sheathing

Discussion in 'Wooden Boat Building and Restoration' started by Luther, Jan 24, 2009.

  1. Luther
    Joined: Oct 2005
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    Luther New Member

    Does anyone out there know if one could sheath an older wooden boat. I have a 48 foot troller built in 1937. She is in pretty good shape but is starting to show rust spots. I was told you can increase the life by sheathing on quarter inch planking. Take her down to bare wood, coat with roofing tar, screw first set of planks on and then epoxy the second coving the seams of the first sheathing. Any ideas would be helpful.
     
  2. pat60
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    pat60 Junior Member

    Colded molding over carvel planks has been done. One example would be Bruce Schwab using that method to restore a 1930's square metre boat "Rumbleseat" and then racing her in the TransPac, but the method your describing is mixing apples and oranges. To sheath an older wood hull with epoxy and veneer it needs to be out of the water long enough for the planking to dry out, all needed structural repairs attended to, the hull faired and then have the thin wood sheathing installed in epoxy followed by a fibreglass covering. It is not a cheap, easy way to fix an old boat. The cheapest, easiest way is to hire a professional to repair the exsisting structure in the manner it was designed and take care of cosmetics yourself. Otherwise you can use it as a learning experience and do all the work yourself if you can afford the time and the yard bills.

    You may hear about doing things like applying tar or some household adhesive or "wonder goo" to take care of your issues but they will not work. I've seen everyting frome window caulking applied to 1/2 wide planking gaps to fiberglass tape over wet hull planking, such repairs just increase the time and expense to do it right the next time.
     
  3. darr
    Joined: Nov 2004
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    darr Open Minded

    Sheathing that lasts

    Luther,

    There is another alternative. We manufacture a material that has been used successfully to sheath older wooden hulls. There is an article available here:

    http://www.fer-a-lite.com/pdf/arevolutioninferroconstruction.PDF

    with photos that shows a 57' wooden boat being sheathed in 1969.

    The process is described in the article, it starts on page 22.

    Feel free to contact me directly.
     
  4. pat60
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    pat60 Junior Member

    Without casting doubt on your product, are you saying that simply covering a hull of questionable integrity with concrete is a viable and economical way to extend the life of a wooden boat?

    Any method has to include fixing the present problems or it can't hope to last. Besides, how would the weight of a concrete covering, synthetic or not, compare to normal repairs or either fibreglass or wood sheathing? I was unable to get your pdf file to load so was unable to see specs. A quick search on google wasn't much more enlightening.
     
  5. darr
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    darr Open Minded

    Pat, you may want to check your connectivity, I just double checked the link that I provided and it is working, it is a large file so if you are on a mediocre internet connection have some patience.

    In addition doing a Google search the first 6 hits will get you to one of the websites with additional information

    You do not simply cover the hull. You first would of course repair or replace any structural members that are absolutely necessary. Not necessarily all of it, but enough to stabilize the structure. If the hull will hold its shape when hauled out, then it is a strong enough candidate. You also want to remove and/or replace any decayed material from the hull. Then you apply the wire plank or mesh stapled to the existing wooden hull, or welded and twist tied to a steel hull. You then apply the Fer-A-Lite material, fair and paint.

    Overly simplified, but you get the general idea. This of course is not the best way to restore a wooden hull, however it is significantly cheaper, generally stronger and no need to ever replace a hull plank again, no recaulking seams, no worms.

    Weight is not a huge issue with this process as the Fer-A-Lite is 60% lighter than a portland cement process, in fact Fer-A-Lite itself is almost neutrally bouyant, the steel of course is not. This will produce a dryer hull and as a result the remaining wood structure should last indefinately, (as long as the deck or cabin is not a sieve) The majority of additional weight will come from the wire plank or mesh material.

    However keeping in mind that you will increase the length and beam of the boat by the material thickness which helps to offset any additional weight. It is my understanding that they had to add ballast to the boat that was done at Boot Key Harbor as it was floating above DWL when put back in the water.

