Multihull in distress.

[yeloya]

If there isn't any facilities that can haul out this size of cat (which I'd doubted) there isn't much to do. You need large pump/s enough to beat the intake of water and then haul it. Maybe a sizeable crane can be used if he can access to the docks. We were involved in couple of salvages of cat but they were only 38 and 42 ft. This is one is massive.. 50 tons of cat with one hull submerged will be a tough job anywhere..And I cannot figure out any floatating bag to keep her afloat..
Anybody knows this marina and their utilities ?


Cheers


Yeloya


Cheers


Yeloya

[tp12]

Originally Posted by s/v Jedi

Exactly, ask any rigger: cat rigging is oversized until it stops failing too frequently. I'm really not joking or trying to slam cats... and it is not the static wind load which is easy to calculate; it is the dynamic loading on the rigging with both wind gusts and waves. The heeling of a monohull is a dampener that the cat doesn't have. Most advantages come with side effects and this is an example. Cats must renew their rigging in a much more strict regime than mono's because of this: not getting away with 20-30 years like some mono's can.

It isn't that bad: some production mono's that had their keels fall off or loose rigs overboard, were fixed in the same way (make stronger until it holds) but the engineers didn't have the excuse of not being able to calculate... they just made it too cheap.

Originally Posted by s/v Jedi

Really?! What kind of education does a rigger need before designing rigs for sailboats? Also, please point us to citations about designing for shock loads on a catamaran

Why post when you don't really know? Just whacking the Jedi huh

Originally Posted by s/v Jedi

You're joking, right? A rigger may have apprentices that are at the bottom of the ladder and who do the grunt work but they can't call themselves rigger. A rigger can design a rig for any monohull, from chainplates, spars, spreaders to standing rigging. For cats they use rule of thumb like I explained before...



They tried for cats and failed every time. Again, when you make such bold statements but you can't come up with citations then it's nothing more than ignorance or at best opinion. I'm pretty sure I can come up with citations to support my position while you seem to sidestep and avoid it altogether which demonstrates that you can't back it up.

There's a rigger in this thread supporting my position so how long have you been in the naval architecture or rigging business to know it better?

Originally Posted by s/v Jedi

Indeed, thank you Pauls

High end riggers then enter the recorded data in computer models that can scale it to worse sea conditions that encountered during the tests/recordings and come up with predictions of the loads for the particular boat in those conditions.

When designs done with the model fail (dismasting, think the Gunboat cats that were all loosing their masts) they update the model to show higher loads so that stronger rigging is put on for future boats modeled.

The only thing that can be calculated is the load related to the boats righting moment RM. You can even add inertia factors, but loading by sea action is purely rule of thumb or computer model predictions

Originally Posted by s/v Jedi

No, I call ignorance because that is what it is. I am sure I can come up with citations from printed literature, not 100% sure I can links to it on-line. And I don't feel like getting my books out for a post that will get a "whatever..." reaction at best. Life's too short for that

I am not a naval architect but I am an engineer and have done many (dynamic) load calculations and read every book about sailboat design there is. Worked like an apprentice for a rigger for a week as well. I'm not sure if your comment was suggesting that I am ignorant on the subject as well, but can assure you that I don't post BS

You've called someone's comment as being ignorant because they haven't provided citations when you yourself haven't. Call them out for being 'whacking the jedi' when you're saying they're being ignorant?! That's disingenuous at best and an arrogant wind up at worst. You've made all sorts of unsubstantiated claims but still no proof. Then you throw out a dismissive comment so you won't be challenged. Quite frankly your credibility is pretty low. Let's see your citations.

Tell me, how does estimating input forces to any load model work differently between a cat and a mono - they're both subject to all the dynamic loading you've mentioned, are they not? Cats also heel until they tip, righting moment etc etc. What's the difference between estimating input forces between the two vessel types and what's the point you're trying to make?

[valhalla360]

Originally Posted by neilpride

Again, Riggers can redesign a new rig or replace a existing rig...

Some can but most I've come across are just guys who've been replacing rigging for a long time and call themselves riggers.

So no unless they have some further qualifications beyond calling themselves a rigger, I'm not trusting that they are structural engineers.

