Building a punt - need help!

Discussion in 'Boatbuilding' started by Sina R.G., Mar 3, 2011.

  1. Sina R.G.
    Joined: Mar 2011
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    Location: Tehran, Iran

    Sina R.G. New Member

    Hello everyone,

    I'm planning to build an English punt in summer. I've already sketched up some designs and plans, however I'm new to boatbuilding and have limited access to certain materials.

    I live in Tehran, a city locked by mountains with no navigable waterways, so finding products needed for boatbuilding in local hardware shops is a difficult task. I've researched about wooden boats and made a list of materials I need, but I might not be able to find a few of them, I'd be grateful if someone could suggest alternatives or places to find them:

    1. Adhesive sealant - the most popular type in stores here is aquarium sealant, I haven't found any marine sealant so far.
    2. Caulking materials (cotton batting/oakum) - oakum is totally out of reach, however I've heard normal cotton would do the job too?
    3. Putty - what can I apply as putty instead of white/red lead?

    Also, when I am done caulking and applying the putty, do I let the softwood swell and paint/varnish after? How long does it usually take for softwood swell?

    Sorry if some of the questions are stupid, I'm new to wooden boats.
     
  2. hoytedow
    Joined: Sep 2009
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    Location: North of Cuba

    hoytedow Bananas

    There are no stupid questions.

    1. You need wood. Do you know of a sawmill nearby? Check there.

    2. Punts are among the simplest to construct, if you can get bronze or galvanized screws, about 2.5cm(1 inch) long and about 3mm(1/8 inch) thick under the head. Flat x head are easier to drive than flat / head. For a small punt build hull no thicker than 7mm(1/4 inch). With regular care, rubber caulk paintable kind will suffice. Avoid silicone aquarium caulk as it is not paintable and will be un-attractive. Paint will last longer than varnish due to sun damage to wood under varnish.

    I hope you will consider these opening remarks valuable.
     
  3. Sina R.G.
    Joined: Mar 2011
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    Location: Tehran, Iran

    Sina R.G. New Member

    Serious replies only, please. Let's keep this professional.

    EDIT: hoytedow, thank you for the useful post, glad you changed it.
     
  4. Petros
    Joined: Oct 2007
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    Location: Arlington, WA-USA

    Petros Senior Member

    Do you have hardware stores that sell construction supplies?

    If so you should be able to buy polyurethane adhesive caulk that will work just fine. The latex type will also work but will not hold up as well. Both types should be paintable. I would think you could find these materials in Tehran.

    On a small hull the polyurethane caulk would work instead of traditional boat building caulking. The oakum or cotton were ancient adaptations to make planks water tight since they did not have good waterproof adhesives. The fibers would swell when wet and seal the seam, modern poly material should accomplish the same thing on a small boat. I have built a number of small boats using inexpensive latex caulk as the only sealant to the hull.

    You might also consider omitting the caulk all together and cover the hull with cotton canvas or heavy polyester fabric and using either oil based paint or some tough outdoor type latex paint to seal the water out. You use a small strip of wood to anchor the edges around the gunwales. Lots of small boats were made this way for many years, from dorys to canoes and kayaks.

    By putty are you referring to a filler of some sort? You can use epoxy mixed with wood flour (fine saw dust) as a good filler.

    Good luck with your project.
     
  5. Sina R.G.
    Joined: Mar 2011
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    Location: Tehran, Iran

    Sina R.G. New Member

    Thanks Petros.

    Most of the local hardware stores specialise in apartment maintenance, so that's good news. I'll try to find some polyurethane adhesive.

    Putty is a filler, it's applied between the planks after caulking. The mixture above sounds promising.

    I'm very much concerned with the time it takes for the planks to swell, it's a fairly long drive to Esfahan where I will punt and I can't leave it in the river for long if I ever plan to visit.
     
  6. peter radclyffe
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    Location: europe

    peter radclyffe Senior Member

  7. peter radclyffe
    Joined: Mar 2009
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    Location: europe

    peter radclyffe Senior Member


  8. Sina R.G.
    Joined: Mar 2011
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    Location: Tehran, Iran

    Sina R.G. New Member

    ^ Nice. Mine is going to be 13ft because of small storage space, but I can still use the plans.
     
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