Lagoon bulkheads

[Simi 60]

Originally Posted by crayiii

The new designs have the compression post on a grid under the saloon floor. Better? I don’t know. We have the new design and have asked Lagoon several times if they will provide us with either drawings or inspection instructions and they refuse to send the drawings and have told us there isn’t anything to inspect.

And you accepted this and continued with the purchase?

[crayiii]

Originally Posted by Simi 60

Drink it up, don't waste a drop.

It takes a special kind of **^# to crap on other people’s boats. Nicely done professor.

[Simi 60]

Originally Posted by crayiii

It takes a special kind of **^# to crap on other people’s boats. Nicely done professor.

And a special kind to continue saying they are great when they are clearly having issues.
How many more people do you want to draw into this debacle?

[crayiii]

Originally Posted by Simi 60

And a special kind to continue saying they are great when they are clearly having issues.
How many more people do you want to draw into this debacle?

I haven’t said they are great. They have issues just like double decker wood trawlers do. Just like monohulls do. Just like every boat. It sounds like you have experience with Lagoon catamarans. So I welcome your first hand knowledge. Thank you for your participation.

[Simi 60]

Originally Posted by crayiii

I haven’t said they are great. They have issues just like double decker wood trawlers do. Just like monohulls do. Just like every boat. .

Yep, but structural integrity shouldn't be one of them

It sounds like you have experience with Lagoon catamarans. So I welcome your first hand knowledge. Thank you for your participation

The only experience I have with lagoons is sailing near them in prior vessels and observing them in our current one.

But having built a couple of cats for myself , helped build a few others and studied plenty of other designers plans and bulkheads I believe I have some experience in what a structural mast bulkhead should look like and how it should perform.

[crayiii]

Originally Posted by Simi 60

Yep, but structural integrity shouldn't be one of them



The only experience I have with lagoons is sailing near them in prior vessels and observing them in our current one.

But having built a couple of cats for myself , helped build a few others and studied plenty of other designers plans and bulkheads I believe I have some experience in what a structural mast bulkhead should look like and how it should perform.

I KNEW we were among greatness!

We currently have 20k NM on our Lagoon and had a real shipwright do a complete structural inspection when we hauled last year since Lagoon wouldn’t supply drawings. There were no issues.

We also had new sails custom made by a local loft. I’m guessing we don’t sail much slower than you but with considerable more range.

[Simi 60]

Originally Posted by crayiii

I KNEW we were among greatness!

:

Don't get to carried away there
I'm just an ex boatbuilder who who has seen what works and what doesn't.

We currently have 20k NM on our Lagoon and had a real shipwright do a complete structural inspection when we hauled last year since Lagoon wouldn’t supply drawings. There were no issues

Fantastic
But that doesn't negate the fact that there are issues with the design and construction of the bulkhead.
Unless of course, yours was done differently

We also had new sails custom made by a local loft. I’m guessing we don’t sail much slower than you but with considerable more range.

Probably right
We can only go 3500nm before needing fuel
But we can carry near unlimited supplies with no problems.

[crayiii]

Originally Posted by Simi 60

Don't get to carried away there
I'm just an ex boatbuilder who who has seen what works and what doesn't.



Fantastic
But that doesn't negate the fact that there are issues with the design and construction of the bulkhead.
Unless of course, yours was done differently

Probably right
We can only go 3500nm before needing fuel
But we can carry near unlimited supplies with no problems.

Our bulkheads (like all the two digit models) are completely different than the older (three digit model) designs.

We crossed the Atlantic with four onboard. Our biggest fuel year was 2021 where we used a total of 1300 liters. During Covid, we didn’t reprovision for six months (with four adults onboard). We aren’t lacking for space or comforts. You chose your boat, I chose mine and it sounds like neither of us have regrets.

I’ll buy you a beer when we get there.

[Pelagic]

Originally Posted by impi

Why did we decide to upgrade a new boats bulkheads?

We did this simply because we owned a catamaran before the 440 (different brand and it had a bulkhead issue). My family are also in the catamaran business selling Outremer, HH catamarans and others (NOT lagoons) and have service contracts with leopard, FP and other brands

I think this was a very reasonable and well researched decision based on the reality that large production catamarans at an obtainable price point... are still evolving.

As someone pointed out, the Torsional Stressing on a catamaran are far more complicated than on a production monohull.

