Waterline transfer levels

Discussion in 'Boat Design' started by valvebounce, Jun 8, 2012.

  1. valvebounce
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    valvebounce Senior Member

    I have a 13ft 1960's speedboat that I am converting into a fishing boat.
    I have not yet had or seen the boat in the water.When I got the boat it had no deck in it.I have replaced the timber stringers,but as of yet not fibreglassed them in.I am putting a new deck in it,but I have no reference point as to the level of the waterline,except the bump strips/strakes on the sides,which I presume were in line,although higher than the waterline.If I follow the tops of the stringers with the deck it inclines forward about 3"
    Could I use the bump strips as a datum,and should the deck be horizontal [level] to the waterline although above it.The back section of deck is 7ft,but will have to be stepped where the bow starts to rise after that.Would it be advisable to fit lengthways feathering pieces on the stringers,or crossways graduated supports on the stringers.Any water below the deck would have passage between the stringers,crossway supports would be on top of the stringers.
    I am lacking the expertise with basic boat design,so any advice will be gladly recieved.
     
  2. PAR
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    PAR Yacht Designer/Builder

    The splash rails are no indication of the LWL. Most often they are slightly stern down with the boat loaded and ready to scoot.

    Load the boat as it is, with sand bags and/or concrete blocks, in all the locations where you'll have weights (engine, tanks, cooler full of beer, etc.) A concrete (8x8x16) weighs about 35 - 37 pounds. With the boat properly loaded up, you can then mark the real LWL, which is just a reference line, for an eventual boot stripe or bottom/topside division line, which is commonly a few inches above the actual LWL.
     
  3. valvebounce
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    valvebounce Senior Member

    Hello again PAR,thanks for your advice,my dilemma is that I cannot put the boat in the water,it is on chocks in my back garden area.
    The boat has a colour change at what I presume to be the waterline,or just above.Maybe this is the bottom/topside division line that you are refering to.I could take a chance and use it as a datum in order to get the deck level front to back.
    The boat is quite shallow sided so standing up in it to move about will have to be done with caution,I intend to fit stainless steel grab rails partway along the gunnels,so having a level deck when stationary will be quite important.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    You are intending making the sole higher than the waterline in a 13 foot boat ? Don't think I'd be doing that.
     
  5. PAR
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    PAR Yacht Designer/Builder

    Taking a guess is a pretty big gamble. Can you post pictures?
     
  6. valvebounce
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    valvebounce Senior Member

    boat pics

    These are the pics of the boat
     

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  7. PAR
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    PAR Yacht Designer/Builder

    I see a lot of hull distortions there and the painted LWL isn't a good indication of the actual LWL or even trim conditions.
     
  8. valvebounce
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    valvebounce Senior Member

    Hi PAR,
    looks like I have a problem.Do you think using the centre stringer as a guideline would work?The boat must have had a deck in it at sometime or another,so the centre stringer was probably a level for the deck.If I elevate the centre stringer to the height of the outer stringers,then screw it down maybe it will give me the original deck level.The deck is 3/4 glassed marine ply,so it is possible it will pull the hull back into shape when screwed down.I will have to adjust the height of the intermediate stringers to suit.
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It's unlikely the stringers supported the decking (sole or cockpit grate). What's missing are the lower futtocks of the frames, which has permitted the trailer or what ever the boat is sitting on, to grossly distort the hull. Pulling the centerline stringer up flush with the outboard stringers will just compound this problem.

    Obviously the hull is V shaped, so why would you attempt to remove this by flattening out the stringers? Replace the athwart stiffness lost by the missing frame bottoms and place the cockpit sole on top of these. It's likely they where just sawn to shape from some 1x4's and also obviously attached to what little remains of the frame sides (upper futtocks). What are the molded and sided dimensions to the upper futtocks? The sided dimension will be the same for the lower futtock pieces, though the molded dimensions may be deeper.
     
  10. valvebounce
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    valvebounce Senior Member

    Hi PAR,
    I am not conversant with what "Futtocks"are.Are they arch shapes that follow the hull shape,that are flat across the tops to take the deck?If so,would they allow bilge or excess water to flow under the deck from front to back.
    My apologies for my lack of boat term knowledge.Do you think the boat is beyond ressurection and might be better as a sea garden feature for our old friend "Davy Jones"
     
  11. valvebounce
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    valvebounce Senior Member

    Hi PAR,just read your communication again,athwart is crossways I take it.
    and the Futtocks are fixed to the stringers and graduated to take the deck,then upper futtocks fitted to them and attached to the gunnels.That way there would be excess water passage between the stringers?
     
  12. PAR
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    PAR Yacht Designer/Builder

    Futtocks are the pieces of sawn frames. The upper portions attach to the sides of the boat, the lower the bottom.

    The pictures suggest the lower futtocks were notched to receive the stringers and laid flush against the planking.
     
  13. valvebounce
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    valvebounce Senior Member

    Hi PAR,

    Thanks for the info,I am starting to get the picture now.
     
  14. valvebounce
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    valvebounce Senior Member

    Mr E,
    Thanks for your interest.I can see the centre of gravity would be too high,and capsizing would be more of a possibility.After speaking To PAR about upper and lower futtocks I have got a clearer picture of how the setup goes and the deck will not end up above the waterline.The futtocks that were in the boat followed the hull shape and were sealed to the hull,which caused watertight bulkheads,they restricted the bilgewater flow from bow to stern,which caused them to rot.Having a bilgepump would have been a waste of time.
    Changing the subject,I worked as a boilermaker apprentice in Whyalla south australia in the early sixties,then in Melbourne as a toolmaker apprentice at general motors.
    I was too young to stay when my dad brought us back to the uk,I have a lot of fond memories of the people and places,coming back to the uk was definately the wrong fork in the road for me to take.
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    Aha! Now i remember who you are. I wish you stayed valvebounce, when I see some migrant ethnic groups spectacularly over-represented in crime statistics, I realise we really should have imported more from the Old Dart ! :p
     
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