1967 48' ChrisCraft Constellation Restoration

That's why I was asking about polysulfide vs 5200, and no fasteners.

 

Maarty, neither polysulfide, nor polyurethanes (like 3M-5200) are suitable as an adhesive in this regard. These are sealants, rubbery, highly distortable, stretchy, sealants. It would be more helpful if you pulled up the physical properties of the products you'd think might be effective and look over their attributes. In this way, you'd understand the limitations of the formulations employed, which is particularly true of material substitutions. It's not practical nor especially desirable to remove fasteners from the equation, in these types of building methods. If you do, you have to physically glue each seam and each plank to each structural element. This would work for a short time, but you would isolate strains and stresses and these wouldn't be as easily shared by neighboring structural pieces, so breakage would become an issue, usually in the weakest areas, such as frames or battens. Also the planks would test the edge glue joint with wet/dry cycling. Monocoque wooden structures are easily possible, but you have to specifically engineer them, which of course is typically a completely different "route" then plank on frame methods.

To directly answer your question about 3M-5200 versus polysulfide, well there are a few different types of each. To keep things simple the polyurethanes are usually mush more aggressive as an adhesive then the polysulfides. The polyurethanes tend to have less modulus of elasticity as well, but this can get complicated pretty quickly with all the various formulations, particularly the two parts and the cyanoacetate activated combinations. The polysulfides typically have less (much less compared to 3M-5200 in some cases) tensile strength, but higher physical elongation before catastrophic tensile failure. To use 3M products as an example, 3M-101 (a single part, moisture cure, polysulfide) is dramatically weaker in most every regard to 3M-5200 (a single part, moisture cured polyurethane), except softness of cure and elongation. You can get other formulations of each goo that can rival the opposition, but most haven't need or experience with these chemicals (except for the LPU's and two part polysulfides used in deck seams). You'll need a short chemistry course, for further understanding of these formulations.

 

In Batten seam construction....there is no caulking bevel on the plank edges to accept caulking. You don't pound cotton into the seam to force the planks apart and stiffen the hull. Only areas without battens like the garbord are caulked.
The batten makes the plank to plank seam watertight . This joint is caulked with goo...not cotton...either Dolpinite bedding or 5200 does the job. 5200 is very effective on batten seam construction and is recommended by many high class boat builders and boat building manuals..

The original posters ,epoxy 5200, hybrid repair is well conceived. The epoxy coating slows moisture absorption and as a result, plank movement. Less movement puts less stress on the 5200 joint and the mechanical fastener.


This type of repair is done hundreds of times a year by first class restorers .

For additional info contact

http://www.danenbergboatworks.com/

http://www.maritimeclassics.com/

http://www.chris-craft.org/discussion/viewtopic.php?t=2872

and read Greg Rossels " The boat builder's apprentice "

 

Ok, now I'm really confused. I guess time will tell if Robster's boat holds together. Very good posts though; I am going to research all of the concepts; more out of interest than anything else. Personally I like fibre glass the best, followed by steel. Then again I've not worked on a wooden hull and have the prejudice that wood was used in the past because nothing else was available. I like PAR's postings the best.

 

Batten seam construction, at least when in Chris Crafts and most North American builds I know of are caulked. Otherwise, the tiny screws on the battens would have to provide all the structural strength. If you epoxy a structure that is designed to swell and tighten up to create a panel, the fasteners will fail. If you want an epoxy sealed boat, either fiberglass over the whole thing, or build something that makes sense with that method.

 

Well Gonzo...no need to guess, simply read . Google Greg Rossel's book on batten Seam construction 5200... and if you re worried that Greg might be pulling your leg read Robert Steward, "Boat building Manual"... consult page 199...batten seam construction, sikaflex polyurethane. And if you are still confused simply contact the Chris Craft classic owners club and they can educate you . If its still a mystery to you contact Danenberg boat works.

 

I don't need to find the information out of a book. I have worked on enough Chris Crafts. Batten seam construction, as they did it, needs the seams to lock. How many of these boats have you worked on?

 

Our family had a batten seamed boat , built by Davis ,for more than 20 years . I know the technique well.

Please clarify what " seams to lock" means then please post the technical document you will present your client when recommending that they pound cotton into the seams of a batten seam build .
And please post the technical literature you hold , specific to batten seam construction, which forbids polyurethane adhesive compounds on batten and plank edges.

I await these enlightening documents.

