New Beneteau's - How is the decks secured to the hull?

[nortonscove]

Originally Posted by billknny

I wonder... does the definition of "failure" include leaks? To me it does. But I am suspecting to Bendy-toy it does not.

There are lots of ways to build boats. More bad ones than good ones. Screws to secure deck to hulls--even if the are glued together with "polyurethane mastic"--doesn't cut it for me for anything except a day sailor.

I was shocked when I discovered that Catalina secured some of their stern pulpits to the hull with self tapping screws. The idea of a deck secured that way just boogles my mind.

But it IS cheap...

Funny how people go off and rip things that don't fit their idea of how it should be done without posting their credentials when questioning the biggest builder in the business. Please indicate which NA program you've graduated from and what sailboat manufacturer you are employed with. I'm also curious as to what you sail and why.

Yes I sail a Beneteau and have found that it is perfectly suited to my sailing in the north Atlantic you know where at this time of the year icebergs and bergy bits drift around haphazardly. And yes I have hit them. Amazingly in this part of the world the large producers are becoming increasingly more popular. If you sail for five months of the year it makes no sense to spend a million bucks to have it sit on the hard for more than half the year. Maybe it's what most builders do but when you are the biggest and follow a successful model everyone wants a bite.

[atlantical]

Its not builders who build boats, its accountants. In the eighties a lot of builders went bust, as costs were too high. They cut costs by reducing materials and labour, and yet building a more desirable boat. Beneteau classic example, the hulls are down to about 7mm thick. There is one chain plate either side, the boat is constructed by moulding the hull, then putting in the engine, and all the fittings, the berths all the furniture, then putting the lid on, they tend to use self tapping screws, which are the best fit, and it only takes one man to do it, they seal extremely well, (when new) over time everything moves, and the screw holes get bigger, and then leak, some boats such as Lancer, and the US hunter, have had serious problems with the decks coming off, due to no chain plates, the stays are attached to a plate under the deck, and when the screws get loose, a hard jive, can split the hull deck seal, and lift the deck.

I have experienced that on an Irwin Citation, not a full split, but every time we had a lot of weight on the jib, with the jib car attached to the toe rail, it would lift the deck slightly and let in a lot of water.

The only boats you will find built to a high standard are older ones, as builders cant build these competitively today, too expensive, also the older boats, make less use of the space inside, a modern thirty five footer, has a double cabin aft, double foward and a nice saloon, an old one, has a double forward, a saloon, and the engine aft.

Another problem I noticed with Beneteau, it would be impossible to get the engine out, without cutting a hole in the cockpit, that was a beneteau 35, the engine access was awful, and there was no way I could see of removing it, without damaging the boat, as it was put in, then the deck was put in on top of it.

[hellosailor]

"Its not builders who build boats, its accountants."
Many companies actually have engineers whose job is to take the final project, whatever it is, and remove components to get the production costs down.
But as to questioning Beneteau's expertise...is there really ANYONE who thinks their use of brass throw-away thru-hulls is a superior, or simply sound, engineering choice? I can't wait to hear the justification for that one.
Glue a keel on with 5200 and they say after it has set up and cured for a week or two, the keel bolts won't have to do anything. The glue will hold the keel on. Forever. Without them.
Kinda the same way you don't find glue failures causing the wings to fall off combat aircraft. Ever see a B17 up close? Ever notice how many rivets are simply MISSING, even from the ones that are still in flight? So much for top-quality mechanical fasteners.

[boom23]

First of all, no company makes a perfect boat. On top of that, "perfect" is different for different people, and it changes over time.

Beneteau has found a recipe that makes their boats sell. There is nothing wrong with that. That's what every company is trying to do. If you want something better (for you), buy your preferred brand. Do not be surprised if you find problems with that boat also...

[Mike Banks]

I am not sure about the boats you mention, but almost all of them have powerful joins where the mast is stepped to the compression post, the shrouds are fastened to their embedded anchors via the deck hold-downs, and the mooring cleats bolts pass through the deck via reinforced deck pads, into the strengthened parts of the hull where they are to be landed.

Those are the main strong points, but the additional deck hold-down bolts can pass through the toe rails, or through water-fall sealed lips moulded into the deck and fitting closely over the deck shelf on the hull.

