Can I use a 5hp 2 Stroke Outboard to run this Boat

Discussion in 'Powerboats' started by RWJData, Sep 12, 2014.

  1. RWJData
    Joined: Jun 2014
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    RWJData Junior Member

    Hi Everyone,
    This is my first post with your forum, so I am looking for your advice please..

    I want to power this boat, pictured, with a 5hp 2stroke outboard, and I would like your opinion as to its effectiveness?

    The Boat is 15ft, and has a good deep V......but I do not want to go fast...just cruise around to fish....I am past the days of going fast!

    I used to have a 14ft Timber Dinghy powered by the old Seagull, and it was not a problem getting around, so I am asking for your valued advice as to this project please.....

    Attached Files:

  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    You could mate, if the propellor is deep enough in the water, but expect about 4-5 knots max.
  3. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    It would get you around in calm waters, but it's nice to have enough power to get you out of situations, like strong currents or sudden weather changes, and be able to get to the best fishing sites quicker, leaving more time to fish or expanding the area you can fish in.
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    The problem with way under powering this hul,l will be its manners and maneuverability, of which both will suck pretty bad.

    I can't tell how much dead rise you have, but the more it is the worse this will become. Judging be her looks, she's probably fairly heavy, so the dinghy outboard will struggle just to get you going and she'll be easily overwhelmed in a contrary current, wind or with any serious load aboard. The boat is also likely designed to carry a couple of hundred pounds on her butt, which means she'll trim bow down sans the 50 HP outboard and fuel, so even more issues.

    How much deadrise is at the transom?
  5. RWJData
    Joined: Jun 2014
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    RWJData Junior Member

    Thank you all for your responses.....
    I take on board all your suggestions and thank you....
    There is about 18* Deadrise in the hull, and yes it will be a bit front heavy, as I have cut out the outboard well at the stern.
    I have a funny story with this boat...I originally bought it for spare parts for another hull I am restoring, but when I looked into this boat it was too good (Construction wise) to throw away....So I am quickly doing it up to get me on the water for this season, while I continue to work on my other project boat which will take a bit longer. I will eventually use the 5hp as the reserve motor on the new boat when it is completed....hence my silly question at the beginning. I hope you can understand why I will run this one on a 5hp...

    I truly thank you all for your input....I may just go ahead with the 5hp to get me going this season, but I will not be relying on it if the weather looks inclement......It is just for a few family outings and close in fishing. I also intend to have very positive buoyancy on this vessel as the under floor, bow section and gunwales will be completely filled with foam.

    Many thanks again
  6. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    It couldn't be any worse than the time tested rowboat.
  7. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    I would expect it to work all right, as long as the propeller can stay in the water.

    This looks like a "warped bottom" design, where there is quite a bit of dead rise in the bow, but it flattens out at the stern. If this is so, this is probably a good thing, as the turbulence from the immersed transom will be less.

    I had a friend who had a runabout with a more constant dead rise. He liked to chase lake freighters into to port, so we spent a good deal of time going at less than planing speed.

    The turbulence from the deeply immersed transom made steering interesting, to say the least. I had to spin the steering wheel lock to lock, just to keep the thing going straight.

    A warped bottom, which most aluminum "row boats" have, is less extreme, and was more popular with runabouts before very powerful outboard engines (over 60 hp) became available.

    I take it that the outboard engine in question is a Seagull(r). If so, it is a good choice. Unlike most, which are designed to push a boat at planing or semi-planing speeds, the Seagull(r) was designed to push boats at far slower speeds, but with greater thrust.

    The one on my sailboat pushed it at about 4.5 kts tops, but would push it against ever headwind it ever encountered, as long as it was in flat water.

    What you are doing is using a planing boat as a displacement one. The worry here is that the planing boat does not need a lot of lateral area under the water to keep it going straight, in strong winds.

    Most non-planing boats have some kind of keel, to act as such lateral area. So if you get caught out in a blow, you may find your boat hard to control.

  8. Grey Ghost
    Joined: Aug 2012
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    Grey Ghost Senior Member

    Maybe on an inland lake. Not in open water IMO.
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