 

Just following along here....Happen to have Sewards book open to pg. 199. Michael, the author is suggesting the use of Sika 241 (and there are many Sika products) as a product that can eliminate caulking the seams in a batten seam planking arrangement. I don't see anything written there to suggest that one would seal all the planks (to keep water out - a futile effort), or try to glue the planks to the frames (or battens).

So based on what I'm reading Sewards text is speaking to the caulking only. In addition Seward states that the seam between the garboard plank and the keel should be caulked "in the usual manner". If the Sika method works so well then why would Seward make that statement? Because of more stress and forces at work in the garboard/keel area?

If I'm understanding their posts correctly (PAR & Gonzo) the issue they have with this build is primarily in the area of how the planks were attached to the frames (or in Sewards case battens) but also with the concept of caulking between planks with flexible sealants. PAR and Gonzo are saying they need to be mechanically fastened and Seward does too. Seward hedges a bit advocating both tradtional caulking (barboard/keel) and Sika (rest of the boat). I wonder why Seward wrote it up that way?

Very confusing.......

 

There is no BATTEN at the garboard !!! You better re read the document. The planks are bonded to the batten. The plank edges are bonded together.

To Quote ... Greg Rossel " There is no bevel between the planks to caulk as the BATTEN does the job of keeping the water out

"The planks are screw fastened to both batten and the frames. Bedding compound is applied to the INSIDE of the plank and the Batten."
"For a truly bullet and waterproof seam, an adhesive caulk such as Sikaflex or 3m 5200 is used instead of traditional beading compound. IT WORKS GREAT ! "

Who is Greg Rossel ??

GREG RÖSSEL grew up cruising on the waters of New York Harbor and spending time in the boatyards on the south shore of Staten Island where economics (more than anything else) made wooden boats the craft of choice. He makes his home in Maine where he specializes in the construction and repair of small wooden boats. Since graduating at the top of his class in boatbuilding technology from Washington County Vocational Technical Institute, Greg has had a multifaceted career. For several years, he was an assistant restorer for a major private collection of antique runabouts and airplanes. Then he spent another couple of years as an instructor and assistant director at Maine Maritime Museum’s Apprenticeshop program. All the while, he was building his own shop at home in Troy, Maine, and tackling a wide variety of smallboat construction and restoration projects. For over 20 years, Greg has been able to work for himself full-time, aside from a few odd jobs like setting up a wooden Whitehall factory in Mexico, custom lines taking and documentation for museums and other customers, and writing over 100 articles for WoodenBoat and other publications. He has also written and illustrated Building Small Boats, a book on carvel and traditional lapstrake boatbuilding, published by WoodenBoat Books. Since the late 1980s, Greg has been an instructor at WoodenBoat School, teaching lofting, skiff building, and the Fundamentals of Boatbuilding. Also, for the past 16 years he has been producing a weekly two-hour radio program about world music which (mercifully) has nothing to do with boats.

Who is PAR ?

Who is Gonzo ?

People read Boat Design net to gain insight into Boat repair and design...these guys have not presented a single link..a single document to back up their ideas. Gonzo states..."I don't need to find the information out of a book"

Beware........

 

Michael: Firstly, you don't answer my question: How many Chris Crafts have you worked on? Secondly, Davis never designed or built Chris Crafts. His boats may be built by a different method, I don't know.
"Seams to lock", means that by caulking them there is a mechanical lock that creates a panel. This is a method that dates millennia.
I never claimed that polyurehtane adhesive compounds are forbidden. I do claim that it may not take the place of cotton or oakum caulking. Also, that 5200 must not be used on wood seams below the waterline. That is a recommendation from 3M.
I am not sure that you can be enlightened. In many other posts you also resort to sarcasm and personal attacks instead of limiting the discussion to facts.

 

Ok so it is time to set the record straight here. I have held my peace with all the sarcasm and personal attacks (seams as though gonzo likes to dish it out but cannot take it himself) and comments such as been call an "amateur" by Gonzo, (Which goes along with his concept of not needing to check facts before he makes bogus comments and accusations) that I am assuming he is some boat repair worker at a yard. And this other guy par, that calls himself a boat designer and builder. Oh by the way par, can you list all the boats you have built? and also have been built by your design? And please explain exactly the materials and processes used? I would be highly interested! Maybe we could learn something from your boats being used for decades to prove your methods actually work.

