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First 40.7 keel reinforcement


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These are good boats that are much maligned since the Cheeky Rafiki incident and hence being sold for a low price in the used market.

I have heard that there are some program that successfully modified and strengthened the keel grid structure, I wondered how would be the appropriate way to do it, and does anyone known of any boat that had successfully did the modification?

Been looking into one of these boats.

Thanks

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6 minutes ago, Caecilian said:

They are built to rigorous maritime engineering standards

Yes, but that is a subjective standard, good enough for weekend cruising or offshore/ocean races?
Have read a few post about the keel even before Cheeky Rafiki happens as I search the past posts here; along with rudder issues.

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Personally I wouldnt go near one that I didnt know the history of based on the reports.  Even the best designed grids could have a sketchy installation by low wage workers on Friday afternoon. If your plan is to cruise or race in relatively sheltered water then why not but crossing oceans? Not for me.

The grid is a major item, I really cant see how you can repair one properly and with confidence without removing the interior, sectioning it out and almost starting from scratch again.

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7 hours ago, ctutmark said:

Jazz, a Bene 40.7, doing the Fastnet just dropped out b/c of a leak at the keel bolts so it is a current issue with these boats, especially as they age 

Jazz was a First 40, not a First 40.7.

I don't know if the grid design is different between the 40.7 and 40.  I don't want to buy either of them.

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3 hours ago, Alex W said:

Jazz was a First 40, not a First 40.7.

I don't know if the grid design is different between the 40.7 and 40.  I don't want to buy either of them.

Grid design should be different: "The hull shape is beamier, lower and sleeker than the 40.7’s. It is also a foot longer than the 40.7 with 25 percent more righting moment" https://www.sailmagazine.com/boats/beneteau-first-40-2

25% isn't trivial amount imho.

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16 hours ago, Wckoek said:

These are good boats that are much maligned since the Cheeky Rafiki incident and hence being sold for a low price in the used market.

I have heard that there are some program that successfully modified and strengthened the keel grid structure, I wondered how would be the appropriate way to do it, and does anyone known of any boat that had successfully did the modification?

Been looking into one of these boats.

Thanks

"good boats"?

I would hardly call a boat that the keel falls off of a "good" boat. Sure, it would be different if that one particular boat had versy individual circumstances and was the only one to have a problem. But that is not the case.

 

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Motored a 40.7 at hull speed into a submerged jetty.  The steering wheel was bent and the helmsman injured  but no damage to the keel structure.  Upon haulout a baseball sized chunk of lead was gone.  That's it.

Personally I think 40.7 keels are plenty strong enough.

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3 hours ago, fastyacht said:

"good boats"?

I would hardly call a boat that the keel falls off of a "good" boat. Sure, it would be different if that one particular boat had versy individual circumstances and was the only one to have a problem. But that is not the case.

 

Good in terms of price, performance and rating.

But I would probably think of walk away if there isn't a proper way to strengthen the structure.

No point buying something that leave you sleepless at night even though it might be strong enough.

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This shit scares the fuck out of me.  I am really digging the Bene First 53, but, fark, I dont think I would risk it.  Too many Bene's lately with issues.   Would make me so nervous.

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You have to click a few stupid survey questions to see the story. Read the BOLD below

Excellent call on withdrawing from the race. 

 

https://www.bournemouthecho.co.uk/news/19500819.racing-yachts-emergency-call-sparks-lifeboat-response/

 

 

A YACHT had to support by a lifeboat crew following an incident during a race between Cowes and Cherborg in France.

The 40-foot yacht issued a 'pan pan' emergency call during the Fastnet race on Sunday afternoon.

The all-weather lifeboat from Swanage was requested to launch after the yacht's crew reported hitting something and suffering a water leak.

A Swanage RNLI spokesperson said: "The yacht’s pumps were initially coping with the water ingress but the situation could worsen very quickly so the lifeboat crew were paged and were soon on their way to the yacht’s last known position.

 

"The yacht had reversed its course and was now heading back towards the Solent but the lifeboat caught up with them just over 30 minutes after launching.

"The yacht’s pumps were still coping with the water ingress so the lifeboat agreed to escort them in to the Solent where the plan was to hand over the escort to Lymington lifeboat once they were nearer to Lymington.

"Unfortunately the plan had to change quickly as the water ingress suddenly got worse as the boats approached Lymington river

"The lifeboat’s powerful portable salvage pump and two crew were quickly put aboard and the water ingress was stabilised.

