GOP Home Build

Discussion in 'Boat Design' started by schultzfactor, Oct 25, 2013.

  1. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    Foredeck sealed.

    Started the big step of sealing the foredeck.
     

    Attached Files:

  2. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    Update

    More hull work, added Chines and sealed forward Gunwales.
     

    Attached Files:

  3. DennisRB
    Joined: Sep 2004
    Posts: 1,265
    Likes: 24, Points: 38, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    In hindsight with the amount of work you done, would you say it was even worth it to use donor hulls?
     
  4. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    Hehe no!! This thing just became bigger and bigger as it went on. The donor hulls were a waste of time, but they got me started I suppose.
    The next build will be from scratch.
     
  5. DennisRB
    Joined: Sep 2004
    Posts: 1,265
    Likes: 24, Points: 38, Legacy Rep: 228
    Location: Brisbane

    DennisRB Senior Member

    Yeah it looked like they set you back more than anything! But as you said it got the project going. :)
     
  6. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    Indeed, I have learned a lot and made a lot of mistakes with this build. Great thing about fibreglass is you can always grind or sand it and start over, if you have the energy.
     
  7. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    What should be the safe clearance from waterline to transom top?
    The Draft unladen is 400mm. When I stand on the boarding platform between the motors it goes to 500mm. Tunnel clearance aft is 150mm.

    As can be seen in the image, the top outboard holes never get wet, even with no bow weight and me standing at the rear of the boarding platform.
     

    Attached Files:

  8. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    Side view with waterline marks
     

    Attached Files:

  9. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,817
    Likes: 180, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Are they XL shaft (25") ? No problems if so.
     
  10. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

  11. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,817
    Likes: 180, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Really ? The swivel bracket looks short on the Honda. Unless you are venturing onto rough water, you should be alright, but don't have it any deeper than around 450mm if you can do it.
     
  12. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    450 draft?
     
  13. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,817
    Likes: 180, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Hull only draft. The old 18' Shark Cats with the 70 hp 20" engines were at least 450mm hull draft, a few engines got drowned, but they were subjected to a lot of offshore fishing in lumpy conditions. Most 16' cats used 20" leg engines because they could not get 25" in less than 85-90 hp. Should be OK, and better if you can get more weight forward.
     
  14. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    Sweet thanks. Once more weight up front, I hope the draft to be under 400 hull only.
     

  15. schultzfactor
    Joined: Oct 2013
    Posts: 109
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Rotorua New Zealand

    schultzfactor Senior Member

    Ventilation Issues

    I dumped her in the lake again this weekend after removing the centre pod.
    I also lowered the motors and am still getting vent issues. The AV plate is runnning at water level whilst underway. The hull is riding perfectly and eats up the chop with no sneezing and seems to be very dry and notably smooth in a choppy lake. I'm really really happy with the way she rides.

    Having "roughened" the hull using a sandpaper like finish is the first thing that comes to mind. In my attempts to fracture the laminar friction, could this be producing mass cavitation from the hull and providing to much aerated water around the prop? Almost like getting cavitation in a foamy sea?

    What might my best options be from here? Four blade propeller, lowering the motor (although the vent plate seems perfect, smoothing the hull( lots of grinding and fairing) or changing the outboards to XL's ( very costly as Honda don't make an extension kit for these motors.
     
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.