Bruce Farr Design ruins Beneteau First reputation

rotrax said:
So there you have it-race them hard and expect a short life but an eventfull one or forget racing, dont go aground or carry too much load on the rig and you will be OK.

Sorry-not for me.
Click to expand...
To carry on your diversion about bikes, I have a Ducati.
I know where I can get that repaired by very serious people who understand structures and whose welding is aerospace stand and then some.
Whereas yacht repair seems to be very often brush'n'bucket. (to use the polite form!).
 
I heard some awfull noises from a modern French boat as it was lifted in Gosport boatyard about 5 years ago.

When it was in its cradle the heads door was stuck.

'Arry the crane driver could not hear the noises-the cranes engine masked it. We concluded the hull had flexed during the lift, despite the strops being positioned correctly.

'Arry and Chris are good-they lift lots of boats and have a gentle touch.
 
lw395 said:
To carry on your diversion about bikes, I have a Ducati.
I know where I can get that repaired by very serious people who understand structures and whose welding is aerospace stand and then some.
Whereas yacht repair seems to be very often brush'n'bucket. (to use the polite form!).
Click to expand...

You have made that point well. My welding was ALWAYS carried out by myself, or if hi-tech was required by Jim Claridge. Jim was Eric Broadly's chassis shop foreman at Lola. He built or directed all the development stuff and prototypes, including Graham Hills Indy cars and John Surtees chassis for the Honda engine.

Where does one get a 40.7 inspected and, if required, repaired to a high standard? Who has the required expertise? What sort of cost is involved for a keel removal/structural matrix inspection?

Anyone know?
 
lw395 said:
Whereas yacht repair seems to be very often brush'n'bucket. (to use the polite form!).
Click to expand...

Quite. I know of a boat repair contractor who is basically a con man who cuts corners on his jobs and does them on the basis that as long as the end result looks good and the short cuts hidden then it will do. The surveyors do know about him but can't tell owners for fear of legal or "direct" action. He is probably far from being the only rogue or less capable operator in the industry which does seem to be rife with all kinds of poor practice. When it comes to keel work, repairs can be very difficult to assess and as I've already said, how can you possibly know how strong it is?
 
savageseadog said:
..... how can you possibly know how strong it is?
Click to expand...


You know how strong it is because GRP repair is not an unknown technology. It is an understood material and there are application techniques that can be used to ensure a good bond and that full strength and integrity is reinstated, hulls are regularly ripped down to remove osmosis and laid back up again, for example, structural epoxy beams are used to hold buildings up etc. I fail to understand why folks find this a hard concept to understand or doubt that such methods exist.

Of course poor quality and no quality assurance will undermine this, but if I was an owner undertaking such a serious repair, I would specify that the repair be monitored by a surveyor, that the repair was approved and that a Quality Assurance / Quality Control plan was developed and in approved. There are competent professional surveyors who are licensed navel architects and there are professional surveyors who cant use a moisture meter, after due diligence, it is probably possible to select the correct one to oversea such safety critical work.
 
BlowingOldBoots said:
You know how strong it is because GRP repair is not an unknown technology. It is an understood material and there are application techniques that can be used to ensure a good bond and that full strength and integrity is reinstated, hulls are regularly ripped down to remove osmosis and laid back up again, for example, structural epoxy beams are used to hold buildings up etc. I fail to understand why folks find this a hard concept to understand or doubt that such methods exist.

.....
Click to expand...
Not entirely sure about that.
Once GRP has flexed a lot, its mechanical properties can change.
There is a lot of faulty understanding of GRP.
The aging process of GRP under fatigue-like conditions is not that widely understood.
In my limited understanding, the work on failure of bonding at the microscopic glass to polymer level is still ongoing.
I've read a few papers but I'm fairly sure I don't have the full story yet.
I just know that old fibreglass dinghies are slow and a bit less stiff than new ones, without anything being visibly wrong.
That seems to be a similar process to what might have happened here?
 
lw395 said:
Not entirely sure about that.
Once GRP has flexed a lot, its mechanical properties can change.
There is a lot of faulty understanding of GRP.
The aging process of GRP under fatigue-like conditions is not that widely understood.
In my limited understanding, the work on failure of bonding at the microscopic glass to polymer level is still ongoing.
I've read a few papers but I'm fairly sure I don't have the full story yet.
I just know that old fibreglass dinghies are slow and a bit less stiff than new ones, without anything being visibly wrong.
That seems to be a similar process to what might have happened here?
Click to expand...

