kudos to whoever built that. Our ski team could benefit from something like that but being we are pretty uncompetitive I doubt we could get the group to shell out the dough for it :rolleyes:

[ski_king]

Your just full of answers!!

But good point about the motorcycle hadn't thought of that. However, I wouldn't think that a motorcycle would be under that kind of load like a boat would plus the thought of a rusting chain......eeks!!

This boat surely is an engineering marvel. I bet that boat has incredible "bite" in the water!! I'd think it would take a pretty hefty engine (if it's one) to turn both of those props and pull that many skiers up.
I have seen and used chains in industrial applications with loads higher than what would be used here. Although, I think I would lean to some of the newer belt drives, just as strong and much quieter.

The result of this setup is probobly something like the Volvo Duo Prop, but in my mind better because the second prop is not in the turbulance of the first prop.

Just my opinion.

[redmike]

buddy of mine had an OLD cobia comp skier with twin 125 johnsons, counter rotating props... if this thing pulls anything like that did....

[RickDV]

So how well does it ski? Can we see some shots of the wake?

It skis virtually the same as a PS197. The wall is a bit softer and the turbulent water is about 50% wider. It really skis quite well. Even with a number of skiers it is on plane in less length than a ski rope.

Attached are some pics from a recent show where you can see how the wake looks.

(Keep in mind that the boat is running 17-19 mph for these acts.)

[east tx skier]

Thanks for the pics, Rick.

[SteveO]

That is a very creative individual. I'd hate to see the routines he dreams up for the show team. Love the Pull Star name

[SKI*MC]

Man i cant get over that... they point was raised before, its its chain driven on 1 prop, how would it be counter rotating?

[peason]

I want one!

[ktn_cmu]

Man i cant get over that... they point was raised before, its its chain driven on 1 prop, how would it be counter rotating?

With ONLY a chain you're not going to be able to get counter rotating props. There are a few ways using chain/gear setups. You could have a planetary gear set around one of the shafts and a gear reduction unit on the other with chain connecting the two. You could also run one shaft on the inside of the loop on the chain and the other on the outside loop with an idler pully. In fact, the second option there would allow for a belt drive quite nicely as mentioned earlier in this thread. Ther are of course other ways to accomplish CR Props, but not if you are trying to eliminate all gears.

Kyle

[ski_king]

I was wondering if he added the extra rudders behind the props at the start or added them once he realized it wount turn unless the rudder is behind the props.
My guess, as ingenious as this setup looks, he knew it was needed from the start. :toast:
I really want to see an inside view on how it all works.

[RickDV]

That is a very creative individual. I'd hate to see the routines he dreams up for the show team. Love the Pull Star name

Here's a pic of the owner "skiing" one of his acts in the show.
The pic was taken on his 65th birthday (July 4).
(His nickname is "Krazy Karl")

[ski_king]

He looks like someone who knows how to use his head.

[Diesel]

With ONLY a chain you're not going to be able to get counter rotating props. There are a few ways using chain/gear setups. You could have a planetary gear set around one of the shafts and a gear reduction unit on the other with chain connecting the two. You could also run one shaft on the inside of the loop on the chain and the other on the outside loop with an idler pully. In fact, the second option there would allow for a belt drive quite nicely as mentioned earlier in this thread. Ther are of course other ways to accomplish CR Props, but not if you are trying to eliminate all gears.

Kyle

You basically described a modern day chain drive transfer case from a 4x4. I am guessing something similar is used in this application. Really when you think about it it might even be as easy as creating an adapter to mount a Tcase up to the bell housing or transmission output shaft. Maybe an offshoot of a chain driven pro-fab transfer case would be a good candidate. Planetaries are used in most T-Cases to reverse the rotation of the front drive shaft so both axles are spinning the same direction.

Love to see some more pics!! :D

[SteveO]

He looks like someone who knows how to use his head.

That's bad.

[RickDV]

He looks like someone who knows how to use his head.

His acts are always something to sink your teeth into (groan!)

[Maristar210]

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