Questions to be asked again

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As to ISO, RCD and MCA standards my hunch is they are layered over each other to address different needs.

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Sadly not that logical, as far as I can tell.

MCA codes (formerly Board of Trade??) was/is the UK's empyrically based standard for craft construction & operation. Having dipped into bits of it, it looks very prescriptive - if you're doing 'X', this is the way to do it, sort of thing. I would imagine it is highly regarded. There is nothing to enforce it for non commercial small craft. 'Harmonised' code here (1MB pdf)

The RCD is a piece of nothing legislation that introduces 4 categories of leisure boat use, and specifies that boats must be designed & build to withstand conditions appropriate to its category, and must comply with harmonised European standards in certain key areas, which it lists in Annexe 1, together with a raft of appropriate / barely relevant harmonised standards - the ISOs.

The ISOs are the harmonised standards, which are agreed across the EU, and should replace UK only standards (we can't be unfair to our EU brethren, can we?). They therefore (IMHO) tend to fall to the lowest common denominator, but have an authority which is potentially greater than UK only standards. Indeed the UK has to accept these harmonised standards (general point, not specific to boats). Perhaps why so many aren't agreed. Perhaps explains your surveyor's attitude to them.

The ISO standards via the RCD are here, so ultimately they are the minimum requirement (within Europe). All we can hope for is that they are critically reviewed following operational experience, and that common sense & engineering can overcome the various commercial interests on standards commititees.

Not an expert, but I've had some experience of how Standards Committees work.

Andy
 
Sorry to reply to myself.....

The relevant standard is ISO 12215-5. Guess what ......

It's not ready. Despite being started in the late 1980s.

May I really recommend yet another .pdf to you ? (sorry)
An Assessment of ISO 12215 Small Craft Hull Construction with Classification Society Rules

This is a well written, but horribly damning assessment of the proposed standard, and of the principle of applying an ISO standard to craft construction, versus classification society rules.

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There are a number of inherent differences between ISO standards and classification society Rules.

An ISO standard is a stand-alone document; very specific, limited in content, scope and text; applicable generally to relatively simple items of equipment, materials, fittings, or auxiliary machinery.

Because of this there is generally no need for interpretations. ISO standards are written to be referred to in specifications and statutory regulations, where
they are applied by and conformance is verified by an appropriately qualified engineer.

By contrast, classification society Rules are developed to be applied to complex ship or craft structures. They contain many inter-related engineering equations based
on a number of different modes of failure, with extensive text on application. There are numerous supporting requirements for materials, welding, structural detail, workmanship and quality control.

Because of this interpretations on application are frequently needed.

Verification of compliance with and interpretations of classification society Rules can only be given by qualified members of the particular classification society who have a sound understanding of the development of and background to the Rules.


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Even allowing for a bit of protectionism, this is scary stuff. There's so much relevant stuff I could quote here, that all I can do is recommend you read it. I bet your back turns cold like mine did. The paper reflects the situation at the end of 2004. I really hope things have moved on. Anyone know?

I think you (Sailfree) might be opening a can of worms here - particularly if people are buying boats on the back of meeting ISO xyz.

Andy
 
The design standards are deliberately vague so that designers have the opportunity to be inovative rather than being constrained. Maybe the means of specifying loads should be more prescriptive, but then again we are talking rules that apply from 2m to 26m IIRC, so even that is unrealistic.

The determining of loads is always going to be problematical with vessels as someone already suggested that a keel should be able to withstand impact a twice max boat speed for example. Clearly there are compromises to be made. That is where operating manuals come into play (something else required by the RCD). The design should have a caveat that if (say) you run aground, you should perform a prescribed inspection procedure. In other words, the designer should give some indication at what point the design parameters have been reached.
 
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The ISOs are the harmonised standards, which are agreed across the EU, and should replace UK only standards (we can't be unfair to our EU brethren, can we?).

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ISO standards are international, worldwide, and not restricted to Europe. European Standards are numbered as ENs (European Normes). Once agreed, ENs are legally required to replace national standards within the EU. Unfortunately, there is no such requirement for ISs; particularly a problem in the USA where standards law varies between states.

I used to chair an ISO committee.
 