"The yacht was then taken to a boat yard for an emergency lift to get it out of the water. Once the yacht was lifted clear of the water the damage to the yacht’s keel was obvious."

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http://newimages.yachtworld.com/resize/1/77/23/4457723_20130920111543592_1_XLARGE.jpg?f=/1/77/23/4457723_20130920111543592_1_XLARGE.jpg&w=1280&h=986&t=1381259169000

 

why not make a full wide SS backer in one part to replace  the little bars as wide as they are

full length fore and aft bent up and down to fit on part top section instead of the separate bars

with several extra holes to drill new bigger longer stronger keel bolts

to sandwich the grid between the lead keel and the top SS solid cap

plus drill holes in the top of the grid hat sections and squirt epoxy inside

then run the new keel  bolts thru the top of the hat sections to screw and glue the grid

 

yes that may cost some boat bucks even need CNC work with over sized SSbar to fit tight

extra bolts holes ect

 

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5 minutes ago, nota said:

http://newimages.yachtworld.com/resize/1/77/23/4457723_20130920111543592_1_XLARGE.jpg?f=/1/77/23/4457723_20130920111543592_1_XLARGE.jpg&w=1280&h=986&t=1381259169000

 

why not make a full wide SS backer in one part to replace  the little bars as wide as they are

full length fore and aft bent up and down to fit on part top section instead of the separate bars

with several extra holes to drill new bigger longer stronger keel bolts

to sandwich the grid between the lead keel and the top SS solid cap

plus drill holes in the top of the grid hat sections and squirt epoxy inside

then run the new keel  bolts thru the top of the hat sections to screw and glue the grid

 

yes that may cost some boat bucks even need CNC work with over sized SSbar to fit tight

extra bolts holes ect

 

That's a lot of fucking around with no reliable strength when you are dome with it.

The boat is basically fucked unless you cut all that fucking "grid" shit out and start over with a NEW keel with a wide enough footing. So at that point just get the fcuking chainsaw and be done with it. Get an old Pearson.

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Overall we are going to see the ultimate result of crevice corrosion of stainless bolts. Boats will be dropping keels in 10-20 years at a reliable rate.

You do know that the ONLY reason stainless is EVER used below the waterline is cost, right? Si Bronze is the only suitable keel bolt material.

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8 minutes ago, fastyacht said:

Overall we are going to see the ultimate result of crevice corrosion of stainless bolts. Boats will be dropping keels in 10-20 years at a reliable rate.

You do know that the ONLY reason stainless is EVER used below the waterline is cost, right? Si Bronze is the only suitable keel bolt material.

Its not about the bolt, but the whole structure.

Replacing the bolts are easy peasy but all the reports I've seen that keel dropping is structural, the post pictures given that they broke cleanly.

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10 minutes ago, nota said:

http://newimages.yachtworld.com/resize/1/77/23/4457723_20130920111543592_1_XLARGE.jpg?f=/1/77/23/4457723_20130920111543592_1_XLARGE.jpg&w=1280&h=986&t=1381259169000

 

why not make a full wide SS backer in one part to replace  the little bars as wide as they are

full length fore and aft bent up and down to fit on part top section instead of the separate bars

with several extra holes to drill new bigger longer stronger keel bolts

to sandwich the grid between the lead keel and the top SS solid cap

plus drill holes in the top of the grid hat sections and squirt epoxy inside

then run the new keel  bolts thru the top of the hat sections to screw and glue the grid

 

yes that may cost some boat bucks even need CNC work with over sized SSbar to fit tight

extra bolts holes ect

 

I agree with Fastyacht that that suggestion is complex and expensive with little to no add'l strength.

Better to pour a single piece keel with built in flanges (6"? 12"? 18"?) at the top to match hull contour and then recessed into hull and secured by adequate backers between the grind section.

Realize the grid does not support the keel in any way; it only gives the hull rigidity

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2 minutes ago, fastyacht said:

That's a lot of fucking around with no reliable strength when you are dome with it.

The boat is basically fucked unless you cut all that fucking "grid" shit out and start over with a NEW keel with a wide enough footing. So at that point just get the fcuking chainsaw and be done with it. Get an old Pearson.

in normal times perhaps

but in an era of very few good boats on the markets

and depressed prices on these

if they can be saved ? with out great cost say 10 to 20 %

btw does loading epoxy with short CF do much for bonding shear strength

 

my other idea would be messier and cost a bit more

remove the gel coat and add glass outside down the keel/hull joint area a few feet each way

then add side bolts into the keel lead

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15 minutes ago, fastyacht said:

Overall we are going to see the ultimate result of crevice corrosion of stainless bolts. Boats will be dropping keels in 10-20 years at a reliable rate.

