Coastal Cruiser

Discussion in 'Boat Design' started by Guest625101138, Oct 25, 2007.

  1. Guest625101138

    Guest625101138 Previous Member

    I have been putting my ideas for a coastal cruiser into a viewable format. An image is attached. It is at an early stage of development.

    Length is 14.7m, overall beam is 1.6m, WL beam 1.14m and displacement 1t.

    It has a 1.2kW wind turbine and 5 X 200W solar panels. There is 9600Wh of battery storage,

    I am planning on a 48V system that will give peak output of 4.74kW. This should give maximum speed of 12.4kts. Daytime cruising using storage, wind and solar should be at 10kts requiring 2.3kW. Overnight cruising using wind and solar for running and charging through the day and batteries at night requires 1.15kW to do 8kts.

    There is enough accommodation for two people overnight and will be roomy enough for four during day cruises. Performance calcs are based on two on board.

    It seems a practical concept. Should take about AUD25k to build and equip it. The hull is in three pieces so this will make it easy to transport and reduces the area needed to build it in.

    Any comments on experience with large solar panels, deep cycle batteries and small wind turbines will be appreciated.

    Rick W.

    Attached Files:

    1 person likes this.
  2. kach22i
    Joined: Feb 2005
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    Location: Michigan

    kach22i Architect

    Nice, kind of kayak-like, reminds me of this:

    Sea Jet
    The Advanced Electric Ship Demonstrator “Sea Jet” undergoes sea trials,
    Nov. 30, 2005, on Lake Pend Oreille in Bayview, Idaho.
    The 133-foot vessel is testing an underwater discharge water jet called AWJ-21,
    a propulsion concept with the goals of providing increased propulsive efficiency,
    reduced acoustic signature, and improved maneuverability over previous
    destroyer class combatants. U.S. Navy photo by John F. Williams
  3. Willallison
    Joined: Oct 2001
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    Location: Australia

    Willallison Senior Member

    Very interesting.... it's always good to see someone thinking outside the usual boat-box - especially when it's more than just a weird computer rendering with no naval architecture behind it.

    Difficult to see from the pic - but I assume that the small keel shown (along with all those batteries) provides sufficient stability...what's she going to be like at rest.

    Furnishing the interior in a practical manner will prove quite a challenge - have you got any drawings of a layout?
  4. TerryKing
    Joined: Feb 2007
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    Location: Topsham, Vermont

    TerryKing On The Water SOON

    Very Interesting!

    Rick, what kind of ratio is there between the power derived from the wind turbine and the drag it creates? I assume the answer is a lot different between a reach and much more upwind...
  5. Guest625101138

    Guest625101138 Previous Member

    I have attached a plan view of the central portion. It is not easy fitting useable accommodation in something so narrow. This is my first pass. Two bunks, table, bench seat will have swivel chairs and provide interior steering position. There is a hatch through to the front deck. The front section will have an anchor well that can be reached from the hatch. There is an enclosed head/shower area. The drive leg will sit into a well under the table. It will be light enough to man handle out of the well for inspection and for transport.

    The need for adequate stability without a weighted keel set the beam. It has a KMT of 0.85m and there will be 240kg of batteries under the bunks just above the keel line. The solar panels weigh 70kg and they are 1.85m above the keel.

    The wind turbine shown is a commercial unit but I might have to make my own unit. I want efficient blades so the thrust force is not significant in contributing to heal. This data is not given for commercial units. I am also considering using 4-quadrant drives on both the water prop and air prop so I can choose which one provides propulsion and which one is generating. This also gives redundant propulsion systems using the solar/battery power.

    Attached Files:

  6. Guest625101138

    Guest625101138 Previous Member

    This information is not readily available for commercial units I have looked at. I can design blades if necessay to optimise the output for the drag. If I went up in size with the wind turbine it would be possible to do 10kts directly into a 15 - 18kt wind with wind power alone. It requires something like 5kW from the wind turbine going into the water prop. This means 2kW to the hull, 1.2kW into water prop and motor losses and 1.8kW extra at the water prop to push the wind turbine through the air.

