Non counter rotating twin i/o's?

[NSBCraig]

It was stated on another thread here-

"Not ALL twin I/O's turn opposite to each other.... as I said a great many are set up with two identical alpha's both turning right. In fact most of the twins I've been on are not counter rotating."

I have never heard of such a thing, but I haven't heard of a lot of things in this world. So...

Why would someone do this?

Besides it being cheaper in the short run, maybe with parts laying around etc, what could be a benefit?

Negatives of course being prop torque at speed making steering a bear, horrible handling around the dock and less speed/ fuel economy since the props are not turning into each other.

Anybody have their boat setup like this?

 

[sasto]

Re: Non counter rotating twin i/o's?

Don't know, Craig. Myself......I don't ever recall being on a boat that wasn't counter rotating. I'll ask around.

 

[Big Island Lifer]

Not the end of the world. Just make sure you have some power steering/ steering assist.




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[Chris1956]

Re: Non counter rotating twin i/o's?

With the power steering on the I/Os, turning the steering wheel is not an issue docking or high speed. You do get some walking of the transom with non CR drives, however, you do get used to it.

 

[Silly Seville]

Re: Non counter rotating twin i/o's?

Umm, aren't the drives geared for counter rotation?

 

[kylejb2663]

Re: Non counter rotating twin i/o's?

I have a 1987 28' Chris Craft Amerosport 284 with twin 5.0s and they are not counter rotating. I don't really notice a difference except when I am idling thru a no wake zone that the boat keeps wanting walk side to side. Docking though is fine, we have power steering which makes it a heck of a lot easier! When I first saw the boat I questioned why it was not counter rotating and did some research, found that their are a lot of boats that are not!

 

[NSBCraig]

Re: Non counter rotating twin i/o's?

Umm, aren't the drives geared for counter rotation?

I was pretty sure that's how it worked.

Chris- I'm not saying power steering wouldn't help, but why would you have your steering fight against the torque when it could be neutral? That of course is for running at speed. When it comes to docking, why would you not want the unbelievable advantage of counter rotating props?

 

[NSBCraig]

Re: Non counter rotating twin i/o's?

I have a 1987 28' Chris Craft Amerosport 284 with twin 5.0s and they are not counter rotating. I don't really notice a difference except when I am idling thru a no wake zone that the boat keeps wanting walk side to side. Docking though is fine, we have power steering which makes it a heck of a lot easier! When I first saw the boat I questioned why it was not counter rotating and did some research, found that their are a lot of boats that are not!

I'm trying to believe that lots of boats are not, but I just can't seem to. Why would you?

I'm not trying to be mean or anything, but I think you were taken and really should put the right drive on your boat.

PLEASE understand I'm not trying to argue or anything and I'm totally ready to eat some crow on this one. BUT I just can't believe that a boat was built without counter rotating props. It's just something that was figured out a real long time ago and why wouldn't you?

 

[Chris1956]

Re: Non counter rotating twin i/o's?

Craig, I am not advocating for non-CR drives. I am just saying that there was no issue steering them, and docking them was easy to learn as well.

I have seen dozens of twin screw I/O, and I don't remember any that were CR. It may because of the shortage of CR props in comparison to RH props. It may just be convenient for boat manufacturers to buy hundreds of I/O outdrives (at volume discount) of all the same kind, rather than guess how many twin screw hulls they will sell and buy CR outdrives for those.

 

[Big Island Lifer]

My father had a '74 26 ft skiff craft with twin mercruisers that were both right hand turning. He did not have power steering. It was a beast to drive on plane. I'm talking white knuckles. It was a light wood boat and would hit 40 mph on plane. It was a cocktail cruiser so it rarely became an issue, but I was a pain.


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[Bondo]

Re: Non counter rotating twin i/o's?

PLEASE understand I'm not trying to argue or anything and I'm totally ready to eat some crow on this one. BUT I just can't believe that a boat was built without counter rotating props. It's just something that was figured out a real long time ago and why wouldn't you?

Ayuh,.... Quite simply, it's E - c - o - n -o - m - i - c - s....

Twins, ei; carbon copies of drivelines are Cheaper, from start to death, than Sisters, ei; C/Rs....

It's debated that SSteel props are Better than aluminum props, right,..??
How come you can still buy aluminum props,..?? Why aren't only SS props available,..??

 

[greenbush future]

Re: Non counter rotating twin i/o's?

I dont mean to hi-jack, but would twin outboards be any different? I see em all the time and they dont have CR, and the old one (1961)I'm restoring isn't either.

 

[Chris1956]

Re: Non counter rotating twin i/o's?

