New construction method?

4

416rigby

New member
I found this quite interesting. A quote from the C-Dory factory website in the "construction" pages.
The hull and it's cabin and deck components are laid up separately and then their molds are assembled together. The parts are then fiberglassed together while still in the molds to insure perfect alignment and to eliminate any possibility of twist. This process is time consuming, but yields a far superior hull to deck joint than any mechanical system.
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Pretty straight forward...seems like an excellent construction method. Sure seems to produce one tough boat.

On another thread, I read this:
Also mentioned by Tom was the development of a 'shoe-box' deck seam for the 22. The deck will be dropped over the hull and epoxy glued and bolted together under the rub rail. The deck won't be bonded to the hull while the parts are in their respective molds anymore. This will speed up the boatbuilding process.

The above information is as I remembered it from what Tom Latham said at the factory party. I could be wrong about some of this, it was a party after all!!

I hope the factory guys will comment on this after the boat show ends. We should get the strait story directly from the factory.
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Hmmm...if true, any thoughts? Could this be the end of yet another era?

Rick
 
I am afraid the later of thease two construction techniques is closer to the truth. This does not mean you should expect warped hulls. The hull and the deck are fitted together with little or no tolerance before anything is added to the interior. With the Hull and deck laminated in place there is no need to worry about warping.

Change does not always have to be a bad thing.
 
That 'shoe box deck seam' quote was mine.

It would be possible for the hull to be held in a cradle/jig to eliminate twist and the new molded interior parts could be bonded in place prior to installing the deck.

If this is true, then the factory could build the boats faster and the interior parts could be built simultaneously with the hull. This would be the same process as the construction of the 28.

If I recall the posts here about the 25, the hull/deck seam is the same 'shoe box lap seam' and it was the source of some leaks.

Most mass produced boats use the 'shoe box' seam and I have repaired many poor ones.

If the seam is well done, the boat could be just as strong as the current seam and it would speed production.

It appears that the factory is currently speeding up production in many areas. I hope the high quality standards of the past are maintained during this process.
 
To erehwonunderground, or perhaps I should say "Herenowunderground". First, welcome to the C-Brats, this is a great site and the folks on here have a wealth of knowledge (and opinions) about things C-Dory and boating related. However, and this is not an attack or criticism, but you joined yesterday, have posted twice, both times with comments about C-Dory construction methods, you are from Auburn, home of the factory; your tagline reads "change does not always have to be a bad thing", and those points in combination raise questions. So, are you a C-Dory employee or affiliated with C-Dory Marine or a C-Dory dealer? Do you have a C-Dory or are you, like I was for a year before I got C-Cakes, a wannabe simply trying to learn from the site?

Please don't interpret my questions as hostile. They are not intended to be so. I'd simply like to have a better feel for where, both figuratively and literally, you are coming from. There are certainly lots of opinions on this site about the molded interiors both pro and con so regardless of your opinion you'd find others in agreement. I rather doubt you'd find many (any?) on the site that would be in favor of changing from the glassed together hull/superstructure to the shoebox "Bayliner" approach and if you have information that the factory is going in that direction I'm relatively certain many on the site would really like to know about that, especially those who may be considering buying a new C-Dory.

I have to admit that I am beginning to be a little concerned about what seem to be more and more "speed up production" shortcuts in C-Dory construction. If the factory is going that way there is little we can do about it but I'd sure hate for C-Dory to become just another thrown together boat. Maybe I'm out of line with my questions and maybe I'm overreacting about factory construction changes. If so the C-Brats will quickly set me straight.
 
The quote said "expoxied and bolted" together. If that's true, that is a joint
stronger than what many (non-CDory) boats have. If the quote should have said
"screwed", that's a bit different. If they are going to epoxy and screw, then
the joint had better be pretty darn good.

Actually, I wonder if nuts and bolts would be such a good idea with an interior
liner glassed to the hull?

Mike
 
I've been through dozens of boat factories while working as a marine free-lance writer for both power and sail and can say that a shoebox joint has pretty much been an industry standard for decades.

When 5200 is added to the joint it is extremely strong and the function of the mechanical fasteners is dependent upon the centers of the fasteners added; the closer the better.

If done correctly, this shouldn't be a problem.