[boatman61]

Guess you've never noticed the difference in movement between cat and mono.. a cat has a much more erratic and multi directional movement that comes in short sharp jerks.. much harder to calculate loads with any accuracy than the relatively smoother movements of a monohull.. couple that in with the greater loads inflicted by the inherent stability.. takes much more force to lift a condo hull than it does to heel a mono..
Are you thinking logically or.. are you merely in blind defence of your chosen form of boat.
Recognise possible weaknesses and reef down early and you'll never lose a rig.. cat or mono..

[valhalla360]

Originally Posted by Pauls

Regarding the posts from Valhalla, Jedi, etc about engineering for shock loads, Jedi has it right. Valhalla, yes you can engineer for shock loads, but to do that you have to know what the shock loads are. If you have an engineering background then you can appreciate that motion at sea is highly variable. Add in variation in rig tune, hull flex (which causes rig slacking and greatly increases shock loads, variation in running rigging loads, etc and you end up with significant variables. If you have done actual rig design then you know that the safety factors used are large, typically in the 2.5 to 4.2 range. Why such a large safety factor? Safety factor = degree of unknown variables.

High end efforts that really need to know the details build a rig and install strain gauges all over it, then record data under various conditions of sea, sail, rig tune, etc.

And yes, I engineer for a living.

Also an engineer (though not structural but I work with several as my primary discipline uses lots of poles and guy wires). Yes, you apply factors of safety but there are well established procedures. And there are factors to account for shock loads.

It's not as someone suggested, you send the boat out and if the mast comes down, you up the wire size next time. Any engineer who takes that approach is at a minimum guilty of gross negligence if not criminal negligence.

[tp12]

Originally Posted by boatman61

Guess you've never noticed the difference in movement between cat and mono.. a cat has a much more erratic and multi directional movement that comes in short sharp jerks.. much harder to calculate loads with any accuracy than the relatively smoother movements of a monohull.. couple that in with the greater loads inflicted by the inherent stability.. takes much more force to lift a condo hull than it does to heel a mono..
Are you thinking logically or.. are you merely in blind defence of your chosen form of boat.
Recognise possible weaknesses and reef down early and you'll never lose a rig.. cat or mono..

I've sailed both, thanks.

Why is it harder to calculate? The higher loads that the catamaran can generate due to its stability are calculable. I agree, the force is more. But it's not the amount of force we're talking about here, it's whether it can be calculated. Them being bigger numbers means you just press more buttons on the calculator ... or, in reality, type it into an excel cell or DB model.

No?

I'd like to see the citations please.

[tp12]

Regarding adding a safety factor - how do you know how much of a factor to add if you can't calculate the original force? That doesn't make any logical sense and appears as guess work. Which is fine ... but then, how is that different to a mono? All the dynamic loading is the same in principle.

[boatman61]

Originally Posted by tp12

I've sailed both, thanks.

Why is it harder to calculare? The higher loads that the catamaran can generate due to its stability are calculable. I agree, the force is more. But it's not the amount of force we're talking about here, it's whether it can be calculated. Them being bigger numbers means you just press more buttons on the calculator ... or, in reality, type it into an excel cell or DB model.

No?

I'd like to see the citations please.

Bog off with your bludi citations..
I've yet to see a test tank or computer model that can replicate what can be met out there in its many variations.. be it coastal or ocean..

[tp12]

Originally Posted by boatman61

Bog off with your bludi citations..
I've yet to see a test tank or computer model that can replicate what can be met out there in its many variations.. be it coastal or ocean..

I'm not asking you for them. I'm asking the man who's asking others yet providing none ...

Pretty bludi cheeky if you ask me

[valhalla360]

Originally Posted by boatman61

Guess you've never noticed the difference in movement between cat and mono.. a cat has a much more erratic and multi directional movement that comes in short sharp jerks.. much harder to calculate loads with any accuracy than the relatively smoother movements of a monohull.. couple that in with the greater loads inflicted by the inherent stability.. takes much more force to lift a condo hull than it does to heel a mono..
Are you thinking logically or.. are you merely in blind defence of your chosen form of boat.
Recognise possible weaknesses and reef down early and you'll never lose a rig.. cat or mono..

I never suggested the loads on a similar displacement cat aren't greater. They certainly are.

You are confusing a cats need for stronger rigging with the inability to engineer for those loads as certain posters have suggested.

