Under-Keel Clearance Table

UNDER-KEEL CLEARANCE 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 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 0,79 0,88 0,96 1,04 1,22 1,41 1,63 1,88 2,17
26 0,83 0,90 0,98 1,07 1,25 1,45 1,68 1,93 2,23
28 0,84 0,91 1,00 1,09 1,28 1,48 1,72 1,98 2,29
30 0,86 0,93 1,01 1,11 1,31 1,52 1,76 2,03 2,34
32 0,87 0,94 1,03 1,14 1,34 1,55 1,80 2,08 2,40
34 0,88 0,96 1,05 1,16 1,36 1,58 1,84 2,12 2,45
36 0,89 0,97 1,07 1,18 1,39 1,62 1,88 2,16 2,50
38 0,90 0,98 1,08 1,20 1,42 1,65 1,92 2,20 2,55
40 0,91 1,00 1,10 1,22 1,44 1,68 1,96 2,24 2,60
42 0,92 1,01 1,12 1,24 1,47 1,71 1,99 2,29 2,65
44 0,93 1,02 1,13 1,26 1,49 1,74 2,03 2,33 2,70
Estimated squat (meters)
24 m 0,21 0,27 0,35 0,43 0,53 0,65 0,79 0,97 1,18
26 0,22 0,29 0,37 0,46 0,56 0,69 0,84 1,02 1,24
28 0,23 0,30 0,39 0,48 0,59 0,72 0,88 1,07 1,30
30 0,25 0,32 0,40 0,50 0,62 0,76 0,92 1,12 1,35
32 0,26 0,33 0,42 0,53 0,65 0,79 0,96 1,17 1,41
34 0,27 0,35 0,44 0,55 0,67 0,82 1,00 1,21 1,46
36 0,28 0,36 0,46 0,57 0,70 0,86 1,04 1,25 1,51
38 0,29 0,37 0,47 0,59 0,73 0,89 1,08 1,29 1,56
40 0,30 0,39 0,49 0,61 0,75 0,92 1,12 1,33 1,61
42 0,31 0,40 0,51 0,63 0,78 0,95 1,15 1,38 1,66
44 0,32 0,41 0,52 0,65 0,80 0,98 1,19 1,42 1,71
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.