Nick
"Valkyrie"
 
Mike,

I cannot be sure about the actual joining method. It could turn out to be screws, rivets, bolts, or ?. The adhesive could be two part epoxy, one part bonding putty, or other modern chemical. I am sure I was told about the change to the 'shoe box joint'.

The boat building industry has many modern adhesives to work with.

I would really like for the factory guys to let us know the exact details. Perhaps after the boat show they will let us know.

I am posting from memory of a conversation at the factory party. Did anyone else hear that conversation?
 
Larry H":23blq2uk said:
That 'shoe box deck seam' quote was mine.

If I recall the posts here about the 25, the hull/deck seam is the same 'shoe box lap seam' and it was the source of some leaks.
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Originally the CD25 was built as the CD22 is currently...glassed together. It was changed to a shoe box joint to eliminate unfairness in the joint (which occured on the longer hull) and to eliminate leaks. The leaks were a result of the way the rub rail was attached; with a shoe box joint the rub rail extrusion forms a natural drip rail and the fastners holding the rub rails can be bedded properly.
 
Although the shoe box lid joint is a long and well proven technique (I had a boat from the 60's constructed that way). The real beauty of the C Dory has been that the hull to deck joint was glassed together--and any fasterners were also epoxyed over. This should have made a leak poof joint. The problem is not with the shoe box joint, but with the execution.

Unfortuately many builders put screws directly into the inner (hull) glass, or put 1/2 wood and screw into this. The other major problem has been unequal application of bedding compound--ie voids--and thus leaks. Remember that leaks can come from water pushing up (spray bow wave etc) as well as rain and from above). The measure of quality of a boat is how well this is affected and that the boat does not have any leaks.

To me the worst joint is that of an aluminum " H" extrusion which the deck (top) and hull (bottom) are inserted into and then pop riveted. There are so may potentials for leakage.

If the shoe box is done correctly it is a superior type of joint.
 
Greetings,

I have just returned from my third visit to the Seattle Boat Show where I spoke with a C-Dory Factory rep.

Here is the story on the new construction method.

The shoe box joint IS going to be used on the new 22's. However, the bonding method is the same as the current 22's. The deck will be overlapped on the hull and the joint fiberglassed inside with an approx 70 oz layup of fabric and mat. Then the rub rail will be riveted on and the inside of the rivets sealed as is done now. From the inside, it will look the same. From the outside, after the rub rail is installed, it will look like the 25 and Tom Cat which are already using this method. This joint doesn't depend on fasteners for its integrity.

After the deck is bonded to the hull, the interior f/g moldings will be installed and then the cabin top. The f/g interior moldings will then be completed with doors, etc.

This production change is being made to shorten the time the hull and deck need to be left in their molds. This also makes the 22 production similar to the 25 and Tom Cat

My thanks to the C-Dory rep for this information.
 
That sounds really nice. So many boats barely have any adhesive in this
joint, let alone fiberglass.

I had to pump silicone into some rather wide gaps on my Searay. The
water would run up under the rub rail, and with proper wind, into
the bildge. I had to dust the bildge with talcum power to figure it out.

It's not worthwhile to discuss what a friend went through with a Bayliner...

Mike
 
How should the rub rail rivets be sealed over on the inside. While cleaning the boat yesterday for our first big trip I found some bumps on the interior of the hull about rub rail height -- starboard side in the v-berth and also in the dinette -- that are soft. I assume caulk and painted over with the interior spatter coat. Standard or not?? Concern or not??

I usually tell my wife that her concerns of this type are premature and out of proportion. So I guess I'm probably just being a little old lady, but I can't resist asking.

As always, thanks for the info.

Greg
 
Greg-

That's the exact same method used to "hide" the rivet ends (or screw ends and nuts, I can't remember which) on my 1987 Cruiser.

Hasn't leaked yet in 21 years, so it must be OK!

