Do you need em'? Yup, if there is a lot of tide, strong storms or wakes, yup.
Example. In Chincoteague, as much as we like the town dock, there are few "no wake" signs, no posted speed limit, and you get rocked now and then by small but speedy boats. There is also a good tide range. and a 3 knot tidal velocity. The picture was taken only a few hours into their first use and we've already worn a noticable grove. There was always a small pile of saw dust resting on the board.
Example. We got hit beam-on by a powerful storm while in Rockhall, tied to a bulkhead. Fortunately, we had a spring line and good breast lines, and our fender board. I've had fenders pop out in these circumstances, and the pounding on the pilings is scary. All we felt this time was some gentle swaying, even as the hail blew horizontally.
Note the grove in the middle, only a few hours old on a calm day. Yes, it should be centered up on the rub rail; we moved it up later. It seems fenders are always placed when dead tired from a long run, in this case about 85 miles. Lucky we got it deployed at all.
Very simple to make from a scrap of 2x6 treated lumber. Any thinner and it will wear through rather quickly. Forget paint.
- Pick a length. Too short, you can shift off the piling. Too long it will be weaker and harder to store. Don't underestimate the side force of a strong wind and chop; 500 pounds is common and 1,000 pounds is possible. Thus, I wanted an unsupported span (the part between the fenders) of only a few feet. Ours is ~ 4 1/2 feet overall and I'm happy with it.
- Drill holes for the line that restrains the fenders horizontally. Our are 5/16-inch polyester line, though some suggest bungee cord. I trust line more. Counter bore the holes so that the stop knots are recessed (reduce wear and reduce snags).
- Drill vertically through the board (3/8-inch to take a 5/16-inch line) to take the time that suspends the board (loop on one end, stop-knot on the other). This takes a long bit, which I was lucky to have.
I've seen 2 other variations worthy of note:
- Fenders on both sides of the board. Sometimes, depending on the dock configuration, it can make sense. In this case, the dock had some horizontal boards that would catch the board as the tide changed, and vertical pilings, that would slide between fenders. A bad dock design.
- Perminant fender boards. Some boaters will hang these on poorly designed docks, to make a smooth surface for their fenders. It can work.
- Fenders on the wrong side, Yup, I've seen boats where the wood rubbed on the hull. Just not thinking.