You do know that the ONLY reason stainless is EVER used below the waterline is cost, right? Si Bronze is the only suitable keel bolt material.

Only an issue if salt water and oxygenated water can get into the joint.  I see plenty of thirty and forty year old boats with stainless keel fastenings with no issues.  However back then they were designed to Lloyds and where there might have been 12 or 14 1” bolts, now we might see 8 or 9 M16 fastenings.  On top of this we are now looking at hull matrix that cannot be surveyed supporting massive bulbs hanging off minimal webs, often sailed by f***wits … so all in all a less than satisfactory state of affairs.

So back to the Bene 40.7, I wouldn’t go near unless I was certain of the provenance 

 

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42 minutes ago, Wckoek said:

Its not about the bolt, but the whole structure.

Replacing the bolts are easy peasy but all the reports I've seen that keel dropping is structural, the post pictures given that they broke cleanly.

Indeed that is true in the Bene. But for every design that has strctural problem there are 20 or 50 others that have stainless waiting to blow. Decades go by and WHAM all starts happening That is coming. In the older days bronze was standard.

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41 minutes ago, nota said:

btw does loading epoxy with short CF do much for bonding shear strength

 

my other idea would be messier and cost a bit more

remove the gel coat and add glass outside down the keel/hull joint area a few feet each way

then add side bolts into the keel lead

carbon fiber destroys all metal it touches.

draw it not understanding

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33 minutes ago, DavidYacht said:

Only an issue if salt water and oxygenated water can get into the joint.  I see plenty of thirty and forty year old boats with stainless keel fastenings with no issues.  However back then they were designed to Lloyds and where there might have been 12 or 14 1” bolts, now we might see 8 or 9 M16 fastenings.  On top of this we are now looking at hull matrix that cannot be surveyed supporting massive bulbs hanging off minimal webs, often sailed by f***wits … so all in all a less than satisfactory state of affairs.

So back to the Bene 40.7, I wouldn’t go near unless I was certain of the provenance 

 

you mean DEoxygenated water.

Still water trapped in spaces tends to dexygenate. That's how crevice corrosion happens. The chromium oxide fails due to lack of oxygen

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4 hours ago, DavidYacht said:

However back then they were designed to Lloyds and where there might have been 12 or 14 1” bolts, now we might see 8 or 9 M16 fastenings

I asked my friend at Lloyds Register and he thinks the last edition of their rules for small sailing yachts was 1955.

Cheeky Rafiki had 9 x M24 + 1 x M14 bolt. It wasn't the bolts that failed.

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6 hours ago, Zonker said:

Whoa, that isn't Jazz, that is another First 40[.7?].  

This is the transom of Jazz (from a friend's photo who was on the boat):

May be an image of body of water and text that says '10A Portsmouth No:917319 No:'

This is the transom shown in the article:

Bournemouth Echo: Picture: Swanage RNLI

 

The photo in the article is awful, but it clearly isn't the same boat.  That one looks like a First 40.7 to me and Jazz is a First 40.

 

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Wow, this is an interesting thread. I have been looking in the 40ft range and wondered why the 40.7s were so (relatively) cheap. Is there a way to check during a survey if one did role the dice? What boat with a similar speed / comfort level would be close to the 40.7? 

 

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5 hours ago, nota said:

http://newimages.yachtworld.com/resize/1/77/23/4457723_20130920111543592_1_XLARGE.jpg?f=/1/77/23/4457723_20130920111543592_1_XLARGE.jpg&w=1280&h=986&t=1381259169000

 

why not make a full wide SS backer in one part to replace  the little bars as wide as they are

full length fore and aft bent up and down to fit on part top section instead of the separate bars

with several extra holes to drill new bigger longer stronger keel bolts

to sandwich the grid between the lead keel and the top SS solid cap

plus drill holes in the top of the grid hat sections and squirt epoxy inside

then run the new keel  bolts thru the top of the hat sections to screw and glue the grid

 

yes that may cost some boat bucks even need CNC work with over sized SSbar to fit tight

extra bolts holes ect

 

Why?

Buy a different boat.

