Under-Keel Clearance Table for 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:
| 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.Report a problem on this page
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