If you haven't been, here's a couple of pictures of the ferry taken in 2004


They (the ferry people) will not care about your bike and whether or not you strap it down.
The best and only things you need do are two:
1) Tie the front brake lever down some to keep the bike in place and stop any rolling back or forth.
2) Use a strap on the clutch side handlebar to keep the bike solid down on the kickstand.
Anything else is superfluous!
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