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5 hours ago, nota said:

my other idea would be messier and cost a bit more

remove the gel coat and add glass outside down the keel/hull joint area a few feet each way

then add side bolts into the keel lead

As others have noted, it ain't the bolts that are the problem - it's inadequate fiberglass structure.

The keels are adequately attached to tissue.

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24 minutes ago, Movable Ballast said:

Wow, this is an interesting thread. I have been looking in the 40ft range and wondered why the 40.7s were so (relatively) cheap. Is there a way to check during a survey if one did role the dice? What boat with a similar speed / comfort level would be close to the 40.7? 

 

If you look at all of the data on the CR incident it looks like it would be hard to inspect for in a non-destructive way. 

J/122, J/120 and various X-Yachts come to mine as alternatives.  Waqueiz Centurion 40S if you can handle a notch slower. 

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I have some very first hand relevant experience with a 40.7 hard grounding having been behind the wheel of an early one in NE. I was driving and witnessed and oversaw part of the repair. 

What I saw was appalling. Bogged in pan-liner poorly done construction is no way to got thru life, son. Altho the boat later made it to PR and back and encountered horrible conditions I have been told. But no way in hell would I sail one offshore, no way, no how.

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The idea of a grid vs a keel sump to secure a keel is beyond me in regards to improved engineering. I’ve seen Beneteau’s that have had their keel and bolts ripped clean out of the grid from extreme grounding but I have yet to see a keel ripped off of a sump box, as the keel is attached to an adequately glassed in hull surface with 90 degree angles on 4 vertical surfaces to add rigidity.

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9 minutes ago, Sail4beer said:

The idea of a grid vs a keel sump to secure a keel is beyond me in regards to improved engineering. I’ve seen Beneteau’s that have had their keel and bolts ripped clean out of the grid from extreme grounding but I have yet to see a keel ripped off of a sump box, as the keel is attached to an adequately glassed in hull surface with 90 degree angles on 4 vertical surfaces to add rigidity.

There are lots of modern boats that share the no keel sump technology though... My Schock 35, almost any J boat. Not a grid but basically bolted to the bottom of the hull. Is it the grid that's the problem?

 

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There are multiple issues.

1. Fiberglass is mystery meat. Unlike metal, you have no freaking idea what is really there.

2. Bonded in liners make construction faster but do not make better. The methacrylate is really quite miraculous but what they do is to get away with a wide range of poorly fitted parts in production building. The parts are the problem. Excessive resin content, big variability in properties from boat to boat are just same boat 30 cm away etc

3. Fiberglass is not a rigid material AND it is viscoelastic. Keels made of metal are essentially rigid in comparison. Stiffness mismatch makes for all sorts of trouble! Massive overloading of localized laminate leading to creep rupture or other problems--loose nuts, leaking, crevice corrosion, dynamic acceleration induced fatigue etc.

4. I forgot what I was going to say next damn it

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Oh right: 4: drilling holes in laminate is suboptimal at best. Yes sometimes you have to but it is not like drilling holes in metal! There is no such thing as "plastic deformation" or "strain hardening" in laminate. Remember it is never even close to isotropic either. Holes really fuck it up. Molded holes are much better but very few want to do the relatively little amount of extra work to do it.

 

 

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"So why doesn't wood suffer the same way?"  Well, it does. But we've been working with it far longer. We don't make the same mistakes because we've been down the path longer. Furthermore, traditional wood construction did not use fin keels.

As for the metal strapping and grids--that came about as a way to deal with all the points I raised above. It goes WAY back!

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I’d say it’s bolting the keel to the top of a collapsable grid structure that is the cause of loss and to blame.

I repaired a keel leak in a Schock 35 this spring. Damaged keel due to hitting a submerged object and leaking through the forward keel bolt. Slight separation fore and aft on the keel joint that was poorly re-sealed. I repaired that and epoxy sealed the keel bolt with thinned epoxy. Boat is dry and solid now due to proper construction and wins the local PHRF. 

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The whole "grid" thing glued in is NOT and never was a superior way to build a strong boat. It was ALWAYS about Production, and Looks. Same applies to powerboats. I've seen ridiculously inefficient foundations in powerboats that were made out of "kits" of all these pieces of fiberglass all layed up into a mold, with ply drops and stuff--basically all lots of lap joints. Then that is methacrylate bonded (which is rarely ever the problem!).  Weight of foundation far greater than taking some structural foam and laminating over it and tabbing properly. You get a lighter, better, stronger, more continuous fiber, less pieces, simpler part doing it the "old fashioned way" but everyone wants shiny gelcoat, baby!

