I looked up both words in my Gaelic dictionary and it gave 'curach' for both...but I see Islay Canoe club use 'curachan' in their title...'Buidheann Churachan Ile'...
Kayak is a 'canoe' which is fully enclosed and you paddle with a two-ended paddle...
Canoe is what most people know an an open or Canadian canoe...you use a one-ended paddle...
I've asked my Gaelic Teacher and a few other native speakers I know and none seem to know a word for 'kayak' and say they would use 'curach' for both...
So, if I wanted to say Kayak Scotland or Canoe Scotland (being the name of something), not a verb, would it be acceptable to say 'Curach Alba' or 'Curachan Alba'?

...is 'curachan' a verb? i.e. 'to kayak' as supposed to 'a kayak'?
Please bare with me, I'm only a relatively new learner!