Structural Integrity Question

[smj]

Originally Posted by UNCIVILIZED

Gents, if you like, I can write up an explanation as to the why behind what I said. And if there's something grossly incorrect in it then I'll have learned something. However, such a thing would likely be a rather lengthy document.
I do have a fair bit of experience with, & knowledge of composite construction. Ergo, my previous statement on this topic.

Looking forward to the lengthy document

[UNCIVILIZED]

Originally Posted by neilpride

I see something similar before, a slight crack developing in the pad área, this one looks horrible ,, by the way we replace some crossbeams last year, one in a Swicht 51 and another in a Lagoon, just to point that to fit the crossbeam in the lagoon we need to pull the bow hulls apart by 1 inch to squezze the crossbeam in position, we use truck straps ...

The repair is pretty straightforward to me, the only isue is the crossbeam , the crack run alongside the pad, so in my shoes i remove the crossbeam and reinforce the área around the pad and looks like a previous repair in the picture , if you notice the caulking in the seam you can see obviously a coat of paint or gelcoat cracked around the seam... is not a Fountain Pajot isue by the way... Cheers...

For whatever reason, it seems the neilpride's thoughts on the damage to this vessel are more or less, the final say or expert's opinion. And I only say that as I don't know his background. However it seems that some of what he said does somewhat run along the lines of my thinking. Specifically in that he states that this damage "looks bad", and other statements which he made, repair wise, in terms of what needs being done correctively mimic what ran though my head when viewing the pictures.

That said, what follows is an explanation as to the reasoning behind what I said, based upon the damage which I saw in the pictures. And why it struck me as being a significant, & structural issue.
Big fixes in the yard are never fun, nor cheap.

The area in question is one of the more highly load points on the boat, given that it’s where the crossbeam mounts to the hull. And that part’s pretty common knowledge. Though if you look closer, compared to most cats, there’s very little structure or hull in front of the beam & it’s mount. Which means the point loading on the hull’s structure will be significantly higher than were it say, mounted 2-3’ back from the bow. Where there would be more hull structure to absorb/spread out the racking & twisting loads from the hull to beam connection .

If one takes more than a passing glance at the pictures, it’s apparent that this is a full thickness crack, through the hull. It can be seen on the image of the inside of the hull, just about where the aft end of the beam pad is, & there appears to be a weeping leak through the hull.
The leak being evidence that the crack runs through the full thickness of the laminate. Because there are no fasteners to weep, where the trailing water stain is.

That said, when composite structures (or most structures for that matter) undergo damage, it’s rarely extremely localized. Think of how much damage a vehicle sustains in a moderate collision/impact, the “crumple zone” thing. Well, to varying degrees, this spreading out of damage isn’t exclusive to cars. Though you may not be able to see as much with the eye. So it’s possible that some non-destructive testing of the surrounding area may be needed.
Depending on the severity of the point loading which caused the visible damage, cracks & micro fractures often spread out from the center point of things kind of like spider web cracks in glass. And determining how much of this is present, & how far it extends can be a tough one to determine sometimes. Thus, the need for a pro to evaluate the damage.

I don’t think that an engineer is needed in that this is going to turn into a court case, but rather to look at the damage, analyze the loads, & load paths in the area, as well as the materials used in it’s construction. All of this to be used as part of the information needed to make a proper repair. IE; one which is as good as, or better than new.
Also, based on his analysis, the determination may be made that this area in both bows needs to be beefed up. Ergo, more labor, time, & materials.
One thing to keep in mind in terms of “overbuilding” the bows where the beam attaches, if they’re too strong or stiff as compared to the rest of the hull nearby, then a new stress riser (point) has just been created. So again it’s wise to have a Pro’s input on such things.
FYI: It's pretty common to do Finite Element Analysis on the significant parts of a vessel when it's being designed. One of the reasons being, so that such doesn't happen. Which IMO is an expert's tool (FEA that is).

I say “part of” (above), because, given that this is a highly load area, odds are there is a specific layup schedule, including fiber axis orientation specified for each piece of reinforcement (fibers) used in the original construction.
There are a couple of ways to get this, albeit only one is exact. This being to get the original layup schedule, as well as the specific materials used to build this section of the boat
-Both the type, & manufacturer of the reinforcements; as strengths can vary hugely in the same weight & type of cloth from one maker to the next. As can the physical properties of resins, & what, if any special techniques which they may require.


For some of these, substitutes may be used, others not so much. Particularly if specialized materials are involved. Though either way, you again need a Professional to make these decisions, & it also may be a case where he needs to consult with the manufacturer to discuss such substitutions. As well as what was used initially.

