Hull flex on modern production boats

[SV DestinyAscen]

Originally Posted by Dockhead

That all seems to make sense, more or less, to me, especially the analogy to cars. There is no question that it is far more efficient and therefore cheaper to build boat this way. But the problem is that while cars are used and then scrapped without ever having structural repairs done to them -- the idea of a "major refit" just doesn't apply to a non-collector car -- boats have normally much longer useful lives which may include some rewiring or replumbing and possibly some hull or keel repairs. A glued-in grid and full hull liner makes any such work vastly more expensive and indeed uneconomic in many cases -- so boats built that way are essentially disposable, destined to a much shorter useful life before scrapping, compared to a normal stick built boat.

Is that OK? Is that justified by a much lower acquisition price? Well, if we start to use boats like cars, buying, using for a while, then throwing them away like something disposable, then probably it does make sense. All I can say is that I have never used boats like that myself. I have never bought a boat new (so far) and have never kept one less than 10 years. I would not personally be comfortable with not being able to reach the plumbing or wiring, or to repair the hull economically in case of damage. I had an accident last year with a fishing boat which probably would have totalled my boat if I had had a full hull liner -- in the event, the inside of the hull was easily reachable after taking apart some of the furniture, and the repair was not too expensive.

I think the resale price of the boats reflect the thought processes. Even with modern cars, most liners can easily be removed with a few plastic tabs. The industry wants low warranty costs.

Marine industry is unique in the sense that the large builder attitude is more like residential housing construction. Easily accessible utilities? What? No. We hide everything behind drywall!

If I were younger and was buying a new boat? I'd go simple layout with minimal furniture from Brittany small builders that seem to actually think about boat ownership.

[Jimmyhenry]

We crewed a Bene Oceans 61 from Borabora to Tonga. It was bought in the Med and sailed back to New Zealand. The noise of the hull flexing was huge. But this boat did the 12,000 + trip and has gone on to do Pacific cruise with no problems. Long term who knows but the flexing does not seem to be a problem other than the noise.

[Polux]

Originally Posted by Dockhead

That all seems to make sense, more or less, to me, especially the analogy to cars. There is no question that it is far more efficient and therefore cheaper to build boat this way. But the problem is that while cars are used and then scrapped without ever having structural repairs done to them -- the idea of a "major refit" just doesn't apply to a non-collector car -- boats have normally much longer useful lives which may include some rewiring or replumbing and possibly some hull or keel repairs. A glued-in grid and full hull liner makes any such work vastly more expensive and indeed uneconomic in many cases -- so boats built that way are essentially disposable, destined to a much shorter useful life before scrapping, compared to a normal stick built boat.

Is that OK? Is that justified by a much lower acquisition price? ....

I believe times have changed. The same thing happened to cars. They were not built with a time line for disposal. Now they are built with materials with a finite time limit and that is well studied by the brands, even top ones.

Simply a 15 year old car has a market that is restricted to the ones that cannot have better and its market value is just a small percentage of the new value.

The brands can car less if the car is going to have problems in 20 years. They care about the car performance now, at different levels and care about the car having not any problems specially on the first 5 years, eventually 10, even if not that important.

Their clients just want to have a good resale value on their 5 year old car while they buy a new one and have no problems on the new car while they own it. That is what concerns builders. Selling cars.

I would say that on boats the time line is a big bigger than on cars but the logic is the same: they just don't car to what happens to a 20 year old boat.

That's the cornerstone of our society; consumption

Without consumption all society would went down, factories would close and the unemployment would raise. What allows us to have inexpensive products is the high level of consumption and production.

Is all this bad? Well it does not even have much sense to ask since it is like that but the truth is that the cars today, on the first 10 years, work better, perform better have less problems and make a bigger mileage than older ones.

Sure old cars without electronics with much thicker metal, with less plastic would last much longer, if carefully maintained but who cares? that maintenance is expensive and it is cheaper to by an used one with less than 10 years and it will perform better anyway.

With the boats it is pretty much the same thing but with just a slightly longer time line that starts to be shorter at the measure that more and more recent used boats come to the market.

[Polux]

Originally Posted by Jimmyhenry

We crewed a Bene Oceans 61 from Borabora to Tonga. It was bought in the Med and sailed back to New Zealand. The noise of the hull flexing was huge. But this boat did the 12,000 + trip and has gone on to do Pacific cruise with no problems. Long term who knows but the flexing does not seem to be a problem other than the noise.

