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Old 16-11-2014, 11:05   #976
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Re: Rudder Failures

No, I wasn't joking. Just search google for broken bulkhead tabbing and find the vast amount of information from surveyors and boat owners who are repairing this problem on older boats.

Repairing Loose Bulkheads - Articles - boats.com

Bulkheads

Fiberglass Boat Bulkhead Repair-Replacment - at CaptainLevis.com

The Hull Truth - Boating and Fishing Forum

Bulkhead/Hull separation - Multihulls4us Forums

https://groups.yahoo.com/neo/groups/...ons/topics/106

The Restoration of a Cal 40 « A Brief History…

Sea Frost

An emergency test - Ocean Navigator - July/August 2004

Is Buying An Older Sailboat And Refitting It Worth It?

I could go on forever. Note that these are all considered "blue water" boats, and that surveyors find cracked tabbing often.

The problem here isn't a Plexus/tabbing one - it is buying an old boat problem. Tabbing doesn't last forever, nor is it necessarily dependent on who manufactured the boat. After 40 years, it simply wears out.

These are the old "blue water" boats many people on CF urge others to buy and take offshore because they are "bullet proof" compared to the newer huntabenelinas, etc.

Here is a professional's description:
"Most fiberglass boats are built with plywood bulkheads laminated to the hull for strength. Typical construction (called “tabbing”) involves bonding bulkheads to the hull with strips of fiberglass cloth wetted with polyester resin. Done correctly, these tabs give an initially strong connection that seems permanent. Appearances are deceiving. Polyester resins used in fiberglass boat construction actually do not bond well to wood. It is quite common on 5 or 6-year-old boats to find that tabbed bulkheads have broken away. This bulkhead delamination results in loss of transverse strength in the hull."

Mark
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Old 16-11-2014, 11:18   #977
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Re: Rudder Failures

Wow - GREAT information Mark. Thanks.

I've got some reading to do.

BTW - to me, this should be the biggest takeaway from this thread:

Quote:
Originally Posted by colemj View Post
The problem here isn't a Plexus/tabbing one - it is buying an old boat problem. Tabbing doesn't last forever, nor is it necessarily dependent on who manufactured the boat. After 40 years, it simply wears out.

These are the old "blue water" boats many people on CF urge others to buy and take offshore because they are "bullet proof" compared to the newer huntabenelinas, etc.
I think that's absolutely right. Just as I think that there is probably good reason to shorten the expected useful lifespan of production boats when looking to buy used (you should NOT expect the same longevity as the old boats). I don't yet have specific facts on that - but I think it's there.
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Old 16-11-2014, 11:32   #978
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Re: Rudder Failures

Quote:
Originally Posted by colemj View Post
No, I wasn't joking. Just search google for broken bulkhead tabbing and find the vast amount of information from surveyors and boat owners who are repairing this problem on older boats.

Repairing Loose Bulkheads - Articles - boats.com

Bulkheads

Fiberglass Boat Bulkhead Repair-Replacment - at CaptainLevis.com

The Hull Truth - Boating and Fishing Forum

Bulkhead/Hull separation - Multihulls4us Forums

https://groups.yahoo.com/neo/groups/...ons/topics/106

The Restoration of a Cal 40 « A Brief History…

Sea Frost

An emergency test - Ocean Navigator - July/August 2004

Is Buying An Older Sailboat And Refitting It Worth It?

I could go on forever. Note that these are all considered "blue water" boats, and that surveyors find cracked tabbing often.

The problem here isn't a Plexus/tabbing one - it is buying an old boat problem. Tabbing doesn't last forever, nor is it necessarily dependent on who manufactured the boat. After 40 years, it simply wears out.

These are the old "blue water" boats many people on CF urge others to buy and take offshore because they are "bullet proof" compared to the newer huntabenelinas, etc.

Here is a professional's description:
"Most fiberglass boats are built with plywood bulkheads laminated to the hull for strength. Typical construction (called “tabbing”) involves bonding bulkheads to the hull with strips of fiberglass cloth wetted with polyester resin. Done correctly, these tabs give an initially strong connection that seems permanent. Appearances are deceiving. Polyester resins used in fiberglass boat construction actually do not bond well to wood. It is quite common on 5 or 6-year-old boats to find that tabbed bulkheads have broken away. This bulkhead delamination results in loss of transverse strength in the hull."

Mark
Surely you can do better than that. An old Islander which has always had a history of lousy tabbing going back so far the Indians kicked Columbus in the ass for bringing it up.
A couple of power boats, one trying to make a water tight bulkhead
A Saga that had a wet bulkhead near the mast and subsequent tabbing failure.
An old Tartan(good boat by the way) that had a small bit of furniture tabbing break lose from an accident.
A Choey Lee with a cracked hull.

