I'll take a guess at some dates...

The original builder, Herb Stewart of HMS Marine used some stout Kenyon
spars on at least some of HMS18 hull #1-71 built between 1970 and 1978.
Herb quit building the HMS-18 in 1978,

Joe Edwards bought HMS Marine from Herb Stewart in 1978. He resumed
production of the HMS-18, renaming it the Potter 19, in 1981 or.1982. He
started with hull number 200 in 1981 or 2.

By 1985 (and probably a lot earlier, I just don't know for sure), Edwards
was using a Dwyer DM6 mast, with a weight of 1.55 pounds per linear foot
(bare extrusion).

In about 1991, Edwards switched to the DM5-style mast extrusion, with a
weight of 1.11 pounds per linear foot.

The P19 mast is about 22 feet long, so the difference in weight between the
two is a little less than 10 pounds (not counting the heavier mast head
cranes found on the DM6 masts),

The DM6 doesn't feel that much heavier to carry around by itself (I've
lifted both masts), but it sure does seem considerably heavier during mast
raising -- when it's acting as a 22' lever arm pivoting around the mast
step.

Fair winds, Judy B
Commodore Emeritus, Potter Yachters of Northern California
1985 West Wight Potter 19 #266, Redwing
Danville/SF Bay, CA
Potter Yachters website at http://potter-yachters.org/
Judy B's Potter Website at http://www.blumhorst.com/potterpages/

Re-commissioning Bijou, a 1977 Catalina-27 Tall Rig, hull #3459 - currently
being 100% stripped and refit with all new systems.
Sailing San Francisco Bay Area
Visit Bijou’s website at
http://www.blumhorst.com/catalina27/catalinahomepage.htm