What were the planking edges of hull filled with in old times

Discussion in 'Wooden Boat Building and Restoration' started by barbarian, Mar 2, 2013.

  1. barbarian
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    barbarian Junior Member

    I remember I read somewhere they would wedge cotton in between the planking boards. Is that correct? how exactly did they seal the hull in old times in sail boats?
     
  2. messabout
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    messabout Senior Member

    Yes, that was true in the olden days and there are many boats that still use that method. It is called caulking. There are numerous special purpose tools that are used in that operation. The main tools are a caulking iron, a sort of flat edged chisel, and a caulking mallet which is sort of a hammer There used to be professional boat people who were highly skilled in the art of caulking.

    When the boat was completed, caulked, and painted it was placed in the water. The seams would leak immediately. After a few days in the water the wood would absorb moisture and begin to expand. When all the planks had expanded, the seams would be so tightly compressed that no further leakage would occur.

    I hope that information is sufficient.
     
  3. PAR
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    PAR Yacht Designer/Builder

    Oakum and cotton are the traditional materials used in the seams of carvel planked boats. This is "paid" with a seam compound of various types, usually oil or wax based. The seam compound serves to protect the caulking from washing out underway.

    It takes a fair bit of skill to caulk a carvel boat, without causing damage and insuring it'll work properly, though with some instruction and if you start on the topside seams first, by the time you get the the LWL and below, you should have enough skill to do a reasonable job of it.
     
  4. Landlubber
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    Landlubber Senior Member

    We still use whiting and linseed oil, mixed together you get what is commercially sold as PUTTY.......as was done by my grandfather.
     
  5. PAR
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    PAR Yacht Designer/Builder

    Most that caulk regularly, make their own seam compound.
     
  6. dinoa
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    dinoa Senior Member

    I remember the seams being coated in red lead after oakum and cotton was paid in. What would be used now?

    Dino
     
  7. barbarian
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    barbarian Junior Member

    thanx guys much appreciated.
     
  8. Landlubber
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    Landlubber Senior Member

    No red lead available in Australia anymore, white lead has gone now too.......sad, cos they were the very best for boats.
     
  9. Petros
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    Petros Senior Member

    the lead is toxic and prevent rot in the seams. Same reason they used to put in house paint, protected the wood from mold and wood eating organisms. Not having lead around was a good thing, we live longer than they used to. I imagine a career in boat caulking with red lead did not last very long, a decade or so at best.

    There are a few traditions where boat building was done without caulk, they would make very accurate mating planks, seal the hull inside and out with oil finish, and than allow the swell of the wood to seal the seams. The old Arab trade vessels were done this way, they used no fasteners on the heavy planks, but laced the planks together with twine made of coconut fibers, through holes bored along the edges of the heavy planks. Hard to imagine large 60 to 90 ft trade vessels held together with coconut fibers, and no caulk, but a replica was built and sailed to China by Tim Severen in the late 1980s.

    The original "stitch and goo" hull, hah!
     
  10. MikeJohns
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    MikeJohns Senior Member

    What about modern sealants? They are very popular with working boats here. The sealant bonds so well it can pull wood away rather than failing on the bond as I saw recently when the shipwright was trying to remove a temporary patch.

    Boats caulked with modern sealants are dry and cope with haulout shrinkage provided they are applied correctly. Surely Ground Chalk and vegetable gum has had it's day ;)
     
  11. JSL
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    JSL Senior Member

    Thay also used wedges with glue above the water line- Left proud and then planed off. If well done you could not seen the plank seams. Like caulking with oakum, this has to be done with great care and the wood species should be the same as the planking.
     
  12. theseafever
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    theseafever New Member

    hello

    I was reading this post and joined the forum to give you one answer. In the early 80's, I spent my 6th grade summer doing what you've queried on an old 40' shrimp boat. I did this entire job by myself at 11 years old. First, I had to scrape the entire hull clean of barnacles with a paint scraper and a face shield on a motorcycle helmet because I had to lay down to do a lot of it. Then I had to dig out all the old packing between the planks. I used a screwdriver and a carpet knife. Once i got all that crud out, I ran a bead of caulk as deep in the crevace as I could. Then, I used a flat paint scraper and packed cotton to the point where I only had enough room to seal it with another bead of caulk. Actually, I had to pack caulk in with my finger and spread it till it was flush. Then I painted that sucker. I hope this helps in answering your question somewhat. That was my experience. We were poor and had no access to expensive sealant or anything like that.
     
  13. PAR
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    Your technique is a common mistake and couldn't be recommend by any professional, that expects his work to be insurable. In other words if the boat sinks and the investigation shows the seam sealant was the cause, guess who gets sued. Without going into a lot of detail, the caulk (what you've called packing string) serves two main purposes, the first is to edge set each plank and the second is to seal the plank seams. Your method will seal the plank seams (for a while), but will not edge set the planks. This will cause excessive movement of the planks, which will spit out the goo in the seams and loosen the plank fasteners..
     
  14. pauloman
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    pauloman Epoxy Vendor

    very often the seams were filled with water and the boat sank -- wink wink!
     

  15. theseafever
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    theseafever New Member

    I reckon you're right. That's why I said it was only one answer that was my experience. Those old shrimpers are still running thirty to fifty years later even though at least one of them went down in it's slip. I came here to learn from the pros and it looks like I'm going to get a good schooling.
     
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