Hull for small autonomous ocean crossing boat

Discussion in 'Projects & Proposals' started by elkroketto, Feb 3, 2017.

  1. Tenedos
    Joined: Feb 2017
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: San Francisco

    Tenedos New Member

    Interesting perspective. Following the same logic, the same can be said for solo and/or non-stop circumnavigations, ocean races, mountaineering, most if not all extreme sports, etc.

    I am sure it would make an interesting discussion. But since this forum is about boat design rather than human psychology, can we maybe stick to the topic?

     
  2. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,566
    Likes: 244, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Your reaction suggests I'm getting near to the money, Tenedos ! Matter of fact, if this ocean drone craze really takes hold, the design of a hunter-killer anti-drone-drone, may need to be discussed.
     
  3. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    http://www.sandiegouniontribune.com/business/sd-fi-xprize-ocean-20170217-story.html

    So at a minimum it's worth a $7 million prize.
     
  4. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,566
    Likes: 244, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    That is a sea-floor robot.
     
  5. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    http://www.pmel.noaa.gov/arctic/news-story/saildrones-monitor-bering-sea

    There are thousands of uses for small autonomous instruments that can cross oceans, even if slowly. From oceanography to studying fish populations, trash density, etc.

    Any brief search on google shows dozens of current applications.
     
  6. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,566
    Likes: 244, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    I'm sticking with my initial impression that the space-cadet demographic is well represented in the several threads of budding ocean crossing drone geeks around here. That "crossing an ocean" is almost always emphasised, gives it away.
     
  7. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    Of course there are a lot of space cadets. But it isn't like concrete canoe races or model rocketry are scientifically particularly noteworthy. Some drone ships ar just to see if someone can pull it off, others are serious scientific or academic endeavors. So what?
     
  8. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,566
    Likes: 244, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    No dramas, it adds a bit of variety to the blue plastic drum party barges, and the polystyrene block boats ! ;)
     
  9. waikikin
    Joined: Jan 2006
    Posts: 2,286
    Likes: 91, Points: 58, Legacy Rep: 871
    Location: Australia

    waikikin Senior Member

    blue drum bogans

    There's been a bit of dough put into tripwire/info collecting style solar/sail drones/bluebottles by our defence, there may be something in it but also could be simply supporting capability of local suppliers as they can do, doesn't seem to be any great veil of secrecy surround the development...
    ... maybe a bunch of bogans on blue drum rafts might be as effective, on my local waterway there seem to be a proliferation of picnic tables supported by blue drums... such is the fashion at present- & probably get their antics onto social media quicker than dispatches.... you can sink quite a few & not even get up for relief... they get towed up/down the port to the days spot & back to base once the esky runs dry...;)... some even sport umbrellas for shade..

    jeff.
     
  10. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    The way I look at it, is that in the US we survey about 1% of the waterways a year, or something like that. Doing any more is just to expensive to justify given that most of the shoreline is used for non-commercial traffic. So for the most part no one really has any idea what the bottom looks like.

    Toss a few hundred of these things off the cost of Maine in the Spring, and by winter you can pull them out of the water in Texas. For less than the cost of a survey ship doing just a couple/tens of square miles a year these things could map the entire coast.

    Even if you figure a loss rate of 50% a year, it's an absorbable cost relative to how much a towed side scan solar array costs to operate. And if the data is less precise than the high tech stuff, it's still worlds bette than what we have now.
     
  11. elkroketto
    Joined: Feb 2017
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Western Germany

    elkroketto Junior Member

    I was not aware of the SeaCharger project - thanks for sharing the link with us!

    The last days I have been working on the hull design - thanks to the help from Maryak I am pretty happy about my first serious attempt. I'd appreciate any comments on this try:

    [​IMG]
    Side view

    [​IMG]
    Front

    [​IMG]
    Aft

    The top has a rounded shape to support the roll-over after an unavoidable capsizing event. I hope to get the keel as heavy as possible to go without a fin / daggerboard so accumulation of sea weed is reduced. What are the chances that this thing will float and move (in a controlable way) over water?

    After refining the design based on your comments, the next step is to build the boat in smaller scale (1:2 or 1:3). Test the stability and the behavior in different conditions...

    @Mr Efficiency: Any discussion are much appreciated. Thanks for sharing your thoughts on this project - I do agree with many of your points. Nevertheless I think this topic is a great hobby project for everyone and what can you ask more for than learning and experimenting in so various fields?

    Thanks again and all the best
    Elias
     
  12. upchurchmr
    Joined: Feb 2011
    Posts: 2,832
    Likes: 87, Points: 48, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    The chopped of stern underwater will make a lot of drag. It will slow down the progress a lot.

    Where will the propeller be?

    Not good if it is behind the chopped off stern. The water won't flow around it.

    Looks like an aircraft carrier, you going to have a drone go with it? Just a joke - I know - my wife says I have not real sense of humor.
    Better make the deck, and the equipment on deck very light so it will not just flop over on a side.
    Keel weights can make that work of course.

    Its not going to turn very well with that much long straight keel. You might not need much turning? But turning is going to eat up a bunch of energy. How much? No clue as to a number.
     
  13. elkroketto
    Joined: Feb 2017
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Western Germany

    elkroketto Junior Member

    You're right with that - I tried to re-design the stern section to reduce turbulences. The picture below shows the current draft with propeller shaft on the lower aft.

    Furthermore I decided to go with two propellers instead of one plus rudder. Why? Other projects indicated that the latter was the main reasons for technical failures (beside faulty software).

    [​IMG]

    The keel's shape is meant to improve course stability - if this is the correct term for going as straight as possibly even when currents are rough. Turning won't be the main priority out on the ocean.

    What do you think about this new design approach? I am especially interested in your opinion on two propellers-idea and how they are seperated from each other. Do you think the stern will interfere with the propellers :?:

    Hope to get as many input on this as possible - Thank you in advance!
    - Elias
     
  14. upchurchmr
    Joined: Feb 2011
    Posts: 2,832
    Likes: 87, Points: 48, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Waste of time, any big flat surface at the stern below the waterline will cause a lot of drag.
    You need to show the propellers and the rudder. How can we know if there will be inteference without knowing where they are?

    If you fail one motor, will the boat make circles?

    Its my assumption that waves will knock this small of a boat off course and then you will have to turn the boat to regain the course.

    How much do you think this boat will weight?

    Sorry, I just realized that the little lines were suppose to be the propeller shaft. Probably a lot of interference, show the prop so we can see how big it is. Can you really get the drive system in the boat with the prop shaft that close to the bottom of the boat?
     

  15. Stumble
    Joined: Oct 2008
    Posts: 1,896
    Likes: 71, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    I see massive amounts of drag, basically it looks like what might happen if a NA professor asked for a design that maximized drag while minimizing load capacity. It's not just wrong, it's unfixably wrong.

    Gofinda boat named Beowulf and scale its underwater profile down to the right size. If you arlength limited then you may need to make it fatter, but if not hold beam and length relative and just reduce the scale to have the capacity you need. Then cut everything away above the waterline and put the smooth arc you have on this on top.

    I see the goal of twin propulsion motors. But there's is going to be a major efficiency loss compared to one larger prop. So you have to balance redundancy with efficiency.

    You may want to add a superstructure offcenter a bit that is just empty space. I was thinking about it, and with the addition it would make it impossible for the boat to remain upside down.
     

    Attached Files:

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.