Since at least part of this crack is full thickness (or so it appears in the pics), & it’s in one of the more highly loaded areas of the vessel, the repair must be done properly.
When doing a repair on glass work, one needs to scarf in the fix, (in theory) in at least an 12:1 ratio. Although given the location of the damage, it might be wise (pending a professionals’ recommendation) to grind an even larger bevel so that each layer of reinforcement being laid in has sufficient overlap/contact with what it’s being bonded to.

So if the crack is full thickness, that’s going to mean grinding away a big section of the hull at that point. Possibly even to the degree that some of the bow will wind up as part of the rebuild. I’m not saying whether such is necessary or not. Just pointing out what might be required to fix things properly.

Additionally, prior to any work being done on the fiberglass, the beam (and net) will need to be removed. Ditto on the beam's rigging.And some temporary staying of the mast will need to be put in place, to make up for the absent headstay when the cross beam is off. Also, there may be mandates which require the tenting off of the area in the vicinity of where the (grinding) work will be done.
And of course, the ordering in all of the correct materials for the job must be arranged for also.

So then, assuming all goes well with the repair of the glass, then a finish to match the hull will have to be applied. Including taping & covering the areas not being re-finished, in order to prevent over spray.
Then the cross beam will need re-installing, along with all of it’s hardware & rigging. The nets mounted, & properly tensioned. Headstay re-attached, & the rig tuned.

So when you start to add up the cost of:
-The yard time (just for having the boat hauled out & placed where work can be done on it, plus the re-launching fee).
-A professional’s analysis of & recommendations for fixing the problem (what's the rate for surveyors, & or engineers of late?).
-Consults with the original builder (rarely free).
-Labor (I'm guessing that time wise this repair, all told, may run into the triple digits, hours wise).
-Materials
With all of these things, the total price tag for a fix can wind up being fairly substantial.

The above is how I was taught how proper repairs are done, if there are flaws in the methodology, I'm open to hearing them. Ditto in terms of other ways of effecting a proper repair (not just doing a quick patch job). And if someone is kind enough to chime in with such, I'd appreciate an explanation of the why behind it, so that I might learn from it. And also direct me to any references illustrating other methods & techniques to enact a proper fix.

[smj]

Best to have a professional lay eyeballs on it. Guessing from four pictures is a waste of time. The statement you made that made sense to me is "thus, the need for a pro to evaluate the damage". Guessing on the damage and possible cost of repair from looking at the photos does the op no good. In fact it may turn him of a boat that is in perfectly good shape but in need of a small repair.


Sent from my iPad using Tapatalk

[colemj]

Again, that crack runs right straight along an obvious interior seam leading to an obvious two-piece join filled with some type of mastic or sealant. I suspect this is a completely separate cap piece of the bow that was tabbed on. Does that mastic-filled joint not raise flags to anyone as to what is happening to the crack? This is certainly not a continuous piece of the deck build.

I haven't seen this type of cap thing before, and don't understand the purpose of it if it is a cap, so hopefully someone with one of these boats can tell us how it is built in this area.

If it is what it appears to be, then the fix is no big deal and most likely no structural issue exists.

I am also pretty positive that on that design, the bows are not racking and taking a lot of forces of the boat. There is simply too much structure and build for that, both in hull volume and bridgedeck underwing, and not much free span. If the crossbeam did not exist, the bows would not be moving in any seaway. The only real forces on this area are the normal compression/tension ones of supporting the rigging - and the reinforced pad does this fine.

Edit: I just googled a bunch of Orana bow pictures and both bows on every boat have that separate bow deck cap piece directly over the crossbeam mount. It is very obvious. So, I am going with this crack not being much of a problem and related to a separate secondary hull/deck join - a pretty easy and inexpensive fix.

Mark

[arsenelupiga]

first thing: i would try to figure out what caused the crack.

Compare build with other bow. any attempt of previous fix evident ?

Poor build, i would probably walk away as there may be other gems hiding.

Else see what it takes to fix in money/time and include in price.

[colemj]

Originally Posted by UNCIVILIZED

Gents, if you like, I can write up an explanation as to the why behind what I said. And if there's something grossly incorrect in it then I'll have learned something. However, such a thing would likely be a rather lengthy document.
I do have a fair bit of experience with, & knowledge of composite construction. Ergo, my previous statement on this topic.

The only thing incorrect is that you have jumped to conclusions based on generalities. In this specific case, I don't think you know enough about the boat, its design, and its build to make the case you are attempting.

