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Thread: Counter rotating motors

  1. #1

    Counter rotating motors

    Thinking again about a repower.
    If I was to fit new engines to my 5.5 sailfish shelf runner would I be better to go the counter rotating prop route?

  2. #2
    Free Membership Dirtyfuzz's Avatar
    Join Date
    Apr 2016
    Location
    Sunshine Coast

    Re: Counter rotating motors

    I would personally, I like the extra control and used to get a bit of torque twist with the old motors
    Mercury 115ct going strong😁

  3. #3

    Re: Counter rotating motors

    Depends on the HP some are not available in CR, cats don't suffer from non counter rotation like a mono does, but, given the option, why not?

  4. #4

    Re: Counter rotating motors

    I disagree, going from non counter to counter on my last kevlacat was night and day. Counter sit alot flatter at cruise, trim levels are closer port/starboard and manoeuvrability going slow/docking vastly better. If theres an option in your hp size I'd definitely do it. It was the reason I went merc on my last boat as they were the onky ones offering CR in 90hp

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  5. #5

    Re: Counter rotating motors

    Quote Originally Posted by wahoofishingcrew View Post
    I disagree, going from non counter to counter on my last kevlacat was night and day. Counter sit alot flatter at cruise, trim levels are closer port/starboard and manoeuvrability going slow/docking vastly better. If theres an option in your hp size I'd definitely do it. It was the reason I went merc on my last boat as they were the onky ones offering CR in 90hp

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    I see that. But mercury wait for new motors is Christmas time.

  6. #6

    Re: Counter rotating motors

    How does the boat go with the current HP? I think I asked before but can't remember seeing an answer, just interested.

  7. #7

    Re: Counter rotating motors

    Quote Originally Posted by Noelm View Post
    How does the boat go with the current HP? I think I asked before but can't remember seeing an answer, just interested.
    It goes ok. I am certainly not unhappy.
    At cruise speed in the messy conditions here I can sit on 4000 rpm all day doing about 19 knots. There are the odd times where conditions allow for a bit more speed but Im a little reluctant to push much over 4700 for any length of time due to the age of the engines. 1999 4 stroke Evindude 70/Suzuki DF70 (same engines rebadged)

    We have been heading out to the Islands about 85km out. Despite them starting first time without hesitation and not having one operational problem with them they are old. The previous owner documented his servicing but the engines clearly havent seen a dealer for a long time. Lots of things below the lower cowling are rusted. It took me an hour to get the banjo bolt out of the fuel rail to replace it today. . it was corroded so badly and ive replaced half of the hose clamps because they were rusted away.I know that one day Im going to have an issue which will involve a dealer and Im fearfull that they will get partway through pulling it apart and find they cant put it back together at reasonable cost.
    As a result im back to considering a repower. At the moment mercury it out of the equation because they cant deliver until Christmas or thereabouts >

    Some Suzukis are available within the next 3 to 6 weeks and Honda have a similar story. Its now down to questioning whether I want to spend the cash now or wait for a problem to raise its head. Currently can get 70 Suzuki's fitted for around 24 k and 90's for 31k> Honda 90's range from 33k to 40 k depending on the stealer/dealer.
    oh ..what to do
    If I invest in new engines Im almost overcapitalising too which Im mindfull of.

  8. #8

    Re: Counter rotating motors

    Yep, you have a problem with the repower options for sure, over capitalising being one of them, but, if you plan on keeping the boat long term, then it kind of helps, running over 4,000 RPM is not an issue, make sure the engine anodes have been replaced.

  9. #9

    Re: Counter rotating motors

    Quote Originally Posted by Noelm View Post
    Yep, you have a problem with the repower options for sure, over capitalising being one of them, but, if you plan on keeping the boat long term, then it kind of helps, running over 4,000 RPM is not an issue, make sure the engine anodes have been replaced.
    Cheers.
    anodes are nest on the list to do tomorrow. Yes we intend to keep the boat a while

  10. #10

    Re: Counter rotating motors

    That price jump from70-90hp seems excessive. They’re the same engine essentially.

    if I were you I’d look at spending chips by replacing all of those hoses/clamps/filters etc and seeing how long you get off of them. Potentially you could get a 1000 or more hours out of them without any major issues. Get the full service manual for them. The money you’d save, and you could bank the cash and wait until a special comes around for the new 100B engines.

