Yep, I did a transfer like this... Not that bad of weather, but took a RHIB from one ship to another, about 10-12' swell... I also did a helo transfer too.
Three years ago out here we hit a nasty storm and got beat up for 3 days straight... That was 90+ winds and 50-60' seas... Nothing like seeing blue water come over the side of a ship that has 40' of freeboard... :eeps