Geeez if your going to be one of Smacks boys you can do better than that.
Go back to Google search and find some real well built older boats that have suffered tabbing failure to a main bulkhead rather than calling on your own experiences as you claimed earlier. I am sure you will find something but I can tell you that you will not find many even though these boats are old because if they were built well they still stand the test of time. You know there are Albergs from the 60's that are still sailing offshore, that's what 55 years. How many of these new Plexus wonders are going to be around in 55 years? My guess....none!
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Old 16-11-2014, 11:42   #979
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Re: Rudder Failures

Quote:
Originally Posted by robert sailor View Post
... Polux tells us that Bavaria is going back to glassed in bulkheads and that is probably a good thing as they are trying to say to their customers, look we may have built a lot of boats very cheaply in the past but we want to position our brand as more capable offshore and an improved structure is one way to do it, good on them, buyers should give their new boats a second look. Maybe others will follow and stop the race to the bottom.
Humm, I did not said that. I said that Bavaria, that is the more conservative of all mass production builders, still uses tabed bulkheads but I have saw that on the very last models, like the recent 41 they, like Hanse and Dehler, use on new boats bonded bulkheads except the main one that is laminated (and I suppose bonded too):

"In collaboration with specialists from Farr Yacht Design, BAVARIA's design and production team work out an individual load profile for every yacht, from which they later derive laminate plans and reinforcements. The focus is on a stable bulkhead, which also manages the forces acting on a CRUISER 41. Precisely fitted into the hull to the nearest millimetre, it is securely glued to the hull across a large area. Particularly strong keel bolts ensure a force-fit to the keel – twice as many as is usual in yacht construction. The mast support conveys the forces of the rigging into the reinforced floor assembly – this kind of distribution of forces is used on modern racing yachts. In addition to the stable hull structure, a massive main bulkhead that is laminated to the hull ensures ultimate rigidity. For protection in the event of frontal collisions, every CRUISER has a collision bulkhead."

BAVARIA Yachtbau - CRUISER 41

I don't know if that talk regarding the boats being stronger is true (I don't have that impression regarding Hanse) but basically they have to justify to their clients why their boats are heavier than some of the competition, namely jeanneau. Weight on a sailboat if not needed is not a good thing and a more modern building process can save weight giving the same resistance as well as a more modern keel (than the ones used on Bavaria) can save weight.

The Bavaria41 weights 8680kg, a jeanneau 4097860kg.

But the Bavaria is lighter than an Oceanis 41 (8777kg) and for instance a Hanse 415, that is heavier (8900kg) has a more efficient keel and more ballast so... the hull is considerably heavier, using similar techniques

I am not saying that the Jeanneau 409 is less strong, they use a different building system (close to the Oceanis) but they claim that their injection building technique (they use on the deck) saves them many hundreds of kg.
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Old 16-11-2014, 11:46   #980
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Re: Rudder Failures

Quote:
Originally Posted by Polux View Post
The Bavaria41 weights 8680kg, a jeanneau 4097860kg.
I gotta think that's a typo. Heh-heh.
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Old 16-11-2014, 13:22   #981
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Re: Rudder Failures

So far all this thread has proven is that boats can do break. And I bet that owners play as much if not more into how soon it happens.
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Old 16-11-2014, 13:44   #982
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Re: Rudder Failures

Quote:
Originally Posted by Polux View Post
I don't know what to say to you and don't want to be rude but Open 60's use carbon and nomex. Go to the sites of top boat builders, specially the ones that are more advanced on the use of top materials and you are going to see you are not right and many passed from balsa, that is cheaper, to airex, corecell and other similar materials. Please search before you reply. Has I have explained to you the problem with balsa is only in marine use and has to do with water absorption and delamination.

For instance Halberg Rassy that was on of the first conservative brands to used cored hulls had problems with the balsa core in several boats needing expensive repairs. They only sorted it out when they passed to foam with closed cells. They say:

"Compared to the single skin hulls in the old days, today's hulls are insulated, which means a superior torsional stiffness of the hull. The material used is a PVC foam called Divinycell. It is fitted when the laminate is still wet, and then covered by laminate. The Divinycell is a superior material for a cruising boat, compared to balsa. The PVC foam has closed cells, which means that the material does not absorb water. The Divinycell will finally be covered with more laminate."

How a Hallberg-Rassy hull is built

As I have already said to you, why the hell would be Dehler using the better balsa core on its cheap versions and the worse foam core on its hugely more expensive epoxy versions (R )?

