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Thread: two right rotation engines

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    Default two right rotation engines

    anyone with a 27'-28' coho run 2 right engines? im thinking of putting 2 175hp right-handers on a 27' coho. does anyone think it makes a big difference compared to a left and a right? can you really feel the torque?

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    Member Kidless's Avatar
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    When I repwr my 28'er, it will be w/ both right turning props. My left hand motor burns more fuel per hr, requires more frequent gear oil changes & of course have to lugg around 2 spare props verses just 1. I also have an electric - hydro steering pump which makes the extra torque of 2 right spinning props a "non issue".
    I've spoken w/ a few folks that are running the Suzuki 300 twins {right turning} & they don't notice any issues; of course there boats are probably heavier than ours?

    Quote Originally Posted by icram View Post
    anyone with a 27'-28' coho run 2 right engines? im thinking of putting 2 175hp right-handers on a 27' coho. does anyone think it makes a big difference compared to a left and a right? can you really feel the torque?

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    I have both right and left turning props and wouldn't have it any other way.
    What-a-Day
    27' x 9.5' Glacier Craft - Volvo 300hp D4 Diesel
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    Denny

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    Default 2 rights

    kidless-thats what i have heard about the lefts as well. as for performance issues, im told the higher the hp the more torque you will notice. im guessing twin 175's are not going to be very noticeable. thank you for your input.
    icram


    Quote Originally Posted by Kidless View Post
    When I repwr my 28'er, it will be w/ both right turning props. My left hand motor burns more fuel per hr, requires more frequent gear oil changes & of course have to lugg around 2 spare props verses just 1. I also have an electric - hydro steering pump which makes the extra torque of 2 right spinning props a "non issue".
    I've spoken w/ a few folks that are running the Suzuki 300 twins {right turning} & they don't notice any issues; of course there boats are probably heavier than ours?

  5. #5

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    I've run a few 26' Boltons for work that had two 150's right handed only motors. You could turn one direction with one hand and need both hands to turn the other way. It also pulled to the right bad over long distance runs at high RMP. I have a left and right on my boat (Yamaha 150's) and don't have any different fuel burn between motors.

  6. #6

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    I've run a few 26' Boltons for work that had two 150's right handed only motors. You could turn one direction with one hand and need both hands to turn the other way. It also pulled to the right bad over long distance runs at high RMP. I have a left and right on my boat (Yamaha 150's) and don't have any different fuel burn between motors.

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    I'm sure the left hand motors have their place w/ certain boaters & boat hulls, "some folks rave their performance"; but from my experience --I'd swap it tomorrow for another right hand motor w/ the anticipation of less maintenance & better fuel economy. But due to the actual expense of the motors; I’ll wait until it’s time to repwr & keep pressing on w/ the ass pain of additional “left” lower unit gear maintenance & extra fuel expense.
    If the torque problem was noticeable when cruising or turning on those boats you mentioned; would recommend installing a hydro -electric steering pump. It should, at minimum correct the problem of battling w/the wheel when turning out of the direction of the rotational torque of the props? And I’m not a straight line driver when out on the saltwater anyway, too many obstacles {trash “logs & debris” on the water, other boats, scenery to the left & to the right, etc}..
    A few benefits of having 2 right spinning motors & of course the steering pump “in my opinion” less expense up front on the purchase of mtrs, {when I purchased my motors – left hand motors were more expensive}, less lower gear unit maintenance, & probably extended longevity of the complete motors.

    * of course there's the added cost of purchasing & installing the steering pump; but the end result should be a boat designed to handle steering input like a sports car on rails





    Quote Originally Posted by GoneAgain View Post
    I've run a few 26' Boltons for work that had two 150's right handed only motors. You could turn one direction with one hand and need both hands to turn the other way. It also pulled to the right bad over long distance runs at high RMP. I have a left and right on my boat (Yamaha 150's) and don't have any different fuel burn between motors.

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    Why not just buy a right turn lower unit and swap them out?

    How much more are you burning per hour with the left turn? It could be a difference in your props, too. Sometimes they aren't a perfect match. I don't notice much difference with mine in economy or lower unit lube color. Just a thought or two.
    Spending my kids' inheritance with them, one adventure at a time.