CR outboards are available in newer higher HP motors. Actually, I think I see more CRs in outboards than Alphas.

 

[Bondo]

Re: Non counter rotating twin i/o's?

CR outboards are available in newer higher HP motors. Actually, I think I see more CRs in outboards than Alphas.

Ayuh,... Absolutely,... CR Alphas are even rarer than hen's teeth...

 

[mr 88]

Re: Non counter rotating twin i/o's?

Had a 1973 Stamas with Non CR twins.I did have to install trim tabs as the boat would list to the port at speed,the cockpit set up did not help as the seating was set up for everyone pretty much on the port side as well.You could ALMOST offset the weight and torque by trimming the outdrives.The tabs were the answer as it rode like a dream with them.
As far as "less speed and fuel economy" because the props are not turning into each other I disagree with.Both props,no matter which direction they are turning need clean water,so they are spaced accordingly.Each one is independent and has no bearing on fuel or speed.Most boats with twins biggest docking problems are wind and current,not both props turning at 750 rpms in the same direction.I/O's with deep V's will wander under 5-7 mph,with or without twins no matter if they are CR or not.
As far as anyone "getting taken" by purchasing a boat with the screws rotating the same way,,,,uhh it's called researching the product before purchasing.Try taking a boat back to a dealer after buying it and telling them you now want a CR drive.No way, No how would that fly and I am not a dealer.
Are CR's better than non ? yes,would it be a deal breaker if I loved the hull and it was set up with tabs,NO.

 

[Thalasso]

Re: Non counter rotating twin i/o's?

Ayuh,... Absolutely,... CR Alphas are even rarer than hen's teeth...

 

[Thalasso]

Re: Non counter rotating twin i/o's?

Depends who made the drives. Mercs use counter rotating engines (for most I/Os).

No they don't. Engines turn the same direction and they use a Bravo 111 drive that has 2 counter rotating props on each drive.

Volvo Penta has what they call the Duo Prop. High performance motors will or might do it that way, but the every day run of the mill engine all rotate the same.

 

[smokeonthewater]

Re: Non counter rotating twin i/o's?

merc has a some counter rotating engines for inboards (IE mercruiser 260mie) but I've never seen counter rotating engines for I/O's... the CR alphas are in effect shifted into reverse for forward gear but they have a different lower unit housing and internals to withstand running that way... they can be bought for a few hundred dollars more than the standard rotation units from SEI. I can tell you that my monte carlo 28 has two right hand rotation drives and I have absolutely zero negative issues.... it is equally easy to dock on the right as the left... I can steer either direction with ease in reverse and pinwheel or slide either way by manipulating the shifters and steering and my friend's regal commodore 28 is the same.... When I first got the boat I was under the same impression that you (nbscraig) are and had intended to source a counter rotating drive.... Now after doing my homework and having actually used the boat, I wouldn't swap to a counter rotating drive if it were FREE.... No way do I want to mess with buying more expensive cr props and having to carry two spares.... I've operated quite a few twin engine boats up to 40' both I/O's and inboard/Vdrives and there really is no major disadvantage to having both I/O drives turn right.

ps I believe but can't swear that bravo's can be run either direction without any modifications... just swap shift linkage and change prop.

 

[kylejb2663]

Re: Non counter rotating twin i/o's?

I'm trying to believe that lots of boats are not, but I just can't seem to. Why would you?

I'm not trying to be mean or anything, but I think you were taken and really should put the right drive on your boat.

PLEASE understand I'm not trying to argue or anything and I'm totally ready to eat some crow on this one. BUT I just can't believe that a boat was built without counter rotating props. It's just something that was figured out a real long time ago and why wouldn't you?

NSBCraig,

I completely understand and I definitely don't think you are trying to start an argument, lol! I did research it before I bought it and almost every other Chris Craft was setup like mine for that year and that model. I also checked the engine serial numbers as well and they are both non C/R's. Called a few Marina's and checked, LOL. I thought it was very weird and that somehow the drives got mixed up but it turns out that they are truly correct. I even posted on this forum before I got it and many people mentioned it was normal for that year Chris Craft.

Do I think CR's are more efficient, of course my friend has a boat with CR's and it's a lot easier to drive and you don't have to use tabs as much- but I like the boat so I am willing to deal with it for now. Not a huge dealer breaker!

 

[AviatorJim]

Re: Non counter rotating twin i/o's?

My boat has a pair of RH turning Alphas (Bertram 25), and i find it handles the same as my single engine boat, except when in close, and then the 2 motors make handling a breeze. I also cruise at idle on one engine and except for turning one direction better than the other I don't have any handling issues.