Submersible Watercraft hull design

Discussion in 'Boat Design' started by Rob Innes, Oct 15, 2022.

  1. Rob Innes
    Joined: Oct 2022
    Posts: 1
    Likes: 1, Points: 3
    Location: Redding, California

    Rob Innes New Member

    Hi. I’m new to this forum but I thought I’d see what sort of inputs I got towards my latest project. I’ve been designing and building submersible watercraft for over 20 years and delivered about 170 of them. For the last two years I’ve been designing and building a much larger 4 seat prototype. This new vessel is powered by a Kodiak marine 6.2l V8 and a Hamilton 212 jet unit. I tried a much different hull design for this larger vessel and I’ve mostly been pretty disappointed with its performance and am looking at doing a major hull redesign to try and rectify these issues. The vessel does not track very well in a straight line and every so often will veer dramatically in one direction for no reason. I tried adding a rear skeg behind the intake which improved stability slightly but slowed steering considerably. I have attached a basic profile pic of the current hull and I will also post pics of the new design I’m currently looking at switching to. Another significant issue is the nose of the vessel goes under relatively well but the tail struggles to follow it under despite several weight and thrust vectoring changes. I believe this issue is mostly due to the center of negative lift (from the main wings) being too far ahead of the center of buoyancy).., as well as an imperfect hull design.

    Things to know: this is a VERY unconventional vessel. It is a compromise between surface performance and sub surface performance and the transition between the two. I realize jet units rob a lot of horsepower but I need the two axis vectored thrust that a jet unit provides. Many of the controls and design considerations are more similar to an aircraft that a boat because it dives based on negative lift and balance and has three axis control (pitch, roll, and yaw). We do not use any ballast to help dive because it is registered as a conventional inboard powerboat and needs to meet all recreational boating standards. It is not a submarine and shares very little in common with a negatively buoyant sub. I am very familiar with small PWC jet units but relatively new to the Hamilton pumps.

    The mistakes I believe I have made with the current design: The hull needs to be a significantly deeper V. Center of negative lift is behind the center of buoyancy. Bow needs more buoyancy. Stern needs less buoyancy. Tail needs to be more tapered, main wing angle (dive planes) need to be steeper.

    I have documented the entire build process for any of those who might be interested. Videos are on Facebook and instagram @qmodelproject. Happy to answer any questions a and listen to your inputs especially in regards to Hamilton jet unit performance, hull and stability designs for jet boats, foil design, hydrodynamics and flow analysis.

    Sorry for the length of this post. I just wanted to be clear exactly what I am looking for help with. Thank you!

    Attached Files:

    Jimboat likes this.
  2. clmanges
    Joined: Jul 2008
    Posts: 575
    Likes: 142, Points: 43, Legacy Rep: 32
    Location: Ohio

    clmanges Senior Member

    My first thought seeing the website was that these would be ideal as props in a James Bond movie. Of course, they'd need some armament, maybe one or two miniature torpedo launchers.

    But please, PLEASE change the text display in your ads. I can only read white text on a black background for about three or four minutes before I go functionally blind.

    But yeah--call Hollywood!
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