SWATH concept design - Feedback wanted

Discussion in 'Boat Design' started by whataboutyou, Aug 18, 2016.

  1. whataboutyou
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    whataboutyou Junior Member

    I used to worked for innotech Canada, who installed products from innotech australia (http://innotech.com.au/Products.aspx). I think the Maxim DDC could manage a stabilization system quite well. It's not that different from an arduino, but the software interface is really nice and it makes making 'intelligent' or predictive control systems easier - both to make and manage because of the graphical, flowchart like interface.

    'Intelligent' software is actually wrapped up being able to do a PID loop. PID loops continuously calculate an error value as the difference between a desired setpoint and a measured process variable. The pid loop attempts to minimize the error over time by adjustment of a control variable.

    I've tried to make my own control system, with LAM (linux, apache, mysql) running a red5 (java) media server. It's not finished but you can create a user, login then use the console to see who else is connected, do peer-peer messaging, execute sql, read/write to the COM ports (control usb devices), access a file browser, write files, open pictures, play videos, watch connected webcams and such.

    But I should note I have a bit of a dislike for control systems all together. My boat will be controllable and driven mechanically, using pulley's, screws, gears, leavers, compressors and human muscle.

    But an auto pilot / stabilization assist would be nice.
     
  2. cmckesson
    Joined: Jun 2008
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    cmckesson Naval Architect

    I designed a small SWATH some years ago for a client, but alas it was never built.

    If you are serious about the SWATH do yourself a favor and buy at least the SNAME Bulletin T&R Bulletin 7-5 "SWATH Ships." This is the 'bible' of SWATH design.

    link: http://www.sname.org/pubs/viewtechnicalpaper?DocumentKey=c7726a07-154b-4afc-a7eb-04b08e8db942

    There are also some discussions of SWATH design that you may find useful in my textbook, "The Practical Design of Advanced Naval Vehicles" which may be easily found on Amazon.

    Finally, regarding the issue of list and trim control: This was a significant issue for the 80 foot passenger vessel NAVATEK II, and was dealt with via an active control system. NAV-II had free-flooding ballast tanks and a compressed air system to blow the tanks as needed in order to maintain her design attitude. Be advised, you need this not only for static attitude control, but to overcome dynamic trim changes as well (Google "Monk moment.)

    Best of luck,

    Chris McKesson
     
  3. whataboutyou
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    whataboutyou Junior Member

    One of the great commandments of science is, "Mistrust arguments from authority." ... Too many such arguments have proved too painfully wrong. Authorities must prove their contentions like everybody else.
    -Carl Sagan

    I wrote more, but the best part got censored, so I'll just say I don't trust experts, or outsourcing. I'll probably end up buying the pnumatic turbine, but if i can cast and build it... i just might do that myself too.
     
  4. whataboutyou
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    whataboutyou Junior Member

    I'll put up a new model soon, based on what Rurudyne said about the legs on the boat doing the splits.

    What if the pontoons could be positioned beside the boat as outriggers, as well as under it to improve the ride. The pontoons in the outrigger position could also be used to provide mechanical energy if the arm which holds them was loose and connected to a leaver / foot pump style compressor, that turns up down buoyant energy of the waves into mechanical energy. *Edit, if the main body of the boat isn't stationary this energy might be negligible.

    Of course the arm would have to be able to be locked into position. But it could have intervals, either the side by size underneath (90), 45, 22 degree positions. This way the legs could still be fairly long (high ride) but also adjustable baised on sea conditions.

    Having a high ride is nice... but it could also leverage small motion into large motion as ad hoc warned about. - the first swath model I did reminded my girlfriend of a pick up truck, and if you've ever been in a pick up truck that has a high ride down a pot hill filled road... It's white nuckles on the steering wheel the whole time as you keep it from heeling over side to side, especially if the rear leaf spring isn't very stiff.
     
  5. whataboutyou
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    whataboutyou Junior Member

    Doing the splits.

    [​IMG]

    [​IMG]

    In this position, something like an outboard electric motor on the back could give speed assist... But for the props on the pontoons to be useable, they'd have to be able to be adjustable (to stay under the water).
     
  6. Rurudyne
    Joined: Mar 2014
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    Rurudyne Senior Member

    Came a toss an open source description for the MK1 Phlatprinter that might be useful to build actual models of your ideas.

    http://www.openbuilds.com/threads/original-phlatprinter.25/

    The current MK3 version can cut wood too, and foam nearly two inches thick (not sure about how thick wood), which has got me thinking it might be darned useful for cutting ply or foam to go into building actual boats (not BIG boats mind you) or camper trailers and not just RC models.
     
  7. whataboutyou
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    whataboutyou Junior Member

  8. whataboutyou
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    whataboutyou Junior Member

    also was thinking today how the windmill would work much better in the 'splits' position, for stability reasons, but also because then it could drive a single prop on the back of the main body. (although an outboard would also be nice)

    Also what Rurudyne was talking about hiding behind an island, because of the low speed issue, instead of just hiding, an extra set of legs could stand the main body on the floor, then the outriggers could easily flap in the waves and collect energy.

    While in this 'docked' position, the captain could sleep, the windmill could catch more energy, and maybe even the outriggers could be detachable to be used as personal submarines.
     
  9. whataboutyou
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    whataboutyou Junior Member

    update body shape

    *length of pontoons changed to 40 ft
    *excess structure removed.
    *removed separation in legs to reduce wave interference and add more buoyancy


    [​IMG]

    [​IMG]
     
  10. whataboutyou
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    whataboutyou Junior Member

    reduced streamlined cabin

    [​IMG]

    [​IMG]
     
  11. Rurudyne
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    Rurudyne Senior Member

    You know, without the ballast needed to submerge the pontoons you're steadily moving towards a wave piercer form
     
  12. whataboutyou
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    whataboutyou Junior Member

    felt like if I wanted to be able to stand on stilts and collect tidal energy a wave piercing form is ideal. Also with all the reduced weight, it could sit inside a wave during a storm.

    Also with the adjustable legs, it gives a lot of deck, on calmer days; but still a lot of protection during the bad ones.
     
  13. whataboutyou
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    whataboutyou Junior Member

    new design

    I think I'm moving back towards a less aggressive design.

    Maybe even a greenhouse in the back dome.

    [​IMG]
     
  14. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    I like to draw pictures of boats also. Manny thousands that I wadded up and threw away.
    Unless you know the math and the formulas to form the size of the pontoons and the legs you are just playing around. If you are serious about building a boat it is time to talk to a Navel
    Architect. Your pictures mean nothing and you are spinning your wheels. PS Start with the design of your living space. 10' x 30' or 15' x 58'??? with that you can electronically draw to scale.
     
    Last edited: Aug 27, 2016

  15. whataboutyou
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    whataboutyou Junior Member

    Added some more cabin space.

    And I like spinning my wheels ;)

    [​IMG]
     
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