We did a practice jump first. As you can see, it took a little encouragement to get him to jump. It's against Dock Dogs rules, but otherwise it would have been very tempting to give him a nudge! Fortunately, he eventually decided to go on his own, and after that the difficulty was getting him out of the water.
We got two "competition" jumps. I put him in a sit-stay just a little ways back from the edge. (I was actually just thrilled that he did that, with all of the distraction!) When I released him he ran up to the edge really well, but both times he paused for just half a second at the end of the dock before jumping. He went 4'6" the first time, and 6'6" the second time; not as far as the Labs were going certainly, but still very respectable, I thought, considering he was half the size and it was his first time.
As I said, the real challenge was getting him out of the water. Once he was in, all he wanted to do was go for a swim! Between me, Sweet Husband and the Water Wrangler we were able to splash enough to attract him and grab his collar.
Moe really had a lot of fun, and so did we. I've uploaded a few more pictures here.