Made some further inquiries, and it happens that there's a way to move to PHPBB, which is one of the most popular boards on the net.
It's a very long procedure: set up an SMF forum system, import all users and messages from this forum. Then set up a PHPBB forum system, and import the SMF data into it.
I've already done all that, but for some obscure reason, I've lost many posts from the 'Shipbuilding' forum, so I'll have to try and import that again.
I first started with the current system, because it doesn't need a database, but I guess I'll have to move on. I guess I'll be also switching the whole Wyatt site to a Wordpress system, which is incredible, and free...