OK, I need some help here. I just bought a used 16, after being out of the sailing game for 15 years. I have no problem getting it all rigged up, but it has a contraption on it that I am unfamiliar with. Can anyone identify the purpose of this collar which sits in the mast slot, and T-bar which fits inside it? The T-bar is about 24" long, and extends beyond the base of the mast about ~12" when attached...(assuming it attaches as I have shown?

The best I can come up with is that it is used as an aid in supporting the mast in the forward cradle on the trailer? But that would cause the mast to extend far off the rear of the trailer?