    We are aware of the material being used on several wooden boats, although only one sheathing is in our records. The rest of the usages have been for replacing or sistering bad frames or floors.

    The material is very tenancious, when applied to wood or concrete, when you break the bond it will be the other material that fails (wood or concrete) not the Fer-A-Lite.

    I also have a video showing us repairing a hull made of Fer-A-Lite that shows just how strong the material is, the point being that a reasonably thin layer of material will create an exceptionally stiff structure.

    The main reasons a fiberglass sheath fails on a wooden hull are two fold

    The fiberglass and wood hull have different expansion characteristics from a thermal standpoint.

    Usually the fiberglas sheath is just not thick enough to support and stabilize the original hull, which when it flexs causes the sheath and hull to separate, then of course you get moisture in the voids and it all goes to pot.

    With our process the Fer-A-Lite / wire plank sheath is sufficient to stabilize the existing hull to the point that the difference in thermal expansion is not enough to break the bond, and since it does not flex as much as a simple unreinforced fiberglass sheath, you do not get the mechanical actions, as a result no voids develop to trap moisture therefore reduced chance of decay.

    This will stiffen the daylights out of the existing hull, it it was not a stiff boat before, it will be afterwards

    This material was originally created by Platt Montfort (he is the person that invented "Git Rot" and Geodesic boat designs) and sold from the mid 60's through the late 80's by Aladdin Products.

    We have been the manufacturers and distributor since acquiring the rights and manufacturing equipment in late 2003.

    Once again, if a person has the time, money and willingness to properly maintain it then the right way would be to rebuild the wooden structure and planking as originally designed. But that was not the request of the original thread.

    And finally, we do not recommend sheathing with concrete of any type. Concrete is porous, hence moisture can migrate and attack the wood and/or steel at the concrete/wood interface.

    For the record, we do not recommend concrete for any usage in a hull structure since Fer-A-Lite is a far superior product.
     
  6. pat60
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    pat60 Junior Member

    Darr,

    Thanks for the clarification about your product. I didn't mean to infer anything about your site other than I couldn't load the pdf. Your explanation about the use of it for repairing frames and such is quite interesting and novel to say the least. A full sheathing job must have been one heck of a project.

    It was a gross simplification for me to lump your synthetic compound with regular cement. As to the whole weight vs increased displacement argument I am aware of the effect, however my concern is focused more on the horsepower to weight ratio of such a modification as opposed to whether she will still sit on the same lines. Increased weight from the sheathing and attendent steel substructure, decreased payload, more fuel usage .....

    The only sheathing jobs I have seen succeed were on boats that had dried out on the hard for an extended time prior to being sheathed with a fairly thick layup. Not the lightweight cloth that some seem to think will work. I have had to remove and repair such clumsy attempts others have made in the past I strongly hope to deter such things in the future. As it is I can only personally recount having seen two done right. One was the aformentioned Square Metre in Alameda done by Bruce Schwab and another in San Diego long ago the name of which I have forgotten.

    I am not a designer or production builder, my own experience has been in the repair of wooden boats both major and minor with mostly classic methods. I am much more comfortable with a wood plane than a keyboard. Thats not to say I haven't smeared my share of epoxy and other goo on wood over the years. Sometimes the new stuff is the best for a given job. The method in the first post seemed to suggest simply over planking the boat with wood without attending to other issues.

    So to go back to the original question, nope, don't do it the way you describe Luther, it won't work. As to Darr's product I am painfully ignorant. If I misread your question then please give a more detailed description of your situation so my opinions can be better targeted to a solution as opposed to a simple nope. Otherwise perhaps other, more informed sources can offer suggestions.
     
  7. darr
    Joined: Nov 2004
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    darr Open Minded

    Hi Pat,

    No inference noted or taken. My background is in technology, and sometimes that tends to show itself in overly complicated explanations that I deliver.

