Lagoon 400 Bulkhead an issue?

[Catalysis]

Thanks I saw the nacelle but the concern I have is that the chain plates (to which the shrouds are attached) are at the top of the hulls - a transverse beam is normally used to provide the stiffness required to offset the tendency for the hulls to deflect.



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[neilpride]

Originally Posted by Catalysis

Thanks I saw the nacelle but the concern I have is that the chain plates (to which the shrouds are attached) are at the top of the hulls - a transverse beam is normally used to provide the stiffness required to offset the tendency for the hulls to deflect.



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LoL, This is the main bulkhead in your Antares 44, obviously with a aft partition to stop the bulkhead from buckling under mast compression loads, the mast and the cap shrouds put a lot of stress in this bulkhead , that's why your boat don't break in 2 , and gime a break please, bridge nacelles don't have nothing related to keep the boat stiff , they are designed to mitigate wave slam or pounding in low bridge clearance multis...

[arsenelupiga]

Originally Posted by Catalysis

Thanks I saw the nacelle but the concern I have is that the chain plates (to which the shrouds are attached) are at the top of the hulls - a transverse beam is normally used to provide the stiffness required to offset the tendency for the hulls to deflect.



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if you open underbelly of lagoon will see several substantial metal(?) reinforcements that are designed to flex more in line with boat geometry. I suspect these play role of transverse beam.

I have not seen any transverse beam. There is another wooden bulkhead in the back, that does not appear structural either. Used to separate engines from living spaces.

[robert sailor]

Originally Posted by arsenelupiga

i cant show you that. It is my best guess after looking in how boat is built. 2 tunnels have reinforcements (metal?) that can be seen from inside. Nacelle and bridgedeck has serious fiberglass thickness in places I was able to check. Risking to be accused of bias will say it anyway - boat appears built structurally very well and this is the reason for extra weight.

Was hoping someone will challenge my conclusion with some facts, but all quiet.

You write like someone who is serious and is trying to learn so I'm not trying to pee on your party but weight in cats is a demon as it really takes away performance. It's cheap and easy to make heavy cats but it takes more skill and it's much more expensive to make light weight cats that are still very strong. The Lagoons are not about performance in sailing, they are about "space" while at the dock or in an anchorage or when chartered with 8 or 10 people and they excel in this part of the market place. There are other cats that appeal to the more serious sailor and they are both lighter and stronger and sail much better but they don't have the party space afforded by the Lagoon. It's like everything else in life, you can't have it all.

[Factor]

Originally Posted by arsenelupiga

if you open underbelly of lagoon will see several substantial metal(?) reinforcements that are designed to flex more in line with boat geometry. I suspect these play role of transverse beam.

I have not seen any transverse beam. There is another wooden bulkhead in the back, that does not appear structural either. Used to separate engines from living spaces.

A metal cored cat - that is definitely a first for me.
Flex is not good - heavy is not good
Stiff is good -light is good

[Catalysis]

NeilPride.
Reread my post - I'm politely agreeing with you.


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[tuskie]

Originally Posted by GordMay

Group Beneteau manufactures CNB, Lagoon, Jeanneau, Beneteau, & many more.
➥ https://www.sgb-finance.com/beneteau-group.aspx

➥ https://www.beneteau-group.com/en/sa...ers/55-83.html

Yes, Gord, you are quite right.

The parent conglomerate is called "Group Beneteau". One of the companies it owns, or financially controls is CNB. This company manufacturers "Beneteau " brand as well as Lagoon. CNB is listed on the Manufacturers Plate of my Lagoon. There are many common components within CNB manufactured vessels.
"Beneteau Group", as you point out, also own (or financially control? ) many other companies such as Jeanneau, Wellcraft, Glastron, etc. These companies seem to operate separately and more independently.
To put it another way, there are quite a few similarities between Lagoon and Beneteau, but not between Lagoon and Jeanneau, Glastron or Wellcraft, even though all are part of the "Group Beneteau " family.

[smj]

Originally Posted by arsenelupiga

i cant show you that. It is my best guess after looking in how boat is built. 2 tunnels have reinforcements (metal?) that can be seen from inside. Nacelle and bridgedeck has serious fiberglass thickness in places I was able to check. Risking to be accused of bias will say it anyway - boat appears built structurally very well and this is the reason for extra weight.



