The phrase "how not to buy a cruising boat" is a noun phrase that refers to the act of learning from the mistakes of others to avoid making similar mistakes when purchasing a cruising boat. For example, a common mistake is buying a boat that is too large or too small for their needs.
It is important to learn from the mistakes of others so that you can avoid making similar mistakes yourself. There are many benefits to doing this, including saving time and money, avoiding frustration, and making better decisions. One key historical development that has made it easier to learn from the mistakes of others is the internet. Today, you can easily find information about the experiences of others online, which can help you to make better decisions about your own life.