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Old 29-11-2010, 08:35   #1
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How Do I Design a 3' Draft Boat to Be Seaworthy ?

Hello everyone and thank you for such a rich and informative forum! I'm Richard, I'm 28, and my dream is to build a sailing boat that I can live on and explore the whole world.

My home port will be the upper river Thames which is navigable through Oxford where my parents live. This requires a draft of less than 3' and a mast that can be lowered to clear 70 bridges. I also want the boat to be sea-worthy enough to cross the North Sea. Ideas:
  • smallest possible live-aboard, perhaps 20' LOA?
  • cold-molded
  • flat-bottomed for beaching
  • leeboards
  • mast in tabernacle
  • well secured internal ballast

Obviously this would be great for creek-hopping, rivers and canals but could I still sail out into the Atlantic and visit my granny in Argentina? How would you design it to make it more sea-worthy? Your first thoughts are much appreciated.
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Old 29-11-2010, 09:17   #2
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See if you can find the designs of Phillip Bolger. He designed a lot of unusual boats that had very limited draft.
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Old 29-11-2010, 09:20   #3
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A Flat Bottomed blue water passage-maker that you can beach?
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Old 29-11-2010, 09:27   #4
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Richard,
Look into the Krogen 38 foot Cutter that was build in the States in the eighties. Krogen designed a lot of power boats but the 38 was the only sailboat that I am aware of that he designed. It is a great boat with lots of room and twin centerboards, one forward one aft. With boards up she draws about two and a half feet. Maybe you can buy one for less than a new build.
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Old 29-11-2010, 13:45   #5
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Thumbs up

Thanks for the tips! I've just ordered "Boats With An Open Mind" by Phillip Bolger.

Quote:
Originally Posted by Shrew View Post
A Flat Bottomed blue water passage-maker that you can beach?
That's about right - a boat for the two extremes of shallow draft creek-hopping and off-shore sailing. I appreciate that these are two completely different boats, but I'm looking for a compromise.

I've never built a boat before. I'm considering short courses at the Boat Building Academy down in Devon. My first build will be a sailing dinghy built in the same way I'll eventually build my liveaboard to practise the techniques.

I think the Krogen 38 foot Cutter is far too big for my construction and maintenance budget/abilities. I'm thinking leeboards to avoid making holes in the hull - are centreboard casings and lifting keels really worth the trouble for a novice like me? Can I go and visit my granny in Argentina in a carefully designed shallow draft boat with leeboards?
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Old 29-11-2010, 14:00   #6
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Cross the North Sea on a ferry some time in the next 4 months and then decide if it is worth compromising safety so that you can sail to Oxford.
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Old 29-11-2010, 14:31   #7
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I don't know about the mast, but look at one of the smaller Southerlys with a swing keel.

Or, design a multi-hull. Or, save all of the design angst and buy a set of plans for a small cruising cat, such as the Maine Cat 30 (which draws around 24" with the daggerboard up).
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Old 29-11-2010, 14:37   #8
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Look into multihulls. As far as seaworthiness in a very shallow draft sailboat, these do the job admirably. You will probably need something to counteract leeway, but I am more a fan of unballasted fins than swing keels. Also, 20' liveaboard is not going to be comfortable.

(Coming from someone who sailed and lived aboard a 22' swing keel boat.)
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Old 29-11-2010, 14:39   #9
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Here you go, everything in one package. You'll need to consult with the designer about the lowering of mast. Parker Marine





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Old 29-11-2010, 14:50   #10
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The reality is your going to have to live with a max of 4ft6in - 5ft headroom...
Is it essential you build it or would you be content with a grp boat with 3ft draught and a tabernacle mast thats seriuosly sea worthy...?
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Old 29-11-2010, 14:58   #11
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Richard hi and welcome to CF. I think something has to give with your requirements. Can I suggest the trip to Argentina and the length. You don't say if you are on a limited budget but presumably as are most of us on here btw, so how about one of these with a tabernacle to lower the mast.

http://en.wikipedia.org/wiki/Hirondelle_(catamaran)

There are other cats to consider like the Warram Tiki 26/28 but if you are thinking of living in London during the winter on board I think the Hirondelle will be more suitable and surprisingly large amount of space on board.

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Old 29-11-2010, 15:09   #12
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Voyaging on a small budget by Anne Hill is an excelent book and has details of a monohull design that is both shallow draft,easy to build and seagoing as well as lots of other useful ideas and advice (ps plywood and ugly to some)

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Old 29-11-2010, 15:16   #13
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If your determined to build your own Maurice Griffiths had some great home build plans.. the best known are the 26ft Eventide and the 30ft Waterwitch... strong seaworthy boats... you can get a CD with the plans for just 6.50quid... well worth the money even just to study...
http://www.eventides.org.uk/images/img87.gif

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Old 29-11-2010, 15:23   #14
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If you are planning to build a boat to save money, you won't. If you are planning to build a boat because you enjoy building a boat, fine.

When you add up all the parts, fittings, mast, rigging, sails, anchors, winches, etc, etc, etc, even if you buy them used it will cost you more than finding a good, used boat that is already equipped.

Thought about it, did the math, decided against it.
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Old 29-11-2010, 15:36   #15
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To be blunt, you don't design a boat. Thats what Naval Architects do, and they spend years, if not decades, learning their craft.

You have, I think, 2 possible solutions:

1. Buy 2 boats - one for puttering about on the Thames and 1 for blue-water offshore sailing

2. Buy a shallow draft multihull - it will be a bit of a compromise for both of your stated goals, but will probably do the job.
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