Extending 18 ft boat at the transom

Discussion in 'Hydrodynamics and Aerodynamics' started by K33von, Jul 3, 2024.

  1. K33von
    Joined: Jul 2024
    Posts: 3
    Likes: 1, Points: 3
    Location: Curacao

    K33von New Member

    I am thinking about extending this boat at the transom on the port
    and starboard side, leaving the engine in the middle.
    This is for storage space and potentially a live well.
    Is this recommendable? And what is this modification called?
    My boat is the one with no engine in the photo.
    I want to build something like the photo with the 30hp Johnson
    has with the two "brackets" in the back on port and starboard side.

    WhatsApp Image 2024-07-03 at 21.25.04_f11f3c6b.jpg WhatsApp Image 2024-07-03 at 20.48.26_bd1c4d9f.jpg
     
    Last edited: Jul 3, 2024
  2. rwatson
    Joined: Aug 2007
    Posts: 6,245
    Likes: 528, Points: 113, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    I've seen that in a few designs. Lots of good reasons to extend the transom. especially for motor protection against wharves.
    You should get a little extra speed with the longer plaining surface, depending on other factors.
    Storage of dry items would be ok, but I think I would build the wet well inside the boat for balance and convenience on such a small boat. If you load one of these extensions with water, you add a lot extra weight outboard, as well as lateral stability issues.
     
  3. K33von
    Joined: Jul 2024
    Posts: 3
    Likes: 1, Points: 3
    Location: Curacao

    K33von New Member

    I found out they are called floatation pods. I will be following your advice and putting the livewell in the center. Thanks for the help!!
     
    rwatson likes this.
  4. comfisherman
    Joined: Apr 2009
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    Location: Alaska

    comfisherman Senior Member

    When fourstrokes started taking over we put what we called "transom pods" most were added to bottom of flat bottom skifs. It made the handling at slow speeds near impossible. The better they tracked the initial lines of the hull the better they did, but too long of transom extensions made for some unwieldy skiffs.
     
    Last edited: Jul 6, 2024
    DogCavalry and rwatson like this.
  5. K33von
    Joined: Jul 2024
    Posts: 3
    Likes: 1, Points: 3
    Location: Curacao

    K33von New Member

    What would your max extension be on an 18 foot boat like the photo? I wanted to go for 2 feet. Maneuverability isn't a big pain point for me.
     
  6. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    2 feet is quite do-able. The issue is mainly structural integrity. The further out you go, the greater the pressure on such a small transom. Chance are, the entire weight of the boat will one day need to be supported on on of the the extensions.
    If you make sure that the underwater shape isn't too square, manoeuvrability wont be too affected.

    Edit - saw this, thought of your project
    FishBOat.jpg
     
    Last edited: Jul 9, 2024
    mc_rash likes this.
  7. mc_rash
    Joined: Aug 2020
    Posts: 183
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    Location: Netherlands

    mc_rash Senior Member

    @rwatson nothing to add to your command except that your picture looks more like a catamaran
     
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  8. comfisherman
    Joined: Apr 2009
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    Location: Alaska

    comfisherman Senior Member

    Tough one to answer, ours were on 14-18 foot work skiffs. Seemed like the shape made more impact than length. Only one real way to find out...
     

  9. Barry
    Joined: Mar 2002
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    Barry Senior Member

    All of our jetboats came off the same male steel jig. The jig was 18 feet and our standard hull was 21 feet but the jig was used for one boat at 23 feet. . I am not sure why you want to have the two pods beside the engine as compared to just extending the entire hull and move the OB back as well.
    This will give you much more storage, more planing surface and more than likely an easier build. It will more than likely reduce the poorer turning ability as Com mentioned.
     
    comfisherman likes this.
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