89 19' regal, 4.3 v6 2bbl, docked in fresh water may to sept, acid washed and stored indoors oct to apr, stainless steel prop (not sure of pitch), when first purchased 7 years ago would easily go 42 mph, now at wot, my wife cant keep 28 mph when I slalom, only goes about 32 with just a couple of people in it, any ideas?