RCD and Stability (Again)

[Guest]

Got in last night to find latest YM had been delivered. looked at index, ah! Elan 31 test, that might be worth reading, I thought. Turning to the relevent page my I eyes went straight for the tech spec bit. Was amazed, 34% aspect ratio a stability curve out of the text books and only Cat B!

So come on someone must know, how the hell can a Bavjaneux with a keel the size of a generous rudder, aspect ratio of 28% and a stability curve of a boat that will quite happily sail inverted be awarded CAT A, every other month?







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[Sybarite]

Under the former rating systems that we had in France the Category 1 = Cat A was practically never granted to a boat under 10 metres. Probably something to do with the possibility of it being overwhelmed by large breaking waves ??

John

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[NigeCh]

read the STIX calculation methods

They don't make sense either and STIX rules the RCD Categories - BUNKUM! - If they were to be retro-applied a Contessa 26 would be rated as Cat 'C' and yet look at how many CO26's have done circumnavs, never lost a rudder nor been dismasted nor sunk nor had to be scuttled .... whereas .... Need I say any more?

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[tr7v8]

Re: read the STIX calculation methods

At the risk of asking a difficult question, I get highly amused by you yotties getting so wound up by Stix and stability curves etc. I watch some of the major yacht races and see major gear failure like rudders masts etc. Most of the issue seems to be structural failure and this is something that the RCD type rules doesn't address. I see yachts with quite high (A or B) type ratings that look quite lightly built, hull to deck joints etc. I also see articles where the major manufacturers are criticised for thngs like toerails bolted with stainless screws into alloy plates which the engineer in me doesn't find funny.

Just as a question how many of the non Cat A yachts make round the world trips, how many have an issue with capsize?



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Draco 2500

 

[halcyon]

Think the size of the marketing budget may come into the calculation.


Brian

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[NigeCh]

Not a difficult question to answer

Most pre-IOR boats were designed to sail. What's IOR, you say. Well it's some stoopid rules about racing and we all know how car racing improves our standard cars ... Nothing changes ... Not even Open 60's soooper refinenments for everyday boats (but it did in an unseaworthy fashion - Perhaps JJ might like to comment.)

And then along came Mr & Mrs Joe Punter who demanded caravan space and a marina bound weekend yot.

And then came along a mass producer in the USA who saw profit in the Mr & Mrs Joe Punter weekenders who would never venture beyond the marina.

And then came along Mr & Mrs Newbie Joe Punter along with the RCD (If you get all the bits and stack them one on top of each other you get an A4 pile 29" high --- add the amendments and you'll increase the height by another 4" )

So we sailors want to sail ... but ....

And as you so rightly say the RCD doesn't address sailability .... that's why most of us sail old and seaworthy proven boats.

To see the worth of the RCD just look at YM April 2003 pages 106 through 108 . What's not said there is that those boats are now being made in the UK by Luhrs Marine Ltd

Now tr7v8, it's one thing put-pottering anywhere and another thing hositing the rags and doing something. When you are in the middle of nowhere and all is nasty you have to believe in your boat - Once upon a short time ago we had a nice simple calc called AVS .... but it's been overtaken by the un-understandable STIX ... We could even simplify it more by doing a simple capsize screening ratio... but that's gone too.

Anyway to answer your question, .... I haven't a clue .... because Mr & Mrs Joe Punter's Cat 'A' boats are only fit for the ARC in milk run conditions if that at all.

For a list of capable boats have a good look at:

http://www.mahina.com/cruise.html




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[AndrewB]

Come now Nige, you know as well as I ...

... If its Cat A, then its capable of sailing around the Horn to windward.

... Let the makers worry about the structure, judge quality by the fitted cupboards.

... We NEED all that electronic equipment, so we can call for help.

... Falmouth CG is never more than an Inmarsat call away.

... If anything goes wrong, someone else is to blame.

... If the air-sea rescue don't come pronto, we'll sue the pants off them.

... The insurance will pay.

Life is a goldfish bowl and the cats are now locked outside.

STOP LIVING IN THE PAST!

 

[ponapay]

Won\'t it be fun when

Mr & mr Jo Punter sue the maker of their inadequate boat rated at Cat A when it capsizes or sink in condition that are clearly le than those found routinely in many oceans.

Lets hope it happens soon.


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[jimi]

Re: Won\'t it be fun when

Perhaps the sailor rather than the boat should be rated? That certainly seems to be my interpretation of the MAIB reports I've seen?

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[jamesjermain]

Re: Not a difficult question to answer

I would if I could work out what you're saying!

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[jamesjermain]

Length is the single most important factor in the RCD and it is almost impossible for boats under 10m to get Category A.

It is quite possible that there is some good and value in RCD and STIX. However, the public face of the regulations - GZ curves, AVSs Category ABCDs, and STIX numbers, are, at best, blunt instruments which serve as rough guidance for the wize, but at worst, highly misleading for the uninformed.

As I have said in this month's YM, 'any rule which lumps an essentially light-displacement 33ft yacht in the same class as a 46ft heavy duty ocean girdler is flawed'.

