Hi Rob, IMHO the most practical size for most boating activities is still 7x50. In that size the Fujinon Polaris series can be obtained with or without a built-in compass. It is a heavy (1.4Kilos), relatively expensive, waterproof, rugged design with (nearly) flat field, long eye relief and very bright image. That company also makes a lighter version, also available with a built-in compass called the Oceanic CX, it lacks some of the best features of the Polaris, but is much more economical. I own both, and while my sailing is MUCH less ambitious than your friends, I find either of them most satisfactory. That said, there are a lot of other waterproof 7x50's on the market that would do a good job, I'm sure.
I have no connection with the Fujinon company other than that of a satisfied customer!
Regards, John