Indeed, Contessa 34s didn't start out with the 'hungry dog' look, they ended up that way. Still, the newly constructed properties of GRP, including repair techniques are understood, but I see the point you're making, the substrate that the repair is made too, may be weakened in a manner that is not detected or understood. An idea, perhaps deflection testing of a cell in the frame and comparing against a known value for new GRP could be used to determine how knackered a stiff section has become.
 
BlowingOldBoots said:
You know how strong it is because GRP repair is not an unknown technology. It is an understood material and there are application techniques that can be used to ensure a good bond and that full strength and integrity is reinstated, hulls are regularly ripped down to remove osmosis and laid back up again, for example, structural epoxy beams are used to hold buildings up etc. I fail to understand why folks find this a hard concept to understand or doubt that such methods exist.
Click to expand...

I think you are being perhaps a little overoptimistic. There is no doubt that composite structures can be made well, where by "well" I mean "able to meet the designer's expectations" but repairing is a different matter. Not only is there likely to be a discontinuity in the reinforcement, but bonds to a cured matrix are unlikely to be as good as the original cure strength.

For many purposes that's fine - there is no structural strength worth mentioning in gel coat (and of course no fibres) so as long as the new stuff sticks reasonably well to the rest here won't be a problem. Many other parts of even modern designs have plenty of excess strength. The bits to worry about are where large and unexpected loads are applied to highly stressed areas ... like a grounding impact at the keel attachment.

The repair procedures for composite gliders are extremely detailed and prescriptive. It would be interesting to know how detailed the instructions are for rebonding the keel support structure to a 40.7 (I presume that the answer is "very detailed") and how closely they were followed.
 
JumbleDuck said:
I think you are being perhaps a little overoptimistic. ..... The repair procedures for composite gliders are extremely detailed and prescriptive. It would be interesting to know how detailed the instructions are for rebonding the keel support structure to a 40.7 (I presume that the answer is "very detailed") and how closely they were followed.
Click to expand...

I don't think I am being optimistic. Beneteau issued repair instructions to their dealers and after sales peeps for the grid; one assumes that the repair procedure was subject to design and engineering. It would not be in Beneteau's interests to recommend a repair procedure that is substandard but of course they could, and it could also be incomplete, or of poor quality, or even both. The only point I am trying to make is that there is no technical reason why a proper repair procedure cannot be developed. I don't know if this is true, but it looks to me that the grid is attached to a cured hull at the manufacturing stage, so if this is the case I assume that the bond strength is fine and therefore any correct repair to cured FRP would also be fine.

I understand that subsequent bonds to cured FRP will likely have less strength than if bonded to FRP before some point in the gelling matrix is reached, I also understand that there may be inherent strength from the original manufacturing method that gets lost when some part of the structure is damaged and the strain is redistributed. What I believe is that all this can be addressed with the repair procedure and that Beneteau are capable of delivering. Interesting that none of the repairers questioned, quoted Beneteau's repair method, from what I can tell in the report.

Anyway, I am out my depth, just trying to second guess what is likely or not. The alternative is that everything is not intentionally substandard and the whole industry is just bumbling along hoping it will be all right on the night with the poor owner believing it is all right on the night. I doubt that though.
 
Last edited by a moderator:
BlowingOldBoots said:
I don't think I am being optimistic. Beneteau issued repair instructions to their dealers and after sales peeps for the grid; one assumes that the repair procedure was subject to design and engineering. It would not be in Beneteau's interests to recommend a repair procedure that is substandard but of course they could, and it could also be incomplete, or of poor quality, or even both. The only point I am trying to make is that there is no technical reason why a proper repair procedure cannot be developed.
Click to expand...

