I agree it is essential for tracking in a slalom course. It is worthwhile if sharp turns are needed as mentioned above. However I found that the added tracking ability can be excessive when you happen to encounter a wave and do not land straight. Then it lurched to the side and I did not liked it. Since my professional skiing days were over, when the fin broke I was happy with the new conditions and never replaced it for the next 30 years. This is my personal view. You decide depending on your intended usage. I also drove J. Crafts with square chine and did not like the flat, g-force turns it exhibited. I preferred the dipping turns of the round chined Dyne. I formed a Show and competitive skiing club in the early 70's and my Dyne with twin 140HP Johnson was awesome. (Had twin mercs and Chryslers before)
I appreciate your input, however for the benefit of new owners I feel inclined to say that I have run mine 25 years with the fin with no ill effects. And, 2mercs' father bought his boat new and added two additional inboard stye dagger fins. One behind and one in front of the dyne fin which produced a very good tracking boat. He has never mentioned an issue, so I don't think a new owner should fear driving with the fin. I have been tempted to add a fin in front of the dyne fin, but i use my boat so little now that it would not be worth it. Plus I no longer drive around the boats. Additional fin area should produce a flatter turning boat which would be a benefit during around the boat pulls. I should qualify this by saying that my boat is a hard core ski boat and is only used for towing. jim
I know this is an old thread but if someone is currently researching I can tell you I got mine from either Ski Supreme or Mastercraft. It might be worth trying any current ski boat manufacturer.
I have a 1974 18Ft. I did not like the skeg. Yes, if is paramount on a slalom course but If you jump a wave and land not exactly straight it will give you unnerving G forces in trying to keep the boat straight. I prefer it without.
It’s true the more fin you have the more straight line control you have. The other function is to keep the roll down, the boat will roll up on its side in turns without it and if you are running twins the outside motor will breech. Daniel