Hi, I have just been reading the comments about keel design. For me this is more than an interesting topic...... for 1 reason I used to be in R&D designing tests for materials, with a speciality in polymers (plastics), for 7 years at British Gas. Reason 2 is that I own a Match 42. This boat has had the recommended modifications, and they are pretty substantial. I have just done the sail:disp ratio calculation, and it works out to be between 26 and 30.4 depending upon the exact keel, rig and sail. So it is a very powerful boat, and I would have thought that the mountings, before the modification, would not have been substantial enough. Having said that, she is very light and requires reefing in 12 knots of wind unless you have an army of ballast on the top rail. The boats natural tendancy to gripe up will, in fact remove a lot of the potential load imposed on the structure.
In the past I have been involved in an insurance case which involved structural surveys. In some respects I was horrified about the lack of scientific knowledge in the reports. However, on the other hand, the surveyor(s) were using empirical techniques and so their findings were not wrong because such a large amount of leeway was inherent in their findings. I think there is a place for the academic (theoretical) scientist and the empirical scientist. However, how does one build specifications and requirements based on empirical? We would get clauses like "should not fall apart in a heavy sea"!
 
One problem that I think GRP has is that, dependant on the QC, it may vary in strength. I would therefore think that any calcs need a bigger safety factor than say a more certain material eg Stainless Steel.

If I were doing calcs I would liken GRP to soil mechanics. You know what should be there and its strength characteristics but you cannot be certain!

When I state emperical I mean more what has been found to work eg the statement that a design does not need structural calcs if examples have performed satisfactory for 5 years.
 
One of the seriously scarey things about materials, and especially composites, and especially GRP, is that the behaviour of the material is totally dependant upon, and radically altered by such manufacturing factors as: GPR cut and density, hardener/gel ratios, temperature and humidity of preparation and curing, and probably most importantly; wetting of the Glass Fibre strands themselves.
GRP, at best (from an extreme scientific point of view) may be described as a hit and miss process.
The saving grace with GRP is it is relatively light when compared to Steel, for instance, and therefore one can afford to add strength by bulking the design of the component up. However, if there is an intrinsic manufacturing defect, such as moisture or air ingress, insufficient wetting or poor mixing, then even an oversized component can exhibit catastrophic failure. We had similar manufacturing problems in British Gas because the sealants (for gas pipes) were often mixed by the side of the road in pouring rain. We conducted 1000's of tensile/flex/environmental/ageing tests in order to establish the significance of environmental factors. Poor mixing and hardener dispersal accounted for most catastrophic failures that I saw. Perhaps, Bavaria have got it right when they have tried to control the curing environment so that their manufacturing process becomes reproducible and the strength and characteristics of the hulls coming off the production line fit better with the design requirement.
I can't see a "backyard" boat yard with a paddle mixer, a couple of cans (hardner and resin), measured approximately by "eye", on an ice cold and damp day creating a hull that can be guaranteed to be close to some design specification! The only way out of this is to over-design.... which brings back in a full circle and perhaps to the root of the problem..... cutting weight (and cost) but cutting the quantity or quality of materials used. But extra weight, in a performance boat means less performance! Boy, I am glad I am not in boat design and construction!
 
The funny thing is that the resin and matting costs are fairly small compared to the cost of building, equipping, staffing and running a modern hull-building facility.
These costs are also fairly small when compared to the overall value of a boat.
But isn't that the irony, so often? You'll probably find the raw materials for the building of the basic 40 foot hull is probably no more than 500 euros. Does anyone know the current price of the materials?
I would guess that much of the price difference between an Moody 46 and say a Bavaria 42 is in the manpower that is required to be used to ensure that the hull is laid up properly, rather than a difference in raw materials. If the Moody's raw materials were 5 times the cost of a Bavaria, (implying a far stronger hull), that would not be a huge proportion of the selling price of the finished article.
But, if Bavaria have efficient mass production techniques, they can trim huge amounts off production costs by saving manpower and improving throughput, and arguably improve the quality of the hull material itself.
Rolling back to the Match 42 keel fittings, it might be that the design was just too radical and someone got their figures wrong, and/or didn't take into acount the risk and damage caused by an extraneous action such as a grounding.
We have heard stories of how such and such a boat hit cliffs at 10 knots and survived. In reality, how many of us would have the confidence to deliberately do that and expect no damage? How many of us have got the confidence in our boats to order a crane driver to drop our boat from 5 feet? I would suggest none of us would! That shows what expectation we have in our boats' designs! Who can guarantee that hitting an underwater rock at 9 knots isn't potentially more dangerous that dropping a vessel vertically? Remember, loading, and consequential stressing and strains, is a 3 dimensional spatial model, subject to many many variables. I would suggest that a boats resilience could be radically altered by tightening or loosening the rigging. Drilling a hole somewhere in the hull might improve performance in one particular test and descrease performance in another type of test.
One has to be a very brave, or well informed, person to decide which tests would accommodate which performance parameters that you were trying to check.
I am still glad I am not involved in boat design or construction!
 