You see racing boats fail because they choose to participate in risky activities and part of that is cutting out the factors of safety down to nil. On a cruising boat there is no excuse for that unless a mistake was made or some new undiscovered phenomenon was found (shock loading isn't undiscovered).

Intentionally using an actual production boat sold to the public as a test to see if the rig is strong enough rather than doing the engineering homework is criminal negligence.

[boatman61]

Sadly criminal negligence is nothing new in the commercial world.. and harder to prove with sailboats.. how many successful prosecutions have you heard off against Beneteau, Lagoon, or any other manufacturer after loss of keels, rudders, gear failure.. et al.. Operator error.
Most of what's out there is designed for coastal playing.. with shelter close at hand to run to.. take them into the ocean at your own risk..

[neilpride]

Originally Posted by valhalla360

Some can but most I've come across are just guys who've been replacing rigging for a long time and call themselves riggers.

So no unless they have some further qualifications beyond calling themselves a rigger, I'm not trusting that they are structural engineers.

Good luck then if you run in some bad luck and dismast your boat..

[valhalla360]

Originally Posted by boatman61

Sadly criminal negligence is nothing new in the commercial world.. and harder to prove with sailboats.. how many successful prosecutions have you heard off against Beneteau, Lagoon, or any other manufacturer after loss of keels, rudders, gear failure.. et al.. Operator error.
Most of what's out there is designed for coastal playing.. with shelter close at hand to run to.. take them into the ocean at your own risk..

Yes and no,

Is there some criminal negligence about? Probably but most of the items would fall under general or at worst gross negligence. I'm sure Beneteau has engineers who run the calculations for keels & rudders. Criminal negligence suggests they knew there was a problem and chose to do nothing about it. I'm sure the engineers didn't think the keel was going to fall off but sent it to manufacturing anyway. That implies a mistake which falls under general or gross negligence.

The problem is most of your examples can be traced back to at least partially to maintenance issues. Since criminal proceedings are held to a much higher standard criminal negligence rarely gets prosecuted.

On the other hand, design by "see if the customer survives" as a certain poster suggestes is easily prosecuted, so no one in their right mind is taking that approach.

[valhalla360]

Originally Posted by neilpride

Good luck then if you run in some bad luck and dismast your boat..

Why?

Assuming the original design was done by a qualified guy and the boat is otherwise not significantly modified, no reason replacing in kind shouldn't work fine.

[Dockhead]

Originally Posted by robbievardon

onavegador,as a former marine salvor I can tell you that if you abandon a vessel then any one can claim the right of "Salvor in possession" if they place a person or tow line aboard the derelict.This allows one to salvage (recover) the derelict at their own risk and cost which would include removal of all parts of the vessel and general clean up costs. Unless the law has changed the owner may be paid out for total loss by his Insurers who are then entitled to return the wreck/derelict to the owner who then bears all the costs for removal and clean up. Had it been me I would have sent the crew ashore, but would have stayed aboard to maintain right of ownership and then tried to organise a vessel to tow boat back to harbour. The cost of tow is open to negotiation between Owner/Insurance Co and salvor. If you take on the Tow you take on the risk. If you succeed you get paid, if you fail you can payout big time, possibly ending up with a worthless wreck to dispose of. If you break down on the highway you expect to pay for a tow and there is minimal risk. Hardly robbery at sea,simply business.

It's a common myth, that staying aboard during salvage, prevents a "loss of ownership". Ownership is not lost in any case -- salvage does not transfer ownership of the vessel, which stays with the owner unless and until a court executes a lien on the vessel to force the payment of a valid salvage claim.

The size of the salvage award, however, may be influenced by the degree to which the owner stays on board and actively participates in the process, so I'm not saying, by any means, that it's a bad idea.


"There are several factors that would be considered by a court in establishing the amount of the salvor’s award. Some of these include the difficulty of the operation, the risk involved to the salvor, the value of the property saved, the degree of danger to which the property was exposed, and the potential environmental impacts. It would be a rare case in which the salvage award would be greater than 50 percent of the value of the property salvaged. More commonly, salvage awards amount to 10 percent to 25 percent of the value of the property."

https://en.wikipedia.org/wiki/Marine...Afloat_salvage