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I’ve done some metal strapping on the A Cat decks and the floors in my cutter are  Canadian steel attached to the steel backbone keeping the cast iron keel attached to the full keel!

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9 hours ago, fastyacht said:

Overall we are going to see the ultimate result of crevice corrosion of stainless bolts. Boats will be dropping keels in 10-20 years at a reliable rate.

You do know that the ONLY reason stainless is EVER used below the waterline is cost, right? Si Bronze is the only suitable keel bolt material.

Well shit. I guess I’ll throw my boat in the dumpster then. 

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I've got an 80s boat with hand laid floors. It's a brick shithouse strength wise. Looks ugly and I've always had shiny grid envy but I know this boat will never die from a keel incident.

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5 hours ago, Alex W said:

Whoa, that isn't Jazz, that is another First 40[.7?].  

This is the transom of Jazz (from a friend's photo who was on the boat):

May be an image of body of water and text that says '10A Portsmouth No:917319 No:'

This is the transom shown in the article:

Bournemouth Echo: Picture: Swanage RNLI

 

The photo in the article is awful, but it clearly isn't the same boat.  That one looks like a First 40.7 to me and Jazz is a First 40.

 

I suspect it is Jameerah, a J/120

P1040425.JPG

J120

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6 hours ago, Alex W said:

If you look at all of the data on the CR incident it looks like it would be hard to inspect for in a non-destructive way. 

J/122, J/120 and various X-Yachts come to mine as alternatives.  Waqueiz Centurion 40S if you can handle a notch slower. 

J120 out of this Fastnet having keel failure shortly after start. Photo looks just as bad as the Bendytoy ones.

Edit. Should read to the end of the thread. I believe the boats been correctly identified above.

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7 hours ago, Zonker said:

I asked my friend at Lloyds Register and he thinks the last edition of their rules for small sailing yachts was 1955.

Cheeky Rafiki had 9 x M24 + 1 x M14 bolt. It wasn't the bolts that failed.

But Lloyds offered a huge amount of redundancy against the moment on the bolts.  Not suggesting that CRs bolts failed, just that the way keel fastenings and supporting structure have developed are increasingly optimistic against what production builders are capable of delivering

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6 minutes ago, DavidYacht said:

But Lloyds offered a huge amount of redundancy against the moment on the bolts.  Not suggesting that CRs bolts failed, just that the way keel fastenings and supporting structure have developed are increasingly optimistic against what production builders are capable of delivering

I looked at a 40 year old Westerly 33 a couple of weeks back, conventional longish fin keel fastened by 13 x 1” bolts.  Also Lloyds specified a heavy fin and tuck laminate in the keel area.  

It might be worth considering that the RCD process in Europe has no in built inspection process, back in the day the Lloyds surveyor would randomly inspect boats in build, I used to turn up at the build shed at 7.00 and the Lloyds man would be waiting outside.  I suspect that they would never have signed off many of the interior liner/matrix structures on the grounds of 1) impossible to inspect and 2) the quality of the bonding.

I would like to suggest that these failures are about chickens coming home to roost, but the practice is so ingrained in the industry that I don’t think that anything is going to change it.

I think liner/matrix on the drawing board are a good idea for all sorts of reasons, but the quality control is the problem.

I don’t see many of these boats making 40 years and beyond as many the Lloyds scantling boats have

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7 hours ago, Caecilian said:

I've got an 80s boat with hand laid floors. It's a brick shithouse strength wise. Looks ugly and I've always had shiny grid envy but I know this boat will never die from a keel incident.

80s Beneteaus are some of the most well made production boats of the era.   It's a shame they are not still at that standard.

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6 hours ago, DavidYacht said:

I looked at a 40 year old Westerly 33 a couple of weeks back, conventional longish fin keel fastened by 13 x 1” bolts.  Also Lloyds specified a heavy fin and tuck laminate in the keel area.  

It might be worth considering that the RCD process in Europe has no in built inspection process, back in the day the Lloyds surveyor would randomly inspect boats in build, I used to turn up at the build shed at 7.00 and the Lloyds man would be waiting outside.  I suspect that they would never have signed off many of the interior liner/matrix structures on the grounds of 1) impossible to inspect and 2) the quality of the bonding.

I would like to suggest that these failures are about chickens coming home to roost, but the practice is so ingrained in the industry that I don’t think that anything is going to change it.

