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Question about props and jack plates

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  • Question about props and jack plates

    Posted by basspro3217

    I installed Boyesen power reeds in my mercury and picked up about 400 rpms. That put me at 5750 my redline is 5250 according to my manual. I have a 26 pitch Laser II. I had a buddy tell me to get my prop repitched to a 27 and have my tips double cupped???? I don't even know what that means. What is you opinon on this? What about a jack plate? are they really beneficial? MY boat is a Nitro 700LX with a Merc. 125. Any help you or anyone can provide would be appreciated. Thanks Terry

    Posted by Striper
    Terry I hope you dont mind me posting your question up so that maybe some others could read and provide some advice. First and foremost before doing anything I would consult a marine technician far more knowledgable then myself before doing anything.

    But I have a few questions and some answers for you. What was your purpose for the power reed, were you have issues with top end speed and fuel consumption?

    As for your friends advice on the 27 double cupped, here is what he is talkng about. The 27 reference is to inches but it is in inches traveled per revolution. This is called the pitch, pitch is the theoretical distance a prop would travel in one revolution.

    The rule of thumb on pitch is that one inch of pitch equals 100-200 rpm - move up one inch and you would decrease the RPM move down one inch and you increase the RPM.

    So by going up in size from a 26 to a 27 your friends advice is to reduce the RPM to keep you away from the redline - but I think that while it will reduce it - it would only drop by at most 200 RPM. But it would still reduce the RPM's.

    DOuble Cupped is a term given to when the prop is curved on both the leading edge as well as the tip, a regular cupped blade only has a single curved lip. Cupping can increase your grip for les slip on the water and decreased blow out caused from excess aeration. It will allow you to also run at a higher trim angle and transom mounting.

    Now to the jack plate. A jack plate is a hydraulic lift that is independant from your power trim and tilt for better efficiency. You can drop the motor down for improved hole shots or raise it for top end speed and fuel efficency. Typically jack plates set th motor back 5-6" and place the prop in cleaner water.

    Now my opinion - since you are looking at $500 - $700 for a jackplate - give or take and a few more for a new prop - call a technician and potentially go on a ride with them so they can get a really good sense for the boats performance. You had mention that the performance of your boat had improved - I think the prop is a good idea if nothing else, but to increase the grip and reduce the RPM's as for the jack plate I am not too sure. But there are smarter people then me regarding the jack plate with your setup.

    Terry - I hope if nothing else I have you to understand some of the terminology and equipment. And cann get quite confusing and you can see how some equipment changes have overlapping effects and whats the best combination.

  • #2
    Posted by Lippers

    I have not heard of using a power reed but I as well moved up to a different prop on my old bass cat and did see some better perfromance.


    • #3
      Posted by basspro3217

      Thank you for all the info. I was just looking for more top end speed. I had searched the internet for boat performance and found the Boyesen Power Reeds web site. I did some research on it and found that other people that used them had seen performance increases on their boats. I did pick up the 3 mph but also picked the extra rpms to go with it. I really appreciate the feedback and all of your information. Thanks for all of your help.


      • #4
        I just put power reeds on my out board

        It really helps on Idle and gives good throttle response... I made several other changes so I can't really contribute the top speed increases to that alone....



        • #5
          I would be very wary about running above redline for extended periods of time. I think with all the improvements you have mentioned you are only going to gain 5-6 mph? Is it worth the money for so little improvement.