They used to say on Bavaria that the boat had to move and flex to work well and that was kind of normal. LOL. In fact that is true that things like doors that did not close and the like did not happened. I had one and I used to think that was pretty incredible that after all those noises everything was alright and working.

I am very curious about the new Bavaria C line, it was said to me that their were very silent because they flex much less. Of course who said that to me was the responsible for the structural alterations and I take it with a grain of salt, but i will pay much attention to the test sails on the new Bavaria.

If what he says is so evident then it will refereed in all reviews by all sail testers.

[Dockhead]

Originally Posted by Polux

I believe times have changed. The same thing happened to cars. They were not built with a time line for disposal. Now they are built with materials with a finite time limit and that is well studied by the brands, even top ones.

Simply a 15 year old car has a market that is restricted to the ones that cannot have better and its market value is just a small percentage of the new value.

The brands can car less if the car is going to have problems in 20 years. They care about the car performance now, at different levels and care about the car having not any problems specially on the first 5 years, eventually 10, even if not that important.

Their clients just want to have a good resale value on their 5 year old car while they buy a new one and have no problems on the new car while they own it. That is what concerns builders. Selling cars.

I would say that on boats the time line is a big bigger than on cars but the logic is the same: they just don't car to what happens to a 20 year old boat.

That's the cornerstone of our society; consumption

Without consumption all society would went down, factories would close and the unemployment would raise. What allows us to have inexpensive products is the high level of consumption and production.

Is all this bad? Well it does not even have much sense to ask since it is like this but the truth is that the cars today, on the first 10 years, work better, perform better have less problems and make a bigger mileage than older ones.

Sure old cars without electronics with much thicker metal, with less plastic would last much longer, if carefully maintained but who cares? that maintenance is expensive and it is cheaper to by an used one with less than 10 years and it will perform better anyway.

With the boats it is pretty much the same thing but with just a slightly longer time line that starts to be short at the measure that more and more recent used boats come to the market.

What you say is certainly true of cars, which are without question much better than they were 30 or 40 years ago. They work out their normal useful lives now with almost no problems, no rusting out, and usually not requiring major repairs, unlike the case some years ago. Then you scrap them.

Is the same true of boats? Maybe, but I'm not sure about it -- boats are different from cars in many ways. All I can say is that I would not want a disposable boat, myself. Others may have different preferences, and that's OK. But for me, a boat is more like a building than it is like a car, and the disposable consumer commodity model might not fit so well. I would not want to own a building, for example, where major repairs or upgrades are not economically feasible -- I expect the fabric of a building to have a reasonably long life and to be capable of undergoing several major renovations, rather than just being torn down.

[a64pilot]

Boats are actually more like houses than cars. Cars have to meet an extreme amount of government mandated testing and minimum equipment.
Just as in the McMansion craze of the last several years, people don’t want quality construction, they of course want the “bling” your supposed to have, SS brand name appliances and granite countertops, but as far as framing, electrical, plumbing, quality doors, windows, not being built on a slab, etc, etc. they don’t care, they want BIG and impressive, and they buy the absolute biggest thing they can qualify for loan wise.
Successful boat builders of course build want people want, not what is best or what they should have, they build what will sell. Many, many builders that won’t sacrifice quality have closed their doors. Of course some very expensive custom manufacturers still exist and always will, but the real money is in manufacturing what sells.

[SV DestinyAscen]

Car manufacturers are way better about considering product end of life concerns.

The car plastics that ppl complain about? Recyclable.

Whether entry level steel unibody or aluminium unibodies - recycled.

Boats just get sunk/shredded/buried/left to degrade in the sun.

[double u]

I'm inclined to think I know e x a c t l y how our ideal boat would have to be built. unfortunately at the present rate it would take me 50 years of slaving away & saving before we could afford it (& at 62 I can't afford that)
sure the closed gridpans glued to the hull are scary (& a hell of a lot of other construction details too!) - but she will have to be affordable!!!
as Casey/Hackler write: the ideal boat is the one that takes you crusing.
our first rtw was on a 34' wharram cat which is about as far removed from "the-ideal-cruising-boat" as possible - but it was a great adventure that I wouldn't want to miss for the world (but not repeat either!)

[2big2small]

To get back to the issue of buying a Beneteau 473 and being concerned about flex, my first boat was a Beneteau Oceanis 361 and I now have an Oceanis 50.

