We've moved them from one dock to another and from one side of the dock to another with jet skis without covering the holes. Never a problem. But we are in a protected cove with no wave action.

Not an expert but think the B tanks were longer, there is 3 10K lifts on my row of slips which are the next gen after the B's. All of them are 23 feet long and I think 32 inch in diameter, think they are called the LG series. The newer UL series which are poly tanks have different dimensions. My slip is 12 by 28 feet and a local installer said it would fit doing a back in. Will be close and since my 27PC has a short swim deck this will help. Only reason to ask about how heavy they are, is if what I might need to move them. I have a winch on the front of the truck and a receiver under to use it to pull up on the trailer.