There are several ways of doing it--all of them on fibre-glass boats seem to work well as long as one does not add additional equipment in areas of the decks not designed to receive such hardware. Mostly decks are strongly reinforced in the areas where clamps, rope jams, winches etc are likely to be landed.

Decks can be strengthened to receive extra equipment beyond that which the designer envisaged, but sometimes the necessary reinforcements are onerous. Rear mounted anchor windlass for kedging and beaching, or even for hoisting a heavy dinghy or ship's launch being such instances, where not only must the deck be strengthened, but so must its attachment to the main hull structure, which may also need extra scantlings to be designed and fitted..

[robert sailor]

It's important to get your thoughts in line..for example because Beneteau builds the most boats makes them the best?? OK let's go with that thought, that would mean McDonald's makes the best hamburger's, right?
Beneteau has learned to cut their costs down to a level that allows many people to afford their product. Having said that their product is not bad considering what it costs.
Nothing in life has really changed, you still get what you pay for, there are no free lunches.

[Jeff H]

I often see these discussions on various webpages decrying the way that this builder or that builder does something, and extolling the good old days. The reality is that most on these discussions are not founded on reality and an understanding of the engineering involved.

To walk through this, almost from the very beginning of fiberglass boat building, manufacturers have counted on glued hull to deck joint. In the early days the glue was a polyester slurry, which we now know is fatigue prone and brittle, losing much of it's strength over time.

Those joints were often augmented by bolts, with nuts and washers, but from an engineering standpoint, the bolt spacing and bearing were such that the bolts provided a minor contribution to the over all strength of the joint.

Very quickly, (by the late 1960's) manufacturers almost universally shifted to adhesive sealants, most of which were urethane based and similar to 5200 or even actually was 5200. By the early 1970's the bolts or screw fasteners were seen as merely holding the boat together until the adhesive cured. Many smaller boats (under 40 feet( literally used pop-rivets and/or sell tapping screws at the joint. This was an ubiquitous practice used by the majority of the builders of the day.

At some point in the 1990's most production builders shifted to glued in bulkheads and deck joints that relied on a new generation of adhesives that came out of the aerospace industry. These adhesives offered a giant leap in the joint strength, and were widely touted as the adhesive bond being stronger than the materials they were bonded to. That part was correct. But the weakness of that theory resulted from the glue area was reduced to the width required for an adhesion equal to the required strength plus a safety factor.

This migrated the failure mode from the glue joint to a delamination of the laminate. Beneteau and some of the EU builders seemed to catch this early and increased the width of the saying surfaces so a larger area of the laminate took the load and therefore experienced a smaller unit load (pounds per square inch) .

The net result is a very strong, durable joint with fewer potential leak points.

As far as the caulk seen on the exterior of the joint, it is my understanding that this is also a high tech material, and that it's purpose is mostly aesthetic and to provide a secondary seal.

Regarding the chainplate in the photo, I am not a fan of the U--bolt as a chainplate for a range of reasons but these are not structural. The idea behind the U--bolt is that the base plate can be sealed really well at the deck. Below the deck typically is a tension member that ties the rigging loads to the internal framing system of the boat in a manner that has been used since the 1970's and has proven to have an excellent service life and has a higher load capacity and is easier to replace than the cheaper to build chainplate bolted to the bulkhead that is often touted by those who are unfamiliar with the engineering behind the other system. And both the tension connection and the bolted to the bulkhead approach are typically much stronger than the chainplate bolted to the hull, unless the hull is specifically engineered for the tensile and bending loads which few are

Respectfully
Jeff

[Stu Jackson]

Originally Posted by atlantical

Its not builders who build boats, its accountants. In the eighties a lot of builders went bust, as costs were too high. They cut costs by reducing materials and labour, and yet building a more desirable boat.>>>>>>>>>>>>>>>>>

I remember this one completely differently. In the USA they pulled this stupid stunt called "The Luxury Tax" brought to you by GHWB. That move put a lot of successful boat builders out of business.


Otherwise, the rest of your comments have great merit.

[atlantical]

I just saw a boat sell, in the boat yard my boat is in near largs Scotland, it was a 28 foot boat built in the early sixties, needed a lot of work, but it was teak on oak, I spoke to the buyer, he told me it would be an easy quarter of a million pounds sterling to build that boat today, he got it for a song, even if he dismantled it and sold the teak, he would make a lot of money.

