As a retired optometrist and long-time cat sailor, I smiled a lot reading this thread. You guys have hit most of the points. Just a couple thoughts:

1. Progressives work well for sailing. There is a power for every distance. You are not just reading your start watch (near vision) and looking for A-mark (distance vision). You are also checking course and flag stickers, cleats and lines on the tramp that are at arm's length or longer (intermediate vision). As you get into your 50's and 60's the lined bifocals are noticeably deficient at this distance (the reason trifocals, and later, progressives were invented).

Both styles take some time to get used to. More so with your first pair, less so on successive prescriptions.

2. For progressives, have both your dress eyewear and sunglasses set at the same position. Going from one to the other will then be effortless.

3. Mike's solution for lined bifocals (a smaller and lower near segment) is a good one, if you can't get used to the standard height when sailing. I have also used it for golfers who had trouble seeing the ball at address. But you need to realize it becomes a single-purpose pair of glasses.

4. Consider polarized sunglass lenses (applies to single vision, as well as progressive wearers). More expensive, but they significantly cancel most of the glare off the water surface, so you don't have a headache from the glare at the end of the afternoon. Transition tints will darken everything (water detail and surface glare) but not cancel the glare like polarized lenses. One drawback to note: some instruments have cover glasses that can polarize light exactly opposite what your polarized lenses are set up to do, blacking out the instrument until you tilt your head sideways 45 degrees. I notice it most when signing on some of the older electronic charge card displays.

5. Wear croakies with your eyewear. They have saved mine numerous times.

6. A broad brimmed hat will not only shade your eyes (more comfort), but also reduce some of the rear lens surface reflections that can decrease clarity by 4%.