Stepping transome contender style

Discussion in 'Boat Design' started by the brain, Jun 14, 2017.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    I can't see any figures that show the transom beam at the chine.
     
  2. the brain
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    the brain Senior Member

    you maybe correct when you guessed 78-80" transom beam at the chine

    I'll mearsure and report back
     
  3. the brain
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    the brain Senior Member

    Mr Efficiency I'm waiting for response on my floatation calculations
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    A cubic foot is 1728 cubic inches, please re-calculate !
     
  5. the brain
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    the brain Senior Member

    I did convert to cubic feet

    7800/172=45.35 cubic feet

    is 45cubic feet incorrect for my smallish pods? or is 4.5 cubic feet correct?

    so 9 cf 60x 9=540 so 540lbs of floatation thus makeing all aft. weight now weightless including kicker is this correct

    TB
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    1728 cubic inches per cubic foot ! 4.5 cubic feet would be a smallish pod. 45 c.ft is near enough to your boat's displacement.
     
  7. the brain
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    the brain Senior Member

    OK so it's worth the time to have pod under diveplateform filled w/ real poured in foam.

    or saying my small pod can hold 1/10th of required for my size vessel? and not worth the effort?

    so w/ pod
    makeing all aft. weight now weightless including kicker is this correct?

    I have the port diveplateform built will now build pod under it, can I go around w/ just portside DP?

    untill I design the starboard DP/ kicker bracket for my heavey honda 9.9

    edit: even though my smallish pods can only hold a little floatation the key is where it's located
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    You have the effects of the pods/engine setback at rest, and a different set of effects once up and running. You want both modes to not be adversely affected by whatever you are doing there. Can you post some more pics ?
     
  9. the brain
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    the brain Senior Member

    please scroll up see image of my plan

    I'm imatateing the stepped hull extention that contender made famous so it's proven techonogoly.

    my next decision looks like a % of pod will be prementely attached to stern thus a hull extension w/ all it's benefits
     
  10. the brain
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    the brain Senior Member

    what do you think of my new helmstation seat
     
  11. gonzo
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    gonzo Senior Member

    Your drawing shows an extension that may touch the water at rest, but is not a step like Contender has. Further, the reserve flotation of the pods would only be what you calculated if the boat sinks to the gunwales. Once on plane the CG will shift aft quite a bit. First, the engine is further aft. Second, there is the added weight of the pods. If you are thinking of a hull extension, that is completely different.
     
  12. the brain
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    the brain Senior Member

    what is CG
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    CG= centre of gravity. I'd say a pod that does not supply any/much lift underway, could become a liability, if the COG is going to be shifted too far aft. Were those trim tabs used much before this OB/pod incarnation ?
     

  14. the brain
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    the brain Senior Member

    "Were those trim tabs used much before this OB/pod incarnation ?" no I installed TT in hope of sabilizeing vessel at top speed,they have improved chimewalk at 50 + Knts. not a complete solution to handleding at TS.

    yes this makes sense for floatation lift to basicalley hold up the aft so when initail holeshot boat will squate less, so bow isn't raised as much as before extra floation, Gonzo here's the reason the boat will be faster (at takeoff not overall speed).

    I'm anxious to try out the homemade floation in pod.

    I'm basicalley extending the shape of pod attached to dive plateform not a real hull extension w/ it's related stringer extension.

    if you'r into # crunching on CG the orginal mercruiser weight was 715LB was replaced w/
    knee brace 45LBs, pod 60LBs.johnson175 engine 383LBs (moved aft 20") total 488Lbs
    weight reduction of 227LBs

    weight of hull only is approchementely 1750LBs minus 2 batteries /40 US gallons of fuel
    TB
     
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