Steel dinghies

Discussion in 'Metal Boat Building' started by Skippy, Sep 21, 2005.

  1. Milan
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    Milan Senior Member

    Oops, I tried to attach few photos, I see that it didn't work. Can somebody explain how can I do that?

    Milan
     
  2. Jeff
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    Jeff Moderator

  3. MarkC
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    MarkC Senior Member

    Milan,

    click the 'Post Reply' - not the 'Quick Reply' and scroll-down. You will see 'Manage Attachments' - there it will allow you to down-load a copy of your pictures on your own computer drive. You click on OK - then 'Upload Attachments'. You then have a little picture on the bottom of your post.

    The other way to do this - to have the picture actually in your text is more difficult - you have to save your pictures to an on-line picture hosting site like sony imagestation or others - you then have to copy the picture's link once this picture is saved in the imagestation and then post the link in your post.
     
  4. MarkC
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    MarkC Senior Member

    While I am no designer or boat-builder - and I will have to tip my hat to Thunderhead who has this experience, however:

    'Unfortunately there are more steps involved in making a steel boat than an aluminum one.'

    - well OK, steel has to be painted.


    'Material handling, preparation and finishing are more expensive, and labour is the highest cost in any job these days.'

    - 'more expensive' - this is debateable - isnt aluminium welding equipment expensive? Ok - you dont 'need' to paint some aluminiums, and steel has to have special tools to cut it.

    Thunderhead wrote:

    'I also think that steel is a fantastic building material. There is a lot said about how aluminium has a higher strength to weight ratio than steel, but for a member of a given size steel is still stronger, stiffer, more abraison resistan, more fatigue resistant (often overlooked by people building aluminium boats) and a lot cheaper. The epoxy paint systems they have now make the rust issue nearly a one sided arguement.'

    Sorry - I was preaching to the converted! Only just read your comment in Wynard's thread on 'Durable Steel Hulls'.
     
    Last edited: Sep 23, 2005
  5. Milan
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    Milan Senior Member

    Thanks for help Jeff and Mark. Let's see will it work this time:
     

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  6. Milan
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    Milan Senior Member

    Some building photos:
     

    Attached Files:

  7. MikeJohns
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    MikeJohns Senior Member

    Milan

    Thanks for the interesting pictures.
    Do you have any scantling info for these boats?
     
  8. Bergalia
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    Bergalia Senior Member

    Difficulties in welding sheet below 3mm ? Is the art of brazing lost ? :rolleyes:
     
  9. Milan
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    Milan Senior Member

    They are built from 3 millimeters thick steel plate, stick welded. Rubbing strake is usually galvanized steel pipe. Rowlocks are just piece of round steel bar (with a steel ball on top) welded on the rubbing strake. Most of the boats are frameless. For floors there are usually few pieces of flat or L profile bars. These boats are largely built by eye, not by precisely following some building plan. When shell is done, it's easy to see if some parts of bottom or sides need a bit of additional rigidity. If that's the case few short bar pieces are welded on those places.

    Milan
     
  10. Skippy
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    Skippy Senior Member

    Thanks for all the answers, this is a subject I've been wondering about for a while.

    Milan: They tolerate rubbing and bumping into the sometimes rough wharf sides or other boats like no other material.

    That's what I would expect. Maybe a few dings once in a while, but excellent survival rates. I have a hard time believing waves would cave in a small hull any more easily than a large one, since the shape of a small hull has tighter radii, which increase strength, to compensate for the thinner material. Steel is one of the most elastic materials around, so I would expect permanant deformation to occur only on contact with shoals and other hard objects. The construction objections sound more realistic.

    That blue yacht in the photo looks nice. I've been finding more advantages to steel as I think about it more, for instance the keel plan can be a little more aggressive (efficient) since it's stronger.

    If the deck is wood or grp sandwich, then the cg will be lower than single-material construction, so the keel ballast can be lighter, partially compensating for the extra hull weight.
    Edit: Okay, I'll back off from that one somewhat. Ballast should be a little lighter proportional to the total weight, but maybe not in absolute amount.
     
    Last edited: Sep 23, 2005
  11. Skippy
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    Skippy Senior Member

    How much of the material strength is retained in a braze joint? That sounds maybe not quite so reliable.
     
  12. Milan
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    Milan Senior Member

    Skippy, these boats are almost indestructible. Even if exposed to extremes, for example collision with a much bigger steel boat they don't sink and its cheap and easy, although rather noisy to repair eventual dents - just whack them few times with a sledgehammer.

    That blue yacht that you like was built in some numbers in The Netherlands during the sixties. I owned one for a while couple of years ago. She was very smart sailer, quite fast. Type's name is Regina. Hull's where riveted 1.5 millimeters thick galvanized steel plates, plywood decks and cabins. They are 7.10meters long and 2 meters wide, with a canoe stern.

    During sixties and seventies, hundreds of small hard chine sloops of similar size, just a bit longer then Regina, 7.5 - 8 meters where built from welded 3 mm plates. Most of these boats are still going strong.
     

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  13. MarkC
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    MarkC Senior Member

    Sorry for stealing your photo milan!

    1.5mm rivited galvanised steel - see, there's the tricks!

    More please!
     
  14. MikeJohns
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    MikeJohns Senior Member

    Milan

    Any idea what size and spacing of the frames and runners ?
    What overlap for the plating?
    What type and number of rivets?

    Very interesting .
     

  15. sal's Dad
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    sal's Dad Atkin/Bolger fan

    Rust?

    One of the biggest reasons steel doesn't work so well in small boats is - RUST!

    We had a 12' light guage galvanized steel skiff, which got some rough use in salt water. The bottom got scraped, and it was a relatively short time before it rusted right through.

    With a heavier guage material, you have a lot more material before rust-through. But this is impractical in small boats. If you can guarantee the integrity of your coating system, steel will work fine.

    Gerr has a pretty good discussion of this in "Boat Strength".

    Sal's Dad
     
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