One month ago, I took a rented Harley Road Glide (800 lbs, give or take) on a tour of the Atlantic Provinces in Canada, which involved 5 ferry crossings, between 45 minutes and 7 hours each.
I'm assuming that things will be about the same in your area. The Canadian Ferries provide tie down points built into the deck; when they position you, try to look for those.
They also provide heavy tie down straps, although my first time was an "adventure" - trying to figure out how THEIR straps worked, with the utter chaos of loading going on! I don't think it would hurt to bring a few of your own, just for extra security, if you have them. If there are a lot of motorcycles,it can be a bit of a scramble for enough tie-down straps to make everyone happy. If you bring your own, bring good ones, that won't slip when locked down.
All the "boat people" (i.e. employees on the ferry) say that the ferries don't (hopefully) go "bump" front to back (unless you run into an Ocean Liner? ;-)); I was amazed at how smooth the dockings typically are- talented pilots, I'd say. But,they do rock left to right, with the wave action (pardon me, that's port to starboard? ha ha) So.....
They always recommend leaving the bike on the sidestand- I believe that's a good idea, since I watched a Canadian couple almost lose their BMW K1200LT off the center stand.
The issue the not ALL ferry employeesget is that, since it's on the SIDESTAND, you need to have your anchor points BEHIND the bike (a foot or two), to keep it from rolling forward (off the stand). If you do that, you won't have any problems.
If enough straps are available, I'd recommend anchoring to those rear points on both sides (from crash bar, or frame member), which is the normal way to do it, and, if possible, compressing the bike over the saddle, and doing the same.
My bike was a rental, and I paid for the full collision damage waiver, so I wasn't particularly sweating it, but if you follow the above, your machine will arrive safe and happy.
Also, keep in mind that on most ferries, once you leave the car deck, you can't go back, so it pays to plan ahead on what you want to take up to the upper decks with you. The ferries I was on were overly heated, in my opinion, so be the third trip I learned to bring cooler clothes to change into, and I was much happier. In my case, security was not a problem; I left my $450 helmet on the bike 3 or 4 times.
My best to you- have a great trip! I'll try not to be jealous! :waving: