The not so benign Med

[mikedefieslife]

Originally Posted by slug

Surge is what cause cleats to tear out or dock lines to break

Which happens in every marina in the med normally in calm times the boats are tugging back and forth violently and stretching their lines or snubbers.

[Bill Seal]

There's also no base on the cleat to spread the load from the top.

[walidada]

Get a Class S and S Swan. There is an abyss in the build and design quality between them and Benneteau/Jeanneau. They are still going strong after 45 years and better than any modern boat.

[De.windhoos]

Originally Posted by mikedefieslife

Which happens in every marina in the med normally in calm times the boats are tugging back and forth violently and stretching their lines or snubbers.

Yes, and I'm always amazed about the number of boats that do not tension their lines properly and/or have very short non-stretchy aft mooring lines. that way you will get heavy shock loads.

I always tie the bowline off in such a way that I have to use a fair bit of RPM to get close enough to the dock and tie the aft lines with the engine still in reverse. that way my boat doesn't swing or goes back and forth too much and therefore reduce shock load quite a bit. For longer stays or if a gale is coming I use additional mooring lines attached to the winches, this gives me nice long lines and additional security.

[Montanan]

Originally Posted by tkeithlu

That's a pretty big cleat to not have even a backing plate, and the structure is one sheet of 3/4" or so plywood - the fiberglass doesn't seem thick enough to add anything. Simply looking at that cleat my mental response is "Someone will tie a pretty heavy boat to this thing," and I'd expect a builder to think the same, even without any engineering. A shock absorbing dock line would help, but really...

There is no plywood in that deck, just layers of polyglassfibers, in that Bendytoy. See photo image expanded for a closer view.

Definitely should have had a sturdy force spreading backer plate. The point loading of the nuts / washers is a failure prone design & fabrication. And a sturdy force spreading topping plate so as to not have just the two pillars of the cleat being force loading points. Top and backing plates are the proper method for mounting a hard point on a boat.

Note the large extra length of the threaded bolt, there would be plenty of length to have installed a thick topping and backing plate. The plates need to be wider than the narrow width of the cleat, think a squarish shapes bigger than the length of the cleat so as to not avail torquing athwartship as has happened in this deck segment. Or at least rectangular with as wide of the narrow distance as possible.

Does make one ponder the engineering and production of the rest of the boat's critical parts.

Seen lot's of med moorings which are poorly protected places subjecting boats to tremendous direct waves and harsh superpositioning of reflected waves off the wall and of course close proximity bashing into adjoining boats. Med Mooring is often not a good practice when bad weather is pending. Better to be tied to a float mooring with proper snubbers deployed [or at anchor] by the bow and not be med moored in rough waters.

IMHO, thus a failure of boat component and of boat owner to place a boat at an adversity of med mooring.

[SVHarmonie]

Originally Posted by Chotu

My new custom boat has 1” balsa where cleats go (for compression strength) and 1/4” aluminum backing plates.

Could you please explain this? Balsa has extremely low compressive strength. You can crush it with your fingers. Balsa is used in deck structure because of its very high sheer strength in comparision to its weight. But compression? Not at all... Balsa is one of the weakest woods in compressive strength.

It is possible that I am missing sarcasm but I don't think so.

[Chotu]

Originally Posted by SVHarmonie

Could you please explain this? Balsa has extremely low compressive strength. You can crush it with your fingers. Balsa is used in deck structure because of its very high sheer strength in comparision to its weight. But compression? Not at all... Balsa is one of the weakest woods in compressive strength.

It is possible that I am missing sarcasm but I don't think so.

I’m sorry. Not sure where you are getting this information from. It’s dead wrong. Balsa is the core with the highest compression strength. Beats all the standard foams. In no way can you begin to crush it with your fingers or even a hammer. It basically splits apart from a hammer blow instead of compressing. I’m assuming you’ve never touched this material.

This isn’t model plane balsa. It’s standard end grain balsa core that’s used in marine manufacturing.

ProBalsa


From the link:

“ ProBalsa is a high-quality organic core material made from end grain balsa wood. Featuring exceptional compressive strength, it is used in a wide range of applications and can also be combined with polymer core materials in, for instance, wind blades.”

Elsewhere: “ In addition to structural honeycombs, Nida-Core also produces other lines, including BalsaLite, a highly processed end-grain balsa noted for high resistance to crushing and its ability to handle excessive dynamic loads with superior resistance to fatigue.”

The NidaCore BalsaLite is the exact product I put in where deck hardware was to go. As you see by the description, it’s a superstar for this application provided you don’t install the hardware incorrectly.

Everything else on the boat is Corecell.

[SVHarmonie]

Originally Posted by Chotu

I’m sorry. Not sure where you are getting this information from. Balsa is the core with the highest compression strength. Beats all the standard foams. In no way can you begin to crush it with your fingers or even a hammer. It basically splits apart from a hammer blow.

This isn’t model plane balsa. It’s standard end grain balsa core that’s used in marine manufacturing.