Here you have the hull specifications for the cheapest standard version:

"GRP hand laid sandwich construction with end grain balsa core for strength and isolation; Supporting bulkheads bonded to the hull; Construction of hydrolyses proofed polyester resin, vinylester in first layer and roving fabrics, balsa wood; core and unidirectional fabrics; Floor beams laminate into the hull to distribute keel and rig forces along the laminate construction "
https://www.dehler.com/media/documen...-38-274415.pdf
and the specification for the R version. They give the R denomination but it is not a racing boat, just a faster and better built boat, obviously considerably more expensive:

"The hull is built using vacuum consolidated hand lay-ups. The laminated construction consists out epoxy resin, multidirectional fabrics and foam core as sandwich material. Internally the laminate is finished off with a topcoat.
A sandwich construction with predominantly foam core and end grain balsa wood in certain areas provides additional strength and stiffness. Integrated aluminium reinforcements are laminated-in for all deck fittings. T
..The floor beams are hand, laminated into the hull, distribute the keel and rig forces evenly along the bottom structure. "

Schwern-Yachten: News
Well, the last quote confirms what I just said -- that balsa is preferable where strength is needed. And if you Google "Open 60 balsa" you will see that Open 60's are built the same way -- Nomex honeycomb and foam of various types in big panels -- this is lighter -- and balsa -- heavier but far stronger -- in high stress areas. I have seen them built. Honeycomb is not practical on cruising boats because of the voids, which would instantly fill up with water in case of any hull breach. And even Nomex honeycomb doesn't quite match balsa for strength.

Attachment 91748

That's from the site of Gurit, which make and supply all kinds of composites, including foam and balsa cores. Core Properties - shear strength, compressive strength of core materials


Most high-end boats still use balsa, at least in high stress areas of the hull, and certainly in decks, where the strength and stiffness are especially important.

It is not true to say that balsa is "old school"; foam is "modern". An engineer would laugh at such an idea. They are different materials with different properties; not football teams. Balsa is supreme for compressive strength, but may be too heavy for very large panels which have been engineered to have enough strength without it. Balsa is also less elastic and absorbs less energy -- so where a design needs energy absorption, then foam is better for that. Balsa is more tedious to work with -- another reason to use foam if the strength of balsa is not needed. Engineers decide what tradeoffs to make in any given design.
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Old 16-11-2014, 13:46   #983
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Re: Rudder Failures

The report of the Cal 40 shows pretty good examples of failed tabbing:

The Restoration of a Cal 40 « A Brief History…

Quote:
One concern was the tabbing of bulkheads to the hull.



Here you can see the space beneath the head vanity cabinet. The thruhull for the sink drain and the head water intake is seen in the center. It was replaced before launching along with most of the others. The bulkhead, which carries the load from the port chainplate, attaches here to the hull. This bulkhead is also attached to the beam by several steel plates welded to the beam and bolted to the bulkhead. The plates can’t be seen here.



Here the debris from scraping the hull is gone and the area of the bulkhead tabbing can be seen clearly. The tabbing was loose and has been removed. One of the plates that attaches the bulkhead to the beam is shown at the left side of the photo. This tabbing was replaced before the thruhull was replaced and other work done that would have obstructed access to the area.



Here, tabbing from an aft bulkhead to the deck is seen and is disrupted. This is the area where the genoa track was (We removed it and filled the holes) and the load on the deck has pulled it up from this half bulkhead, which is just forward of the ice chest. This area was also ground down and retabbed.



Here, another area on the starboard side, is seen with disruption of the tabbing from bulkhead to deck. This is adjecent to the starboard chain plates. It was ground down and retabbed.
They sure did some great work on that boat though. Wow.

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Old 16-11-2014, 13:58   #984
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Re: Rudder Failures

And though no pictures, the account of this Cheoy Lee 48 ketch breaking and nearly sinking is pretty sobering:



An emergency test - Ocean Navigator - July/August 2004

Quote:
Joss was hauled and fully repaired in Aruba. Upon close inspection it was determined that during that fateful three-day trip our forward bulkhead tabbing broke away from the hull, resulting in oil-canning of the hull and a fracture in the fiberglass. The boatworkers of Aruba told us that many vessels heading east arrive in Aruba with shattered and broken bulkhead tabbing.
I do admire the sailors for how they handled it though. Tough dudes.
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Old 16-11-2014, 14:06   #985
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Re: Rudder Failures

