Under-Keel Clearance Table

UNDER-KEEL CLEARANCE OTHER SHIPS (Other than container ships)
ST. LAWRENCE RIVER, QUÉBEC TO MONTRÉAL

Modification of the table: effective on 2013-04-01

The actual amendment establishes new parameters for vessels width between 40.0 m and 44.0 m

To promote safety and efficiency of navigation and environmental protection, the Marine Communications and Traffic Services Officer (MCTSO) has the power to issue, in some cases, directions to a vessel under section 126 of the 2001 Canada Shipping Act. In exercising its powers, the MCTSO will consider the under-keel clearance for vessels transiting the area above Québec. The Marine Communications and Traffic Services will determine the required under-keel clearance of the ship according to the parameters given in the table below:

UNDER-KEEL CLEARANCE OTHER SHIPS (Other than container ships) ST. LAWRENCE RIVER, QUÉBEC TO MONTRÉAL
Vessel Beam not exceeding Vessel’s speed over water not exceeding (knots)
7 8 9 10 11 12 13 14 15
Required under-keel clearance (meters ; which included estimated squat and the manoeuvrability’s safety margin)
24 m 0,80 0,90 0,97 1,06 1,24 1,44 1,66 1,92 2,21
26 0,85 0,92 1,00 1,09 1,29 1,49 1,73 1,99 2,29
28 0,86 0,94 1,03 1,13 1,33 1,54 1,79 2,06 2,37
30 0,88 0,96 1,05 1,16 1,37 1,59 1,85 2,13 2,46
32 0,89 0,98 1,08 1,19 1,41 1,64 1,91 2,19 2,53
34 0,91 1,00 1,10 1,23 1,45 1,69 1,97 2,26 2,61
36 0,93 1,02 1,13 1,26 1,49 1,74 2,02 2,32 2,69
38 0,94 1,04 1,16 1,29 1,53 1,78 2,08 2,39 2,77
40 0,96 1,06 1,18 1,32 1,57 1,83 2,13 2,44 2,84
42 0,97 1,08 1,21 1,36 1,61 1,88 2,18 2,51 2,91
44 0,99 1,10 1,23 1,39 1,65 1,93 2,24 2,57 2,98
Estimated squat (meters)
24 m 0,22 0,29 0,36 0,45 0,55 0,68 0,82 1,01 1,22
26 0,24 0,31 0,39 0,48 0,60 0,73 0,89 1,08 1,30
28 0,25 0,33 0,42 0,52 0,64 0,78 0,95 1,15 1,38
30 0,27 0,35 0,44 0,55 0,68 0,83 1,01 1,22 1,47
32 0,28 0,37 0,47 0,58 0,72 0,88 1,07 1,28 1,54
34 0,30 0,39 0,49 0,62 0,76 0,93 1,13 1,35 1,62
36 0,32 0,41 0,52 0,65 0,80 0,98 1,18 1,41 1,70
38 0,33 0,43 0,55 0,68 0,84 1,02 1,24 1,48 1,78
40 0,35 0,45 0,57 0,71 0,88 1,07 1,29 1,53 1,85
42 0,36 0,47 0,60 0,75 0,92 1,12 1,34 1,60 1,92
44 0,38 0,49 0,62 0,78 0,96 1,17 1,40 1,66 1,99
Manoeuvrability/safety margin (meters)
0,61 0,61 0,61 0,61 0,69 0,76 0,84 0,91 0,99

* An exception to the margin of safety / manoeuvrability is allowed for a ship with a width not exceeding 24 m at a speed of 6 to 7 knots. Only in this case, a margin of 0.58 m is accepted instead of 0.61 m.

The above parameters are presented on the basis that the vessel’s Master or Officer-in-charge has given consideration to other specific elements which may have an impact on under-keel clearance, some of which are: the accurate determination of water level (including tides) during vessel’s transit; the vessel’s speed; the wind and waves effects and the vessel’s response to it; the estimation of the vessel’s draught (changes in ballast); any additional squat effects due to passing within close proximity to the bank of the channel or when meeting / overtaking another vessel. The vessel’s Master or Officer-in-charge has the ultimate responsibility for the vessel’s safety at all times.

Source : Canadian Coast Guard (TC-L95-133; AMA8035-10-1); Notice to Mariners No. 462 of Edition No. 17 of 1995. Modification : 2013/03/21.