Hello Nanaimo (?),
we have taken a few ferries left and right in Europe.
Experiences were mixed : SOME ferries provide special attachment buckles in their floors, and heavy duty straps with... eh... I don't know how you call these, but they make a "crack-crack" sound and can be tied VERY tight -> the ones they use on trucks. These methods were used on ferries to and from the continent to the UK. The boatsmen secured the bikes in the presence of the bikers, and asked specifically if this was o.k. with the biker.
I PRESUME they will always do this on storm-prone journeys such as the North Sea.
All other ferries (Italy (Genova) to Tunesia and back / Italy (Venice) to Greece (Igoumenitsa) / Turkey (Cesme) to Italy (Ancona) / Finland (Helsinki) to Estonia (Tallinn)) didn't have ANYthing to secure bikes or a just few short bits of thick rope... To our frustration and surprise of course.
We (luckily) always have good and long straps with us - to tighten our luggage rolls and to tow a bike in case of breakdowns in the countryside.
We park the bikes on the left side (in the direction you enter the boat), close to metal bars which you find all over on the side walls of boats.
We then park the bikes on the sidestand and in first gear -> because --without special attachment buckles in the floor-- a bike is more stable on 3 "standing points" then on the 2 of the "double stand" (?) plus 1 front OR rear wheel -> the triangle is larger.
Then we attach our straps on 2 or rather 3 points : front, rear and middle of the bike, on different heights as to provide as much stability as possible, and to as wide as possible attachment possibilities in the side walls of the boats.
To protect the bikes from damage-through-rubbing (by the straps), we use a few newspapers (preferably yesterday's). We also add some sort of padding between the bike and the boat wall - another newspaper, or just a reasonable distance.
We also turn the mirrors inward - they tend to stick out more.
That has always worked fine, even with rough sea.
We also undo the straps before entering a harbor, for the boats can make a few rough movements when docking -> we then sit on our bikes, or move them away from the side a bit and hold them tight. Then we're ready for the inhaling the fumes of all the other vehicles starting their engines long before they can ride off :-)
Wish you healthy and undamaged crossings in Europe !
Iris and Trui
2 belgian women, often travelling on motorbikes (now on DR650SE's)
2nd overland from home to Northern India and back, April-October 2002