Eye ball performance predictions.

Discussion in 'Boat Design' started by river runner, Sep 28, 2011.

  1. river runner
    Joined: Jul 2011
    Posts: 172
    Likes: 6, Points: 0, Legacy Rep: 91
    Location: Colorado

    river runner baker

    I don't know anything about power boat design. I know a tiny bit about sailboat design. I know a bit more about seakayak design. I consider myself an authority on flatwater canoe and river dory design.
    Canoes, Kayaks, and row boats are simple boats. I believe that I can look at one and make predictions about it's perfomance. I think that if you can't, you need to go back to boat design 101. I also think that I can make changes to a design and predict, with some accuracy, what the consequences of that change will be. I think if you can't, you need to do some more studying.
    I have been repeatedly told, on this forum, that this is not impossible. I can't, for instance, look at a canoe and say that it would be good for whitewater or it would be fast on a lake. I can't say, for instance, that if I give a boat more rocker it will turn better, but track worse. I think this is crap. Sure, if two boats are very similar, it would be hard to tell which one has the better PC, etc., but you can certainly make generalities about disimilar boats based on their shape.
    Am I rigth or am I wrong?
  2. tunnels

    tunnels Previous Member

    Before the days of pen and paper everything was done but eye .
    Go to the pacific islands and they make canoes all done with gentle curves in the hull so the out rigger drag is taken into consderation to steer the simply shift weight into a differant place in the hull and the boat changes a couple of degrees one way or another . Boat builders were Gods they had a gift there were heavenly beings .
    If a boat looks nice is fair and has beautiful lines 99 times out of 100 its a good boat .
    Most new modern drawers :eek:dont have a eye for for anything .
    Smaller power boats i always lofted out full size on the wall not the floor so you could stand back and have a look from the other side of the room . Plus they were always drawn at 3.5 degrees planeing angle like they should be . If you have the eye mate you are worth your weight in gold ,also to go with having an eye for shapes and forms etc and the like goes having the feel for things sas well and knowing what is happening and whats the reason why its doind what its doing !! :D

    When designing tunnels we set the boat at 3 degress and created a level line along the side of the coaming panel and put a strip of black tape then checked with the steerer where the boat felt good when it was running flat out. took video as well and put a level across the tv screen to check out black line with the performance predictions .
    Strange ??
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Experience can compensate for a lack of design fundamental understanding, but without it, taking guesses is well, a crap shoot.

    In the old days, before tank and model testing, much was done by eye, but those observing also knew the fundamentals as well. Looking a quartering wave and determining if it's too far forward or aft, means you've seen hundreds of them and know the difference between a good one and one that's not so much. Very few that admit to:

    can say with reasonable assurance that they have sufficient understanding to affect reasonable changes.

    If you have the time and money to toss at your "ideas" for a canoe or kayak design, go for it, but honestly, learning this way is usually expensive. Learning the fundamentals, isn't so much about understanding the places to put the various "centers" so much as, realizing what you can and can't do while accepting the compromises you must. In other words, sure you can add some additional rocker and improve the maneuverability, but how badly will this affect other aspects, are these new design traits acceptable, how much additional rocker will offer the maneuverability you desire, how will you handle the redistribution and/or increase of displacement, etc., etc., etc.

  4. Wavewacker
    Joined: Aug 2010
    Posts: 709
    Likes: 25, Points: 28, Legacy Rep: 226
    Location: Springfield, Mo.

    Wavewacker Senior Member

    PAR, very well said! :)

    Anything can be made difficult and perhaps it's the degree of difficulty that leads to perfection as it rarely happens by accident.

    While experimentation may be expensive it's also the best teacher for the investment made, especially toward failures.

    Confidence, determination and persistance makes dreams come true.

    I have always been a student in life, pehaps not the best but willing to learn what I can. I believe I have a good eye as well, but I'll need skills never used to build an acceptable boat, there is no expierence in that arena.
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