minimalist cruising, sailing, rowing design

Discussion in 'Boat Design' started by scotdomergue, Jan 27, 2009.

  1. scotdomergue
    Joined: Jan 2009
    Posts: 139
    Likes: 9, Points: 18, Legacy Rep: 45
    Location: Twisp, WA USA

    scotdomergue Scot

    I'm in process of designing my ideal boat (current vision). Current thinking and drawings below. ANY THOUGHTS AND ADVICE WILL BE GREATLY APPRECIATED. Note that I'm fairly clear about what I'm trying to achieve, but also recognize my relative ignorance and am open to any and all ideas. My current boats are an old Venture 17 (small cruising sloop set up with oars as auxilary power) and a Feathercraft K-light (folding kayak). I'm an experienced small boat sailor and kayaker.

    Design Parameters/Concept, Cruising-Sailing-Rowing Boat:

    Purpose: minimalist single handed cruising, adequate for occasional 2nd person; fun to sail, good for rowing.

    Design parameters:
    - Minimum weight to be easily driven by sail or oar, for ease of transport and handling, and for beaching and righting by single manhandling.
    - Small cabin; space equivalent to a small backpacking tent, comfortable to sleep one or two; can stow Bike Friday (folding bicycle) on one side forward if only one person is to sleep in the cabin.
    - Cat rig with dagger board for simplicity, ease of single handed sailing, light weight, etc.
    - Cockpit deck/benches flat like a racing dinghy, with strap on floor to hook feet and sail with butt/body out over water (like a Laser, though more freeboard); height set to mount oarlock pins directly for ideal row-rig dimensions.
    - Sliding-seat rowing for power, aerobic exercise, comfortable and efficient use of body; tracks for seat mounted directly on (or built into) cockpit floor, w/ grooves & adjustable location attachment for footplate.
    - Under floor storage channels for dense stuff (eg. water, canned food, tools), in both cabin and cockpit - when adequately loaded provide ballast probably adequate for self-righting.
    - Hatches in cockpit benches allow stowage of oars, mast sections, boom, sail, etc. with long things extending into cabin.
    - Positive floatation.
    - Intended to handle the worst of weather/sea conditions on sea anchor with mast, boom, oars, etc. safely stowed – if ever necessary.

    Current design:
    - 16 feet long, of which the forward 8 ½ feet is cabin.
    - 5 foot 4 inch beam.
    - 5 inch draft (board up; probable range of draft from 4 inches when lightly loaded to 6 inches heavily loaded), an additional 24 inches draft with board fully down (29” total).
    - Rounded canoe/dinghy hull with 3 foot wide transom, expected to plane fairly easily with adequate wind (particularly when lightly loaded).
    - Cabin floor at design waterline (5 inches above lowest point on hull).
    - Cockpit floor slightly sloped toward stern from 2 ¾ inches above waterline (forward) to 2 inches (at aft end); self-draining through holes in transom.
    - Foot strap along center of cockpit floor and eyebolt center forward to attach safety harness.
    - Aft deck (cockpit benches) at 10 inches above design waterline and 15 inches wide.
    - Oarlocks mounted on outside edge of deck/cockpit benches.

    - Hand laid epoxy/fiber over foam core (1/2 to ¾ inch foam core, glass/Kevlar/carbon fiber)
    - Dagger board is stainless steel or stainless steel core with foam-core, filler & epoxy-fiber to shape; top of dagger board will clamp/seal to top of trunk; alternate cap clamps/seals to top of trunk if dagger board is out.
    - Carbon fiber tubes (or carbon fiber over foam core) for mast and boom; bottom of mast built into hull, remainder in 2 sections, each fitting into section below.
    - Plexiglass (or similar, clear) hatch door/cover for entry to cabin; all hatches to have secure latches and seals.
    - Anticipate weight of boat at about 150 lbs; about 200 lbs (max 250 lbs) with all row and sail rigging; carrying capacity expected to be up to 800 lbs (displacement about 1000 lbs).

