Having just disassembled all of the various stainless bits from the bow of Harmonie for resealing, polishing, and inspection I can confirm that the axles for the anchor rollers are welded to the side plates. They pass through holes in the plates, and are then welded around the edges.
A bolt would have been so very much easier... Except for that detail, it is a nice, simple, robust design. Other than needing rebedding, polishing, and a few pieces of hardware that had corrosion issues, things looked great.
I know that there was at least one major redesign of the SM bow roller system after our boat was built, so yours might be different...
Hopefully in a week or two we'll have pictures of the "new and improved", or at the very least, newly shiny, bow. Water intrusion into the port side locker should be greatly reduced.
Fort Lauderdale, FL, USA
On the hard for another four days.