    Have a play in reasonable conditions and forget about your RPM for a bit. Find out what speed the hull rides best at. I found the old KC was terrible until 19knots but perfect at 23. From 23-28 no difference. I ran the Yamaha’s F60’s at 5000rpm all the time and for what ever reason it didn’t bother them a bit. Even running them at 5800RPM for long periods did nothing but drop the fuel usage from 1.3/1.4l/km to 1.1/1.2 km/l.

    At the end of the day 21/22 year old engines are worth next to nothing. The fact that you’ve had not one operational problem is a great thing that should give you confidence, once you’ve replaced all these perishable things at a cost of a dealer service. While you’re at it, using the service manual you’ll probably find online, do the service yourself. The 20/50/100 hour mandatory services alone will cost way more than that under warranty. In fact there’s a marine mechanic teaching you how to do a service ++ in Brisbane with your own boat that included would cost you less than the first 3 services plus the perishables.

    Put the money you would spend on new engines in your mortgage offset account and run the hell out of those old engines. If the ride/fuel sweet spot happens to be 4900RPM, burn them knowing you would have repowered anyway and if one blows, then pull the trigger on new100B’s. There’s a very good chance that by the time they blow, you’ve saved off your mortgage+20/50/100 services the cost difference between 70 & 100B engines if not more. Then you can have cash on hand for a sale where a 100B is the similar price to 70A’s
    Democracy: Simply a system that allows the 51% to steal from the other 49%.

  11. #11

    Re: Counter rotating motors

    Cant comment on counter rotating issue but I have repowered an older boat....and I can offer the following thoughts...Lovey is on the right tram here...take your time and find the best deal you can.Your current set up works just do what you need to do ..and have a good plan against a day when one of them pancakes 85km out.

    Repowering really is not an investment...its a cost and its turtles all the way down.. you really want to save your own money to buy them outright.The return is hopefully is more reliable motors ,less stress for you out on the water.I ended up finding a second hand motor from a dealer..80 hours on the clock and full warranty,it all takes time.

  12. #12
    Ausfish Addict disorderly's Avatar
    Join Date
    Sep 2006
    Location
    In the Jungle/Mission Beach Hinterland

    Re: Counter rotating motors

    There is some good advice above..

    mate I wouldnt worry too much about what might happen in the future with your motors...if they are running well join your local VMR and make sure your radio or phone works at the distances you are travelling from land (or get a Garmin inreach which uses satellite) ..

    just drive them till they drop and worry about it then...hopefully by then we will be back to boat show specials and the like where you can actually get a decent deal....

    Thats all assuming ,like most of us, you need to work to survive and pay for a house and family..if you have wads of spare cash laying around then get your transom re-rated and buy a pair of the biggest and shiniest motors around and just send it....

  13. #13

    Re: Counter rotating motors

    Agree with the above if money is tight but if its affordable and you are keeping the boat long term I'd go new now. Imo 85km is a distance offshore that you need reliability for safety and you need to be self sufficient. If you can trust 100% in your old donks then sure but when youre 85km out with the wife and it blows up to 20kts and one donk dies my money is on you wishing you spent the $. Long way home on one motor or even longer slopping around waiting for a tow... Thats if you have vhf and mobile reception too.

    Let's face it boating isn't cheap, its not an investment, its purely fun. Imo you can not put a price on the safety of your family and breaking down and getting towed home is aboht the best outcome of the potential outcomes.

    Lifes short... Get the shiney new motors and enjoy [emoji14]






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  14. #14

    Re: Counter rotating motors

    Quote Originally Posted by wahoofishingcrew View Post
    . Long way home on one motor or even longer slopping around waiting for a tow...
    Doesn't that give you a heap more time to convince the missus that spending the money on new motors is a good idea.................At least that's how it goes in my head ........Who am I kidding.

  15. #15

    Re: Counter rotating motors

    Quote Originally Posted by scottar View Post
    Doesn't that give you a heap more time to convince the missus that spending the money on new motors is a good idea.................At least that's how it goes in my head ........Who am I kidding.
    Either that or she's sold the boat before you get back to the ramp [emoji1787]

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