My thinking is it would be next to impossible to get a gsd back on the kayak unless your in water where you are able to stand. I have an ocean kayak and wouldn't bring a gsd out on it, but that's me.
Nigel. I agree with Huntergreen.
My background is in water safety and it’s hard for me not to throw my 2 cents in when people ask on this forum about kayaking, paddle boarding or canoeing with their dogs (especially large dogs like GSDs).
Aside from the “holes” it sounds like you have an ideal place for practicing kayaking with your dog. You in a life vest. Your dog in a life vest.
I don’t think it’s safe for you or anyone else to venture into deep open water with your dog on any of the above mentioned boats or paddle board.
The process of drowning begins with only a few good gulps of water then add panic to that and about 3 to 5 minutes...
Then throw a panicked dog into that mix.
Adults can drown in just a few minutes.
Even with life vests, It’s a recipe for disaster.
And lastly I’m going to write something that will be unpopular to some GSD owners. GSDs are not built for swimming.
They are very muscular. Their coat does not deflect water it sops water up like a sponge. A wet coat is heavy to carry. That becomes a lot to drag through the water.
GSDs can be good swimmers. But It takes a lot of energy and strength to pull that weight through water.
Again it’s my two cents.