soot

Reaching out to anyone who has been able to fix problem of minor soot developing on hull after 50-60 hrs of cruising Hunter 44DS 2004 Yanmar 4JH3E 2400 hrs (1500 hrs added during last 27 months) no visible smoke engine runs very well and starts immediately WOT rpm 3800 Cruise rpm 2800 (75% of...

My 14yr old 1650hrs 2gm20f runs beautifully. Sounds pretty smooth. There's no black smoke but only slight white/greyish smoke. New exhaust and mixing elbows. Question is on long passage I'm seeing greyish bubbles that breaks to soot on water. Very little but noticeable. Should I be concern...