Stix Calculation

[Guest ynot]

I want to get cat three for a elliott 9 ....anyone out there can help with stabilty specs ???

[Brett Bakewell-White 0]

Why dont you call Greg Elliott as a start?

[Battleship 100]

would be good if there was a database somewhere so once it was done for a certain design it wouldn't have to be redone.

There must be GZ curves for all sorts of designs out there.

[Brett Bakewell-White 0]

That would be fine except Kiwis don't understand the concept of one-design and so there are very few classes where the boats are all the same. Our office has provided generic stability calcs for a number of classes on the basis that the class controls the issue to owners and that it will only apply to class compliant boats. The majority of boats in New Zealand are however unique and so all have to prove compliance on an individual basis.

 

Adding a dodger, davits, a radar arch, changing the keel, or tanks, or re-rigging with a heavier mast could all mean that a boat that previously passed will no longer comply.

[Cameron 77]

Brett, what would a ballpark cost be for getting a STIX calculation done ?

[John B 106]

Is a letter from the designer no longer acceptable for category ratings?

[Brett Bakewell-White 0]

A letter from the designer backed up with calculations proving stability is fine. But the designer must be happy himself as he is declaring the boat as safe and complying with the requirements, and the only way that he can do that is by working through one of the available methods. I certainly wouldn't want to have to stamd in front of an inquiry without knowing that the numbers had been done correctly, but I can't speak for other designers. I know that there are a number of designers who refuse to provide a declaration.

 

We charge approx. $450+gst to provide a declaration using owner supplied information. If we have to measure or incline then it is more likely to end up around $1500+gst. We have to create an accurate 3D computer model, input the relevant data and figure weights - to be honest we make absolutely no money in this process and we in fact subsidise the owners simply because I think that it is an important exercise. If the boat is one of our own designs then there is no charge as it is something that we will have worked through during the design process and is one of our design deliverables.

[tuffyluffy 76]

Perhaps, if there is enough interest, we could organise a bulk deal on 5-10 boats and enable Brett to make a buck, and the owners to share a bit of a bulk discount?

 

I'd be interested if its late spring/early summer, anyone else?

[Dibley 3]

A letter from the designer backed up with calculations proving stability is fine. But the designer must be happy himself .........................quote]

 

Yes, Brett has it spot on. As long as a 3D model can be created, then it's fairly straight forward working out the VCG, which is what the inclining experiment achieves. As far as Stix is concerned, again, very simple but key is VCG positioning so Righting Moments can be ascertained.

 

Nice job Brett.

[Guest]

For someone who thinks STIX is a brand of cracker.

 

Is this number found / worked out / whatever to find if a boat will self-right if knocked down / rolled or for some other reason?

[Dibley 3]

For someone who thinks STIX is a brand of cracker.

 

Is this number found / worked out / whatever to find if a boat will self-right if knocked down / rolled or for some other reason?

 

Ha. Yes, but it also looks at down flooding angles [ie] as well. Flick me your email and I'll send you a STIX Sample from one of our Australian 10 metres.

Kevin Dibley

[Guest]

Our office has provided generic stability calcs for a number of classes on the basis that the class controls the issue to owners and that it will only apply to class compliant boats.

 

Brett did this for the Reactor Assoc. It was certainly helpfull when Trish did her Trans Tasman Trip in "Wishbone".