Was hoping someone will challenge my conclusion with some facts, but all quiet.

I wish you would bring some facts to the table to substantiate your conclusion.
Why would Lagoon ad a massive amount of extra weight so they could have non structural bulkheads? Wouldn't it be smarter to make the hulls thinner, use higher tek materials and structural bulkheads and end up with a stronger much lighter product?
Please let us know when you hear back from Lagoon and the designers.


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[tuskie]

Originally Posted by arsenelupiga

if you open underbelly of lagoon will see several substantial metal(?) reinforcements that are designed to flex more in line with boat geometry. I suspect these play role of transverse beam.

I have not seen any transverse beam. There is another wooden bulkhead in the back, that does not appear structural either. Used to separate engines from living spaces.

Not sure exactly what you are referring to, but haven't seen much in metal except davit brackets. The mast compression post that you mention is a heavy fibreglass beam type structure and there are numerous heavily fibreglassed attachments. Is that what you are referring to?

I disagree about the main bulkhead not being structural. The Lagoon 400 has several bulkheads that are coved and heavily fibreglassed in place. I doubt that this would be done if not structural. The engine bay bulkheads also seem structural. Why would you remove a glassed in bulkhead? It has been explained to me that much of the design is about allowing the internal spaces to be large and not constrained by structural bulkheads. Many of the "walls" or simply partitions, not true bulkheads. Ths also allows many internal layout options.

Then again, unlike some others on this forum, I don't know everything. I'm sure the experts will enlighten me. In fact, I recently learned from another thread that it's quite alright to overload a catamaran because everyone does it.

[tuskie]

Originally Posted by smj

Please let us know when you hear back from Lagoon and the designers.

I doubt whether Lagoon or VPLP would be involved. Besides, we are well endowed with forum experts who regularly criticise these designs and obviously know much more than anyone employed by these companies.

[smj]

Originally Posted by tuskie

I doubt whether Lagoon or VPLP would be involved. Besides, we are well endowed with forum experts who regularly criticise these designs and obviously know much more than anyone employed by these companies.

I'm sure Lagoon or VPLP would be able to tell you if the bulkheads are structural or not as they designed and built the boats.
I agree with your previous post about the bulkheads being structural, can't personally see how a catamaran couldn't have structural bulkheads with the loads involved.


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[arsenelupiga]

i do not know if it is metal. That is why i put questionmark like

metal (?)

I am not going to do destructive testing to prove.

thats that from me. anyone, please post useful info regarding nacelle for benefit of L 400 owners.

[peterp]

Originally Posted by arsenelupiga

i do not know if it is metal. That is why i put questionmark like

metal (?)

I am not going to do destructive testing to prove.

thats that from me. anyone, please post useful info regarding nacelle for benefit of L 400 owners.

I received this link today see below a write up on the Lagoon 42S whilst it is somewhat off topic, the reporter does go in to some detail on Lagoon construction methods which may be relevent to this thread.

http://tmglagoon.com/wp-content/uplo...-Boat-Test.pdf

[arsenelupiga]

Originally Posted by peterp

I received this link today see below a write up on the Lagoon 42S whilst it is somewhat off topic, the reporter does go in to some detail on Lagoon construction methods which may be relevent to this thread.

http://tmglagoon.com/wp-content/uplo...-Boat-Test.pdf

Great insight !

It does confirm that is metal used.

And wood has no structural relevance - thanks good for this one - i could not sleep with wood being structural and rot that one cant control like all other cats

weight / sail area is actually slightly better in L400 than L42.

my entry for upwind is 5 kn in 10 kn true at 55 true in similar conditions. This seem better than what stated for L42. Reaching, lagging for a knot or so with gennaker due to better geomerty of L42 for such conditions.

[leftbrainstuff]

Originally Posted by Bill4

Top Tip for finding a surveyor: ask the marina/yard where the boat is based for a list of recommended surveyors and make sure the one you choose is not on the list! We did that and then flew our own surveyor in.

+1

Find your own broker. One who is technically competent and not a sales wah wah type. One has built, cruised and fixed boats. Fly him in and tell him to play tough cop.

Any broker who can't give you proper feedback, validated proof of repairs or who doesn't treat you respectfully should not be allowed to control the negotiations.

If your bs meter is flashing red then trust it. Bs and boat selling are never far apart.

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