    There is absolutely nothing finer or more beautiful in the world than a well designed, well built and properly maintained wooden vessel, power or sail.

    Sadly, there are fewer and fewer examples being built or remaining in service.

    You are right about the need to dry out the hull, in addition we recommend sanding the hull down to bare wood, removing all thru hulls, hull mounted sensors, rub rails etc...and as mentioned removing any obvious rot or decay before applying the material.
     
  8. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    Another method of sheathing an old wood hull is the c -flex method which for those of you who are not familiar with the product, is a fiberglass plank about a foot wide which comes on a roll and is basically 2 layers of heavy fiberglass cloth stitched together around small pultruded fiberglass rods running the length of the roll.I have used it in both new construction and to rebuild hulls where a large hull section is gone from storm damage.
    It has been used in sheathing old wood shrimp boats,my understanding of the method is the c-flex is stapled over the wood hull transversly(sheer to keel) in a bed of urethane adhesive such as 5200 to give a tenacious but flexible interface.It is then wet out with polyester resin,then followed up with a substantial mat/roving layup.The advantage of this or the feralite method is that it provides an impervious outer layer which wont rot out from the inside.
    I should point out that i have cold molded over a large wood hull but im not sold on it as a long term solution unless its on a lightweight boat where weight matters.
    Steve.
     
  9. darr
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    darr Open Minded

    Steve,

    I am not sure what difference you are talking about as far as a "impervious outer layer which won't rot from the inside".

    Utilizing the method you suggest, the only treatment that the existing wood of the hull would receive is the 5200 being smeared on, this would not seep very far into the existing wood, with the Fer-A-Lite method you would actually get a large amount of resin penetration into the existing wood, thereby protecting it for a much longer period of time (similar to the concept of "Git-Rot", which was developed by Platt Montfort as well), this fact alone would tend to make the Fer-A-Lite method a longer term solution.

    I think the method you suggested would actually tend to create a weaker connection between the existing hull and the sheath after a given period of usage, after the wood/5200 bond lets go as a result of moisture causing a delamination between the bond (I mean by this, that we are talking about a wood hull that has lost strength due to decay and rot), this moisture penetration would occur around all the staple penetrations that would allow wicking moisture between the existing hull structure(and its retained moisture) and the fiberglass sheath, right through the 5200 sealant. Keep in mind that this is still a flexible structure and you will get seepage around the staples after they are "worked" for a while from the flexing.

    What you would end up with is three layers, Wood, 5200 and C-flex with the staples penetrating through all three materials, hence no barriers, very quickly I think you would have moisture condensing and wicking unless you are in an area with low humidy and no temperature swings.

    I am also not sure that you would get a strong bond within the C-Flex if it has 5200 smeared on one side it, it cannot be thoroughly saturated with resin, I will try a lay up on a small section this weekend to test this theory.
     
  10. Steve W
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    Steve W Senior Member

    Darr,as i said in my post i do not have personal experience in sheathing with c-flex and since im not trying to sell the stuff i offer it up only as an alternative
    to cold molded wood sheathing and i may not have all the details of its a use in this application correct so one would need to contact Seaman composites for the details,i have however used it in new construction and repair but that was over 20 years ago.
    You will notice that i did not infer that it was superior to your wire plank and fer-a-lite product for this application,just another option for the op to research,that said,i believe the intent with the seaflex is to essentially lay up a heavy enough sheath that can carry the structual loads,or, as you say,stabilize the hull, so the original hull becomes somewhat irrelavent,any moisture that may find its way thru is not going to harm the thick fiberglass skin.
    With your system isnt the wire plank material made of steel and stapled to the existing wood hull creating some of the same potential problems you cite for c-flex? is the fer-a-lite an epoxy or polyester based material? if it is polyester i would be skeptical as to its adhesion to the existing wood hull and no,the amount of penetration of even straight unthickened resin be it epoxy or polyester into wood is not much although certainly more than 5200.They are all relying on their adhesion to the surface.
    Steve.
     