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[NigeCh]

Numbers and practicality

There was an old rule of thumb about timber beam spans in buildings. It was "Divide the span in feet by 2, round up the number to the nearest whole number and add 2""

ie a span of 15 feet = 15/2 = 8 +2" = 10" x 2" at 16" centres.

It's nice to see that the latest complex set of Building Regulations calculations are just under the above example.

My Contessa 26 with an AVS of 164 degrees can sail the world and yet she is classed as a RCD Cat 'B' or 'C' depending which insurance company you talk to.

Isn't it time that YM stood up and had a good go at the anomolies in the RCD? - But nothing yet, not even as an editorial. When was the last time that YM said anything about the RCD and why sailability of proven boats is more important than new boats silly numbers?


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[NigeCh]

And there\'s the rub ...



AndrewB worked it out ... It's what we can say here and what you can't print in YM.

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[jamesjermain]

See my other posting to this thread. NM

.

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[NigeCh]

As Descartes said ...

'Plus ca change, plus c'est la meme chose'

or as he said in his 'Discour sur la Methode', 'When does the circle become smaller than the point?'

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[ponapay]

That sounds very sensible - bring

in ratings for all at sea.

Then the insurers will have no excuse for high premiums. They will only insure those sailing in accordance with their rating.

Perhaps there should be more discussion/insistence on mandatory qualifications as the RCD and STIX seem to have too much commercial pressure on them for then to be useful to real sailors. Bring back AVS and proper curves (for boats and for the ladies).


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[Aeolus_IV]

I'll start by saying that there are far wiser people on this forum than me, however the following observations strike me (as this topic surfaces again):

"Horses for Course" seems appropiate. With there being a number of (sometimes mutually exclusive) requirements driving the design of hulls and rigs there are natuarlly going to be a range of solutions. Ranging from a heavy long keel boat to a light-weight narrow fin racing adrenaline machine. This is normal, and to be expected.

Volume manfacturers of boats want their product to be seen as modern and dynamic, so naturally use elements out of the yacht racing world in the production of cruisers or club racing boats. We have all seen the adverts starting that Such and Such has successfully converted thier very fast racing hull into a cruiser for the family. We'd all like to think that if we buy a new car that some little part of it has been derived from F1 racing, so it perhaps no suprise that this approach is taken. Apart from that, the costs of designing and building molds for hulls must be expersive, and re-use of common componets is a key to keeping costs down.

Where I feel that we, as potential buyers and users of boats, are let down is in the difficulty in understanding the "pros and cons" of any given boat. Trying to condense many different factors into a single number is doomed to be miss-leading at best and dangerously inaccurate at worst.

Buying a boat isn't like buying a car, there are more factors to be taken into consideration.

In buying a boat we rely only on our interpretation of a few numbers, AVS, STIX etc. for which there seems to be no generally understood interpretation. I understand AVS, but STIX is a mystery.

I feel that rather than trying to condense this information, they should be open with the data. Tell us the facts about a boat, so that we can see what they are selling, and make like for like comparisons, and undertand the suitability of a boat for a given use. How can this be reduced to a single number?

Ignorance seems to be the buyers biggest problem, not understanding the boats, and in doing so letting the manufacturers drive where boat design heads.

Just my view, Jeff.

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[Guest]

Still plenty of interest then?

I have to agree with all the comments. I refer to AEOLUS IV, 'buying a boat is not like buying a car'. What is scarry, whilst we are all familliar with the current RCD / STIX debate, Joe Punter, new to the sport, will go to the boat show be 'sold' on a nice new safe CAT 'A' package with affordable cheap finance, not having had the experiance of 'growing up' with old leaky tubs like a lot of us have (no I dont still own one) he does'nt have this experiance (or want it). This means he will have less chance of knowing when things 'feel' right, or wrong.

Then what happens is, after having done a crash course (at best) with a charter company in the Med or Far East for YM or coastal skipper, he is off, believing he has a bullet proof package.

More responsability should be placed with the manufacturer to provide guidance, especially to 'new' owners with little experiance.

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[NigeCh]

Sorry, I don\'t agree with your last paragraph

> 'More responsability should be placed with the manufacturer to provide guidance, especially to 'new' owners with little experiance. '

If you take Ted Brewer's 'Sailing Comfort Formula' you can apply manufacturers data to get a number which will give you a 'sort of' indication about the boats sailability. This number is just a number, but it may be a good starting point to compare boats prior to purchase.

In terms of sailing, the manufacturer's responsibility ends with compliance with the RCD .... and the RCD is, IMO, flawed. If we take cars, then it is not the manufacturers responsibility to tell us how we should drive that car otherwise they would go out of business paying my speeding fines. It's up to us how we sail boats. It's also upto us to determine just how good an RCD 'Cat A' boat is ... There are some new boats Cat A boats that I would happily sail anywhere on and some that I wouldn't touch with a bargepole.

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[charles_reed]

In other words

you're resisting the abdication of all personal responsibility in decisions one takes.

But it's obvious that the RCD is seriously flawed - any litigation should surely be against those who set up a fool-law (theirs is the duty of care not the manufacturers).

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