Stepping transome contender style

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

  1. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    Stepping transome contender style

    Benefits more speed/faster holeshot

    1.additional hull space/stabilizing like a larger vessel.

    2.additional _-- cubic feet floatation

    3.minimize boat rocking motion

    4.dive platforms area approxchmentil 30”Wx 20”L

    I design to be removeable.

    there will be a dive none slip first boarding step at bottom of each pod.


    Any suggestions
     

    Attached Files:

    Last edited: Jun 14, 2017
  2. gonzo
    Joined: Aug 2002
    Posts: 12,255
    Likes: 188, Points: 63, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    There will be a small amount of extra reserve flotation when the boat is at rest. However, you are adding weight to the boat. How do you think that will increase speed or better the hole shot? It will surely lessen it.
     
  3. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    I'll take the extra flotation and the additionale weight which can be pre calculated correct?

    here is the approchement area of pod 30"w at top section by 20" setback by 15" height how many LBs of flotation can fit this area, what's the ratio 2LBS
    PF flotation will surport 200LBs or 60 lbs of buoyancy per cubic foot.

    20"x 30"=600 squared
    hieght of pod varies between12/15" so 13 is average
    600sq x 13=78oo"
    convert to cubic feet

    7800/172=45.35 cubic feet
    if my calulations are correct w/ 45cb of PF in each pod total 90cf PF will esenualley make engine and related aft. weigth which includes a brand new honda9.9hp it weights 120LB now weightless making boat heavei yes more powerfull no more effeiceint yes.

    60 lbs of buoyancy per cubic foot. so 45x60=2700LBs


    the aluminim will be 1/16" maybe 4-6LBs each pod
     

    Attached Files:

    Last edited: Jun 15, 2017
  4. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,144
    Likes: 123, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    That boat does not look all that beamy. Engine setback might not suit it.
     
  5. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    96" beam

    Engine setback
    might not suit it ??
     
  6. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,144
    Likes: 123, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Measure chine to chine at the transom.
     
  7. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    looking at the image I'd say no less than 90" chin to chin

    minizing the rocking would be very nice improvement
    the trim tabs help so floating pods must also contribute to stabilizing the rocking motion.
     
  8. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,144
    Likes: 123, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Won't be anywhere near 90 inches, maybe 75-78.
     
  9. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    I'm still waiting to hear if my floation calculations/theroy are correct?
     
  10. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,144
    Likes: 123, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    I'm waiting to hear what the beam across the chines aft, is.
     
  11. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    Starcraft referrs to beam as transome width, my vessel is 92" is this concidered narrow/unboxlike/ compared to simaliar vessels?

    obvevsiouley a wider boat will track/handle better than a less "beamie" vessel maybe this 92" beam is main contributer to vessels unstabilillity at top speed?

    attach spec sheet I have underlined Vf22 same hull minus hardttop.
    thanks TB
     

    Attached Files:

  12. gonzo
    Joined: Aug 2002
    Posts: 12,255
    Likes: 188, Points: 63, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    You calculated the reserve buoyancy. That is irrelevant to the speed or behavior of the boat at planing speeds. At those speeds, the pod will be out of the water and will only contribute to weight, increase bow up (squatting) and most likely slow down the boat. If you are looking at better hole-shot, a lower pitch propeller and long trimtabs is what you need.
     
  13. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    I just added floatation I'll calculate LBs of later.

    I have completely occuppied the inside pod area w/ homemade floation so now the water inside pod has been reduced by 95% thus reduceing overall aft. weight proballey gain 2 knts at wot.

    it's hard for me to understand the engineering logic behind designing a pod to takeon water.
     

    Attached Files:

  14. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,144
    Likes: 123, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    It was a flooding pod, that you have now added buoyancy (plastic bottles ?) to ?
     

  15. the brain
    Joined: Sep 2016
    Posts: 235
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: AL

    the brain Senior Member

    yes Sir you are correct pod has to either be completely sealed or in my case drain.

    I'll take floation wherever I can fit it.

    in process of designing floatation pod for under port diveplateform. will incorpate as DP surport.

    edit waiting for response on beam size
    TB
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.