Spent a little time with our American cousins a few years ago being flown around in their Chinooks from their floaty things. The blade fold system was used regularly but being a manual system it looked to be a bit of a faff when windy.
The USN & USMC use the CH-46 Sea Knight, not the CH-47 Chinook.
Yes, they are very similar... but the CH-46 is smaller and specifically designed for ship-board use.
The CH-46 does have power blade-folding. If they were manually folding them, perhaps the system wasn't working on those particular aircraft.
UH-46 Sea Knight
