Pretty much all our beginner boards use a "power box" connection that looks like this, with a single screw:
This can most easily be confused with the tuttle, which takes two screws:
We also have one board (the Bic Core) that takes a trim box fin:
We have a chart showing screw lengths for the various boards (PDF here). These are only guidelines, and may vary slightly depending on the fin. In particular, some of our advanced boards have a Deep Tuttle box which can also use Tuttle fins, but the screw lengths will differ:
Always use washers when attaching a fin, both a metal and rubber washer, with the rubber the only part that touches the board. Otherwise, the metal will eat into the board:
and make the hole too big:
Types of Fins
by Geoff Moore, 2008.
Fin type is determined by the kind of sailing, not the type of waterway (lake, river, ocean, bay, etc.).
Vertical fins are mainly for maximum efficiency and pointing upwind. The higher the aspect ratio (length / width) the more efficient the fin. Such fins tend to be touchy and respond to foot movements, making the board handling more difficult.
Swept fins gently curve backward, and dampen out the touchiness of the fin-board interaction. Most freeride / recreational sailors will be best off with one of these fins, and it should be a staple fin for the days when there are no weeds.
Wave fins curve back dramatically, and make the board much more maneuverable. Because they are "low" aspect ratio, they are slower, don't point upwind as well, but they are more resistant to spin-out and can carve harder turns.
The stiffness of the fin dramatically affect the way and how well it performs, for all these types of fins. If you are buying a fin, I would strongly recommend G-10 construction, and CNC milled (i.e., the blank was shaped by a computer controlled robotic grinder).
Weed fins spill weeds. There are fins for light weed, and for heavy weeds (steeper angle back). For Cayuga, you need a heavy weed fin. There are also weed-wave fins, that work well with some boards and for weedy wave sailing sites.
Personally, I like True Ames fins more than other brands. I've broken other fins, they have failed to perform well, but I've never had a bad True Ames fin: http://www.trueames.com/pages/windsurf
Follow the link below to find the Fox-True Ames light weed fin, which is my favorite fin that I've ever owned of any kind. It is very fast. They are sold on the Outer Banks, at the Fox shop in Buxton, NC. I think you can order one online, as well.
Curtis also makes nice "pointer" weed fins, and they seem to be more popular than True Ames. Don't know if that is a distributor thing or what.