Boat building in progress

Discussion in 'Metal Boat Building' started by evantica, Feb 15, 2010.

  1. KajWestergard
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    KajWestergard Junior Member

    When do we get to see the inside of the boat ?
    I´m very curious.
     
  2. Arvy
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    Arvy Senior Member

    Hi Hakan,

    Very interesting way to build a boat indeed, if I were you I would certainly read up on the scantling rules to determine what size of frames etc you do need. Myself I prefer the German Lloyds as they are quite easily to understand and available for free as well.

    One point of criticism tho, I see that some of the buttocks in your hullplating (between the 1st and 2nd chine for example, start counting at the sheer) are at the same vertical position. This causes this place to be a weaker spot in your hull, so you might want to take some extra care in the frames and longitudinals at that location. Luckily there are only 2 plates at that location with the buttock in line (this is causing a spot with 4 welds coming together into 1 place) so you might still be safe.

    Best practice is to have at least 1 frame distance (with a frame between them) between 2 buttocks, just like you would build a brick house. Which is much stronger than this.

    About the painting please don't use powdercoating like someone suggested

    What size is this boat, and what is the thickness of the hullplating you used?

    Keep the pictures coming.
     
  3. KajWestergard
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    KajWestergard Junior Member

    Hi Arvy,
    that was a good observation, I´m a ashamed that I didn´t notice.
    I was more concerned with the absense of a propeller aperture in the keel,
    which for me suggests that Hakan is going to carve out the aperture from the rudder and that´s no good way (as we all know :)

    I must confess that i sent him a private message in swedish about the matter
    and that I at the same time suggested to him to get a copy of "The elements of boatdesign" by Dave Gerr to get his framing dimensions right.

    So now it´s not private anymore, now You all know :D
     
  4. evantica
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    evantica Senior Member

    Hi there fellow seamen...
    Kaj: Yes the engine is a bit of a headache, and have no priority right now! yes It should be on priority list but...If I find an engine cheap and good enough I'll buy it, I'll rather spend my hard earn money on completing the hull and enterier and on the boatdesigner, who will arrive as soon it get any warmer!

    Arvy: Thanks for mention the "plating positioning weakness" and constructiv info, appriciate this! The size of boat is approx: 8,5 m x 3,2 m, draft 1,60 m
    about the weight I don't know yet, this have to be calculated! Hull plating is 4mm and 5/6 mm on the keel + a massiv piece of iron along the lower keel section! (will check in on the German Lloyd)
    Also of interest?! I have an ide' of using-if possible-the orig. frames from the lotsboat. These are quite huge and strong and in Oak, what do you think? I can then weld some "taps" and connect them to the hull/frame. This is just a "thought" I have so... like to hear what you say on this... also a pic from the inside when I turned her ower= nothing done! "Rear end of boat"
     

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  5. Arvy
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    Arvy Senior Member

    @kaj, I share your concerns :) but my eye fell on the seams right away, so had to tell him that right away. Btw I have read dave gerr's book, but would recommend using the book only to get an idea of how things work, but use more flexible (as in more flexible in positioning of frames and longitudinals) rules like german lloyds.

    @hakan, hull plating thickness is good, I would probably have used the same with the extra thickness on the keel (extra weight at a low point) even tho most rules will tell you that 4 for the keel would be enough.

    I don't really think that using the old oak frames is a good plan, for more than 1 reason (some of them are gut feelings however).
    first one: The old boat had the hull on the frames, now you have to remove the old wooden hull from the frames. but the steel hull has an offset to the old frames of the thickness off the old hull. This will leave you with a gap you will have to fill up somehow.
    second one: this is more a gut feeling, but steel and wood behave differently under load and with different temperatures, I have no idea how this would work out and what it would do the the shape of the hull.
    third one: an important part of the hulls stiffness (which is really important) comes from the rigid connection between the frames, longitudinals (or chines) and the hullplating and the deck. With the extra space between the hull plating and the wooden frames, it will be difficult to make this connection rigid.
    fourth one: if you would drill taps into the frames, and then weld those taps to the hull, you will have a gap for sure, and imagine the boat healing over, all the load of the water that doesn't get "transfered" through the chines would be placed upon the taps giving you a huge point load, with might cause the tap to be pressed into the wood, which won't do good to the hull shape, but even worse under repetive load the weld might get fatigued and break off or even puncture through the hull.

    One further point of concern: how are you going to put frames into the keel? If you decided to use the old oak ones, it will be very difficult to place them into the keel and somehow connect them to the plating. If you decide to use steel frames, you will need to think about how you are going to weld them that deep into the keel. Normally one would use slot welds to do this.
     
