I fitted the 'White Collar' Deck Ring to Aero 1141 late last year.
I didn't clean-up or make good the existing wear on the gel coat before fitting it.
Prior to fitting I had been using 250 uM ptfe 'Friction Tape' on my masts collars; doing this greatly reduced the rate of wear on the gel coat, but they did have to be inspected & replaced regularly; about annually.
I had just replaced the whole, 9, 7, 5, set when the new deck ring arrived.
As a precaution I kept the Friction Tape on the collars until:
Dave Rickard ruled use of a similar Laser Tape to be out of class.
I capsized the 7 on launching. When righted the inboard end of the boom
discharged a load of sand and mud onto the deck straight down into the mast
tube. That totally ruined the tape in just one day's sailing.
As Dave R has commented.
And I noticed the 9 mast had substantially greater resistance to turning,
i.e. gybing in light wind the boom wasn't going right across.
My 9 collar would seem to be slightly larger o/d than the 7 & 5.
The tape has been off for some 4-5 months now; during which all 3 rigs have been sailed, extensively.
The 9 mast 'groans' under pressure.
There are now scratch marks on the inside face of the deck ring, and around the full depth of all masts collars; so clearly the gelcoat is still being rubbed.
However:-
There is still a lip, < 1mm, about the thickness of my fingernail, all around the lower inside edge of the deck ring and the gelcoat lining the tube.
So any scratching of collars and gelcoat below the level of the deck ring is contained.
When I checked, coincident with Richard Bentley & Marleckin's comments of mid July, I found what appeared to be clear evidence of further gel coat abrasion in the form of a ring around the gelcoat corresponding to the lower part of the mast collar.
I cleaned the boat, including the mast tube.
The ring disappeared, turned out it was the fine material from collar on deck ring abrasion deposited on the gelcoat, and until cleaned looking for all the world like gelcoat wear!!
If you see this I suggest you 1'st clean the mast tube.
At the time of fitting the deck ring I took photographs of the mast tube. I would now have to take some more and compare in order to be certain that the gelcoat is still wearing; albeit if that is the case then I am certain at a much slower rate than without it!!
I hope this helps.