In fact, based on what I see, I am betting you are completely incorrect on this.

That doesn't make anything you wrote wrong in the general sense - just not in this specific case.

Mark

[colemj]

Yeloya, you seem to know this boat. Was the design ever stretched? It is obvious to me that there is a separate deck cap piece on the bow. The only explanation I can come up with is that this didn't start as a 44' boat, and a foot or so was added to the bow after the deck mold was made. So FP just made a cap piece to fit.

The other explanation I had was that the purpose of this separate deck cap was to allow access to the crossbeam mountings. However, it appears from the photos that there is already interior access to this area.

Mark

[neilpride]

Originally Posted by UNCIVILIZED

For whatever reason, it seems the neilpride's thoughts on the damage to this vessel are more or less, the final say or expert's opinion. And I only say that as I don't know his background. However it seems that some of what he said does somewhat run along the lines of my thinking. Specifically in that he states that this damage "looks bad", and other statements which he made, repair wise, in terms of what needs being done correctively mimic what ran though my head when viewing the pictures.

That said, what follows is an explanation as to the reasoning behind what I said, based upon the damage which I saw in the pictures. And why it struck me as being a significant, & structural issue.
Big fixes in the yard are never fun, nor cheap.

The area in question is one of the more highly load points on the boat, given that it’s where the crossbeam mounts to the hull. And that part’s pretty common knowledge. Though if you look closer, compared to most cats, there’s very little structure or hull in front of the beam & it’s mount. Which means the point loading on the hull’s structure will be significantly higher than were it say, mounted 2-3’ back from the bow. Where there would be more hull structure to absorb/spread out the racking & twisting loads from the hull to beam connection .

If one takes more than a passing glance at the pictures, it’s apparent that this is a full thickness crack, through the hull. It can be seen on the image of the inside of the hull, just about where the aft end of the beam pad is, & there appears to be a weeping leak through the hull.
The leak being evidence that the crack runs through the full thickness of the laminate. Because there are no fasteners to weep, where the trailing water stain is.

That said, when composite structures (or most structures for that matter) undergo damage, it’s rarely extremely localized. Think of how much damage a vehicle sustains in a moderate collision/impact, the “crumple zone” thing. Well, to varying degrees, this spreading out of damage isn’t exclusive to cars. Though you may not be able to see as much with the eye. So it’s possible that some non-destructive testing of the surrounding area may be needed.
Depending on the severity of the point loading which caused the visible damage, cracks & micro fractures often spread out from the center point of things kind of like spider web cracks in glass. And determining how much of this is present, & how far it extends can be a tough one to determine sometimes. Thus, the need for a pro to evaluate the damage.

I don’t think that an engineer is needed in that this is going to turn into a court case, but rather to look at the damage, analyze the loads, & load paths in the area, as well as the materials used in it’s construction. All of this to be used as part of the information needed to make a proper repair. IE; one which is as good as, or better than new.
Also, based on his analysis, the determination may be made that this area in both bows needs to be beefed up. Ergo, more labor, time, & materials.
One thing to keep in mind in terms of “overbuilding” the bows where the beam attaches, if they’re too strong or stiff as compared to the rest of the hull nearby, then a new stress riser (point) has just been created. So again it’s wise to have a Pro’s input on such things.
FYI: It's pretty common to do Finite Element Analysis on the significant parts of a vessel when it's being designed. One of the reasons being, so that such doesn't happen. Which IMO is an expert's tool (FEA that is).

I say “part of” (above), because, given that this is a highly load area, odds are there is a specific layup schedule, including fiber axis orientation specified for each piece of reinforcement (fibers) used in the original construction.
There are a couple of ways to get this, albeit only one is exact. This being to get the original layup schedule, as well as the specific materials used to build this section of the boat
-Both the type, & manufacturer of the reinforcements; as strengths can vary hugely in the same weight & type of cloth from one maker to the next. As can the physical properties of resins, & what, if any special techniques which they may require.


For some of these, substitutes may be used, others not so much. Particularly if specialized materials are involved. Though either way, you again need a Professional to make these decisions, & it also may be a case where he needs to consult with the manufacturer to discuss such substitutions. As well as what was used initially.

Since at least part of this crack is full thickness (or so it appears in the pics), & it’s in one of the more highly loaded areas of the vessel, the repair must be done properly.
When doing a repair on glass work, one needs to scarf in the fix, (in theory) in at least an 12:1 ratio. Although given the location of the damage, it might be wise (pending a professionals’ recommendation) to grind an even larger bevel so that each layer of reinforcement being laid in has sufficient overlap/contact with what it’s being bonded to.

