How to Properly Caulk a 1930's Elco Carvel hull?

Discussion in 'Wooden Boat Building and Restoration' started by Tangusso, Mar 7, 2010.

  1. Tangusso
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    Tangusso Junior Member

    I have read a great deal about this topic. Having never done it myself, I took into account everything I could get my hands on. I have determined several things for sure:

    1. I am going to use cotton as the original builder did.
    2. I am going to use some sort of sealer on top of the cotton
    3. I will likely not use epoxy paint (though I am still a bit up in the air)

    Unfortunately thats the sum total of what I feel confident about. The questions that remain:

    1. After reefing the seems and sanding them clean is it best, given the methods I have decided to use, to prime the seems with a typical paint product, or should I use CPES to condition the wood first?

    2. After applying a CPES, can I then use a typical primer prior to installing the cotton, or are these methods / product not compatible?

    3. Is the cotton always primed over after it is installed between the planks?

    4. What is the best product to use as a top sealant after the cotton is installed / primed? Bear in mind that I dont want to glue my hull together to the point that plank repairs are very difficult later.

    5. Is there an advantage (or problems related to) using a coat of CPES on the bilge area of the interior of the hull?

    6. Should linseed oil ever be used to treat the bilge area of the hull?

    I hate it when the stuff I know is so small in comparison to the stuff I have to learn! Any suggestions from very experienced members?
     
  2. Landlubber
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    Landlubber Senior Member

    Tangusso,

    Are you referring to the ubderwater areas of the hull regarding caulking?

    If so we generally do not use cotton here, we use hemp, or oakum.

    Let me know before we go any futher. (the cotton rots out).
     
  3. Tangusso
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    Tangusso Junior Member

    The entire hull will need to be caulked. I was unaware that cotton was not to be used below the water line. Feel free to outline the methods you would use, and provide as much explanation as possible.
     
  4. Landlubber
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    Landlubber Senior Member

    Before you do any caulking, the fasteners must be checked first and any loose fastenern will need tightening or replacing. Roves can be pulled up if the nail is still in good condition. A few will need to be pulled to determine this.

    Before the caulking job is done you can red lead the woodwork or even better white lead if you can get it. Same applies to after the job is done.


    After raking the seams clean, no sanding is done as you stated. You can make a nice rakinhg iron from the tang of an old file, just heat it up with the oxy and bend the little sucker around, grind it sharp (as in a chisel shape) and away you go.
    The caulking is gently hammered into the open seam, care being taken that the wood is not forced and that the caulking also does not get shoved through the seam. It is a delicate balance of wacking and tapping actually. You will need a few caulking irons, , they will be available from the local yard anyhow, I often loan mine out as long as they are hit with a wooden mallet and never iron heads. There is a shipwright mallet, but just use a wooden mallet for now, the balanced shippys mallet takes a while to get used to and most likely not needed in your job.

    The putty used is a mixture of whiting and boiled linseed oil, enough oil to make a nice compound. This is then forced over the caulking with a flat scraper, use a strong one (thick, not wide).

    Away you go!
     
  5. missinginaction
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    missinginaction Senior Member

    Landlubbers right on the money. My nextdoor neighbor at the boat yard is a retired Navy lifer who really knows his stuff. He was a Chief petty Officer his whole life and is now aproaching 90 and still going strong. Every spring as he and some other guys prep his 1913 all wood beauty I've watched them caulk the seams just about exactly as landlubber describes. I never, NEVER hear any hammering or banging, it's a pretty gentle process as he says.

    Landlubber, you know more about this than I ever will so I'll ask for Tangusso. What about the epoxy sealer he mentioned? I don't believe that he wants to seal those planks as the idea is to let them swell up and seal against the calking in the seams.

    What say you?

    Also Tangusso, if you've not seen a wooden boat like this launched be ready for a little stress. Have a few hefty pumps ready. I've seen a few of these craft sit for a day or two in the backwater being pumped while they swell up. You'd think that they were sinking but eventually the wood seals up pretty good.

    Good luck with your project,

    MIA
     
  6. Tangusso
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    Tangusso Junior Member

    Thank you for the response MIA. The reason I asked about the CPES is because I read the following: (Can you tell me if you agree with this author?)