Interesting report on the sinking of the Hanse as a result of failure of the rudder stock (see the thread Rudders). In the report an annex refers to the US standards hanse designers used for the structural strength of the rudder stock. Part of the standard is reproduced in an Annex.

Trying to print off the relevant pages but at present my laptop locks up with the file size!

WRT amounts of material I think it is a bigger factor than you suggest. once did an excell spread sheet to compare certain boats and worked out that quality boats were only 20% dearer than production boats if you calculate the price in Pounds sterling/kg of weight.
 
I was pondering the price/kg ratio. We had an Oceanis 461, cost £175,000 and weighed about 12,000 kg. At the time a contender was the Moody 46. It weighed in at 14500kg, but cost well in excess of £300,000+VAT. So the ratio difference was more than the 20%. If you take a Bavaria 50 at £170,000 and Beneteau 50 at £250,000 (?) then the ratio is nearer 50% between these 2 mass manufacturers based on length, but nearer 20% when based on weight.
But, at the other end of the scale, in racing, improved sail area and lowered weight are the objectives, so the aim is to increase the very ratio we were discussing.
Interesting enough I was comparing our boat's spec with the Maxi 1300 etc as tested in December 2006's Yachting World.
Bavaria Match 42: Retail inc VAT £138k, weight 7300 kg.
Maxi 1300 : Retail inc VAT (to same spec) £285k, weight 8300kg. So ratios of price/weight are not consistent by any means, and cannot be used to mean anything!
There is no question that a boat build like a brick *** house will cope with hitting something better than a flimsy boat. However, if the lightweight vessel is well designed and built, it might actually be stronger than the heavy vessel. Look at racing cars, who could contemplate rolling a Ford Mondeo at 120 mph and survive? Yet a lighter racing car can survive 200 mph! (Where's the price/weight ratio comparison here?)
I personally think that Bavaria, and similar companies, are rewriting many of the rules of materials design. There is a possibility that a 7500kg boat might be stronger than a 15000kg boat. It might be that a piece of GRP hull 8mm thick made by Bavaria would be stronger than someone else's 20mm thick GRP, if the thicker sample has not been laid up properly or has moisture/air ingress or incorrect or non-optimised ratios of resin, hardener and matting.
It is all very complicated and therefore probably cannot be resolved. Design criteria are notoriously difficult to establish, as are safety margins. We might design a boat that can hit the seabed at 7 knots and survive unscathed. However, that boat might be picked up by a wave at a harbour entrance and dropped onto the seabed and the boat will disintegrate even though the boat might be only doing 2 knots!
It is very empirical. One problem does exist for sure; as manufacturers try to tweak their designs and reduce weight and cost, then they do run the risk of catastrophic failure if they do not get their sums right.
On the Hanse, I remember reading something about it. Was this the case of a badly mounted autopilot chaffing the top of the rudder stock?
How is this for a question? Is a 50 foot sailing boat selling at £600.000 necessarily better and stronger than another selling for £200,000? It might have more luxury, more style, it might actually have a better hull design and sail faster, it might even be 2 x the weight, it might be totally over-engineered, but would it be a stronger boat? And would that excess strength ever be necessary? I don't know the answers to these questions but I do know this;
In a Force 10 in the Channel I would want to be on the £600,000 boat doing 8 knots in comfort, and in 12 knots of wind in the Solent I think I would prefer to be doing 8 knots rather than standing still! Horses for courses and boats according to requirements and budgets.
So, should boat builders be prevented from designing and selling boats that do not meet certain strength/design criteria if they don't adhere to standards? Should the public be protected from itself? Its difficult because the sea is such an unpredictable place.
 
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