I think liner/matrix on the drawing board are a good idea for all sorts of reasons, but the quality control is the problem.

I don’t see many of these boats making 40 years and beyond as many the Lloyds scantling boats have

^^THIS I bolded and oranged it.

As for "good idea on drawing board" it is a complicated many facet problem.

But there are other aspects I didn't mention before that are influencing this

Emissions regulations (what does THAT have to do with it?)

--> affects secondary bonding. Traditional tabbing and lamination of interior structure depends on either long "primary" bond window, or other ways to ensure a good secondary bond.

In the current DCPD and low emissions production environment, there is almost no bonding window at all. But Methacrylate will bond fabulously to cured DCPD with essentially no prep. So instead of shitty tab joints failing, they get tenaciously bonded parts. So done correctly yes, it can be a good structure.

Let's look at the inspection problem.

Once a laminate is down, there isn't much to inspect. Haha. However most resins are translucent and with no gelcoat, a traditional molded in place part can be visually inspected for poor wet-out, bubbles, resin puddles etc. For a grid structure, that has to be done to the grid part BEFORE it is plexus bonded to the hull. See my earlier points about the problem of building a good grid part inside a female mold. To me that is a significant problem of structural efficiency. The kits are often designed for production efficiency not structural continuity.

If you are doing resin infusion this is a whole different kettle of fish. TPI had some very sophisticated processes going on for SCRIMP of very thick parts. If you fuck that up the hull is trash so....better get it right. I saw a 4" thick stack they infused. I was at their shop 20+ years ago with a client who was considering a SunDeer build there.

If you vacuum bag or infuse, all bonding is "secondary" anyway.

Ultimately, the problem for the customer and the surveyor is that fiberglass is uninspectable. That is the real quandary. Metal boats and wood boats, you can measure everything and know what you got. Fiberglass, forget it.

 

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But I think that the Lloyds’ man would say that if you cannot prove the integrity of the bond then don’t do it … if I were employed as owner’s rep I would be in a bit of a quandary 

I guess that there are ways and means to provide a jig to ensure that the structural liner is bonded effectively to the inside face of the hull, whether this happens with French production yachts is another matter.

I have memories back in the day of the rush to get the deck down inside the Plexus window, so I guess that there is a danger that the hull liner might go down with areas that are not bonded.  I have seen RIBs where Plexus bonded liners have separated from the hull, I believe due to building quality issues.

Ultimately these are all issues to do with quality control and the associated costs.

the LR process provided the QC that CE marking doesn’t, I have consistently argued for over 20 years that the RCD lowered the goal posts that set quality boat builders apart from the dross.

The top end boat builders that I work don’t to structural liners.

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Nice that you were involved in boat building that were surveyed by LR.  But 95% in the same era were not. 

I agree that with Plexus that bond quality can be very variable. I think glassed in floors/frames are more robust. You have to break the tabbing bonds and tear the glass to make a failure. I *think* that this is a more failure tolerant method.

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17 minutes ago, Zonker said:

Nice that you were involved in boat building that were surveyed by LR.  But 95% in the same era were not. 

I agree that with Plexus that bond quality can be very variable. I think glassed in floors/frames are more robust. You have to break the tabbing bonds and tear the glass to make a failure. I *think* that this is a more failure tolerant method.

It is--but only as long as:

1. the tabbing is carried out withing the bond window or

2. the tabbing area is suitably prepared for secondary bonding

3. the tabs are engineered properly including ply drops and ply lengths, analysis for peel inducing loads, etc.

4. the root fillet is carried out correctly and also that it is considered in the engineering

Failed tabs and bulkheads are  one of the common problems of the "old days" after all.

Poor practice can fuck pretty much anything up.

Polyester resin has lower secondary bond adhesion than Vinylester, which is less than epoxy.

The thing about a tabbed joint is that you can in fact inspect all the steps along the way to ensure no screw ups. The one you cannot easily catch is someone fucking up the air with silicone.

Big methacrylate bond jobs are strange because if you look at any old production boatbuilder, you will see this enormous roll of excess methacrylate here and there. "Blind" bonding indeed. When highly loaded parts are properly bonded with acrylic adhesives, you inject the adhesive into the space, and you control the space with spacers. You inject until all squeezeout and you fillet the excess as you remove it. NONE of this is carried out on most production hull-deck or liner-hull joints. And in the case of grids, you cannot see one side of the bond line anyway.