I find the 50 to be far more rigid than the 361 ever was. You could kind of feel the latter flex while under sail. I sail my boats rather hard. I did over 21k miles with the 361 in 4 years of active sailing—over 5 years of ownership, and I sailed the 50 nearly 8k miles in my first year of ownership.

Even though the 473 is one generation older than the 361, it looks like they have pretty much the same building philosophy and weaknesses so here’s my advice. Only buy a 473 that has been very lightly used unless you’ll be sailing it very little yourself. Because, yes, you can expect the bulkheads to start separating after 20k miles. They’re just glued together and the hull assumes a permanent bana shape over time, for lack of a better term. Even such a boat that has not been sailed but just sat in its slip with all rigging under full tension all the time will be permanently deformed. You can see this in the forestay that becomes slack no matter how much you tension the other stays. (The forestay on Beneteaus usually has no turnbuckle so you can only work with the rest of them but ultimately you’ll need to remove it, shorten it, and add a much needed turnbuckle. The stay itself may have stretched a bit too of course which is not helping things.)

This permanent deformation of the hull is an issue on most modern boats, not just Beneteaus, and should not deter you of getting one. It was an issue on wooden boats too and is even on steel boats, but nowadays it is most pronounced on the light grp ones. I’d buy a 361 again with no hesitation however. I loved it! You can reglue the bulkheads, add a discreet metal plate if necessary, it’s not a big deal, it all keeps working. Doors still close fine for instance.

I get the impression from owning the 50 now that Beneteau strengthened their hulls some for this generation (it followed that of the 473). So I would recommend you get an Oceanis 46 instead of the 473. Unless you’re tall. I don’t have enough head room in the area around the compression post in the 46 and all doors are too low. The settee is also not deep enough for comfortable sitting. Overall I would still get a 46 over a 473 though for the much better galley and bathrooms, and the liferaft locker, but that’s just personal preference.

As mentioned in previous posts, these boats have hand laid, non cored hulls with a structural liner and vacuum bagged, balsa cored decks. The 473 has a keel stepped mast, the 46 is deck stepped.

About the structural liner, I once met a Frenchman who told me how a killer whale strike on his 361 off the coast of Argentina had totalled his boat by rupturing the bond between the liner and the hull. The hull wasn’t breached and he made it to port allright but the boat was now landfill material. I was sailing my own 361 when I met him and a few weeks later we were cruising in humpback whale breeding grounds off the coast of Brazil. When one of them, much longer than our boat and at least 5 times heavier, surfaced right next to us to stare us into the eyes, we were feeling rather queezy.

But my overall opinion is that Beneteaus have several models that are unsurpassed in interior layout, they’re very rationally built in terms of access to everything, and they usually offer the best deal for our money the way we see it so I’d say go for it.

[olaf hart]

My local boatyard puts all new euro boats in slings, and leaves them on.

It uses cradles not a travel lift, but won’t leave euro boats on their keels alone, too much deformation of the hulls if they are not in slings as well.

They have shown me a few out of slings, the bottom around the keel was concave.

Link this to a grid hull liner with uncertain bonding .....

[2big2small]

As to whether hull flex is a design feature, nope, it isn’t. It is the undesirable side effect of the desired strenght, weight, and construction material (grp) combo, and mostly also of the building technique. I think it’s safe to say that manufacturers have to put quite a bit of effort in to mitigate flex in spite of the chosen (economical) building technique and materials.

With the same quantity of the same materials they could build the same boat with a honeycomb structure for instance and get something way stiffer than what they deliver now, but this building technique is still outrageously expensive.

For our modern sailing yachts, the stiffer the hull, the better from nearly all points of view (performance, longevity).

The vikings used to build their drakars with very flexible hulls which helped enourmously for the stability of these non ballasted boats. They would flex and “remain stuck to the water.” Our modern equivalent is the inflatable dinghy. But flexibility doesn’t provide any significant stability advantage to a ballasted monohull or a multihull, certainly none that weigh against the disadvantage of loosening bulkheads, and material fatigue, and gelcoat cracks, and ...

But overall we do get great boats for the money in exchange, with ever larger parts of the population able to buy in.

[2big2small]

Originally Posted by olaf hart

My local boatyard puts all new euro boats in slings, and leaves them on.

