New guy!

Discussion in 'Boat Design' started by BHOFM, Jun 15, 2008.

  1. BHOFM
    Joined: Jun 2008
    Posts: 457
    Likes: 14, Points: 0, Legacy Rep: 247
    Location: usa

    BHOFM Senior Member

    I have just retired and want to build a small sailboat!
    I have built several in the past, from 8 to 25 feet!
    I am very capable in wood working!
    I have two circumnavigations under my belt in a Gulfstar
    41, 1975, 78!
    I have been sailing since 1949! I am a pilot, retired photographer,

    I am working on some plans, these are very rough renderings
    of what I want to do!!

    Requirements are:

    Pull with older Toyota PU
    under 900 lbs
    Draft under 2'
    Simple to build
    under 16', city code, if you want to keep in at home not inside
    Overnight capable for two

    It will be used on a local lake, trips of 10 miles or less,
    weather sometime rough, but lots of places to ride it out
    at anchor! I have sailed this lake for over 40 years!

    The is what I have come up with, I would like to keep it
    close to what I have drawn, but am open to suggustions
    as to keel and mast placement

    length 15'
    Beam 7.5'
    Freeboard 2'
    Mast above keel 16'
    Draft 23" 315lbs per inch of hull immersion
    Sail area aprox. 130Sqf
    Ballast 200lbs concrete in plywood cases skeg

    Framed in cedar with cedar stringers and battens
    3/8 ply bottom
    1/4 ply sides and deck

    Laminated cedar spars
    Rope rigged with wooden blocks

    I plan on a canopy over the cockpit for overnighting,
    insects are not a problem here!

    I can make my own sails and blocks!

    The flat floor is needed due to some physical limitations!

    I am very versed in math and think I have worked most of
    this out,,?

    What I need to know is,

    Will it float?
    Will it float right side up?
    Where to place the keel?
    Where to place the mast?
    How much rake in the mast?

    See attached docs:

    BTW, I looked at seveal boat forums and this one seems to be
    the best of the best!
  2. Guest625101138

    Guest625101138 Previous Member

    Welcome to the forum.

    You might find that you could have some great fun with Delftship. It allows you to produce reasonable renderings of a boat in short time once you have practiced. You can then add complexity such as framing and any detail you care to. The software is free. Just Google Delftship and download the file after registering.

    Others here will be able to guide you towards a whole range of existing plans that represent good value but I think you know enough about boats to make a good stab and there is nothing like the thrill of launching something of your own creation.

    Delftship (or its precursor, Freeship) take a bit of learning but there is ready advice available here. It allows you to make nice drawings quite quickly and you can then get sheet development from the file.

    I have attached a lineplan of a slight variation of your hull. If you get Delftship I will post the fbm file so you can play with it. At the 200mm (8") waterline shown the displacement is around 900lb.

    The hull looks beamy to me but once healed the beam will reduce.

    I do not like the idea of concrete inside wood for a keel but I guess it is an economic solution. I would look around for a chunk of steel that could be faired with timber and glassed up.

    I would also make sure there is enough solid buoyancy in the hull so the boat will float if swamped. You selection of sheet thickness sounds about right. Delftsip can be used to give weight calculations quite easily as well.

    Rick W.

    Attached Files:

  3. BHOFM
    Joined: Jun 2008
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    Location: usa

    BHOFM Senior Member

    Thank you for your quick replay and interest.

    I looked into having a steel skeg make, rough shaped and
    welded to a plate that could be bolted to the keel, it was
    three times what we have planned for the entire project!

    I do not have equipment for working with steel. the
    concrete is less than $10. I had planned on glassing the
    inside of the case to protect the wood.

    I have a large amount of foam for flotation.
    I also have a large amount of waterproof 1/4 ply in
    2'x6' sheets that was on shipping crates for scaffolding.
    I am a pack rat by nature!

    This is to be a bare bones project, cheap is the main
    thing! I have plenty of time.

    I will look into the design program thing.

    We sold our Catalina 25 last year because of high mooring
    prices, from $400 a year a few years ago to $200 a month!
    And if you pull the boat out and don't keep paying the fee,
    they can't guarantee you a mooring next year!

    I would like to do this for around $500, less the sails and
    motor! I am planning on an electric motor with a small
    B&S running an alternator! Sort of a Hybrid set up where
    you don't need the gas motor all the time!

    Speed is not a factor at all, I would like for it to go to
    weather reasonably well and sail uprigh for the most
    part! My wife does not like the boat on it's side all the

    Thanks again!


    Bald Headed Old Fat Man
  4. messabout
    Joined: Jan 2006
    Posts: 3,168
    Likes: 333, Points: 83, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    The dimensions of your proposed boat along with the sail area and mast height, suggests that you will not need any ballast. The more weight you add, ballast or otherwise, the more problematic things become. Keep the boat as light as is reasonable, consistant with structural integrity.