Quote:
Originally Posted by robert sailor View Post
Geeez if your going to be one of Smacks boys you can do better than that.
Go back to Google search and find some real well built older boats that have suffered tabbing failure to a main bulkhead rather than calling on your own experiences as you claimed earlier. I am sure you will find something but I can tell you that you will not find many even though these boats are old because if they were built well they still stand the test of time. You know there are Albergs from the 60's that are still sailing offshore, that's what 55 years. How many of these new Plexus wonders are going to be around in 55 years? My guess....none!
Like the Alberg 37? Survey - Â*

But really, you missed my point in your snarkiness. Glass tabbing is not the end-all of quality. I don't know why you think I come down on the side of Plexus (or should I say "one of Smacks boys)? While I think a construction design is possible, and is done for some boats, where Plexus-glued main bulkheads are better than tabbing, I don't think the pictures I have seen of varnished wood glued to fiberglass with Plexus is one of those.

In fact, I don't think wood is a proper main bulkhead material to begin with. And if you want me to get pedantic about quality, our boat was built with its main beam and structural bulkheads as part of the PRIMARY hull layup. The only secondary bonding done on them is the glassing of their tops to the deck. So I could easily point out that your "high quality" "blue water" boat construction examples are nothing more than shades of mediocrity.

And if you don't think that 40yr old "blue water" cruising boats are experiencing tabbing failures, then you must be one of Minaret's boys…

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Old 16-11-2014, 14:09   #986
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Re: Rudder Failures

Quote:
Originally Posted by smackdaddy View Post
And though no pictures, the account of this Cheoy Lee 48 ketch breaking and nearly sinking is pretty sobering:

I do admire the sailors for how they handled it though. Tough dudes.
Keep in mind that they experienced 27-30kt winds with gusts to 40kt. These are not conditions a Hunter or Bene could survive because they are not a Perry-designed "blue water" boat.

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Old 16-11-2014, 14:10   #987
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Re: Rudder Failures

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Originally Posted by sailorboy1 View Post
So far all this thread has proven is that boats can do break. And I bet that owners play as much if not more into how soon it happens.
I agree with your first part, but not so much with your second part (racing not considered). I think age plays a large role.

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Old 16-11-2014, 14:13   #988
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Re: Rudder Failures

Quote:
Originally Posted by smackdaddy View Post
The report of the Cal 40 shows pretty good examples of failed tabbing:

They sure did some great work on that boat though. Wow.
Don't cherry-pick from my list to make a point - that is Robert's prerogative...

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Old 16-11-2014, 14:19   #989
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Re: Rudder Failures

Quote:
Originally Posted by colemj View Post
Like the Alberg 37? Survey - Â*
Hey! I did the Harvest Moon Regatta with Maarten on a Pearson 365 a couple of years ago! Very cool guy. Here we are battling horrible conditions in the cockpit:





AND Lou Stahlberg also did my survey! I'd recommend him in a heartbeat. Awesome surveyor.

Definitely looks like some issues with that tabbing in his Alberg:

Quote:
Tabbing disconnected in some places



Some of the bulkhead tabbing had become undone and was repaired.
Of course, he did a great job rehabbing Joan III. And he's my kind of sailor:

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Old 16-11-2014, 14:40   #990
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Re: Rudder Failures

The Cal 40 was a great boat in its day and pretty much cleaned up on anything racing out on the Wet Coast. Cal's are OK constructed but no one I knew considered them top line boats so I'm sure these boats that have been raced hard and put away wet are now getting long in the tooth and are showing their age although nothing as catastrophic as the near new Bavaria that was posted. I don't consider this as an example of a well built blue water cruiser, your going to have to dig deeper.

Glass tabbing and through bolts are seen in many better built boats, sort of a belt and suspenders approach.

The Cheoy Lee is a pretty boat but there again no one I know considers them a top of the line cruiser. Dig up some pic's of old Oysters, HR's,Moody's,Amel's,Malo's,Contests...that sort of blue water boat and show me pic's of failures in the main bulkheads. If you dig hard enough you may find one or two but it will be a bit harder for you.
Like you I don't think that plywood is a great bulkhead unless its completely encapsulated in FG but even then water can over the years do damage if it gets in around the chain plates but in those days it was as good as it got and by and large it worked quite well. Laminates in my mind are the best bulkheads and tabbing them or a combination of glue and tabbing is probably the best but that's not in the cards for the entry level boats. Tabbing should be done in epoxy as it is far better than polyester for getting a good secondary bond.

It is not hard to build a good boat, its simply not cheap. I know little about the construction of Cats so I'll take your word that you have one that has been well built.

And finally I guess if I had to choose between being a Smack boy or a Minaret boy I'd most definitely choose the latter. Cheers
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