There's websites for both places meaford.com and thornbury.ca that are good places to start. There are marinas
in both places I think they are municipal, also one in Owen Sound.
I was born in that area though on the other side of Owen Sound and spent my first 19 years there, I cannot imagine living on a boat in winter up there anywhere in Bruce, Grey or Simcoe counties. Don't want to dampen your plans but the snowfall is incredible and the howling winds off Lake Huron and G. Bay are just unreal in winter. Winter storms pick up massive moisture when the lakes are open and they pretty much always are open now and they dump it when they hit land. Have pictures from when I was a kid standing on the snowbanks head
even with the utility wires. Seems like all we ever did was shovel snow. Even now with global warming and all it is still pretty nasty. They don't call it the snow belt for no reason.