As for me, I started building WOOD COMPOSITE boats, (a concept that some of you obviously know little about) when I was 12 years old. This was in 1978. At that time I attended Westlawn School of Yacht Design and pursued passionately, boat building design with wood. Mainly because I wanted to advance wood boatbuilding technology and bring it out of the dark ages techniques such as “soaking wood hulls with water to get them to seal”, and using cotton caulking, which has been used since the beginning of time on wooden seams and the reason why thousands of wooded boats are at the bottom of the ocean. And also because of all the wooden boats that I was observing that were rotting faster than people could repair them.

By the time I was 18 I had already built an 18’ ski boat, a 21’ inboard cabin cruiser, and built a 24’ Thunderbird sailboat, all of plywood using the west system epoxy and ALL of them are still in use today. But not all of my experiences were successful. I did a lot of trial and error as not very many people at that time even heard about the products and methods I was using.

One of my errors was actually using a method that gonzo suggested “If you want an epoxy sealed boat, either fiberglass over the whole thing”. This method actually is the worst thing you can do with wood. I tried it when I was learning about using fiberglass and wood together on a 16’ ski boat I had restored, and fiberglassed the whole bottom of the boat. It worked for awhile but after a few years the fiberglass sheeting was pealing off the plywood like a banana peal and the boat became an addition to my garden landscaping. AT that time I began to study the differences of materials, structural properties and expansion/contraction effects. Little did I know at the time was that fiberglass expanded and contracted very little and wood a lot. Therefore the wood expansion on my 16’ ski boat caused the fiberglass to de-laminate off the wood, trapping water between the two and was literally popping the fiberglass and epoxy material right off my boat.

Contrary to some of the people on this post want to believe, most ANY wood boatbuilding method can be used to create a composite and watertight boat, as long as you make sure that the wood will never saturate with water. Therefore the properties of the wood will not vary much, and the true properties of the epoxy and adhesive will work as designed. On my methods, I could virtually take out most of the fasteners, especially on the hull planking, (making sure of course that the wood is resealed) and the planks would still never come loose. Because they would not get wet as some here are trying to claim.

I also find it interesting how people can be so contradictory to themselves. Such as, 5200 will peal off like a long noodle with one comment, and then turn around with another one and say that if using 5200, you can never take the plank off without ripping it off and damaging the frame it is fastened to. But wait, the same person is saying that 5200 is not an adhesive! So why would it adhere so much as to take the seam with it? it only proves that these people know little knowledge about these products and are only ranting about personal opinions and experiences that they are trying to blame certain products for wood boat failure. But it is true that you do not want to saturate wood with water when using 5200, which would defeat my whole concept anyway now wouldn’t it?

The fact of the matter is, even though I am rebuilding a Batten planked wood boat, the result of my method is now changing it to a wood/epoxy composite hull. And yes it will move and flex like it is supposed to and designed to do, just like your supposedly “locked cotton caulked planked hull” which by the way is not locked at all, as you now have a waterlogged boat that grows, shrinks, flexes, vibrates and moves with every change in temperature, climate change, boat movement, etc etc.

Oh and FYI, I am a materials engineer and composite subject matter expert for the Boeing Company and have studied, tested and worked with many types of epoxy, E-glass, S-glass, wood and carbon fiber for decades, and have the track record and reputation to back it up, and also I probably make more per month than some of you guys do in a year. So just a little advice for all you here on this blog. Do not assume you know anything about anyone unless you ask some questions! an intelligent person gathers facts first before he makes any decision or assumptions.

 

Gonzo, Michael is the "village idiot" and constantly speaks about things he doesn't know. He reads lots of books (apparently) and thinks he knows, when in fact he has no real experience, nor any practical advise to offer. Personally, I think he's a bored teenager that wanders from discussion boards to chat rooms to opinion areas, around the net, offering what he thinks is good advise, but what really comes out his inability to define or extrapolate any of his concepts, precepts or real world expertise. I've challenged him repeatedly and he's failed to respond 99% of the time and when he does, he changes the subject.The books he states where written, in some cases many decades ago, when some still believed in polyurethanes as the cure all to end all, of wooden boat ills, but as has been typical for Michael, he's talking out his butt and attempting to pass himself off as someone that has something to offer, when in fact he's just an arm chair quarterback looking at the game with hindsight goggles, which he hasn't bothered to clean lately. Michael, do yourself a favor and read the "originally published" dates of the books you're preaching from.

To prove my point, he lists "GREG RÖSSEL" then a brief bio about him which is a cut a paste directly from the very first link that appears in a "GREG RÖSSEL" search on Goggle (an Amazon.com link for one of his books)! You see Michael, the difference here is, I actually know the guy, you're just a cut and paste artist!

