Step 1: Setup
I had a piece of C-section steel beam I had rescued from scrap, which I had used to load the bike into a van. It's easily strong enough, light enough to pick up, and nicely fits the bike tire. The edges are over an inch high and prevent the bike from slipping off sideways.
To use this on the boat, first I need to remove the safety lines. They are designed to easily unclip on the starboard bow (the bit shown in the photo). Then I adjust the dock lines to pull the bow against the dock and hold it securely (usually closer than shown here). The ramp rests on the coaming (wood rail) and is secured with a rope to a deck fitting. This stops it sliding off with the bike's weight on it. It needs to be lined up with a clear space behind to get the bike on. Well, actually, it doesn't, but it's easier that way.