Need some advice on hull action in following seas

Discussion in 'Boat Design' started by 5akman, Sep 1, 2012.

  1. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    A bulb, of sorts, low down, and also an increase in freeboard at the bow would help for sure. But how much?

    The principal dimensions of your boat may mean, for its location and prevailing sea conditions, that it's prone to being caught out as such. Thus you may help to move the "tipping point" and even change the response/behavior from 'ok' to 'waooahh ****', from a fraction of a second to several seconds. Time enough for you to make corrective action.

    If you're really concerned, get someone to do some simple model testing for you to gauge how much difference it would make to your hull in the prevalent sea conditions that exist where you are. No point adding it if it doesn't make much difference. There is only so much one can do with a limited size, whilst maintaining the basic design intent of the boat.
  2. tom28571
    Joined: Dec 2001
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    tom28571 Senior Member

    There are plenty of boats with bows as sharp or sharper than yours that work in rough offshore conditions. Think Carolina sportfishermen. What is different on your boat is the apparent concentrated weight near the bow and the forward location of the rudder. Look at the dimensions of a bulb that might add significant buoyancy forward. It would probably have be very large to have appreciable effect and modifying the bow would be a big job. The fishtail rudder is cheap, easy to do and would be a good thing on such work boats even with no following sea problem.
  3. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    Fishtail rudders are a fairly common addition here. In our case it's most often done to improve boat handling around nets or to improve manuvering characteristics while landing. Strong tidal currents of 3 or 4 knots can make even a simple landing not so simple.


  4. 5akman
    Joined: Sep 2011
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    5akman Junior Member

    Cook Inlet tides in the 5-8knt range are real fun. Then throw in some following seas while trying to navigate the Kenai river mouth! The rudder mod is definetely on my list of projects.
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