[Gerry Zagorski]

No first hand experience but saw this chart online and it says to add 6 inches to shaft length for rough water so it looks to me like your 87 inch shaft should suffice. However, thinking this through further you'd need to add another 36 - 48 inches to the numbers in this chart to allow for the bow rise in 3 to 4 foot seas and still keep your prop in the water.

For what it's worth, I just spoke to a friend who has the 26 Sea Hunt gamefish and he just had one professionally installed over the winter and it's the 87 inch shaft. He hasn't run it yet so hard to say what it will do in 3 to 4 foot seas. I would imagine the longer the better but I doubt even the 100 inch shaft will be effective in 3 to 4 foot seas. ...

Hope this helps