Not only are these threads a nice way to look back to good memories, it also forces some interesting after thoughts, I think !
Exile me to Cruising Anarchy, but the notion of purposefully degrading your boat's handling or performance for a small ratings advantage seems ... unthinkable.
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IOR was just a compromise of two handicap rules, rules which were meant to have different boats competing together in the fairest way.
Measurements were over simplified to allow local and
cheap measurers. So: it worked in getting many people into racing.
Re-reading all this, It strikes me (wrongly ?) that the succesful introduction of level-rating classes may have changed the game:
My feeling is that, before we had to go to one or the other level-rating class to get good racing, owners and crews were looking for a nice boat (obviously rule typeformed) and tweak it in details (such as sailplan) for the best rating/performance ratio, in the most common weather-conditions.
Later in the ton-cups heydays the game had changed, one would be looking to have a boat designed to improved polars over the previous winner, which quite logically ended rating higher than level, then tweak it through loopholes to fit into the target rating.
It was not so much "degrading your boat's handling or performance for a small ratings advantage" but retaining the performance while decreasing the rating through ugliness. First measurement .4 or 5 of a foot above level, micro-baloon her down to class without loosing speed. Introduce the distortion into next year's original drawing then do it again.
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Equally wrong, may be, were the early actions, like bringing a boat up to level by taking genoa-penalty (over 150% LPG). Closer in speed in their level-class the boats were less nice to sail and ... less competitive in pure handicap races, the Holland Nic 33 is a good exemple - much more effective in handicap .2 or 3 of a foot below 3/4 ton. Not as "visible" as ugly distortions but equally deceiptive IMHO.
After going through this, we had, in our little racing community, a "light brigade"- no rating-tricks - boat designed and built without any "target-rating". It was a huge success in handicap races, with a Channel Race win overall (in an Adm-cup year !) and a Fastnet class win.
She fell into oblivion, while the "tonner" the rest of our group of sailors sailed in the same year remains a benchmark despite a lesser success list. She had duly beated all the tonners but ... totally escaped front pages, nobody was interested.
This was not what people were looking for.
At the time, I chose to crew on the tonner, not the handicap racer, much more "in" and attractive probably. Reality has claimed its dues: I have never won the Fastnet

Is not all this how things go in life.