Built 8x8' Floating Dock in Barn - Now Need to Transport It to Site!

[PILOON]

I have made quite a few docks with drums and can say yours will float high and be very unstable at that size.
Better stability was 12 x 12 with 6 barrels with 2 being in the center.
Standing at any corner will cause a fair dip.

If it were me I'd add 4 or even 6 ea 4" lag bolts and washers at each corner to tie the sides to the 4 x 4 corner posts.