ProBalsa

Chotu,

I do know what balsa IS and its strength relative to other materials. I stand by my statement that as far as comressive strength it is the LOWEST of all the choices you could make. Here is some data for you for compressive strength parallel to the grain:

Loblolly Pine 49.2MPa
Sitka Spruce 38.7MPa
Red Oak 46.6MPa
Yellow Poplar 38.2MPa
Balsa 14.9MPa

So there is some data courtesy of the Forest Product Institute. Do you have other data??? You are comparing balsa to other normally used core materials, but cleats SHOULD NOT BE BOLTED THROUGH CORED PANELS.

Solid fiberglass (the go-to choice for premium boatbuilders under cleats) is an order of magnitude higher than these numbers.

[Chotu]

Originally Posted by SVHarmonie

Chotu,

I do know what balsa IS and its strength relative to other materials. I stand by my statement that as far as comressive strength it is the LOWEST of all the choices you could make. Here is some data for you for compressive strength parallel to the grain:

Loblolly Pine 49.2MPa
Sitka Spruce 38.7MPa
Red Oak 46.6MPa
Yellow Poplar 38.2MPa
Balsa 14.9MPa

So there is some data courtesy of the Forest Product Institute. Do you have other data??? You are comparing balsa to other normally used core materials, but cleats SHOULD NOT BE BOLTED THROUGH CORED PANELS.

Solid fiberglass (the go-to choice for premium boatbuilders under cleats) is an order of magnitude higher than these numbers.

Yikes!! Not talking about putting pieces of lumber into a boat here. That’s where we are at a disconnect.

You are thinking in terms of a design spiral not suited to light boats but extremely heavy ones where the loading is much, much higher due to inertia. Even then, nobody puts chunks of pine in the core. Solid fiberglass is just fine if you know precise locations, but there is a small weight penalty. An enormous weight penalty if you don’t have the precise location of all deck hardware as you lay up the hull. I built an extremely high performance catamaran.

It’s just fact. Balsa is the strongest core (actual marine core, not lumber) in compression.

Still thinking you’ve never touched a piece of end grain balsa though. You described it as something you can crush with your fingers. A hammer doesn’t even crush it. You’re not talking from experience. You’ve never evaluated and used different marine cores to build a boat.

There is nothing wrong with through bolting a cored section of hull given your core has good compression strength, which balsa does.

And mine has been tested at levels orders of magnitudes beyond this thread. 50’ high windage catamaran at anchor through a category 4 hurricane. Direct hit of the eye. These same cleats and core held just fine.

Only my 2 bow cleats held the whole thing. At anchor though the category 4 direct hit.

[arsenelupiga]

lagoon has similarly build cleats but we never had issues even in 80 kn and 2 m chop waves on mooring. I think it is all fiberglass actually. Not even hair cracks meaning no serious twist of fiberglass.

Manual explicitly says that clets are designed to be used with longitudinal force.

Washers have done proper job. Strengthening the whole area may cause larger structural damage to the hull if even larger surge comes. LAgoon has plenty of cleats so one can tie so that main force is mainly longitudinal, presume benetau as well.

nothing to see here, move on. next time tie better.

[GarthGregory]

A serious contributing factor if not the main problem , is in stern to mooring , using a way to heavy a quarter warp and which also has no stretch . If one has surge from say a passing ferry , there is the surge of a yacht weighing many tons with no give in the warps . I have seen a number of yachts with cleats ripped out , both modern and old heavier built type . I have tried the heavy rubber type absorbers and have had them all break . I have now backed all my deck cleats ( S/Steel 316 - 200 x 80 x 8 mm ) and bedded them in epoxy . The studs instead of tapped to 20 mm , I have tapped them to 70 mm .More important I have binned my heavy warps from a doubled 16 mm on each quarter , down to a doubled 8 mm ,with a shorter single 6mm line for stretch - much more comfortable and quieter . The breaking strength of modern rope is VERY high . My 2 cents worth

[NSboatman]

...all the metal boat owners are loving this thread.

These days, I really only worry about pulling cleats out of docks, not the other way around!

[GarthGregory]

What you are looking at is not Balsa core , it is a glassed in Marine Ply backing board to spread the load of the cleat .

[CassidyNZ]

Originally Posted by SVHarmonie

I do know what balsa IS and its strength relative to other materials. I stand by my statement that as far as comressive strength it is the LOWEST of all the choices you could make.

This is probably off-topic but you’re referring to balsa that is being compressed from the side (parallel to the grain). Balsa used in an end-grain application is as strong as most timbers, stronger than many and almost certainly the strongest strength:weight ratio. I recall many years ago building reefer truck bodies using end-grain balsa and demonstrations done hitting end-grain balsa very hard with a hammer left almost no perceptible dent. In end-grain configuration it is very strong.

I can’t believe any boat builder would use balsa in anything but end-grain lay-ups. It used to be the go-to core material before the exotic composites of today.

Still, I’m not suggesting that mooring cleats should be bolted through a section of cored deck and using flat washers as backing plates . . .

[slug]

A cleat is designed to be loaded longitudinally and in sheer
I don’t see evidence of sheer loading on the torn out cleat

I suspect that the cleat was loaded off axis or in tension and this incorrect load tore the cleat from the deck