Cruising a Beneteau 40.7

[Kiwi Clipper]

Thanks. Just looking it up as a boat by name; a class of submarines, a University research ship ... but no Beneteau 40.7!
In one translation the name means "Deep Sea"... Always interesting where a new inquiry takes you. in._TO did you have any impressions as to how the conversion affected the performance or cruisability of the boat?

 

[Zonker]

The report goes into great detail regarding the design and methods of production of the Beneteau 40.7 and Beneteau's quality controls, and it left me feeling Beneteau had been doing a great job at its production methods and quality control.

That is fucking hilarious. As someone who knows how they are built.

 

[GBsailor]

The boat was called Umi Taka. I think it has changed hands a few times since it was modified.

umi has been cruiserized, walk thru transom, full dodger, fore and aft bimini, lazy jacks. etc. when it was racing it won the IRC north americans i think. he was on the 40.7 facebook page. the owner has had it for over 10 years now. hope this helps

 

[GBsailor]

has anybody seen this

how much for the mod? 1 boat dollar?

 

[Kiwi Clipper]

That is fucking hilarious. As someone who knows how they are built.

Zonker: This is actually a serious subject on which people may make life impacting decisions. Hoping you can share with us your superior knowledge on the subject and maybe give us some background as to how you learned how they were built. Thanks.

 

[Kiwi Clipper]

umi has been cruiserized, walk thru transom, full dodger, fore and aft bimini, lazy jacks. etc. when it was racing it won the IRC north americans i think. he was on the 40.7 facebook page. the owner has had it for over 10 years now. hope this helps

That helps a huge amount. Since this thread is about Cruising a 40.7 and there are so few that have actually made the carbon conversion, would like to hear how the owner thinks the carbon rig has helped/hurt the performance of the boat as a cruising boat.
Also interesting the Boat won the IRC North Americans --- guessing that was after the carbon conversion. There was a lot of speculation years ago that the rating change would negate any performance gain from changing to carbon.
Like to see pictures of the walk through transom etc.

 

[Zonker]

Zonker: This is actually a serious subject on which people may make life impacting decisions. Hoping you can share with us your superior knowledge on the subject and maybe give us some background as to how you learned how they were built. Thanks.

I can't get too much into it. NDAs and all that.

I used to work for Farr Yacht Design and was involved in the design of the 36.7 which used exactly the same build method.

It's a production built boat, built to a price target. The internal glued in grid is well engineered for normal or extreme sailing loads (unidirectional E-glass on the tops of the tophats for example; double bias in the webs). It's an economical choice to build the grid in a separate mold and then bond it in with Plexus. It's not exactly how you'd design a one off raceboat for example. On those boats the internal structure is all fitted piece by piece and taped in place with layers of glass or carbon. Much easier to fix and more impact resistant (I think)

BUT - and this is a big caveat. If you ground it hard, you can damage the grid; usually the bond between hull and grid fails or the grid itself fractures. Repair is often very costly because you have to take apart the main saloon cabinetry to get at the area that typically fails (back edge of the keel region). Sometimes the damage is not readily apparent or you can't tell how much of the grid has separated.

It is not a grounding tolerant building method. Would I buy one? If I was sure it hadn't been grounded hard, maybe. I'd sure be a little more cautious about navigating around rocks though.

I can't speak to Beneteau's quality control methods. It's a modern factory environment which does mean typically some checks and balances. Do they do a test each truck of resin that comes into the factory? Hope so. Check that the rolls of cloths are actually 450 gm/m2 and not 422? Who knows?

I'm not wild about the construction quality of MANY brands of production boats. Lots of them use this method. It saves money but it's not easy to fix.

That answer your question?

 

[estarzinger]

Zonk hit the main points, quite well. I will add one (at the bottom of this post)

It's a production built boat, built to a price target. It's an economical choice to build the grid in a separate mold

Yes, you have to understand the target market. "Corners are cut' to lower the price and that has clearly been a decent business trade-off/decision.

Sometimes the damage is not readily apparent or you can't tell how much of the grid has separated.

The difficulty of non-destructive inspection of the grid bond is highlighted in the MAIB report. This poses a difficulty for those who are looking at a used boat and depending on a survey.

Repair is often very costly because you have to take apart the main saloon cabinetry to get at the area that typically fails (back edge of the keel region).

And also highlighted in the report . . . . there was no 'factory approved' repair method, and a 'proper repair' can potentially cost more than the value of a used boat.

I can't speak to Beneteau's quality control methods.

I add some context here. Beneteau's 'manufacturing tolerance' standards are pretty loose - 'Good enough'. We had Australian friends who took delivery of a new Beneteau, and the deck had been put on 38mm off center (left to right) and when queried about this the factory said that was 'well within spec'. The grid placement inside the boat also has somewhat loose tolerances. Plexus can fill gaps, but it is not ideal, and the gap-filling material can/will fracture under high dynamic loads.

