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Counter Rotating Props on Twin Engines
|Author||Topic: Counter Rotating Props on Twin Engines|
posted 08-27-2002 11:53 AM ET (US)
I have recently purchased a 230 Outrage. It had a 225 Optimax on it - but now has no engine. I made the deal with the idea of getting two 115 four stroke Mercs on it and have found that they don't make a counter rotating Merc 115 4 stroke. The dealer through which I am dealing is only a Merc dealer.
Yamaha and Honda both have counter-rotating units available in their F115 and F130 engines, respectively.
My dealer sent me to another Whaler dealer who deals in both.
I was told by that (Yamaha&Honda) dealer - to his credit - that with hydraulic steering - it would be OK to use the Mercs since counter rotating props make little difference unless you DO NOT have hydraulic steering.
He sent me to another Whaler dealer who coroborated (sp?) this.
Can anyone comment on this? Is it true? I would think the Yamaha dealer would not say it unless it was, since he may lose the deal if I go Merc (i.e. back to the original dealer).... He says he's done a few with no complaints and pointed out that BW is offering its Conquest with twin Merc 115 4 strokes...
Any input would be appreciated.....
posted 08-27-2002 01:24 PM ET (US)
I had a 22' revenge with twin V4 115's non counter rotation engines. I had mechanical steering (push-pull cable). It was a bear to steer. Hyd steering is a must. I would also recommend the C/R engines as the torque made the boat list to the port more while underway. As I understand, all CR engines are achieved in the gear case. For what ever reason in my experience only the high HP engins (150 hp & Up) are offered for this option.
posted 08-27-2002 01:41 PM ET (US)
WLS - thanks for the input. Did you ever have hydraulic steering installed on the boat? Did it improve it? I hadn't even considered a listing issue.........
posted 08-27-2002 03:03 PM ET (US)
My bud has a 23' Seacraft which had CR 130 Yamahas. He has since repowered with 115 Zuki 4 strokes that are not CR. He has NO problems with torque or listing. Hydraulic stearing is a must. Although he lost 30 hp, he only lost 1 mph on top and 1 mph at cruise and has bout 30% better MPG. Boat loaded runs about 39+ knots WOT.
posted 08-27-2002 03:32 PM ET (US)
See Cetacea 63, and the Whaler with twin 115Merc 4-strokes. Perhaps "Outrageman" can give you further information.
Generally, as mentioned, you will not have a problem, provided your Hydraulic steering is properly done. I have twin 115's on my much lighter 18 Outrage, and it handles beautifully, without steering pull. See JimH's bracket reference section, and particularly look at the Teleflex SIDE mount hydraulic steering comments. I believe this to be the ultimate steering setup for twin non-CR engines.
All engine manufacturers only offer CR with the big 4 3/4" hub gearcase/props used for the V-6's. Yamaha uses these big props on their F115 so that they can offer CR, which is also why the Yamaha's weigh more. Mercury doens't do this, instead using the mid-size 4 1/4" gearcase/props on 125Hp and below. This smaller gearcase is not made in CR, because the smaller props don't give as much torque to the rig.
Once again, a Teleflex SIDE mount cylinder, mounted in the starboard engine, between the engines, with tilt tube reversed (a simple process), is your answer to a great no feedback steering setup. Also be sure to use a Steersman grease nut/O-ring at the ram end, removing the O-ring in the tilt tube.
posted 08-27-2002 04:36 PM ET (US)
I have a bunch of experience with the Merc 115's that are not CR.
There is a lot of port list, but that can be corrected with trim.
Steering is not a problem.
Because, however, it is not CR, spinning the boat with opposing shift (one forward the other reverse) is not quite as good as it could be.
posted 08-27-2002 04:58 PM ET (US)
Thank you all very much. I appreciate the feedback (no pun)........
posted 08-27-2002 05:02 PM ET (US)
Thank you all very much. I appreciate the feedback (no pun)........
posted 08-27-2002 06:44 PM ET (US)
You will see more listing and will not be able to manuever in tight spots as a set of counter rotating engines will. I had non counter Evin. v-4's on my 22' OR and have recently repowered with a single. I have been driving a friends boat all summer (280+ hrs) with counter Yam 150 HPDI's...its a dream to manuever in tight spots!!! My 22' would always want to go left a LOT easier than right with the non counter motors. If it were my $$$$ look at the Yam HPDI's....you wont be sorry!!!
posted 08-27-2002 07:12 PM ET (US)
It sounds like there are two issues here:
Every outboard motor with a right-hand (RH) propeller has a tendency to want to turn to starboard more easily than to port. This unequal steering effort can be compensated somewhat by adjustment of the trim tab (usually part of a sacrificial zinc anode under the cavitation plate).
If you two motors, you will have twice the amount of unequal steering torque. If you have counter rotating engines then the steering effort returns to a balance.
In either case, hydraulic steering is a must. As LHG notes, this will take most or all of the unequal steering effort out of the equation.
The second issue is propeller torque. In high-horsepower installations with large propellers, propeller torque will have a tendency to induce a list into the hull. Naturally, this is eliminated with counter-rotating engines.
posted 08-28-2002 08:36 AM ET (US)
With all the great feedback - I am going to go with counter-rotating engines either Yamaha F115s or Honda F130s.
Thanks to all of you again.
posted 08-28-2002 10:11 AM ET (US)
FYI due to the high gear ratio on the Suzuki 115's, my bud runs a 24" prop.
posted 08-28-2002 10:36 AM ET (US)
What are the F-series going for these days?
posted 08-28-2002 11:55 AM ET (US)
No I never had Hyd steering installed on the 22' When I bought the 25' I spec'd Hyd steering. A big difference. As you indicated I would opt for C/R engines reguardless of mfg.
posted 08-28-2002 04:07 PM ET (US)
My guess is that a set of Yamaha 115's are going to cost you $2 grand more than the identical engines in Mercury form. For some reason, besides being ligheter in weight, the Merc EFI also produces a cleaner engine, 3 star rated vs Yamaha's 2 star.
As one with a lot of experience with twin non-counter-rotating 115's, I don't think it's worth the extra 2 grand. The Mercs will also be quicker, running the smaller diameter props creating less drag. The Yamaha's are more like a "Bigfoot" situation.
But in either form, everyone seems to really like these Marc/Yamaha joint venture engines.
posted 08-28-2002 08:43 PM ET (US)
ihg - actually the quotes I've been getting have the Yamaha 4 stroke 115 at about 1K less than the Merc 115 4 strokes.
Perhaps you were referring to the 2 stroke models?
posted 09-03-2002 06:25 PM ET (US)
From what I've been hearing, I was assuming you would be quoted about $7000/ea for a Merc 115 EFI 4-stroke (Bass Pro shops). So you are saying the Yam's are $6500 each? That would be a good deal.
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