4ft is probably adequate, I previously had a 4ft pole for mine before it blew away towing a boat, and it worked well. But when I made this one which is closer to 7ft tall I definitely noticed a huge difference in the visibility of my float.
Im not so much concerned with its ability to rise above larger waves as I don't beach dive when its rough. But even in calm or roller seas I noticed that the taller flag waves and moves significantly more and is easier to see off off a tall bow due to the extra long flag pole.The movements of the board are amplified on the long pole into a constant tall flag waving even on calmer days.
Ive had enough close calls to know that a 5ft flag on a 10ft pole isn't enough in some cases, and I still rely first on my eyes and ears to keep me out of trouble.
But I do think my giant double flag did enough for my floats visibility that Id always like a flag that tall. But for all that the banks board offers over a boogey board I may need to suck it up.







