surface prop for small outboard

Discussion in 'Props' started by wayne stratton, Jun 21, 2017.

  1. wayne stratton
    Joined: Jun 2017
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    wayne stratton New Member

    Is it at all possible to use a surface drive propeller on a small (9.8) outboard.. this would be used on a freighter canoe.. I am aware that the water intake must be below water line.. 9.8 tohatsu takes its water just above hub.. a lot of searches have revealed little info...
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The water intake will have to be modified. Often they are remote and attached to the transom
     
  3. wayne stratton
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    wayne stratton New Member

    is there anywhere in NA where I could purchase a surface prop that would work with a 9.8 hp outboard... I am sure I could modify water intake so it would be lower on the unit
     
  4. baeckmo
    Joined: Jun 2009
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    baeckmo Hydrodynamics

    It's not just a question of simply purchasing a propeller. A surface piercing propeller for a specific power and speed is working under conditions different from a submersed propeller for the same operating point. In general, it has a larger diameter and a lower rotating speed than the propellers normally fitted to your outboard. It is not likely that you would find a surface prop off the shelf.

    In order to find out what is possible, you have to know the resistance characteristics of your boat and the speed target. From there, the required prop diameter and blade area will be calculated, and finally the propeller shaft speed. I'd say that the diameter fitting into the propeller aperture of the outboard is probably the limiting factor, unless you have an exceptional hull.

    So, why a surface propeller in the first place?
     
  5. wayne stratton
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    wayne stratton New Member

    I am try to navigate shallow water.. my canoe is 24.5 feet in length and a beam of 42 inches.. not going for speed, just shallow water travel.. my river sometimes drops to 5-6 inches in places. most times I can get along well just by tilting the engine to shallow drive... looking for an edge that's all.. my motor is a 9.8 tohatsu short shaft and it goes along quite nicely
     
  6. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Back in the late 70's there was an attachment that was called a Riffle Runner, that bolted to the ventilation plate and you could raise the motor up and still get good performance.
    Have not seen one for awhile. Normally they would be mounted on say a 12 - 14 foot aluminum boat for running rivers. In this configuration, quite a bit of the prop was covered when the stern was lower until the boat began to plane. Not sure if it would work on a canoe. Google Riffle Runner, lots of stuff there
     
  7. jorgepease
    Joined: Feb 2012
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    jorgepease Senior Member

    Contact these guys- baumannprops.com to see if they can cup your existing prop. They did mine, I run my prop completely above the surface though my boat has a tunnel. You might have to go down a couple of sizes in pitch but makes a world of difference.
     
  8. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    You can buy one already set up for surface drive.

    I have a rifffle runner in my shop, I've never used it though, although I've been curious as to how well it would work
     
  9. OCB
    Joined: Dec 2015
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    OCB Junior Member

    Can you tell me where to buy a surface drive props off the shelf ?

    I see Hering is very close to you and makes SD prop's.

    Tech Info Hering Propellers http://www.heringpropellers.com/tech-info/

    I'm hoping to find someone who will share data on a current boat, motor, prop. I will build the boat around the prop. I want to start with a haul design for 25' or under ? The smaller boat, the better it will for me.

    Thank you


    OCB
     

  10. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

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