Hull for small autonomous ocean crossing boat

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

  1. sinmania
    Joined: Sep 2012
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    Location: Bulgaria

    sinmania Junior Member

  2. chinaseapirate

    chinaseapirate Previous Member

    >Elkroketto. you have not mentioned a price range yet so maybe this is not out of my league to offer design advice here... You did mention a desirable feature of more solar capture area (what? lots of power for radio or cameras ?), ability to self upright, and that speed wasn't a major concern. If that is correct then believe me you can toss just about any concerns with drag or efficiency details out the window so to speak. LWL defeats any design innovation, improvement, or refinement over a broad range of criteria. On a small model/autonomous boat battling super typhoons, rouge waves, vicious currents and curious sea monsters on a daily basis (not to mention a regular old storm which is almost certain to send just about anything without a human aboard skipping/tumbling/flying way off coarse if not to the bottom or to pieces) sea survivability is the primary concern or no? Here it is - the ultimate autonomous vehicle - sleep at home in peace while your baby is alone at sea getting some rays - survives anything imaginable thrown at it - and no! its NOT that ridiculous dome constructed soccer ball. A picture can describe a thousand words, but I'm not into that. I just listen and visualize.

    Three 8" diameter plastic pipes 20 feet long. Four 3" diameter plastic pipes 20 feet cut into approx thirds. Three 55 gallon plastic drums. Three 75watt AC motors with shafts and props. Looks like a "peace sign" For any visually impaired readers that is three hulls, two in the water and one directly overhead. 12 strut beams, four from each hull between and at each end of the shared center pod made of the plastic drums. Not much to fabricate, just three 100% water proof access hatches (covers) and you can seal them on long voyages if the computer doesn't *****. Should be plenty space inside for whatever - 100+ hours of battery power, electronics, (maybe even old but free SSB radio if SAT link is too expensive). Wrap the center pod full diameter with solar panels and you should get at least 200-500 watts. In glassy water you get almost 2 suns. I wouldn't worry about loss of efficiency in this case with the two props in the water. With electric you can pulse drive them , and steer with them. the propellers can be mini wind turbine blades - you might push the theoretical limit of 85% prop efficiency (off the charts already at 70% which 99.9% of boats/ships don't reach. 5 knots at 80RPM with 1/10 hsp and 14 inch diameter cast aluminum 2 blade prop 7% blade area or something like that...magic of plastic tooth gearing. I think you could equip it with a water ballast and submerge the two hulls like a SWATH for ultimate survivability pretty easy if it warns you or figures it out for itself whats up. Downside? - if you need "stealth", go with your sea turtle drawing and the lead weights.

    What type of autonomous control are we talking about? like it sends/receives text messages at sea? or full remote (high speed SAT link with realtime video !! ) piloting capabilities? or hit the start button, turn it loose and wait for it to be where it is supposed to go?

  3. MurphyLaw
    Joined: Aug 2012
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    Location: Mars

    MurphyLaw Senior Member

    Before you chose the best hull, consider the area you are going to have to cover with solar panels to get the power you need to move in any direction.

    10 square meters of solar panel in a 40kt wind and 6kts ocean current is probably going to need more than the 1KW of power the panels will produce, to travel in any direction.

    The wind is going to be your biggest problem, the more solar panels the more drag the more power needed. My advice is make it neutrally buoyant and in poor seas submerge and travel just below the surface say 5m.

    If it is never going to carry passengers then you may as well go for a submarine hull, I would make a tube that has flexible solar panels that can by rolled out in good conditions and no other boats are nearby, in poor weather conditions or if boats are detected nearby it would submerge to 5m and wind the solar panels back into the hull. Then you are traveling underwater with the most hydrodynamic shape and no wind resistance, low on power then go to the surface and collect sunlight and communicate with base.

    If you make it neutrally buoyant then it will always float the the surface if something goes wrong, you will use fins and the forward speed of the motor to keep it at a depth of 5m, if the motor stops it will rise to the surface. Make it out of CoreCell S foam which can withstand depths of up to 800m and will make it virtually indestructible if it collides with other boats, nets etc.