The issue with how jibs are rated is a serious one and has been taken up with the SCHRS international committee, so your concern is not falling on deaf ears. One note on this subject is jib area is working for you upwind and downwind, so it is possibly twice as effective per area unit of spinnaker. That is unlikely really the case but it is a possible explanation as to where the number is coming from.
The weight penalty is a peculiar one, we will dig into that as well. I will say that at the top of the F18 fleet, 25 lbs easily results in the 2% change noted. There is a very detailed paper regarding this that was recently published including the statistics to support this.
Unfortunately at the moment there are a number of different F16 ratings (every manufacturer has one that isn't just the published F16 rating). I'm not quite sure what the solution to this is. If you have measured weights for the Isotope fleet and can generate an average, that would be more than fair I believe for the SCHRS rating.
I was trying to be idealistic, because our local fleet did as you are suggesting for 2 years and it doesn't result in a 'fair' rating per SCHRS (see the jib vs. spinnaker area issue above). If your fleet is okay with this, then go for it. I just kindly suggest setting up a fleet SCHRS focal point that can generate ratings for the frankenboats given basic input data for future events. That is what we do locally-I run the ratings as I volunteered, it is fast for me, and my number doesn't change (F18's have been 1.000 for a while now). I will kindly generate numbers for other boats if they can provide the input data, or if I am at an event and not fixing the bottom of my daggerboards, I will help measure. I will see what I can do to become an approved measurer.
Last edited by samc99us; 02/14/18 04:40 PM.