    Your mast is a pretty short one. I'm in favor of that, but it will tend to dictate the configuration of the rig. You will be using a lug or gaff headed sail in order to get that much sail on a short mast. Either of those types will do the job. A square topped rig will help avoid too much boom length. Too much boom can be a misery when sailing off wind. In any case a short mast will diminish heeling tendency and the extreme beam that you have mentioned will provide a huge righting moment.

    The boat is not likely to be a fast one but it will be more comfortable and spacious than most boats of its' length.

    I suggest that you find a copy of Skenes' Elements of Yacht Design for help in determining the position of the mast and board (or keel). as well as inumerable other essential bits of information. The book is available in paperback and is not costly. ISBN 1-57409-134-4 cover price $19.95. The best buy you can get if you intend to pursue this project. The book will save you a lot of grief, and probably money, if you study it for a little while. There are other excellent books on the subject but this one is probably the most cost effective.
  5. Knut Sand
    Joined: Apr 2003
    Posts: 471
    Likes: 30, Points: 28, Legacy Rep: 451
    Location: Kristiansand, Norway

    Knut Sand Senior Member

    Can't be that expensive for a boat like that?
    A keel 160 cm x 60 cm x 2 cm will weigh approx 120 kg's (ready grinded), give better steering properties, it can be made swinging or retract (swinging is better against grounding....).

    To work with steel, you will only need a drill (which you probably already have) a grinder (cheap) and a lot of patience (and discs also cheap), (And patient neighbours and ear protection..., breating mask).

    Normal construction steel, coated with zinc epoxy, should do well as the boat is not intended to be on water for an extended period.

    If you use concrete, place some insulation mats against the hull (chop up some camping mats, plactic, and then concrete. Add a hose loop into the vet concrete for a rope to make it possible "easy" to lift up = (Divide into sections of approx 40 - 50 kg of concrete...You'll be on your knees the day you need to take them out...). If you intend to lock it in place, do that with some (bolted) beams across on top of the concrete.

    Added; Didn't read full through your reqirements, sorry, flat floor= concrete is a simple solution.
    Last edited: Jun 16, 2008
  6. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 489, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    You budget sounds overly optimistic, but several designs come to mind, including a couple of mine.

    Before getting into the actual scantlings and design elements of the boat, you should develop your yacht design education a bit. I mention this because your proposals for proportions, structural elements and the questions suggest a less then reasonable understanding, of the engineering and concepts necessary to develop a design. At least one you be willing to take your wife and family farther from shore then they can swim back to.

    In this regard it may be best (and considerably faster) to build from a set of stock plans. The looks could be altered to suit your desires, but the engineering and hydrodynamic requirements would be already met, with the likelihood of it floating, with the decks facing up on launch day being quite high.

    It actually takes some pretty clever engineering and design skill to develop a small boat that is cheap and easy to build. It would also be nice if it preformed nicely as well. Small boats in particular have less margin for error, so weights, structure, "centers" locations, stability, etc. need to be pretty finely tuned.
  7. BHOFM
    Joined: Jun 2008
    Posts: 457
    Likes: 14, Points: 0, Legacy Rep: 247
    Location: usa

    BHOFM Senior Member

    The reply I was expecting.

    This is all in the planning stage at this time! I have a lot
    of the materials I will need on hand. Performance is not
    an issue, it will just be a get a way thing, overnight now
    and then.
    I have looked at several plans and this is the closest I have
    found. It will need to be a bit shorter, it must be under 16
    feet overall!

    All the boats I have built in the past have been on a gig
    inverted, this one is different, and I am unsure of a few

    The plans are a bit brief?

    This is very close to what I want, but it needs to be fixed keel, I don't see that as much of a problem as it carriers
    internal ballast anyway! I don't care for the bow spirit or
    the sloping cabin bulkhead, these are minor things I know!

    Thanks for all the nice information, I will throw it up and
    see what flies!
  8. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 489, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Blue moon was pre taped seam concept and is a traditional plywood over frames build. My records show the design had a bad tendency toward weather helm, which most corrected with a bigger headsail. She'd be an easier, stronger, more water tight and less costly build using modern methods.

    A reasonably skilled wood worker could employ these plans and create a boat. The cabin profile, bulkhead angle and some other elements could be easily changed without compromising the design.

    Blue Moon is 20' over all, which includes the false clipper knee and rudder. She's 16' on deck, which means she could fit in a small garage without the stem knee and rudder, while being constructed.

    You'll find most of these free or low cost plans are less then complete and certainly with limited construction and material advise, let alone a living designer to consult.

  9. BHOFM
    Joined: Jun 2008
    Posts: 457
    Likes: 14, Points: 0, Legacy Rep: 247
    Location: usa

    BHOFM Senior Member

    I want to thank everyone that replied!

    We have had a change of plans, no wood was harmed yet!

    We are going to build a 12' daysailer.

    I found a nice set of plans online, free, with most of the details
    we will need.

    Do not see any need to change anything, but maybe a bit
    heavier centerboard!

    This design will better fit the material I have on hand, a
    large stack of 1x12x12' clear cedar, this is full 1' stock!
    I have 24 boards!

    Thanks again for all the advice!

    Attached Files:

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