Location of floor in boat?

Discussion in 'Boat Design' started by mnmattie, Apr 4, 2015.

  1. mnmattie
    Joined: Jan 2013
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    Location: Minnesota

    mnmattie New Member

    Hi guys,

    I'm working on a Forester Playmate (14'4" Trihull) and it's a very shallow boat! The floor almost seems that it's too high in the boat. When designing a boat, how do you know where to put the floor in relation to the hull of the boat? The floor in this boat is already soft so I'll be tearing it out to do stringers and a floor anyways.

    Just knowing what to look for, especially in relation to floor height of a boat and where the floor ends should meet with the hull. Thanks!

  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    For older boats, it will often look like the decks are too high in the hull. This has to do with several reasons; from the depth of the hull (especially a tri-hull where you have to be above the tunnels), to modern regulations that require higher bulwarks, to the intended purpose of the boat and the need to bend over the gunwale.

    Modern designs generally tend to high bulwarks just from a liability issue. This, and the desire for more below volume, drives the big boxy look of modern small powerboats. Really, you have to decide what you are going to do with the boat.

    Here is a modern 16' Glastron, notice the "automotive" style of seating and consequent distance between the deck and the gunwale.


    And here is a 17' Boston Whaler, notice that the height between the deck and the gunwale is about 2/3 the Glastron

    http://www.aquaticbermuda.com/Whaler_front_view - Copy (2).jpg

    And here a Forester 15' tri-hull...somewhere in the middle.


    BTW, strictly speaking what you are talking about is the cockpit sole. In boat/ship building the 'floors" are the lowest transverse structural members. Cockpit soles and decks may rest on the floors, but they are not the same.


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

    Obviously in such a small boat you don't want the sole even an inch higher than it needs to be, which is somewhat dictated by the need to clear the tunnels, as mentioned, to enable a continuous flat surface. You could add some light alloy side rails to give a feel of more security, if they aren't going to get in the way too much.
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