True. I actually knew that the ascent line would be a better place to hang on, but was having trouble applying it. I was the first of a group of six who ascended at the same time, and someone else got the spots on the ascent line that were above 20 feet and below the bar. :-( The captain said that we'd better not get away from the line, and if we did get blown off, we should deploy our SMBs and be prepared to wait at least an hour for them to come get us. So, I was a little overly careful to stay close to the hang bar. What worked reasonably well was keeping a very light grip on the bar, more for reference, and letting it go when it moved a lot, but I was pretty much finning the entire time. It wasn't scary or anything, but it was definitely work. Practice will definitely help.
It was a dedicated dive boat a couple hours off of the North Carolina coast, in the gulf stream, so it's a strong current at the surface. Waves were averaging about 3 feet; I think they'll run trips in up to 4-foot waves. The ascent line ran down from the bow, with the current flowing from bow to stern. The hang bar was directly below the boat, running from the ascent line toward the stern. The procedure was to finish your safety stop at the hang bar, then swim well below the propeller and ladder to the tag line, at least 10 feet behind the ladder. Surface, wait far enough back on the tag line that nobody can fall on you, and swim/pull your way back to the ladder along the tag line when it's your turn to get on the ladder. Wait 5 feet back until the crew says to go for it, then get up the ladder (a fins-on ladder) as quickly as possible. We ended up a good 20 feet or so behind the ladder on the tag line, so that was the swim back, and getting up the ladder with fins on was tough. They do exits with fins on and regulator in so you can swim back to the boat (or at least catch the tag line) if you fall off of the ladder. 2 or 3 people fell off each time we finished a dive. Exciting stuff, heh.