[Emouchet]

I have seen from my own eyes a brand new Beneteau 38.1 being handed to its owner at a Bénéteau dealer in spring 2018. Same boat.

By that time, I had my rigging changed on my 1995 Dufour 39 Frers at the same marina. I was waiting for the marina employé in charge of rigging jobs to help me finishing tuning my mast.

In the middle of the afternoon, the rigger got called in like an emergency to service the brand new Bénéteau that was just splashed. This was now his top priority job...

So, our tuning job was delayed for 2 days because the rigger told me he had to rush design, manufacture and install serious stainless steel backplates for each of those U bolts… There was originally no back plates, only washers and a nut…

While waiting, I had plenty of time to compared our new rigging with the one from the Bénéteau: our boat and this one are almost the same size, with only 250 lbs displacement difference. Our mast it also shorter.

I could see that they have "optimized the cost": my shrouds, forestay and backstay are all 1x19 3/8 wire, while on the Beneteau the largest wire was 5/16 to be best.
May be 5/16 means you can save on backplates too ??

[MarkI]

I have ordered a 2020 Beneteau 46.1.

They have dispensed with the wood toe rail entirely. I think that is great choice. Maintenance wise, less wood to refinish.

The comments on glue taught me some things thanks everyone.

I wondered if anyone knows how the Stanchions are installed?

They go straight through the joint in question, providing about a 3/4" stainless penetration and if closely fit, then really strong lateral support. IF they are backed up with bolts underneath going into the stanchion, and they obviously have a top collar, so they would act as bolts connecting and keeping the hull and deck together. It is only every 2 meters or so, but with the glue it is probably a fantastically well engineered solution.

Compared to my friends 2018 Catalina, the stanchion design seems much better. The Catalina has separate right angle brackets for each stanchion, and several fasteners going through the deck. Way more penetrations than one larger hole IMHO. And lots of opportunity to collect water puddles that seep into the boat.

As for the Beneteau Quality argument, yes, they add maintenance cost with certain decisions (through hulls, sail drives). But this keeps entry cost down, and defers the eventual cost over the years. It is a conscious choice. For things that are really not that hard to replace it is a fair choice, but not for everyone.

I believe the engineering is excellent, and provides the most cost effective solutions, which on the whole work quite well. Are there stronger boats? Certainly.

[GordMay]

Greetings and welcome aboard the CF, Mark.

[Davo1404]

Originally Posted by Jim Cate

Interesting! The toe rail pic shows a bung. All very well, but what's under the bung? Self tapper or a proper screw/nut/backer? And in the last pic, is that u-bolt thing the "chain plate" for the split backstay as it appears? I'd wonder what structure is under the deck there, and how it distributes the stresses from the stay into the hull? Surely does not inspire great confidence in this observer!!

Jim

This is why you see stress fractures around these loaded area's on these yachts after a few years of use.

[Wireless1]

Originally Posted by hellosailor

Dan-
Think about all the complaints you've heard about "can't get that goddamn 5200 off!". The material they use may not be 5200 but it is similar, it ain't budging if it was applied to clean surfaces. The mechanical fasteners are actually just there to hold the deck and hull together while the adhesive sets and cures, which can take a full week.
Remember that commercial airliners and combat aircraft have important bits like the wings GLUED on. It can work.

The aluminum tub in my Lotus Exige “S” is all glued together with some aircraft orange glue that oozed out when it cured in places that you can’t see. I’ve been under the car and tried to pull a blob of it off with some vice grips to see how strong it was. The vice grips lost that battle....so I stopped worrying about stuff that is glued together nowadays. I don’t worry about my Beneteau 473 hull to deck joint now either.

[thlamers]

Just a word of caution from one who has been around for a while!

While 5200 is a wonderful product and I do use it in some structural applications it may not be "forever". More than once I have dug this product out of a seam to find it has turned to a wax like substance with little strength or adhesion.

A discussion with a 3M tech rep disclosed that its expected life is 10 years. I am sure this is a ballpark number but urethanes are usually protected by a sacrificial anti-oxidant and this can be used-up in time. See the effect on automotive clear coats which constitute a "time bomb".

Tom