I`m pretty sure my ratio is 1.58, tried a few 4 blades and planning was horrible to impossible, it really only seems to like the 5 blade with alot of cupping. I`m 1.5" below hull right now, Id love to take the 2" extensions back out get that sweet rooster back but I`m not sure how she`d plane. A 1" extension would probably work perfect. Some things to try in the future.