I've heard occasionally of people managing to get passage on yachts and other boats and I would like to try this. How can I find a boat to ride on and what would be the likely conditions of carriage?
Your best bet is to sign up to a crew-finding website like findacrew.net. A friend who cycled from London to New Zealand did this for the ocean parts - hung out in port and used the site.
What was observed is that there are different levels of opportunities. Some berths require that you have licenses or sailing experience, or a particular skill (eg cooking), while others will take anyone.
The alternative, if you have the time (like she did) is to hang out by the docks and ask people - even if they aren't taking anyone, they may have heard of someone who is. Often it's just spur of the moment opportunity.