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23 hours ago, Raz'r said:

I hate these threads. But I did drop my keel last year because of one of these, and was quite happy with what I saw.

I still hate these threads.

At least you dropped it on purpose.

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At least you can replace bulkheads and tabbing relatively easily, you can also see where it has failed … usually by sliding a screwdriver underneath the tab(s).

Even if 95% of building wasn’t to Lloyds it did drive quality standards in companies that had 100A1 builds in the shed.  Lloyds bailed from small craft pretty soon after the RCD came in in 1998.  

Back then I bemoaned that there was nothing to distinguish a boat builder who built up their reputation on quality and good practice from cheap mass production builders.  Many good yards went out of business because the customer could not discern the difference.  Nothing that has happened since has convinced me otherwise.

Poor keel supporting structure construction is endemic of this malaise.

The Bavaria Match keel failures imo are more significant than the Bene 40.7.  

I also think it would be good practice if all sole boards in way of keel fastenings should be readily removable, if it takes me an hour to unscrew them to do my job, then I can understand why this might be put off in an Atlantic storm.

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57 minutes ago, Caecilian said:

What I dont get is why the keel failures on the 40.7's occurred  when they apparently went through rigorous and thorough testing of the laminate engineering. 

You are never going to actually see that engineering...

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2 hours ago, DavidYacht said:

What testing?

from sailnet link above;

As others have noted, this is a very unusual failure for a small keel root detachment failure. Normally, in these failures there is a large area of the laminate that is pulled loose, and often the hull is pulled free from the frame and pan. In this case the keel bolt washers (which are rectangular plates that span between each pair of bolts and are roughly 5/16" thick stainless steel which was compliant with the ABS standard at the time the boat was built but which should have been 7/16" under the current ISO 12215-9 standard) sheered through both the hull and pan, and sheered through the bottom of the transverse frame as well. I can't even visualize what directional force would cause that type of failure except fatigue at the edges of the plates taking a toll on the matrix and causing it to weaken to the point of failure.

The laminate in this area was all solid glass and was made up of uniaixial and biaxial fabric. The pan and frame structure is glued to the hull skin with an engineered adhesive. The tan color is probably that adhesive.

A hard grounding would have been expected to pull the forward bolts downward tearing them out of the hull and tearing the joint between the pan and the hull, and would have pushed aft edge of the keel up through the hull tearing the matrix back there. But in the photo there does not appear to be those kinds of compression marks aft the aft end of the keel. If the boat was run aground in a surf and was sideward to the waves, you would similarly expect one side to have sheered outward and torn the laminate outward and had a inward sheer failure on the opposite side of the keel. You would expect the transverse frame to be completely mushroomed on one side, but it does not appear to be the case. And if the boat was dropping vertically on hard bottom (similar to one of the contributing causes of the failure on the Cape Fear 38 some years ago) you would similarly expect to wide spread delamination and crushing of the frames.

To me the mystery here is the comparatively clean cut opening which almost suggests a failure mode where the boat was lifted vertically while its keel was held down some how. (I am not saying that actually happened just at first glance, that is how the damage looks).

But I am also interested in the fact that the boat in the picture looks like a 40.7. The construction and inspection during building of the keel attachment is outlined in the report on the sinking of the Cheeki Rafiki. https://assets.publishing.service.gov.uk/media/55408664e5274a157200005b/MAIBInvReport_8_2015.pdf

What was evident in the report was that the Beneteau 40.7's went through an extraordinary testing and inspection process compared to most production boats, with layup made up of precut laminate and the resin weighed. Hull thickness measured at each keel bolt hole on each boat, and each penetration on each boat with the coupons from through hulls tested for thickness and resin/reinforcing properties. And lastly the construction process is observed during construction by an independent testing company. That level of care just is not done on production boats.

And in the Annex C&D to the report, the Wolfson Unit, did a detailed analysis of the structure of these boats. https://assets.publishing.service.g...nnexesToMAIBInvReport08-2015_CheekiRafiki.pdf

There is a chart with their results of the analysis. The table summarises the results of assessing the structure design, and concluding that depending on the element the design was between 1.05 to 7.96 in excess of the requirements of the standards when the Cheeki Rafiki was built, and that only the washer thickness would not comply with current standards. It also noted that Cheeki Rafiki was built differently than the original design, (and alegedly other 40.7's) and as built one of the designed keel bolts was missing. While that would have met the ABS standard of the day, it would only meet 95% of the current EU ISO 12215-9 standard.