  6. Brent Swain
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    Brent Swain Member

    I've worked mostly this year repairing wood damage, where bolting wood on steel has resulted in the steel rusting thru. Keep the wood away from the steel as much as possible.
    Forget the transverse frames , just go longitudinals, as they are far more effective in strengthening and supporting the plate. With good longitudinals , transverse framing becomes irrelevant.
    The bermuda rig for my 31 footer cost me under $300, far less than a junk rig would, with all that extra line. Used sails for a bermuda rig are a fraction the cost of materials, and are available verywhere, ready made.
    Give your self a pilot house, and don't force yourself to sit out in the rain. Boats without pilothouses are bad seamanship.
     
  7. Arvy
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    Arvy Senior Member

    How could I forget about the rusting :)
     
  8. evantica
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    evantica Senior Member

    Brent & Arvy, thanks! I hear what you say...
    1st. The Ol' wooden frame: I've allready calculate the "space" between the hull/frame= no real problem there and I do belive I can do this ridgid.
    2nd. I dont know about temerature steel vs. Wood purhapse this is a huge problem, I have no idea!?
    3d. About the keel /wooden one: The Ol' wooden Oak keel will fitt like a glove in that keel space! I had an Idea of welding some plate "over the wood"= to hold it in place (yes I know the welding heat/wood will burn so please no funny comment;) )
    Finnaly: is there away to protect it from rusting, wood/steel?
    and Arvy will you please try to explain it "better" / in another way? purhapse with a drawing or picture??? Would really appriciate it!!!
    (My brain is sometimes not that clever to translate)
    """"Forget the transverse frames , just go longitudinals"""
    pic' on the keel sec. Oak
     

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  9. Arvy
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    Arvy Senior Member

    You need to isolate the wood from the steel and make sure no water can accumulate between the wood and the steel (wood by itself is moistly already). Very difficult to do.

    Which part would you like to see in a different explaination (or a drawing)?
     
  10. evantica
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    evantica Senior Member

    Hi arvy! the part I want you to be "clearer" about is "Forget the transverse frames , just go longitudinals" Do you mean no Frames ? Just Longinals ?
    Hakan
     
  11. Arvy
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    Arvy Senior Member

    Hi Hakan,

    It wasn't me saying that, it was Brent, I would never say such a thing :) but I don't want to start that discussion in your thread.

    Grtz,
    Arvy
     
  12. Brent Swain
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    Brent Swain Member

    Yes . No frames . Just longitudinals, as frames have been proven totally irrelevant in boats the size of yours, time and time again. .
    Now that you have got the wood out of the boat, keeep it out . Use it for interior joinery only, not structural. There is no reliable way to stop soggy wood from corroding out any steel under it, especially in low, damp areas ,like the bilge..
     
  13. evantica
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    evantica Senior Member

    ok & thanks for answer! Heres another one... The next step is to weld her up from the inside. But I'm a bit unsecure If I shall weld her completley first? and then put in the frames/ longitudunals? or...
    Purhapse it's better do some frames/ longitudunals first?
    I intend to do some "stabiliser" som make her steady and not bend and so before anything!!!
    The reason for asking is: If I weld the "longitudunals" -right inbetween where the steel plates meet/"chine"-will this be a stronger connection?
    or/if I weld it before and then weld the Longitudunals in place? Hope you know what I'm asking???
    And how about dimention in millimeters on those Longi./ Frame you suggest?
    If you have the time and kindness to answer I appriciate it!
     
  14. Brent Swain
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    Brent Swain Member

    The chines are longitudinals in themselves, structurally. They are phenominally strong ,without anything added. Put the longitudinals betwen the chines, on the plate, where they are needed for stiffness. You need to put the longitudinals in before welding ,to stop the shrinkage of the longitudinal welds from turning the plate into a roller coaster, which would make it extremely hard to force the plate straight and get them in. Dont put any transverse framing in before welding the longitudinal welds. Otherwise, stiffening the hull at frames, while longitudinal welds shrink longitudinally, will lead to major distortion between frames.
    I use 25mm by 25mm by 10mm angle longitudinals.
     

  15. evantica
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    evantica Senior Member

    Hi there someone? I have a question, look at the picture, Will it be /or not? nessecery to weld a Longitudunal where the steelplates meet (Red arrow). can I leave it like this pic'???
    and "Brent" sead 25x25x10 for longitudunals, isn't this a bit "over do"??? I don't say you're wrong Brent just wanna know.
     

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