So if the crack is full thickness, that’s going to mean grinding away a big section of the hull at that point. Possibly even to the degree that some of the bow will wind up as part of the rebuild. I’m not saying whether such is necessary or not. Just pointing out what might be required to fix things properly.

Additionally, prior to any work being done on the fiberglass, the beam (and net) will need to be removed. Ditto on the beam's rigging.And some temporary staying of the mast will need to be put in place, to make up for the absent headstay when the cross beam is off. Also, there may be mandates which require the tenting off of the area in the vicinity of where the (grinding) work will be done.
And of course, the ordering in all of the correct materials for the job must be arranged for also.

So then, assuming all goes well with the repair of the glass, then a finish to match the hull will have to be applied. Including taping & covering the areas not being re-finished, in order to prevent over spray.
Then the cross beam will need re-installing, along with all of it’s hardware & rigging. The nets mounted, & properly tensioned. Headstay re-attached, & the rig tuned.

So when you start to add up the cost of:
-The yard time (just for having the boat hauled out & placed where work can be done on it, plus the re-launching fee).
-A professional’s analysis of & recommendations for fixing the problem (what's the rate for surveyors, & or engineers of late?).
-Consults with the original builder (rarely free).
-Labor (I'm guessing that time wise this repair, all told, may run into the triple digits, hours wise).
-Materials
With all of these things, the total price tag for a fix can wind up being fairly substantial.

The above is how I was taught how proper repairs are done, if there are flaws in the methodology, I'm open to hearing them. Ditto in terms of other ways of effecting a proper repair (not just doing a quick patch job). And if someone is kind enough to chime in with such, I'd appreciate an explanation of the why behind it, so that I might learn from it. And also direct me to any references illustrating other methods & techniques to enact a proper fix.

Wow, no idea why they mention me here.. could be from the Yard guys topic and the wild discussion about construction metods or Rudder failure topic to..

I dont think you are to far when you claim is a structural isue , the top crack run close to the aluminium toggle pad, if the FG pad área fail the rig is gone, could be from overtension the crossbeam shroud, not a crazy idea, since if you overtension the crossbeam it take a banana form pulling both hulls to the center and stressing the área in question, or a collision , who know, without see the bows in situ hard to make a clear opinión, based in the pictures to me its still a bad crack... and the repair like you say call for grinder and FG in the área, without the crossbeam could be funy to keep the rig in place , bow cleats can do the trick with the spinaker and jib halyard ..

Yeloya is a FP agent if i remember well, let me know if im wrong, so we dont expect to see any negative comment about this boats, he claim they are solid, i say they are a big pile of dog **** but hey dont take my opinión for granted, each in their own, saying that i take your post seriously and your advice to...

I open this topic http://www.cruisersforum.com/forums/...-a-138817.html so fórum members can learn a bit how the mast is assembled and that include few pictures in how a crossbeam is tensioned and mounted in a large catamarán...Cheers...

[UNCIVILIZED]

Originally Posted by neilpride

Wow, no idea why they mention me here.. could be from the Yard guys topic and the wild discussion about construction metods or Rudder failure topic to..

I dont think you are to far when you claim is a structural isue , the top crack run close to the aluminium toggle pad, if the FG pad área fail the rig is gone, could be from overtension the crossbeam shroud, not a crazy idea, since if you overtension the crossbeam it take a banana form pulling both hulls to the center and stressing the área in question, or a collision , who know, without see the bows in situ hard to make a clear opinión, based in the pictures to me its still a bad crack... and the repair like you say call for grinder and FG in the área, without the crossbeam could be funy to keep the rig in place , bow cleats can do the trick with the spinaker and jib halyard ..

Yeloya is a FP agent if i remember well, let me know if im wrong, so we dont expect to see any negative comment about this boats, he claim they are solid, i say they are a big pile of dog **** but hey dont take my opinión for granted, each in their own, saying that i take your post seriously and your advice to...

I open this topic http://www.cruisersforum.com/forums/...-a-138817.html so fórum members can learn a bit how the mast is assembled and that include few pictures in how a crossbeam is tensioned and mounted in a large catamarán...Cheers...