    "The use of CPES replaces red lead paint. Traditionally red lead was so useful due to the lead acting as an astringent on the wood surface. This poisoning of the wood retarded wood decay. CPES does this a different way. The ability to prevent rot is due to the fact that CPES coats the cell walls without clogging the tubular structure of the wood cell. This microscopically porous surface is fine enough to prevent bacteria from entering the wood while allowing the much smaller water molecules (moisture) to transport in and out of the wood. Any bacteria or mold spores in the wood are encapsulated by the epoxy and rendered incapable of growing. The wood is indigestible therefore rot cannot progress. Insects or marine borers cannot eat it either. Another benefit of the use of CPES is its ability to "glue" the paint to the wood. When paint is applied to semi-cured CPES, a molecular bond is created when the CPES fully cures under the paint layer. Old dried out lumber will absorb a lot of CPES much the same way it will absorb water. This allows restoration of old and mildly decayed wood. In this instance CPES is being used to bond the seam material to the wood as well as paint. "

    The entire posting in context can be found at:
    http://www.star-distributing.com/howtoguides/drybilge.html
     
  7. gonzo
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    gonzo Senior Member

    I have seen used and used cotton below the waterline. It depends in which country you are in, the materials change. Either way, check the fasteners first and don't overtighten the caulk or you can rip the planks off the fasteners, deform the hull and/or break frames.
     
  8. Landlubber
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    Landlubber Senior Member

    Yes Gonzo, I hear of cotton being used a lot, it must be a cold water thing. Here it is no good ast the water temp is quite high. Because of this hardly anyone uses cotton, not worth the risk.

    I had to caulk a southern trawler one yeear, it had cotton, but it stank seriously, and had gone all black.
     
  9. Tangusso
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    Tangusso Junior Member

    Can anyone with experience comment on the use of CPES on the plank edges? Can this be used in conjunction with red lead primer or instead of it? Any thoughts on the linseed oil thing?
     

  10. John Riddle
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    John Riddle Junior Member

    Tangusso:

    I don't consider myself a caulking expert but I've done a fair amount of it in my work with good results over the years. On planks the thickness of the Elco's, it's usual to use cotton caulking, at least here in the US. I think here, oakum is reserved for thicker planking, say 1-1/2" or more with wider seams. I've worked on 40 year old planks that still had good cotton in them, even when it wasn't painted under the seam compound. (I'm on fresh water Lake Erie and that may be a factor).

    I suspect you'd be fine using CPES to prime the seams but I don't know that it would be any better than red lead. I do know Red Lead primer adheres well and stays put. My source for red lead here in my area is discontinuing it but as far as I know, you can still get it at Kirby Paint in New Bedford, MA. Their web address is: http://www.kirbypaint.com

    The normal practice is to paint a couple coats in the seams, coating the cotton well before the seam compound goes in. Its main function I think is to keep the oils from prematurely leaching out of a traditional seam compound, causing it to harden and lose its flexibility. The paint also tends to "lock in" the cotton to keep it from squeezing out of place when the planks swell, or so I understand.

    Your boat is probably planked in cedar so if it was me, I would choose a traditional soft oil-based seam compound because it won't crush the plank edges when the hull swells. If the hull isn't overly dried out and the seams are already tight, the polysulfides and others would probably work fine also as long as the hull is kept tight. The downside then would be if the boat is allowed to dry out and the planks shrink away from each other, the edges may splinter and tear away due to the adhesive properties of the compound. It's a judgment call.

    Bilges were typically left unpainted but were coated with Cuprinol wood preservative on a regular basis in the days when you could get the good stuff. Now, I think the closest product to the old Cuprinol is Jasco Copper Green. I think that thin coats of CPES or Boiled Linseed Oil are probably OK, functioning mainly to slow the absorption and release of moisture in the planking but I don't think they deter rot the way Jasco can if the conditions for rot to grow are right.

    What boat did you buy? I had some conversation with you back when you were still looking. Do you have a picture or two?

    Good luck!

    John
    Riddle Boatworks
     
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