camper boats and water ballast

Discussion in 'Boat Design' started by sand groper, Jan 20, 2010.

  1. sand groper
    Joined: Jan 2010
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    sand groper Junior Member

    Newby poster here. I've sailed a bit and live in country WA.

    I want a shoal-draft camperboat to use on an inlet where draft can be very restrictive as so much of it is shallows and the depth can vary daily.
    Launching is difficult due to a shallow 'ramp' too. And howling south-easterlies are frequent.

    Winching a lead keel up and down all the time would require heavy batteries and it's just more weight to tow, so a conventional monohull trailer-sailer is out unless the heavy c/board was replaced by a light board and ballast.
    I can't fit in a Red Baron cat t/s and can't find a 6m Jarcat, and rather than build one I might as well build an 'ideal' boat.

    So I had a look at Bolger / Michalak / duck boat etc. type boats and they have good points but none seem quite right. Thought about a mono-ised Jarcat 6m concept too.

    My thinking is to buy a low car trailer and build a ply or f/sandwich 'fat sharpie' to fit it, with leeboard(s) or maybe just lots of flat sides as per hobiecat to reduce leeway. It might have to be a motorboat upwind, and reaching might be as close-winded as it gets, but that's no problem with a small yacht-propped 4-stroke.

    Presumably ballast would be required and it would be great to have a heap of battery capacity and solar-panel awning/bimini thing and electric drive with back-up generator instead of a petrol outboard, but if there's a lot of battery, then why not winch a keel up and down ??? So the design process kind of goes round and round.

    A question re water ballast - obviously an internal tank does work, and an external tank similarly, but would an external tank that self-fills and drains very slowly through small holes do much the same job if these holes were continuously submerged ? It sorta makes sense but any thoughts on this would be appreciated.

    If anyone has a design for a floating tardis that is light-ish yet stable, tough, and roomy inside and out and can sail through 180ยบ (a converted polypropylene lap pool under venetian blind sail/shade perhaps) then let's have it ! Having spent so long thinking about converting an FD or a surf boat, or making a hobie plus hartley into a trimaran it's about time for some more sensible ideas.
    regards, Rex
  2. Tiny Turnip
    Joined: Mar 2008
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    Tiny Turnip Senior Member

    A couple here, one water ballasted, and the others a slightly different take for shallow cruising grounds.

    Hope there's some ideas, or food for thought. Cheers!

    Swallow boats bay cruiser:

    a water ballasted 6m design. 450kg all up empty, plus up to 400kg water ballast:

    a blog from the owner of bay cruiser #1:

    Mitchells Explorer:


    A slightly different take on the swing keel: a 4.5m dinghy like camper displacing 360 kg, with a deep, high aspect ratio *hand winched* swing keel:

    The Winklebrig:


    A 4.8m (plus bowsprit) twin bilge keel (retracts into the cabin seats, keeps the floor clear of centreplate) 650kg ballasted design. My own boat. Not particularly fast! draws about 350mm with plates up. No longer in production.

    I sleep 2 adults and 2 kids in my WB. very cosy, but works. Ideal for 2 up.
  3. sand groper
    Joined: Jan 2010
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    Location: southwestern australia

    sand groper Junior Member

    Thanks for that Mr/s Turnip. The bay cruiser certainly looks good and reasonably launchable -a breakback trailer might help at my intended location. Your Winklebrig is a looker two.
    I'm a bit wary of bowsprits and bumpkins because they can make sail and boat handling difficult, but the bay cruiser line about going to windward in a blow under jib and mizzen makes sense.
    Lack of speed isn't a problem here as the south coast inlets are all small. There's not much cruising to be had as the coast is either a long sandy lee shore or a long rocky cliff lee shore and there's hardly an island or harbour for many miles.
  4. messabout
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    messabout Senior Member

    Bolgers Black Skimmer fits fairly well with your original post. The Skimmer will sail in 50cm of water. Not just float, but actually sail. It has a flat bottom, damned clever leeboards, and its' skeleton is on the outside which makes a very clean interior while providing protection for the skin. It uses precious little ballast...I think about 175 kg. Yawl rigged with free standing masts. It also has flooded bow compartment which is not for ballast purposes but does have real world advantages....Like a self cleaning anchor as well as a useful place to bathe/shower while inboard but remote from the cabin. Not a boat that you would want to do a round Oz trip but quite nice as a camp cruiser.
  5. sand groper
    Joined: Jan 2010
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    Location: southwestern australia

    sand groper Junior Member

    Thanks Messabout. I hadn't spotted that one before and it looks good apart from the 500 lbs of concrete. Presumably a water tank might do the same job though 2.4 times greater in volume of course.
  6. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    Welcome, sand groper.

    It occurs to me that water as ballast would be illusory, at best, especially fresh water, which has less density than the salt water it would be displacing. Wouldn't that want to lift the nether parts?
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Shoal boats don't need ballast, nor is it desirable in most small craft to do so. There are a lot of shoal cruisers that don't use lead other then a sinking weight on the board(s).

  8. sand groper
    Joined: Jan 2010
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    Location: southwestern australia

    sand groper Junior Member

    So maybe a flat-bottomed hullform that's something between a DUKW and a Dutch botter around 5-6 m long and 2-2.4 m beam ?
    Presumably it could go to weather to an extent depending on a shallow full-length keelkeel / boards / slab-sidedness and so on and would handle a blow until it suddenly tipped over. Ballast would negate this I guess.
    What's on my shopping list is a 2.5m cockpit, 2.5 m cabin, sitting headroom for a 1.85m man and trailable. It doesn't have to be pretty, just strong and light-ish.
    In fact I kind of want a 'heresy boat' (A Heres-hof ?). Made of steel sheet / foam sandwhich coolroom panels, plastic, whatever. I like the classic 'proper' boats but would like to experiment a bit.
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