It uses cradles not a travel lift, but won’t leave euro boats on their keels alone, too much deformation of the hulls if they are not in slings as well.

Even just leaving the boat in the water without tension on the rigging will permanently deform it over time. The keel pulls the center down and the ends go up.

Regardless which boat you have, it’s not a question of whether it will deform but how you can mitigate and delay it. The slings are a good solution as long as you don’t forget to loosen the rigging too.

I use my boats all the time and there’s nothing much I can do. But I don’t worry about it because it’s not a show stopper except on the most flimsy ones.

[Polux]

Originally Posted by Dockhead

... But for me, a boat is more like a building than it is like a car, and the disposable consumer commodity model might not fit so well. I would not want to own a building, for example, where major repairs or upgrades are not economically feasible -- I expect the fabric of a building to have a reasonably long life and to be capable of undergoing several major renovations, rather than just being torn down.

Sure, we all can have our view point. I have the same regarding an already old sport car that for some subjective reason worth much more for me than what the market value and that I don't think in selling.

But what makes the parallelism with boats and houses or with boats and cars is not our subjective view on the subject but market value and devaluation.

A car devalues even faster than a boat but an house devaluation with age has nothing to do with the one of a boat that is much, much closer with the one of a car.

May also be pointed that on the last years the boat devaluation has increased due to the big number of newer boats available on the used market.

A 10 year car has less than half of its initial price, a boat has about half value, a house can and many times have a superior value than the initial price, depending on the market and if not the devaluation to half price is much longer than 10 years.

And that's value of the things (on the market) and the devaluation with the years that determine their useful life.

I am not referring to sentimental value or the time a car or boat can be maintained in functional condition but the time where it is cheaper to buy a newer used boat or car than continue to maintain an old one with a lesser performance.

On a house the time that it is cheaper to build a new one tan recovering an old one curiously have very different timelines in Europe and the US but that is linked mostly to the soil value and building traditions. In Europe many houses more than 50 year's old still retain more than its half value regarding building a new one.

[rourkeh]

I have seen brand new French production boats like Beneteau etc that were sailed across the Atlantic on their own bottom for delivery. The bulkheads and cabinetry had separated and there were cracks in the hull to deck joint. You get what you pay for......

[Dockhead]

Originally Posted by Polux

Sure, we all can have our view point. I have the same regarding an already old sport car that for some subjective reason worth much more for me than what the market value and that I don't think in selling.

But what makes the parallelism with boats and houses or with boats and cars is not our subjective view on the subject but market value and devaluation.

A car devalues even faster than a boat but an house devaluation with age has nothing to do with the one of a boat that is much, much closer with the one of a car.

May also be pointed that on the last years the boat devaluation has increased due to the big number of newer boats available on the used market.

A 10 year car has less than half of its initial price, a boat has about half value, a house can and many times have a superior value than the initial price, depending on the market and if not the devaluation to half price is much longer than 10 years.

And that's value of the things (on the market) and the devaluation with the years that determine their useful life.

I am not referring to sentimental value or the time a car or boat can be maintained in functional condition but the time where it is cheaper to buy a newer used boat or car than continue to maintain an old one with a lesser performance.

I think it's very good to put objective numbers to this question.

But to compare properly you need to factor out land value from house prices. With the land price taken out, then a building does look quite like a boat. The fabric of the boat, like the fabric of a building, has a fairly long useful life, and if maintenance and updating takes place, then the value is fairly stable. Car-like depreciation might take place during the first few years for a boat, but after that, not so much, at least not if it's a quality boat. After 10 years and up to maybe 40 years old, I think quality stick-built boats will not depreciate at all provided the condition is kept up. For example, the old Moody Carbineer 52 from the '70's continues to be much in demand and is sold for as much as 250 000 euros or more when in good condition; see: 1976 Moody 52 Carbineer - Boats Yachts for sale. I suppose in nominal currency units (say 500 000 DM) it's worth more than it cost new. My own boat is also worth not less than what I paid for her 8 years ago, but of course I spend money every year keeping her in good condition, updating the systems, etc., and I will lose all that money when I sell her.

Another good example is the Contessa 32. Most of us would consider her somewhat outdated, but she is a good, strong, well-built boat which sails well even by today's standards, much in demand, and sells for more than the new price in good condition.

So it depends. A disposable boat with a limited life might depreciate like a car, but good quality stick built boats -- not so much after the first few years.