Bridge Transits / Denison Canal

The Bridgewater Bridge is managed by The Department of State Growth (Transport) To arrange the opening of the Bridgewater Bridge, ring 6263 7235. The Bridge can be opened between 9.15am and 4.00pm – 7 days per week but will not open if the breeze is more than 25 knots. Please note, 2 hours notice is required.

Clearance when Bridge is down:

  • Low tide: 2.9m
  • Medium tide: 2.5m
  • High tide: 2.1m

There are special rules for going through the Tasman Bridge. These are defined in the Marine and Safety (Pilotage and Navigation) Regulations 2017 and relate to which navigational spans certain vessels can use.

  1. Vessels over 25 metres in length, or tugs, may use the main navigation span and only after permission is granted from Tasports.  No other vessels are to pass through the main navigation span;

a.   Where a vessel intends to pass under the main span, a long, 10 second, horn blast will notify the vessel’s intention

        2.  Vessels between 15 -25 metres in length should pass through the designated secondary span;

a.   If the vessel is proceeding upstream the designated span is the aperture under the secondary navigation span immediately eastward of the aperture of the main navigation span.

b.   If the vessel is proceeding downstream the designated span is the aperture under the secondary navigation span immediately westward of the aperture of the main navigation span.

        3.   Vessels not exceeding 15 metres in length and recreational vessels must not cause or allow the vessel to pass under the bridge through the main navigation span, or the secondary navigation spans either side of the main navigation span, unless otherwise authorised to do so by MAST. Boaters should be aware of expected shipping movements before going out on the water. These are published in daily newspapers and can be found on the Tasports website.

Operating in River Derwent Brochure

General information for transiting Marion Narrows and Denison Canal 19 December 2018

The attached chartlet of Marion Narrows provides depth information laid over Chart AUS169.

  • The chartlet is NOT FOR NAVIGATION PURPOSES and has been provided for guidance purposes only
  • Mariners are strongly recommended to use AUS169 when navigating this area
  • The depths on the chartlet are those measured on the date shown on the chartlet
  • Depths are in metres, referenced to Chart Datum using the Hobart Tide Tables
  • Conditions continually change at the Narrows and depths experienced may differ from the chartlet

The attached route data provides a vessel track through the Marion Narrows area as of the dates shown on the file. These tracks can be downloaded to mobile devices and to some chart plotters via portable storage devices such as an SD card. Conditions continually change at the Narrows and the deepest route may differ from those provided.

Denison Canal and Marion Narrows Information Sheet – 19 December 2018

Marion Narrows Chartlet 19 Dec 2018

Marion Narrows  Route 19 Dec 2018 (PDF)



  • Mariners are advised not to attempt to enter Blackman Bay through the Narrows in heavy north-easterly conditions
  • Only vessels with a shallow draft should transit the Narrows  and only after the skipper has sought local knowledge.
  • Navigate only at high tide and in daylight hours

Tidal Streams

  • The main stream of the flood tide runs into Blackman Bay – ie, in a north-easterly direction at the Denison Canal and a south-westerly direction at the Marion Bay Narrows. The reverse applies for an ebb tide.
  • Tide times can be calculated with reference to tide tables with the following adjustments:
    • Flood Stream commences 2 hours 27 minutes after low water at Hobart
    • Ebb Stream commences 2 hours 16 minutes after high water at Hobart

Remember to adjust for daylight saving time. Mariners should remember that tide conditions may differ depending on factors such as barometric pressure, prevailing winds etc.