And yet, with all of this care in design, construction, and with values exceeding the standards of today, this is the second of these boats to lose a keel.

One other interesting item in the Cheeki Rafiki report is a table looking at boats which have lost keels since 1984, which are summarized in Table 4 below.
Table 4: Summary of ISAF data on keel failures
Cause of failure Number
Undefined 40
Welded fin failures 11
Grounding or collision 8
Hull/internal structure 8
Keel bolts 3
Keel cant system 2
Total 72

Its interesting to me that over 20% of the failures are due to grounding, collision, or hull/internal structure failure, while 4% is was actually caused by keel bolt failure. That said, there were a number of keel bolt failures last year in older boats that would skew that number quite a bit.

Lastly, while these small root footprint keels are definitely more difficult engineering problem, over my lifetime, boats have been losing their keels no matter how long their keel root and how they were built. My family's CCA era Pearson Vanguard lost its encapsulated keel in 1970 due to a hard grounding. A number of IOR era boats lost their keels (Drum being the most famous) despite having a comparatively large keel root, and yes, newer designs are losing their keels as well, which is why World Sailing (AKA the former IYRU) is studying this issue as we speak, and hopefully will come up with better standards.

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the report is frightening

Quote

During the course of the investigation, the MAIB received much anecdotal evidence regarding matrix detachments on Beneteau First 40.7 yachts. Areas notable for detachment were in the forward sections of the matrix, commonly attributed to the vessel slamming, and the area around and aft of where the keel is attached to the hull, commonly attributed to the vessel grounding. MAIB inspectors visited four Beneteau First 40.7 yachts that had all suffered detachments of their matrix in bays around the aft end of the keel as a result of grounding. Additionally, two of these vessels had suffered, or were showing signs of, matrix detachment in the forward section. One further Beneteau First 40.7 yacht was visited, which showed signs of matrix detachment in the forward and aft sections.

 

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I have heard that there are some program that successfully modified and strengthened the keel grid structure, I wondered how would be the appropriate way to do it, and does anyone known of any boat that had successfully did the modification?

So far the answer is no, not that you couldn't but it would require some skill. Maybe build some more floors?

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Slice the boat into 4 long parts, along the keel then at the deck level, 2 pieces of hull and 2 deck parts.
Full chrome moly frame chassis from a  NASCAR builder with mast step and keel attachment, glue the fibreglass back on, good to go for a few more years..

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3 hours ago, Sailabout said:

Slice the boat into 4 long parts, along the keel then at the deck level, 2 pieces of hull and 2 deck parts.
Full chrome moly frame chassis from a  NASCAR builder with mast step and keel attachment, glue the fibreglass back on, good to go for a few more years..

See X-Yachts

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Take a look at the entrants in any offshore race. You will see most of them are the production boats you spend so much time maligning. Almost all of them finish, almost never do any have catastrophic failure (so few that most comments are about a single incident that happened several years ago, and was a boat that had been grounded and never properly inspected/repaired), and, more often than not, these same horrible, unsafe, poorly built boats, take the podium places in those races. And many many many more that don't race but are out cruising the world. 

 But sure makes you sound knowledgeable when you jump on the bandwagon knocking these terrible boats. Sorry, Benneteau is not the biggest boat builder in the world because they build such crappy boats. If they did we would be hearing about their boats sinking every day, there are thousands  of Benneteau built boats out there. 10s of thousands. 

but sure makes you sound like a very knowledgeable sailor to talk shit about how bad they are. Lol. 

 

 

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Surprised there you aren't knocking them for fin keels and spade rudders we know how dangerous those are.  Lol

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10 minutes ago, Baldur said:

Take a look at the entrants in any offshore race. You will see most of them are the production boats you spend so much time maligning. Almost all of them finish, almost never do any have catastrophic failure (so few that most comments are about a single incident that happened several years ago, and was a boat that had been grounded and never properly inspected/repaired), and, more often than not, these same horrible, unsafe, poorly built boats, take the podium places in those races. And many many many more that don't race but are out cruising the world. 

 But sure makes you sound knowledgeable when you jump on the bandwagon knocking these terrible boats. Sorry, Benneteau is not the biggest boat builder in the world because they build such crappy boats. If they did we would be hearing about their boats sinking every day, there are thousands  of Benneteau built boats out there. 10s of thousands. 

but sure makes you sound like a very knowledgeable sailor to talk shit about how bad they are. Lol. 

 

 

Statistics. That is all you are saying.

 

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