I did a 7 day liveaboard out of Sharm in February 2011. I would strongly recommend taking at least a 5mm wetsuit. The sea temperature is OK 22+ however the prevailing wind seemed to be a northerly, which had a significant chilling effect. Remember also that some dive sites will be a distance from the anchorage and if the mother ship has a full complement of divers, you might be sitting in the RIB for some time after your dive, waiting for the divers who have better air economy than you! Overall, I thoroughly enjoyed the week's diving which was full on. An additional benefit is the lack of other day boats and liveaboards which meant that you had the dive sites to yourselves - we were the only boat at the Thistlegorm, where we did an afternoon dive, followed by a night dive and then a breakfast dive the next morning.