I don't know why you were mentioned here either, though I surely appreciate your stepping in & shedding some light on a few things.
Just as I know that if I see a full thickness crack in fiberglass on any boat, but particularly on one where it's obviously been repaired before, that there's a problem (likely a significant one) which bears investigating.
And I stand by what I said about how such things are looked into, as well as repaired.

colemj, I don't disagree that sans crossbeam there wouldn't be a huge amount of racking of the hulls on a boat like this. Though she definitely needs that beam in order to remain a sailboat. And seeing the discontinuity of the fiberglass structure inside of the bow in 2 directions, in addition to the cracks inside & out around the bow says to me that she needs some love in order to keep that beam there permanent like.

[colemj]

Originally Posted by UNCIVILIZED

colemj, I don't disagree that sans crossbeam there wouldn't be a huge amount of racking of the hulls on a boat like this. Though she definitely needs that beam in order to remain a sailboat. And seeing the discontinuity of the fiberglass structure inside of the bow in 2 directions, in addition to the cracks inside & out around the bow says to me that she needs some love in order to keep that beam there permanent like.

Again, the two directions are exactly those of a separate cap piece and follow obvious join lines. One direction is the hull/deck join and the other is the very obvious deck/deck interface that is filled with sealant on the outside.

This looks like a simple hull/deck tab that broke. The fact that it goes through the entire layup is because I don't think it was ever part of the entire layup originally.

Mark

[UNCIVILIZED]

It is what it is, & since neither of us is contemplating buying the boat, I'm not going to lose too much sleep over it.
The irony being, for all we know, the post could be someone pranking us, to see how far the topic runs, & how much time people put into advancing their theories. But then, that's just a hypothetical.

[yeloya]

[QUOTE=neilpride;1712384]
Yeloya is a FP agent if i remember well, let me know if im wrong, so we dont expect to see any negative comment about this boats, he claim they are solid, i say they are a big pile of dog **** but hey dont take my opinión for granted, each in their own, saying that i take your post seriously and your advice to...

I am not and have never been an agent of FP. We are an official service point for FP, I like their boats and therefore all of catamarans in our charter fleet are FP. I have never said that they are the best boats around but I believe they are very strongly built. (Otherwise I wouldn't take the Orana for my Atlantic trip.I did Marmaris to BVI in 5 months and came back after 14.000 nm without any scratches on the boat)

I have always said my negative comments on any boat as well as on Oranas. (they are poorly finished..) Some 80-85 Oranas were buit but lost tremendeous market share to L450 that came up with fly bridge. FP then decided to answer with Helia which became a major success for them. (100 of them were sold in less than 2 years)

Back to the issue; I am just laughing to the comments made basing on 3-4 pics that were posted. One needs to know specifically what has caused this, any trace of damage anywehere else. Then one needs to grind the cracks until solid laminate and see exactly how far the cracks are going. Everything else would just be a speculation..

Cheers

Yeloya

[colemj]

Originally Posted by yeloya

Back to the issue; I am just laughing to the comments made basing on 3-4 pics that were posted. One needs to know specifically what has caused this, any trace of damage anywehere else. Then one needs to grind the cracks until solid laminate and see exactly how far the cracks are going. Everything else would just be a speculation..

I had a specific question for you - is that top deck of the bow end a separate piece from the rest of the deck mold? If not, why does it have that join?

Mark

[yeloya]

Originally Posted by colemj

I had a specific question for you - is that top deck of the bow end a separate piece from the rest of the deck mold? If not, why does it have that join?

Mark

Yes. Since 2004, starting with Lavezzi FP is using vacuum infusion moulding and in two pieces. Earlier models like Athena had the deck in two pieces (semi spherical, the joint line being just ay the buttom of the boat) + the roof.. Not very good IMO..

So, all recent models of FP have two pieces mould and what you see in one of the pictures is the join between the two pieces.

Hope this helps.

Cheers

Yeloya

[colemj]

Originally Posted by yeloya

Yes. Since 2004, starting with Lavezzi FP is using vacuum infusion moulding and in two pieces. Earlier models like Athena had the deck in two pieces (semi spherical, the joint line being just ay the buttom of the boat) + the roof.. Not very good IMO..

So, all recent models of FP have two pieces mould and what you see in one of the pictures is the join between the two pieces.

Hope this helps.

Cheers

Yeloya

Help me out a bit more here understanding this. Are you saying that the small piece on the deck of the bow is part of the bow hull mold itself, or is it a completely separate piece from both the deck and the hull molds?

Most boats I am familiar with have the deck laid up as a single structural piece, with the hull as another - and the two are then joined with a hull/deck joint around the perimeter.

This one seems a bit different than that, with that strange little piece on the bows.

Mark