The boat obviously fills a meaningful market segment, but there are compromises made which don't necessarily perfectly suit the used buyer who wants to go long-term blue water cruising. It can ofc work - plenty have done it, but there is just an additional risk factor. I'm not knocking the boat, but I hope potential bluewater buyers actually understand the set of compromises they are buying (all boats entail compromises).

 

[Kiwi Clipper]

I can't get too much into it. NDAs and all that.

I used to work for Farr Yacht Design and was involved in the design of the 36.7 which used exactly the same build method.

It's a production built boat, built to a price target. The internal glued in grid is well engineered for normal or extreme sailing loads (unidirectional E-glass on the tops of the tophats for example; double bias in the webs). It's an economical choice to build the grid in a separate mold and then bond it in with Plexus. It's not exactly how you'd design a one off raceboat for example. On those boats the internal structure is all fitted piece by piece and taped in place with layers of glass or carbon. Much easier to fix and more impact resistant (I think)

BUT - and this is a big caveat. If you ground it hard, you can damage the grid; usually the bond between hull and grid fails or the grid itself fractures. Repair is often very costly because you have to take apart the main saloon cabinetry to get at the area that typically fails (back edge of the keel region). Sometimes the damage is not readily apparent or you can't tell how much of the grid has separated.

It is not a grounding tolerant building method. Would I buy one? If I was sure it hadn't been grounded hard, maybe. I'd sure be a little more cautious about navigating around rocks though.

I can't speak to Beneteau's quality control methods. It's a modern factory environment which does mean typically some checks and balances. Do they do a test each truck of resin that comes into the factory? Hope so. Check that the rolls of cloths are actually 450 gm/m2 and not 422? Who knows?

I'm not wild about the construction quality of MANY brands of production boats. Lots of them use this method. It saves money but it's not easy to fix.

That answer your question?

Thanks for explaining. Your caveats are to me consistent with the report and the report findings. Most important you are not taking a shot at the 40.7 but rather at many boats that could be affected by this method of creating structure for boats. I get that the boats may be designed strong in the first instance, but depending on manufacturing processes and also thee impact of a hard grounding, or even a series of groundings or other events, it can be seriously weakened.
To me the most telling part of the Cheeki Raffiki report was the finding that there had been multiple prior groundings and in 2011 there had at that time been separation between part of the frame and the hull and repair of that separation had been attempted, followed by other maybe not "hard" groundings, but groundings.
The fact that a few other known boats have experienced similar issues seems not surprising, because to me, it seems the percent of any given boat that might be mistreated or abused is going to be much higher than the number of 40.7's reported thus far. Makes me worry there are others. Given that there are probably 10,000 or more boats out there built this way, and thus 10,000 families affected, the question has to be how to reliably inspect, and how to reliably repair gets pretty accute.
Maybe someone with your expertise will try to put together a program for that. It would be a great service.

 

[Zonker]

Repair? Each damage is different so you can give guidelines but probably not a general procedure. If the grid is cracked you really need to try to get laminate schedules for it to repair because repairing with mat/roving won't be strong enough.

Inspect? Drill dozens of little holes in the middle of the shear webs of the grid and use a borescope to see if the grid is still bonded locally.

Tap for fractures in the grid (most should show up as decent cracks).

Blue is hull. Green is grid. Purple is bonding paste. Red is borescope holes looking at the bond or for fractures.

From Cheeky Rafiki report. Red ellipses are some of where you'd have to borescope to see if the grid is detached.

When it gets detached you have to cut away all the part in between the grid, grind the grid surface and re-glass. Ugly job that will take a few weeks I would guess.

 

[Zonker]

Also I'd guess but not 100% sure - one big hard grounding is a lot worse than multiple slower speed groundings. mV^2 and all that.

7 knots squared = 49, versus 5 squared = 25. Twice as hard a hit just for 2 more knots of boat speed. So if you are buying one and the owner says "yeah we've run aground" the question is "how fast" and was it sand/mud or something firmer.

 

[Kiwi Clipper]

Also I'd guess but not 100% sure - one big hard grounding is a lot worse than multiple slower speed groundings. mV^2 and all that.

7 knots squared = 49, versus 5 squared = 25. Twice as hard a hit just for 2 more knots of boat speed. So if you are buying one and the owner says "yeah we've run aground" the question is "how fast" and was it sand/mud or something firmer.

