IMS

[Jeff H]

I am surprised that the Synergia is doing so well over in Europe. We had no problem beating it with a 40.7 on corrected time and boat for boat in the States.

As you note, I have been extremely impressed with the motion of the early IMS boats in a chop. For that matter, my Farr 11.6 (a 10,500 lb 38 footer whose bow shape I consider a precurser of the early Farr IMS typeform boats) has one of the most comfortable rides in a chop that I have ever experienced. For the first year I had the boat I would brace myself expecting to colide with every wave. It was only after a year or so that I stopped doing that since the boat does not colide, it slices.

I am discouraged to hear that the International Measurement System has gone the way of earlier rating rules.

Jeff

 

[Stephen Ditmore]

How it works in practice: Designer buys several VPPs incuding the IMS VPP. Designer may calibrate his/her favorite (non IMS) VPP using real world data, creating an "in house" VPP. Designer runs candidate design through all the VPPs. The boats that do better according to the other VPPs than according to the IMS VPP are the ones that are built.

It's a fair point about a mimicing the characteristics of cruising designs. Lets say you've set out to develop a handicap rule, and you have data generated by racing racer/cruisers against flat-out racers. Those characteristics typical of racer/cruisers will be rewarded to compensate for the speed difference. If someone then comes along and builds a flat-out racer that mimics the parameters of a racer/cruiser (but with a lower radius of gyration because the weights are more centrally consolidated) that new boat will be underpenalized. For more discussion of rating rules see http://www.boatdesign.net/forums/showthread.php?t=3368 and http://www.boatdesign.net/forums/showthread.php?t=3618&page=4&pp=15

Having said all that, I still think the IMS VPP is a pretty good predictor of performance.

 

[interested]

Having said all that, I still think the IMS VPP is a pretty good predictor of performance.

So why is it necessary to have age allowances?

 

[Jeff H]

So why is it necessary to have age allowances?

Because there are tactical advantages to having a boat which is actually faster. The age allowance attempts to compensate for that tactical advantage which is one that you can't predict with a VPP program.

Jeff

 

[Wardi]

Surely then this same logic should be applied to any boat which is slower, not just older ones, so slower boats should progressively get more allowance to compensate!
It doesn't make sense!

How does this give confidence that IMS accurately predicts performance accross all designs when it seems from the evidence in this thread that it is only accurate for boats designed to the rule or are big ones with a tactical advantage??!

 

[ErikG]

Wardi!

You need to differentiate between IMS VPP results and the rating system IMS.
The IMS VPP is just one of the most widely used VPPS and was disigned by/for ISAF (I think). The results the IMS VPP gives are pretty good as far as I can judge wehen it comes to evaluating the speed of displacement yachts.

In IMS (handicapping system) the results are then used to even out the playing field. BUT as the IMS board discovered that recent built boats are built for the rule and most older ones aren't (at least not as much) they created the age allowance so that boats should be able to compete crew vs crew (not boat vs boat).

In reality it doesn't really work. It worked in a fashion until designers figured out how to optimize for the rule, and after that it mainly was/is ****** (pardon my french). As have all the handicapping systems before it.

The speed predicting the VPP does has NOTHING to do witht he age allowances and Wierd things that has to do with the rules.

Personally I don't know if the part that promotes tippy boats (old cruiser boats style) is in the VPP itself or is a part of the IMS handicapping system, but I bet someone here knows.

Personally I say:
Leave handicap sailing for the average Joe sailor, who owns a boat because he loves sailing and racing. Let the big boys play in Box-rule-racing where the fastest boat and crew wins! These boats will become obsolete ever so quickly and will then race handicap races with the rest of us (but without the pros onboard, and penalized by the handicapping system whaterver it's called.)

Proffesional sailing should not be handicapped, box rule or OD is the only way!

 

[Wardi]

Personally I say:
Leave handicap sailing for the average Joe sailor, who owns a boat because he loves sailing and racing. Let the big boys play in Box-rule-racing where the fastest boat and crew wins!

Erik, I agree with you 100%!.
It seems to me that the big guys are prepared to spend the money to go faster, so why not encourage them to spend it in a way that actually advances the art of yacht design by making fundamental improvements rather than just trying to optimise against a rule.

It is really a pity that so much money is put into Olympics, AC, One design and Offshore racing and yet so little is aimed at making "real" improvements which can be then be applied to all other classes. It is really only in the area of rigs, materials and construction techniques that we see any big benefits being passed on.

I am sure this is why development dinghy classes around the world are still very active and are seen as being at the forefront of new cutting edge developments. They do this on a shoestring budget by comparison and consistently come up with some amazing improvements. This is because they are not constrained with ratings, one design rules etc.

 

[water addict]

At the higher levels of handicap, the guy with the most money wins most of the time. IMS is no different than older rules. It's a bit more elegant than IOR and CCA were; it's a better model for predicting boat performance, but it still has flaws. And those flaws will be exploited- the folks with the most money can exploit the flaws more completely.