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    The left spinner burns about 1.5 to 2.3 more per hr when cruising. The burn rate is excactly the same on both til about 4k rpm. Also tried 3 different sets of props {3 bladed 21 pitch, & 2 sets of 4 bladed "18 & 19 pitch} & all are giving about the same results.
    The oil is black after 50 - 60 hrs on the left & clear "like new" on the right after 100+ hrs. Also had the dirty oil checked & there's no wtr..
    Kind of like those new v6-300's anyway


    Quote Originally Posted by spoiled one View Post
    Why not just buy a right turn lower unit and swap them out?

    How much more are you burning per hour with the left turn? It could be a difference in your props, too. Sometimes they aren't a perfect match. I don't notice much difference with mine in economy or lower unit lube color. Just a thought or two.

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    Well that is interesting. You should check into the cost of a new lower unit (right turn) and just swap it out with the left turn. Power head is the same. Or just switch from left to right and see if there is a difference.
    Spending my kids' inheritance with them, one adventure at a time.

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    Kidless,

    I would have concern that you have something happening in that left hand motor lower unit causing both the added fuel burn as well as the black oil. To me, it sounds like it may be a bearing or gear failing, unless it is documented that that is just the way it is with left hand motors in the series you are running. It might be worth looking at closer while you are under warranty and it can be fixed before you have a failure.

    Jim
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  12. #12

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    Kidless: I would agree with JRogers that you MAY have a problem with you counter rotating lower unit and woulld recommend checking it out before you put it in the water this year.

    I have both a standard and counter rotaing units (DF300s) on my boat and I have never seen any difference in fuel burn, had any additional lower unit maintenance on the counter and the oil is the same when I change it each year. I see no reason, execpt for a small additional cost for the initial purchase, for not using a standard and a counter on a twin engine boat.

    SB

  13. #13

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    Kidless: I'm pretty good at changing my lower unit oil every 100 hours and use Yamaha lower unit oil. With around 1200 hours on each motor my lower unit oil is mostly clear at each changing. I would also suspect with the black looking oil and extra fuel burn in that motor their is a lower unit gear problem. Does the black oil have any different smell or extra metal in it?

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    Default Rotation direction affects mechanics?

    Open post (not directed to a specific member):

    I saw on The Simpsons that toilets swirl the opposite direction in the Southern hemisphere.

    That might sound inane, but I would equate it to the inane-ness of a left turner innately having more problems than a right turner when they're side by side, and both operating in unison - and almost analogous arguments too.

    Please correct me with technical facts/reasons if I'm wrong; I'd welcome it; it would be another chance for me to learn and for you to teach. Lord knows I've got a lot to learn; it remains whether you (some one on here) have lots to teach.

  15. #15

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    Mitch,
    I change my lower unit every 75-100hrs and have never noticed any differance in color or differance in fuel burn. I agree with the other guys, it sounds like you have a problem.

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    Quote Originally Posted by FamilyMan View Post
    Open post (not directed to a specific member):

    I saw on The Simpsons that toilets swirl the opposite direction in the Southern hemisphere.

    That might sound inane, but I would equate it to the inane-ness of a left turner innately having more problems than a right turner when they're side by side, and both operating in unison - and almost analogous arguments too.

    Please correct me with technical facts/reasons if I'm wrong; I'd welcome it; it would be another chance for me to learn and for you to teach. Lord knows I've got a lot to learn; it remains whether you (some one on here) have lots to teach.
    While the right and left hand rotating lower units look the same, in fact they are built in the same housings, the inner parts are quite different. Both engines turn the driveshaft down to the lower unit in the same direction, so the gear to cause left rotation as opposed to right rotation is actually aft of the pinion(gear on driveshaft) instead of forward of it. All of the forces and bearing loads are different in the left rotating gearcase. The different types of bearings and the loads on them in the left case could cause premature viscosity break down in the gear oil. That being said, there still shouldn't be any difference in performance, the gearing is the same so the output should be the same, they are designed to do just as much work as the right handed case.