Awesome response and thank you. The troubling thing about Cheeki is that from 2007 on it was owned by the same company. It wasn't someone buying a boat and they didn't know the history. But also they had just won some races. So at least at that point the boat was functioning just fine.
To me, there are hundreds of these boats doing just fine. But if a boat has had any hard grounding or multiple groundings, it should be tested before any long distance ocean trips far from shore.
The important part is that if the boats are sound, they are wonderful and worth a lot. So that at least makes it economic to do the testing.
So maybe you have to have a specialized surveyor who follows a protocol something like this:
Start with a boat history. That helps you know what to look for.
Then in the water inspection. Look for every visual clue.
Sponge the whole inside hull dry. Now, does it leak. If it does, find the leak. But also If the grid has been sitting in a lot of water, especially alot of salt water, that introduces a factor that could cause issues.
Then out of the water inspection. Hammer testing. Visual deflection sitting on the keel.
If any evidence that suggests possible problems with the keel itself or the keel bolts, then drop the keel.
Then borescope examination. After identifying every area of potential problem then do the examination for that area. Probably there are key areas that should be tested regardless of any other evidence.
Do you think there is any kind of xray or infrared examination that could help find cracking, separations or delamination in the hull or grid?
At this point it seems like if you found nothing, you could issue a certificate of "No evidence of Structural Issues regarding Keel". The boat could be sold and cleared for off shore cruising.
But if you find something, then to me you have to have an appropriate expert design the fix. Call Zonk.

 

[brineonbow]

has anybody seen this

 

[Kiwi Clipper]

Zonker.
Still thinking about the issue. Suppose you find some separation. What if we designed a new formula goop made of glass or even carbon, epoxy, etc. that you could make holes in the frame, then blow into the void spaces that would settle maybe two inches deep, that would bond to the bottom of the boat, and to the frame to hold the frame in place. Then you could also put screws parallel to the bottom through the frame and into the cured goop. One benefit: if any of the screws ever break they are your new canary.
You'd have to figure out how to make the goop bond. But thinking now of my 40.7, there are no signs or history that suggest any problem. But given the risks of open ocean travel, the unlikely possibility of defects in the original bonding, the ("killing by 1000 cuts") and possible deterioration over time, I could see where a solution something like this could substantially increase the security of the bond and decrease the risk of keel failure.
On another thread, another of the Farr office graduates chimed in about the 40.7 as follows: "Working at Farr's office we designed quite few yachts for Beneteau. We attempted to take the lines from a successful IMS 40 footer and produce the 40.7; the result was an extremely heavy, yet nice 40 foot "race" boat. The laminates in that boat were so conservative that they will survive several centuries of abuse. And this is something I see in Beneteau's builds; they don't want boats coming back with warranty issues." To me, that's just the boat I want to take on a blue water journey.
So given that a 40.7 today is about $100k used, compared to a comparable new boat at $300k+, if you could spend another $2k to $5k or maybe even more, to greatly enhance the keel/hull bond, what a bargain! If this asks too much, say so, I will give you an email and you can charge me to go down this road.

 

[Joakim]

Also I'd guess but not 100% sure - one big hard grounding is a lot worse than multiple slower speed groundings. mV^2 and all that.

7 knots squared = 49, versus 5 squared = 25. Twice as hard a hit just for 2 more knots of boat speed. So if you are buying one and the owner says "yeah we've run aground" the question is "how fast" and was it sand/mud or something firmer.

It's very complex. Speed squared tells the energy available for damage. But even more important is how fast that energy has to be spent.

Around here you mostly hit granite. Sometimes you bounce over and sometimes you find a steep edge and the boat stoppes completely in a very short distance and crew gets thrown around. Sometimes you get stuck on top.

Even a very well built boat can get considerable damage at 5 knots, if the stopping distance is short enough. Lead keel helps a bit, because its damage makes the stopping distance a bit longer.

There have been several systems developed to help increasing the stopping distance. The leading edge of the keel made of rubber or with an outer shell and some water in between.

If not repaired, the structure is weaker and the following grounding can be much worse.

What really striked my with the report was the fact that there had been quite serious damage and the grid had been repaired, but the keel had not been taken off.

Around here you always take the keel off, if there is even close to that kind of damage. I have had two groundings with much less damage and in both cases the keel was took off. It's not possible to do a thorough inspection and repair with keel attached.

 

[Bryanjb]

A big concern is the prep work when applying the smoo between the hull and the grid. Friends with a wrecked 40.7 reported that the smoo easily "popped" off when they were in the process of glassing the grid back to the hull. They said a whack with a hammer sent the smoo pucks flying, no grinding required.

Another big drawback with hull and liner construction is the inability to accurately inspect the bond between the two. Can a surveyor actually say if the bond is good?

 

[Joakim]

Can a surveyor actually say if the bond is good?

Doesn't tapping with a hammer work for this? Or is the bonding paste too soft to give a firm sound when well bonded?

 

[Zonker]

The bonding paste (I would assume Plexus) is very hard.

But... I wouldn't trust hammer testing that much. Too much variability in things like "how thick was the layer in each individual pocket" - did half of it pop off in the pocket but some is still bonded? Without disassembling all the cabinetry (which is unlikely for a survey) you'll only know which areas you can get access to.

It's a good first start, as is a visual inspection of each pocket of the bilge. You're looking for cracks especially right in the corners as well

 

[tane]

how about ultrasound tests?

 

[Zonker]

Sure. Write a cheque for $5K for an inspection... honestly don't know how effective it would be in this sort of structure. Not an expert by any means in this sort of NDT. I think it's often used in cored flat panels to find de-bonds/never bonds but in this, I don't know.