Well, yes …. and no. (I'm Irish … I can get away with that!) I went off to the hardware (think building & garden supply super store) store because that's where the ship told us to go. I waited for a cold day, wore both pairs of socks and staggered forth. I made the mistake of buying a size that I could get off by pulling at them. I didn't realise you actually toe them off with with the tip of your shoe to the heel of the other. So my boots were too big for my feet and too tall for my short little legs. I swapped them on the boat with one of the many similar discards. I left my boots for posterity on the ship when I left.
Long and short… yes, I'd order a bigger size. You could always resort to the old fashioned trick of drawing an outline around your multi-socked tootsies on a piece of stiffish paper and then comparing that to the actual size of some real gumboots. Some internet sizing charts give an inch to shoe size chart. I don't know how US men's shoe sizes work. Come to that, I don't know how Aussie ones work either! If you are going to hire them and collect them onboard the ship, I bet you'd be able to change them… I bet people order the wrong size all the time. I think I read that somewhere on these forum pages. Probably back a bit. You could try searching by "boot exchange" or something similar. I know the search function isn't flash … you have to think of a unique phrase or word before you can expect any hits.
The denser the knit of the wool sock the better they work … at keep you warm … and dry. The very best socks are made from a mix of pure merino wool and possum fur. Yes, that's right. Made in New Zealand … sensibly from long ago imported Aussie possums (they are a protected species here) which are a terrible pest in NZ.
This is one company that sells them … in NZ … They ship and the US$ against the NZ$ rate is good in your favour. This type of textile is excellent for hats, too.
Jan, did the HEAVY wool socks effect the size of the boot you wore? Did you go a size up?
I can always count on folks in here to help with the subtleties of the trips.