Great Sandy Strait Southbound Transit
Guide (Urangan → Wide Bay Bar)
Great Sandy Strait Southbound Transit Guide. The Great Sandy Strait is a tide‑controlled waterway where progress is dictated by depth, stream strength and daylight rather than distance. A southbound transit is built around clearing two depth gates, Sheridan Flats and South White Cliffs / Ungowa, while aligning arrival at Wide Bay Bar with the final stages of the flood. For yachts drawing 1.8–2.0 m, tide height becomes the controlling factor, and the Strait rewards skippers who plan movements around the tide curve rather than the clock.
The Great Sandy Strait Southbound Transit Guide northern section provides workable depth through most of the tide cycle, but the southern section becomes restrictive at low water. Depths at LAT in the shallowest areas sit between 1.8 m and 2.0 m, and the channel edges fall away quickly into drying banks. The Strait is predictable when approached with disciplined timing, conservative pilotage and accurate channel‑keeping. The plan below follows the natural sequencing of the Strait and is written for skippers who want depth‑aware, practical navigation guidance rather than general commentary.
1. Urangan → Round Island Channel
This leg positions you for the tide‑critical sections ahead and confirms set, drift and tide behaviour before entering the Strait proper. Depths are 3–4 m in the dredged channel, with a clean, well‑marked exit from Great Sandy Straits Marina. This is the point where you confirm whether the tide is running early or late, whether the stream matches prediction, and whether wind‑against‑tide is creating chop across the bay. The approach to Round Island is straightforward, but skippers avoid cutting across the flats north of the channel. Departing early enough to reach Sheridan Flats with the correct tide height is the key decision here.
2. Round Island Channel → Sheridan
Flats
This leg brings you into the first shallow zone, where accurate channel‑keeping becomes essential. Depths remain 3–4 m, shoaling as you approach the flats. The channel meanders across broad shallow ground, and the marks must be followed precisely. The stream is moderate but can build in fresh SE winds. This is where you begin to feel the Strait’s shallow‑water character. The goal is to arrive at Sheridan Flats near slack water with sufficient tide height for your draft. Skippers often reduce speed here to fine‑tune arrival timing.
3. Crossing Sheridan Flats (Depth
Gate #1)
This is the first controlling depth point of the entire Strait and must be timed with the correct tide height. Depths are typically 1.8–2.2 m at LAT in the marked channel. For yachts drawing 2.0 m, this is a mid‑tide or better transit, ideally on a rising tide. For 1.8 m draft, low water is possible but tight, and most skippers still prefer mid‑tide for margin. The flats are broad and shallow, and the channel is not deeply cut; even small deviations from the marks can reduce depth significantly. Crossing at or near slack water avoids strong stream in shallow water, which can push the vessel sideways toward the banks. Sounder readings fluctuate here due to soft mud and sand, so skippers watch for trends rather than reacting to every dip.
4. Sheridan Flats → Garry’s Anchorage
This leg gives you depth relief and acts as your primary buffer before committing to the southern Strait. Depths improve to 2.5–3.0 m at LAT, and the channel becomes more defined. This is the first point in the transit where you can relax slightly and reassess timing. Garry’s Anchorage is the primary staging point for the southern Strait, offering reliable holding in sand and mud with protection from most directions. If your tide window for South White Cliffs / Ungowa is not ideal, you stop here and wait. Many skippers plan their entire transit around a controlled pause at Garry’s to ensure they hit the southern depth gate with the correct tide.
5. Garry’s Anchorage Narrows (Stream
Gate)
This section is governed by stream strength rather than depth, and timing determines vessel control. Depths are 2.5–3.0 m at LAT, so depth is not the constraint. The narrows accelerate the tidal stream, especially during springs, and the bends require positive helm control. Transit at slack or early flood/ebb depending on direction. Northbound vessels often meet southbound traffic here, so skippers maintain a listening watch and announce intentions on VHF 16/73. Anticipate set in the bends and avoid over‑standing into the shoals on the inside of the turns.
6. Garry’s Anchorage → South White
Cliffs
This leg positions you for the second depth gate and allows fine‑tuning of your tide window. Depths are 2.0–3.0 m at LAT, with increasing stream as you approach the southern Strait. This is where you confirm whether the tide is rising as predicted and whether you are early or late for the next gate. Several temporary anchorages exist along this stretch, allowing you to pause if needed. The channel edges fall away quickly, so skippers maintain tight alignment with the marks. This leg is often run at reduced speed to ensure arrival at South White Cliffs with the correct tide height.
7. South White Cliffs / Ungowa (Depth
Gate #2)
This is the second controlling depth point and must be taken with adequate tide height and manageable stream. Depths are 1.8–2.0 m at LAT, and the channel can shoal after strong weather. For 2.0 m draft, this is a half‑tide rising minimum. For 1.8 m draft, +0.2–0.4 m is workable but still conservative. The stream runs hard here, and shallow water amplifies its effect. Skippers avoid low water and peak stream. The bends require accurate positioning, and the channel edges drop into drying banks. This is the point where tide height and timing matter most; once clear of this section, the remainder of the Strait is more forgiving.
8. Southern Strait → Inside Wide Bay
Bar Channel
This leg transitions you from the Strait into the bar‑influenced southern channel, where depth is workable but margins are narrow. Depths are 2.0–3.0 m at LAT in the marked channel, with extensive drying banks on both sides. The channel is narrow and must be followed precisely. This is where you align your progress with the bar‑crossing window. Skippers avoid shortcuts across the banks, even when the tide is high, as the seabed is mobile and uncharted shoals can form after strong weather. The final turn toward the bar channel is exposed to wind and swell, and vessels often feel the first signs of ocean influence here.
9. Wide Bay Bar (Exit)
This is the final gate of the transit and must be timed with the last of the flood for safe sea state and depth. Wide Bay Bar is shallow, mobile and heavily influenced by swell. Skippers cross on the last of the flood, avoiding ebb‑against‑swell conditions that produce steep, breaking seas. Official waypoints and guidance take precedence over any generic description, as the bar shifts frequently. The inner channel carries workable depth, but the outer banks can break in moderate swell. Once clear of the bar, vessels alter course for their offshore destination or continue south along the coast.
Mechanical and Electrical Repairs
Resource
If you are headed somewhere remote consider the need to expand your knowledge base or have an information resource on board. Why not get a copy of my book The Marine and Electrical and Electronics Bible 4th Edition. By and for yachties, with everything from batteries and charging, solar and wind, diesel engines and marine electronics and so much more. Your complete systems guide. 650 pages of practical advice. Go to Boat Books for a copy or order through Amazon. By an Australian yachtsman for Australian Yachtsmen and Yachtswomen. Marine systems are my profession so let me help you.
Great Sandy Strait Southbound Transit Guide - Summary
The Great Sandy Strait Southbound Transit Guide is all about a tide‑timed sequence built around clearing Sheridan Flats and South White Cliffs / Ungowa with enough water under you, using Garry’s Anchorage as a flexible staging point, and arriving at Wide Bay Bar for the final stages of the flood. With accurate tide interpretation, disciplined channel‑keeping and conservative timing, the Strait becomes a predictable, depth‑reliable passage for yachts drawing 1.8–2.0 m. The Great Sandy Strait Southbound Transit Guide for valuable information.