    Attached Files:

  2. Tcubed
    Joined: Sep 2008
    Posts: 435
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    Location: French Guyana

    Tcubed Boat Designer

    I like .

    A few points;

    The cabin looks like it will interfere with rowing unless you plan on putting the oarlocks and rowing position very far aft or the companionway is huge enough that you partly enter the cabin at the end of the pull stroke.

    I think you're going to find it's quite a challenge to keep water from entering the storage in the cockpit floor. You obviously want to put the weight there but i see damp items. Creative solutions are called for or eliminate the cockpit and have flush deck instead.

    Something you should seriously think about is to not go with that conventional daggerboard. It is certain to leak and you can't get at it so easily and the case is right in the middle of the only internal living space . Lots of probs.

    Some alternatives;

    Daggerboard in front of mast. The case goes right through the boat-no leaks, out of the way, efficient, but larger turning radius and rudder must be larger and well balanced. Control lines leading aft can control it.

    Leeboards. This is the most efficient since they have a cambered section for one tack only . Won't break when grounded. Impossible to leak.

    Lee daggers. Same as above but does not ground well and more effort when tacking. Advantage is cleaner shape and no "clutter" on side of boat.

    One offset daggerboard. This would go right through the cabin so no leaks but out of the way. In practice the assymmetry is barely noticeable, if it is well designed and deep enough.

    That's it.
  3. timothy22
    Joined: Feb 2008
    Posts: 95
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    Location: florida

    timothy22 Junior Member

    L. Francis Herreshoff desingned what he called a beach cruiser to exactly your design goals, and arrived at a similar solution, published in "Sensible Cruising Designs." His was about the same beam, less deadrise, harder bilge, and about half the sail area. Here is where he departed from your idea. The hull remained that of a capable day sailer with side and fore decks. The "cabin" was obtained by using a standing lug rig, essentially a trapezoid roughly in the shape of a normal sprit rig, with the sail laced to a boom and a yard across the top, hoisted up the mast. The cabin occurred when he lowered the sail, tilted the mast aft in its step, and draped the sail over it, yard on one side, boom on the other. And he used leeboards. I am not sure I would use foam core in a small beachable boat. One of the DuPonts stopped at our yard coming and going to the Bahamas every year, and every year we would have to fix the bottom of his Boston Whaler and drain several quarts of water out of the core. The bottom is just too thin. Put your foam up under the side decks where it will help keep you upright if flooded.

  4. scotdomergue
    Joined: Jan 2009
    Posts: 139
    Likes: 9, Points: 18, Legacy Rep: 45
    Location: Twisp, WA USA

    scotdomergue Scot

    Thanks to both! Timothy, I'll look for the book - looks interesting and may give me ideas . . .

    TTT, You make good points!

    RE: cabin - rowing interference: The lines down the cockpit floor indicate tracks for sliding seat. Yes, the rowing position is well aft of center of boat, with oarlocks mounted between 10 1/2 and 11 feet back from the bow of a 16foot boat. How big a problem do you think this is? Exactly how would it manifest as a problem? I expect to balance weight with gear toward bow inside the cabin. It seems to me that this will work reasonable effectively. I've set up my Venture 17 with a similar rowing position (necessary because of cabin) - fixed seat, over 6 foot beam, oarlocks 21 1/2 inches above waterline and weighing 800 lbs, it's much harder to row than will be the new boat!

    RE dagger board in Cabin: At the very least, raising the dagger board would get water in the cabin - not a great situation. For a variety of reasons I'm now leaning toward a center-board design. I agree that this, as with dagger board, would take up space in the middle of a very small cabin which isn't ideal.

    RE cockpit floor storage leakage: After thinking about your comment, I'm currently thinking to access this space from inside the cabin and from the deck hatch behind the cockpit. Thus no holes in the cockpit floor or side walls (except the drain holes/tubes out the transom). Fresh water in sealed containers and other things in dry-bags will probably be what goes here, but having unintended water get in isn't great in any case.

    Thanks again!
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