The Bob Steward book (Boatbuilding Manual) was written in 1970! Though it has received some updates (5 in fact) the bulk of the information is essentially the same 1970's text! Yea, listen up everyone, lets continue using nearly a half a century old information and techniques. Now there's a good idea, congratulations Michael, you once again have proven how little you actually know.

Danenberg is the classic "throw back" that I mentioned previously. He once was a well respected restorer and repair expert, but now has fallen way behind the curve, well entrenched in penetrating epoxies and polyurethane myths, rather then accepting the facts of testing and long term evaluation, much of which is done by the very formulators he promotes!. Maybe someday he'll wake up, but don't hold you breath as he's seen the data, but still refuses to back away from long held beliefs. It's a sin, but he's a lot like others that were once respected, like Larry Pardey, who though once well regarded, still thinks that epoxy is a passing fad!

Lastly, most of you are missing the dramatic differences between bedding compounds, sealants and adhesives. These terms aren't interchangeable, though some are using them as such here (which shows their experience level). You sometimes can substitute certain types of sealants for a bedding compound, but it depends of the formulation. Anyone that uses an aggressive material like 3M-5200 hasn't any real world experience with this goo on wood. If it remains stuck, it will rip up huge sections of wood in attempts to remove it. 3M-5200 has it's place, but not in a repair or replacement prone environment such as planking seams, particularly in light of the other products available for the same use.

As for Robster, I suspect we have very similar concepts and ideas, but are getting stuck on phrasing. Yes, I can list my design work and just about every client as well, including the production work currently underway.

The physical properties of 3M-5200 are well documented. I've seen this stuff hold 2.5 ton ballast casting in place when all the bolts have been sheered in a hard grounding! I've also personally pulled it out of many hundreds of feet of seams that unwitting owners and repair personal have applied it to. This is a common theme in the repair industry and also well documented. For those that just can't buy into the realities of these things, well you can sit beside some formerly well noted folks, but you're still relying on incorrect assumptions.

This is the same lesson we all have gone though, but it doesn't discount the materials or method in general, though your techniques and application (at the time) may have been less then acceptable.

You aren't the only engineer here Robster. I'm a two times over one myself. Maybe it would be better if you were a little more clear about the process you employed on your Chris Craft. You see, we get lots of "this sort of thing" and the usual reaction is to dismiss it out of hand, for the resulting long term damage it does to the yacht. I think you got caught up in this particular attitude, which I (as well as others) initially used. I think you may have taken some of the comments incorrectly or personally, which wasn't isn't our fault (nor my intention), but since my initial posts about this "technique" I have let the thread develop basically unmolested. Only recently have I rejoined to again dispel myths about these materials and their once popular, but now testing reinforced, not so much use.

My issue with your "technique" is the penetrating epoxy, which is a waste of money for diluted goo and the heavy bodied sealant used in you repairs. The penetrating epoxy will not stop moisture vapor ingress. This isn't debatable, it's well proven, just pick a major brand formulator and talk to their technical advisers. You stated an overcoat with epoxy, but I assumed a single coat, though I may be wrong, so how many overcoats of neat epoxy, before the planks were bedded? Did this overcoat include inside the faster holes? I'll assume so, (there's that assumption thing again) with your experience level. If you had to guess, how thick was the neat epoxy coating? Any reinforcements? In short, what about a straight up schedule for the "technique" and we can start this over with respect to clearly more expertise then the "usual suspects" (with similar posts) with 3M-5200 smeared all over their boat.

 

Par par, you are missing my whole point. First of all, seams as though your mind is stuck on trying to compare or mix wood composite methods to old cotton seam methods. I am absolutely not. and also for all the traditional guys out there, I thoroughly agree that 5200 should never be used or mixed with a traditional cotton/water soaked planking method. and if you try and repair a traditionally build wood boat with epoxy or caulking like 5200, the new repair will not expand/contract the same and also will trap water around the repair. causing total failure. I am sure that is what you and gonzo is talking about here. As I stated in the start of this thread, I am REBUILDING, NOT REPAIRING!!! and so therefore I am only using ONE system, not mixing old methods with new.

 

I edited my post to address some of your questions (Robster) and you posted before I could re-post. So if you would have a look at the last portion of my previous post and lets get everything sorted out and down to a level playing field again, of course if you're willing?

For what it's worth, I've played with similar ideas of what I (now) think you're talking about and it has some promise, but as you'd expect also some issues of it's own.