  11. TeddyDiver
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    TeddyDiver Gollywobbler

    I believe the real problem is hidden benieth the wood.. It's the iron/steel nails and/or bolts used to fasten the planks to frames are rusting away. So they should be replaced.. no sheathing can help in this. Good news is it's quite simple work to do.. but it takes time
     
  12. apex1

    apex1 Guest

    As Teddy Diver mentioned, are you shure to have a problem with the wooden hull? Have you done the good old "riggers knife test" ? You may have just a prob with the fasteners. Smile then.

    Regards
    Richard
     

  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    In spite of the advertising and hype in products that are the next "miracle goo" that can save traditionally built wooden boats, in all cases it will be cheaper to just repair the boat with conventional methods.

    In fact, you have to do this anyway in order to expect reasonable life, from the new wonder coating, being applied.

    There's only one product that I know of that truly does seal up an old wooden hull, permit the wood to move around and not allow the planks to rot underneath the new coating. Unfortunately, I'm held to a none disclosure agreement until mid summer, so you'll have to wait.

    The bottom line on this issue is usually quite simple. Planks move for several reasons, most related in two areas, moisture gain/lose and the grip of fasteners.

    Applying anything over planking with questionable fasteners is folly. I don't care what anyone says in defense of their product, if the substrate isn't firmly secured to it's framing structure, no coating or sheathing will survive for long. This means you have to address the fasteners (at least). This is the whole point. In Darr's defense, he did point out this simple truth in his post.

    A well fastened, well caulked carvel that has a solid structure and good seams, doesn't leak. I've caulked too many boats to tell you why this is so, but trust me, if your boat has been recently caulked and it's leaking, the caulk wasn't the job that was needed.

    In short, cold molding, strip planking, thin or thick 'glass sheathings or the more exotic materials like concrete, polyurethane or other "miracle" old boat saviors are just wishful thinking if the boat isn't sound.

    This said, you can offer an old hull a few additional seasons of life with a sheathing, but a wobbly, rotting mess will be found under this sheath in short order.

    Luther, in your case you boat is suffering from a common problem, we call it iron sickness and it's an accurate description of what's happening. You're boat not only needs to be refastened, but the holes restored as well. As an iron fastener rusts, it swells up and "eggs" out the hole it's in. It also ruins the surrounding wood. Sometimes, if you're lucky, new fastener holes can be drilled, new fasteners inserted and the old holes plugged. Often it's the case where the surrounding damage prevents this and wholesale repairs to framing elements has to be incorporated into the mix.

    Once the fasteners swell up and destroy the holes they were in, the separate elements of the planking, frames, stringers, structural floors, etc. all start to move around. Planks grind their seam to a pulp, frames saw into stringers, floors release from frames, etc. and it's quick, downward spiral of leaks, broken structural elements until you can't afford to keep her any more. This is why it's important to have yearly haul outs and inspections, so you can catch these things early and nip any issues in butt, before they become major problems. It was once common practice for yacht owners to care for their investments, but it seems the current trend is to let haul outs wait a few years, inspections even longer and routine preventive maintenance a thing of the past. Most wait until the marina calls and says the boat is below the boot stripe and having a 5 HP pump installed, before owners do anything about the issues that haunt their yachts.

    In the end Luther, the cheapest route is to properly fix what is wrong, after a skilled and careful assessment. If you want to apply a miracle goo after that, it's up to you, but it'll be hell to pay, when future repairs come down the pipe and a concrete, 'glass or other "skin" has been applied, all hampering and increasing the time, effort and cost of these repairs. It would be nice if we didn't have to plan for repairs, but the moment you don't, you can rest assured you'll need to. At least this has been my repeated luck with boats of all sizes.

    To answer the question about Fer-A-Lite's resin type, it's a polyester.
     
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