Your blog can be about anything that you enjoy, not just sailing. If you have a pet rock collection, that might be the topic you want to blog about. There might not be a huge audience, but what the heck, you enjoy that so go for it. Mix it up with a few of your life experiences and you have got something to say to the world.
They are many free platforms out there that will get you started. I use blogger.com because its free and there is no limit to what you can do out there. Blogger is owned by Google and they make it very simple to post and edit. I try to post 2-4 times a week to keep readers coming back. I donot have a hugely popular blog but over the years have well over 500k hits. Not bad. You can also sign up with ads and make a few bucks if you wish. So get out there and make it happen. Your blog is not going to write itself!