You didn't state what size dock you have in mind, but even a small one might act like more of a diving board rather than a stable platform, given the construction details you've listed here. I'm thinking the supports for such a platform would need to be massive, if any hope of rigidity is to be realized.

Unless you're going to add posts or piers to support the free end?

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.