Recent purchase of a 1999 Mainship Pilot 30 with a Yanmar 4LHA. Any idea what the original prop was? Boat had a 21 x 21 LH that was in bad shape. Prop shop suggested 22 X 20 LH. Have vibration starting around 2200rpm's. Noticed an article stating the early Pilots had an issue with vibration and noise, corrected under warranty. Shaft was checked, new cutlass bearing and packing gland. Any input would be appreciated.