    The most important feature for going directly into the wind is the efficiencies of the blades and power transmission. The motors/generators are 90% efficient. Both the air and water props can be designed to give around 88% so overall efficiency is better than 60%. This is good enough to get a good proportion of the wind speed into the wind. However I am not planning to rely solely on wind power. The diameter of the wind prop ends up being too big. It will be handy to have batteries being charged at night if anchored.

    Rick W.
  7. lewisboats
    Joined: Oct 2002
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    Location: Iowa

    lewisboats Obsessed Member

    One of my observations would be that it would be a wet ride...very little buoyancy forward to lift the bows so waves would be penetrated rather than rode over.

  8. Guest625101138

    Guest625101138 Previous Member

    I agree. Hulls like this tend to just carve through waves. The forward 3.4m will be foam filled and contain no more than an anchor well.

    The benefit of the fine entry is that there is no inclination to slam so ride should be comfortable. Speed is relatively slow for a 48ft boat anyhow.

    Buoyancy builds toward the central accommodation and it is very light so I do not expect continuous green water over the windscreen. I thought about a reverse angle screen to reduce the likelihood of water running up over the solar panels. It would also allow one more solar panel but it increases wind drag.

    I might draw a reverse angled screen to see how it looks.

    Rick W.
  9. kach22i
    Joined: Feb 2005
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    Location: Michigan

    kach22i Architect

  10. Guest625101138

    Guest625101138 Previous Member

    The optimum hull to do 10kts without stability constraint is something like 60ft long and 18" WL beam. It takes around 1.15kW to do 10kts. This would need to be stabilised with a deep keel or outriggers. Either of these increase the power requirement.

    Once you fit outriggers the boat loses its self-righting ability and I have the opinion that small boats should have solid buoyancy to stay afloat and be self-righting.

    The bigger boats being developed for ocean crossings are trimarans but much heavier and much more expensive than I want to put into a boat:

    Rick W.
  11. Chris Ostlind

    Chris Ostlind Previous Member

    Duffy Voyager

    I assume you've already studied this boat from Jim Antrim.

    I like what you are doing, Rick. You've made some very interesting solutions to the standard mindset limitations for a skinny boat and its efficiency potentials. This looks to be a fabulous project and I'd like to follow it as closely as your comfort permits.

    I'm not too sure that a skinny tri could not be given self-righting properties, though.

    There's an awful lot of electric power on board to drive a pump to flood and/or fold an ama if the main compartment could be made watertight. That could change a whole bunch of behaviors on board, knowing that righting is available at the touch of a button.

    Attached Files:

  12. Guest625101138

    Guest625101138 Previous Member

    I had not seen the Antrim design. It is almost what I described in the previous post. This is what an optimum hull for 12kts would look like. However it has limited range. There is no energy collection.

    I am after some usable accommodation and enough flat space to fit commercial solar panels. I am aiming for 8kts continuously so I have to have enough energy collection to average 1.2kW. I would hope to run at 10 kts at 2.15kW for a 12 hour day using wind power to top up batteries at night while anchored.

    I have purchased small batteries and a neat little electric motor so I can do some trials on one of my slender hulls. I will trial most aspects before I start building.

    Rick W.
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    There is one operational hassle tho.
    Most folks attempt to find a nice quiet harbor for overnight , so the required recharging breeze may require anchoring away from shore , and the comforts of smooth water, and close facilites.

    Also most wing generators do make a noise from the blades while in operation.

    Certainly minor compared to a diesel of any type , but for sleeping , it will have to be accepted.

    Some areas might have enough tide for a larger underwater prop to be let astern ,while at anchor, to create quieter energy?

  14. Guest625101138

    Guest625101138 Previous Member

    I have considered the forward raked windscreen. It allows one more solar panel. The power output will more than offset the extra weight.

    I have also confirmed I can get it on a traler that has a width limit of 2.5m. The attached plan view shows one of the possible ways. There may be better ways but I would need to spend more time with it.

    Rick W.

    Attached Files:

  15. SeaSpark
    Joined: Mar 2006
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    Location: Holland

    SeaSpark -


    I am very impressed with your ideas, and the effort you put in to them.
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