Need help to understand harbor info from Reeds almanac
From Dielette port information (Reeds almanac, area 18, Central N France):
"Outer hbr entr dredged to CD+0.5m; accessible for 2.5m draft with Coefficient > 55"
1) "harbor entrance dredged to CD+0.5m" - let's say hbr.entr was drying land with 2m over CD, so after being dredged to CD+0.5m, it is now 1.5 over CD. Correct?
2) "accessible for 2.5m draft with Coefficient > 55" - what coefficient almanac talks about?