And that is where I think you may be overoptimistic (stress on the word "may"). There may (stress repeated) be some composite structures for which a good repair simply is not possible, or economically possible. As a parallel, if rot gets into the join between the main chassis rails and the cross members at the back of a Citroën DS, you are Stuffed with a capital S. Although it's just a matter of welding, the sections are so complicated and so much metal has to be cut away to get to the problem area that scrapping is the only sensible option.

Perhaps the only satisfactory cure for a delaminated grid on 40.7 is to strip out the entire interior, cut out the grid and rebond from scratch. Certainly possible ... but would anyone pay for that? For all the assurances we have about the specification and implementation of the previous repair to Cheeki Rafiki, four men died when - apparently - it failed again.

I hope this doesn't sound argumentative - it's not meant that way, and I completely agree that in many cases composites can be repaired very well indeed.
 
JumbleDuck said:
....
Perhaps the only satisfactory cure for a delaminated grid on 40.7 is to strip out the entire interior, cut out the grid and rebond from scratch.....
Click to expand...

I've seen a few repairs to various boats where I'd hazard that the new reinforcement added was, on its own, stronger than the original structure. The old hull skin is mostly there as a mould to lay up a new structure.
Costs a bit more in materials, but possibly cheaper than analysing things to the nth degree?
 
JumbleDuck said:
.... I hope this doesn't sound argumentative - ...
Click to expand...

Not at all, it is an interesting discussion, so much good information being discussed. I think you may be right that removing the interior and re-bonding the whole grid could be the only solution to fixing yachts with this type of design due to the difficulties of inspecting.

This is the glue which is used to bind cured laminates together: -

http://www.itwplexus.com/industries/marine.cfm

Plexus "Fiberglass Fusion" Adhesives have revolutionized the way boats are designed and built. When applied to fiberglass and other composites, they dissolve a thin layer of each mating surface and actually fuse two composite surfaces into one, creating a chemically cross-linked bond so strong that the composites will delaminate before the bond fails.
Click to expand...
 
It is all a bit different to the time Joshua Slocum built a 30 foot sailing canoe with just the toolkit salvaged from his wrecked ship with timber from trees felled on site in South America.

IIRC it got him and his family back home.
 
''Royal Yachting Association has drafted enhancements to its Sea Survival Handbook relating to
the possibility of a keel failure''. Perhaps we have to accept that this is now part of the risk we take with modern designs.
 
rotrax said:
WOW- becoming an accepted risk. As if there are not enough risks already.....................
Click to expand...

Better than being a risk that shall not be discussed.
I suppose there are three major bits that can fall off a yacht, mast, rudder, keel.
Racing boats have to prepare for the first two...

I think fin keels are here to stay, like heavier- than-air flight.
 
JumbleDuck said:
That's very interesting. That has come in since my composites days, and looks like the very stuff.
Click to expand...

Those adhesives are methyl methacrylate with benzoyl peroxide catalyst. Scott Bader have a similar range in UK.
e.g. http://www.scottbader.com/adhesives/selector/330/crestabond-m1-60

I have used a Plexus adhesive once. Rather smelly and messy! Good gap filling. I can't comment meaningfully on its strength but find it hard to believe it can compare with a full lay up, particularly in a thick bond line - Plexus say some grades can be used over 1" thick.

Here's an example for JD - I had a glider (Astir) on which the original hollow mainspar end pins that plugged into the opposite wing root ribs had to be replaced with solid ones (as a result of stupid overspecified fatigue testing by the RAF on behalf of the ATC). This meant cutting off the end of the mainspar of each wing - horror! probably the most critical highly stressed bit of the whole aircraft - and rebuilding it round a wooden block holding the steel pin. The rebuild scheme was very precisely specified by the manufacturer and involved a long scarf and a build up of multiple layers of glass cloth in very specific positions and orientations, only permitted to be done by repairers who underwent specific training on it.

That is how critical repairs need to be handled - you can't just leave it to Joe who knows all about repairing GRP, he's done it for years.
 
You must log in or register to reply here.

Share this page

Top