There's nothing you can do about losing posters that stop sailing and go onto something else. But, you can gain new members like the CSBB used to do.
But not anymore. The CSBB is isolated due to the format that results in an obscure location on SBO; the format can be mended to connect to the main forums. When was the last time we saw a new face in here?
Thanks for the compliment. It's easier in fact to do a photo/journal piece on the the other forums. I don't need a remote photo server of my own and can upload photos right on the same page. Looking at the first posts on Trailer Sailer, someone has knit photos and text having to do with paint.
I've used the newer forums for long enough so I don't miss the threaded capability. The one thing I do like about this format is that you don't have the cut and paste ability. Too many on the main sailing forums. (SBO, Sailnet, Cruising Anarchy, Woodenboat), abuse the ease that you can barf text all over the page, then add their two words at the bottom. The new forums are not perfect and in fact, I believe they could improve to increase traffic.
But to not have moved forward with the tech, we're down to our smallest participation, and the trend will obviously continue.