For some reason, some additional comments on ORC aren’t appearing. I’ll just post them here for everyone to see Dave Lynch further question JAM’s rating and US Sailing’s reponse.
From Dave Lynch, in response to US Sailing’s response to his earlier questions regarding Jam’s rating.
Interesting, and thanks for the sleuthing. There were a couple of items I hadn’t noticed, and it’s helpful. Here are a few thoughts in return:
Difference in 2-blade or 3-blade feathering props. One would think that a 3-blade feathering prop would cause more drag than a 2-blade. In contrast the change was coincident with the change in rating from 540 to 533.
Similarly, one would think a roller furling headsail would be less efficient, and thus slower…that change also happened coincident with the faster rating in 2021 compared to 2017.
The issue of crew weight is a bit hard to evaluate. Given the size of the boat and the need for the boat to be sailed well it’s pretty reasonable to assume the boat is fully crewed for most races. In both 2017 and 2021 the maximum crew weight was 907kg, while in 2023 it was 850kg. Assuming weight of an average crew is 185lbs (84.1kgs) that 57kg (a single smaller crewperson) doesn’t seem like much…especially on a boat that displaces 36,000 lbs.
Changes in D/L ration: from 111 (2017 w/ the aluminum rig) to 106.6 (2023 w/ the carbon rig). Not much of a change. Even less of a difference from 2021 (107.7).
Considering how small the changes are from year to year, and even considering the potential of additive effects, I’m still finding it hard to understand how they can add up to an 18spm change in performance.
And US Sailing’s response to David’s additional concerns:
A 2 bladed feathering and a 3 bladed folding prop are very differently treated. In absolutes the changes are small but lots of small changes do lead to large changes. If I mis-typed it as 3 bladed feathering that is my mistake, the current prop is listed as 3 bladed FOLDING.
Yes, furling will be slower than changing jibs, Jam is now rated as changing jibs having previously been rated with furling jibs. They probably should have been rated this way all along.
None of the noted items aside from possibly the rig composition which in default values mean a carbon rig will have a lighter weight and lower CG had a large individual impact on the rating.
The list was more to point out that the inputs for the boat actually were not the same so it’s a little bit of an apples to pears comparison but not as bad a comparing apples to chickens.
There are always efforts to improve the science and the VPP. This is ongoing work by a group of very smart people. Here is the list of those involved with the ITC (International Technical Committee) being those who work directly on the VPP https://orc.org/index.asp?id=62. This is done proactively versus sailors having to protest ratings as is the policy in other rating systems. As the pool of boats being rated has grown so has the work by the ITC to be sure the rule is fairly rating all boats. There are some types of boats which are rare outside of North America (ULDBs) and there has been a directed effort to make sure these boats are accurately and fairly rated by ORC as their numbers have grown in the database and more performance data has become available. Same for relatively wide boats for their length such as Class 40s.
Kurt grew up racing and cruising in the Midwest, and has raced Lasers since the late 1970s. Currently he is a broker at Swiftsure Yachts. He has been Assistant Editor at Sailing Magazine and a short stint as Editor of Northwest Yachting. Through Meadow Point Publishing he handles various marketing duties for smaller local companies. He currently is partners on a C&C 36 which he cruises throughout the Northwest. He’s married to the amazing Abby and is father to Ian and Gabe.
I don’t know if this even matters and everyone knows but me, but our own Chris Tutmark is now Head Measurer for US Sailing.
Yes, he’s been active on the prior post. Thanks for writing in.