Ana
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Really? 6 foot waves? May have appeared that way but I am pretty sure you would not get in the water with 6 foot waves...
But that might just be me...
To be fair vertical distances are difficult to estimate.
Less consider the rest of the post.. 1 vessel, 1 captain, 1 DM (or deckhand) and 4 divers.
I think the vessel could be a little as +/- 15foot, and be ok with the Coast Guard. 3foot waves on that small craft will make for a very sporty transit, as well as boarding. I can see how it would feel like 6', even very large values of each of those 6 feet.