Homebuilt boat for Baltic Sea?

Discussion in 'Boat Design' started by Jim Holm, Apr 4, 2019.

  1. Jim Holm
    Joined: Apr 2019
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    Location: Sweden

    Jim Holm New Member


    I will begin to say that I have no experience in boat building or of sailing.
    I have build a live steam model boat but that's all.

    I want to start a project to be able to pilot it across to Baltic Sea.

    As I'm a very inexperient Helmsman/builder I want it to handle rough water very well so if (or when) I make a beginner mistake I will have a bigger marginal of error.
    It should also be very simple to construct so I don't get tired of it and put on the shelf.

    I really like flat-bottoms because of the great speed and simple in design/construct, however I understand that these designs does not handle rough water very well.
    I did consider something like a military beach-lander at first but maybe a simple cabin cruiser would be good?

    It should be under 25ft and powered by a inboard and made from plywood
    My priorities for this project is...

    1. Simple construction
    2. rough water capable (ocean worthy)
    3. good fuel economy
    4. speed
    5. ?

    So my question is do you have any suggestions on design and rules of a thumb in boat designs?
  2. Alik
    Joined: Jul 2003
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    Location: Thailand

    Alik Senior Member

    Why not buy second-hand boat and get some experience? Or better, join sailing school first...
    Doug Lord likes this.
  3. Jim Holm
    Joined: Apr 2019
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    Location: Sweden

    Jim Holm New Member

    I need something to do at home and some exercise for my brain so I sleep well at night;).

    I have looked at second hand boats but I would like to tweak with the drive train, hull and everything, something to make me busy.
  4. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Buy an old wooden boat. Renovating it will keep you busy enough. :D
    kerosene likes this.
  5. Dejay
    Joined: Mar 2018
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    Location: Europe

    Dejay Senior Newbie

    I'm a newbie so I can't give you trustworthy advice. But I also want to build a boat that is capable of coastal cruising in the baltic / north sea. So someone please correct me if I'm wrong. I've started reading "The Nature of Boats" which gives a good overview of boat types. I should probably spend less time on this forum and more reading ;)

    I think you have to specify more and make compromises. Your requirements are naturally contradictory. Like how fast do you need? Does it need to be trailerable? What range?

    Simple construction means glass sheathed plywood and hard chines.
    Beaching capable would mean a catamaran or a flat bottom Dingie. They can be larger too. Or maybe a sea bright skiff.
    But catamarans aren't simple to build and sea bright skiffs are more complex than easy to build dingies.
    Dingies can be fast but not especially fast. Except maybe when they are planing but that is not very fuel efficient. Gerr describes a flat iron Dingie, an Offshore Skiff Cruiser/Commuter with 8.6m LOW, 2.4 beam, 2500kg displacement with an 75hp outboard motor going 16 knots. Something like 1.2L per mile at that speed.
    Fast in general is not fuel efficient, if the cost of fuel is a concern. 6-8 knots in displacement mode is probably much more sensible.
    Fuel efficient means long and light, nothing else matters as much. Which increases cost and complexity to build.

    This is as far as I got in the book :)

    I'd love to know if offshore capable monohulls always need ballast, or at least a lot of extra weight near the bottom. Compared to a multihull, that would make them always more fuel inefficient.

    Maybe a "power proa", a long slender monohull with accommodations that gets it's stability from a small outrigger not needing as much structural reinforcement as catamarans and that is easily demounted for trailering. But I haven't seen plans for something like that, only for sailing proas and they are kind of shunned for their "exotic" shunting.

    I'm also going to take a sailing class for a boating certificate. Knowledge even in the absence of experience should improve the margin of error more than any boat alone can.

    The suggestion to buy a used boat for tinkering is probably the most reasonable one.
    Blueknarr likes this.
  6. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

  7. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member


    I don't usually hijack threads like this but

    Your advice is spot on. Some of the most trustworthy I've seen on this forum. I hope the OP heeds it.
    tlouth7 likes this.
  8. Dejay
    Joined: Mar 2018
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    Location: Europe

    Dejay Senior Newbie

    Thank you! But lets hope I can heed my own advice ;)

  9. Jim Holm
    Joined: Apr 2019
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    Location: Sweden

    Jim Holm New Member

    thanks for you great advices and infomation!

    To clarifiy a bit.
    Speed is low down on my priorities but not negligible and breaching is not necessary, it has however need to be trailerable and that means a max width of 3500mm but favourably max 2600mm

    The DE25 cuise looks nice...

    Great website Jürgen Sass!
    I read you articles and found them very intresting.
    The three designs presented in article Långfärdsmotorbåten looks very intressting especially the Bogskär design.

    Is it possible to get plans for the ribs (spanten)? Then I can scale them and get a basic frame to go after.
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