    In the case of Kidless, I would suspect that the gear case has an internal problem and have it looked at. If the pinion to gear spacing is incorrect, the gears can wear excessively causing excess heat and "burning" the gear oil, or a bearing or gear shimmed too tightly could also generate excess heat. Anything that generates excess heat is robbing power, possibly causing the performance loss. There is no inherent reason for a left handed motor to burn 1.5+ gph more than the other.
    Casey
    Yamaha Dealer
    Petersburg, AK

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    Default 2 rights

    akfish, great info thanks. but whats your opinion on the performance difference while driving/manuvering? is there a signifficant differnece between 2 rts vs a left and a rt?




    Quote Originally Posted by Akfish1 View Post
    While the right and left hand rotating lower units look the same, in fact they are built in the same housings, the inner parts are quite different. Both engines turn the driveshaft down to the lower unit in the same direction, so the gear to cause left rotation as opposed to right rotation is actually aft of the pinion(gear on driveshaft) instead of forward of it. All of the forces and bearing loads are different in the left rotating gearcase. The different types of bearings and the loads on them in the left case could cause premature viscosity break down in the gear oil. That being said, there still shouldn't be any difference in performance, the gearing is the same so the output should be the same, they are designed to do just as much work as the right handed case.

    In the case of Kidless, I would suspect that the gear case has an internal problem and have it looked at. If the pinion to gear spacing is incorrect, the gears can wear excessively causing excess heat and "burning" the gear oil, or a bearing or gear shimmed too tightly could also generate excess heat. Anything that generates excess heat is robbing power, possibly causing the performance loss. There is no inherent reason for a left handed motor to burn 1.5+ gph more than the other.

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    Performance wise, I don't think you will notice much difference at all. Handling on plane shouldn't be affected, with that size motor and hydraulic steering, you shouldn't feel too much torque when the motors are trimmed properly and the trim fins are adjusted correctly. At low speeds you will notice that the stern will crab to one side because both props are spinning the same direction, you can use that to your advantage when docking at times, and just know that it will have that tendency so that you can avoid it working against you.
    So basically, you may see some effects, but I don't think in that size boat you are going to be too negatively affected. And as mentioned before, both props and lower units will be the same which helps in the spares department.
    Casey
    Yamaha Dealer
    Petersburg, AK

  19. #19

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    Kidless,
    Have you verified when filling your fuel tanks that you are consuming more fuel on the left motor? The yamaha fuel management systems are not exactly accurate from motor to motor. We have seem great variances in the yamaha systems before.
    If you have verified that infact you are consuming more fuel on the left, I would say you defiantly have a problem. Contact you favorite Yamaha dealer and get that lower unit looked at.
    As for left and right turn lower units, left hand lower units do have more moving parts and may have a shorter life span because of that. I personally have not noticed any difference in fuel economy or oil condition on any of the several hundred left hand motors we have run or worked on.
    Feedback from the commercial side of things is that the left hand units do not last as long, but the pros of having a counter rotator out ways the con of the shorter life span.
    Over long distant runs, running two right hand motors will keel the boat over slightly and cause a right turn. This is easily compensated for but very annoying.


    Quote Originally Posted by Kidless View Post
    The left spinner burns about 1.5 to 2.3 more per hr when cruising. The burn rate is excactly the same on both til about 4k rpm. Also tried 3 different sets of props {3 bladed 21 pitch, & 2 sets of 4 bladed "18 & 19 pitch} & all are giving about the same results.
    The oil is black after 50 - 60 hrs on the left & clear "like new" on the right after 100+ hrs. Also had the dirty oil checked & there's no wtr..
    Kind of like those new v6-300's anyway

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    thanks akfish1. that helps

    Quote Originally Posted by Akfish1 View Post
    Performance wise, I don't think you will notice much difference at all. Handling on plane shouldn't be affected, with that size motor and hydraulic steering, you shouldn't feel too much torque when the motors are trimmed properly and the trim fins are adjusted correctly. At low speeds you will notice that the stern will crab to one side because both props are spinning the same direction, you can use that to your advantage when docking at times, and just know that it will have that tendency so that you can avoid it working against you.
    So basically, you may see some effects, but I don't think in that size boat you are going to be too negatively affected. And as mentioned before, both props and lower units will be the same which helps in the spares department.

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