Monos also went thru an evolution of bulkhead failures before best design and production practices were acknowledged.
It takes time on different proving grounds with varying Sea conditions, Boat Speed Rig forces and hull loading motions to highlight structural weaknesses.

That is not a failure in design concept or production methods, just a fine tuning the manufacturer of weight sensitive catamarans need to make.

Thanks Impi for your intimate insight on this issue

[fourlyons]

Originally Posted by Pelagic

I think this was a very reasonable and well researched decision based on the reality that large production catamarans at an obtainable price point... are still evolving.

As someone pointed out, the Torsional Stressing on a catamaran are far more complicated than on a production monohull.

Monos also went thru an evolution of bulkhead failures before best design and production practices were acknowledged.
It takes time on different proving grounds with varying Sea conditions, Boat Speed Rig forces and hull loading motions to highlight structural weaknesses.

That is not a failure in design concept or production methods, just a fine tuning the manufacturer of weight sensitive catamarans need to make.

Thanks Impi for your intimate insight on this issue

This sounds reasonable, until you remember that multihulls have been built for decades without this failure. Because it's been known for decades how to properly attach bulkheads.

This is most certainly a design and construction method failure. These cats aren't even particularly light.

[smj]

Originally Posted by fourlyons

This sounds reasonable, until you remember that multihulls have been built for decades without this failure. Because it's been known for decades how to properly attach bulkheads.

This is most certainly a design and construction method failure. These cats aren't even particularly light.

Are heavier cats always stronger than lightweight cats? Or do heavier cats have more loads on them making them weaker?

[wingssail]

Originally Posted by Pelagic

...Monos also went thru an evolution of bulkhead failures before best design and production practices were acknowledged...

Oh really? I didn't know that.

I do understand that wooden boats of old often had movement in their structure, which the advent of fiberglass cured. It that what you are referring to?

[malbert73]

The current Groupe Beneteau structural practices in both monos (Beneteau) and multis (Lagoon) reflect IMO too far on cost cutting side.

The extra cost of properly tabbing in the structural grid before placing furniture in the Beneteaus, and the extra cost of properly built and tabbed bulkheads in Lagoons while still in build phase - would have to be negligible compared to overall cost- I am estimating 5K tops per boat in materials and labor. But the market eats the boats up at boat shows so until consumers start caring it won’t change.

So I do take exception with the practice of “cheaping out” on structural members. I have owned and operated several old boats (1966 Luders 33, 1984 C&C 30, current 1987 Tartan 40) and none had ANY bulkhead or structural issues. Age/cosmetic sure, but I wasn’t tearing boat apart to fix bulkheads.

It’s just not that tough to make the bones of the boat “permanent quality” while it’s being built. And it doesn’t add that much weight compared to everything that gets put in later.

[crayiii]

Originally Posted by malbert73

The current Groupe Beneteau structural practices in both monos (Beneteau) and multis (Lagoon) reflect IMO too far on cost cutting side.

The extra cost of properly tabbing in the structural grid before placing furniture in the Beneteaus, and the extra cost of properly built and tabbed bulkheads in Lagoons while still in build phase - would have to be negligible compared to overall cost- I am estimating 5K tops per boat in materials and labor. But the market eats the boats up at boat shows so until consumers start caring it won’t change.

So I do take exception with the practice of “cheaping out” on structural members. I have owned and operated several old boats (1966 Luders 33, 1984 C&C 30, current 1987 Tartan 40) and none had ANY bulkhead or structural issues. Age/cosmetic sure, but I wasn’t tearing boat apart to fix bulkheads.

It’s just not that tough to make the bones of the boat “permanent quality” while it’s being built. And it doesn’t add that much weight compared to everything that gets put in later.

Yeah, either VPLP screwed up big time on the bulkhead calcs for the 450 or Lagoon didn’t follow the specs.

[Chotu]

Originally Posted by smj

Are heavier cats always stronger than lightweight cats? Or do heavier cats have more loads on them making them weaker?

This is something a lot of people definitely don’t understand. The lighter the boat the stronger it is in many cases. Counterintuitive, but SMJ is right. if you keep the bulkheads constant, butake a light weight boat, you end up with an incredibly strong boat because the forces are low on those bulkheads.

if you keep the bulkheads constant again and go way up with the weight, like boats in this thread, you start to run into problems where the bulkhead can’t keep up with the loads.

Making a boat lighter is always going to make it better.