Joe. :teeth :thup
 
I have a differing opinion than the consensus with respect to the 22 at least: The boat is very lightweight and attains acceptable strength through the means and methods of construction more so than any other factor. I therefore believe that a "shoebox" hull-to-deck joint would detract from the boat's stiffness, rigidity, and overall quality. It's one thing to have this arrangement on a heavily built boat like, say, a Rosborough, where the parts are too thick to flex, but not on the CD22. It would be akin to the difference between a bolted vs. welded joint in 2 metal pieces. Also, is a company that moves from unitizing parts to shoebox construction really likely to use epoxy to augment the joint? It would be nice to think so, but 1. doing so would negate much of the cost-savings of shoebox, and 2. you can't gelcoat over epoxy, so cosmetics would be a challenge. I might be wrong, but I really doubt C-Dory marine uses or has ever used epoxy in any part of their structural hull construction. Only the very finest and most expensive boats are built with epoxy resins. One thing I will concede is that moving to shoebox will save time and expense in the construction process. Just like using pre-fab thermoplastic gunnel cubby inserts and lazarette hatches saves over building and installing the same using FRP. Does anyone think that these changes have been an improvement? If this change occurs I will be happy to have ownership of a "pre-shoebox" C-Dory 22. Regards, Mike.
 
I think that the hull/deck joint is a structural design issue, and there are many ways of solving that problem. Obviously, the glassing method used on the previous 22s worked well. Journey On's deck/hull joint, which is whatever they use on C-25s has also worked well, with no leaks. What makes either method work is the detail design and execution.

We've owned 3 Catalina sailboats, from a (small) 22 to a (large) 36. To the best of my knowledge, all used a shoebox joint, and none gave any problem, including leaks. On the 22 I holed the hull, the factory lifted the deck and slid a new hull under. That second joint worked as well as the first. Though the owner got a lot smarter. The 36 survived 6000 nmi of blue water sailing. So it's not the type of joint, it's how they make it. And C-Dory seems to be doing a good job, either way.

Boris
 
Boris: not to be contrary, but don't boat manufacturers switch to shoe box chiefly to cut production costs? C-Dory marine has touted its glassed together hull/deck joint for years as imparting strength over other joining methods, and that extra time in the mold ensures a fairer, truer, more consistent hull. Has research now shown that these advantages no longer hold true? I don't think C-Dory's will start falling in half as a result of this change, but it's clearly an incremental degradation of build quality in favor of production efficiency, like many other little corner cuts we've seen over the years. Luckily most C-Dory owners will never push their boats beyond recreational use and things will be fine. In fairness, C-Dory has also incorporated many (mainly functional) improvements as well, but hardly any in the area of basic build quality. Note that you hardly see any threads about pre-2000 dories cracking, flexing, leaking in the cuddy floor, etc. Of course, this is all just my personal opinion. food for thought on a cold, wet Seattle afternoon. Mike.
 
Dont quote me on this or hold me responsible if I am wrong but...... I believe the "shoebox" concept and a certain Mr.Latham disappeared at approximately the same time .
Marc
 
Mike-

I have to agree with you wholeheartedly!

Back for a few years after I first bought my used 1987 CD-22 Cruiser in '98, I sometimes wished I'd bought a newer model.

The last 5 or more years have convinced me otherwise!

Between the QC problems experienced in that period and the reexamination of my own boat, I no longer feel that way at all.

I'm very much convinced now that I have the best boat possible, built by the Tolands very carefully by hand, and by painstaking craftsmen who cared about, and took individual pride in their product.

Today, I would not trade "up" to a later model "for love nor money"..........er, ...

well, what does she look like and how much money does she have? Does she like to cook on boat trips, too?


Joe. :lol:



westward":3j8rbndo said:
Boris: not to be contrary, but don't boat manufacturers switch to shoe box chiefly to cut production costs? C-Dory marine has touted its glassed together hull/deck joint for years as imparting strength over other joining methods, and that extra time in the mold ensures a fairer, truer, more consistent hull. Has research now shown that these advantages no longer hold true? I don't think C-Dory's will start falling in half as a result of this change, but it's clearly an incremental degradation of build quality in favor of production efficiency, like many other little corner cuts we've seen over the years. Luckily most C-Dory owners will never push their boats beyond recreational use and things will be fine. In fairness, C-Dory has also incorporated many (mainly functional) improvements as well, but hardly any in the area of basic build quality. Note that you hardly see any threads about pre-2000 dories cracking, flexing, leaking in the cuddy floor, etc. Of course, this is all just my personal opinion. food for thought on a cold, wet Seattle afternoon. Mike.
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OK, manufactures may use the shoebox joint because it's the cheapest way, but my thesis is that done correctly, it's a good way of joining the hull and deck. Catalina has done this for 40 years without a problem through my personal experience. C-Dory apparently is using several different methods and as far as I know, all are done well.

Boris
 
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