ALLSAIL · PITTWATER · EDUCATIONAL TOOL
Quick Anchoring Calculator
The chain is scoped to the highest water in the next 24 hours. Swing is checked at the lowest.
CHAIN TO PUT OUT
49.7 m
Plus 6.0 m of bridle loop. Veer 55.7 m off the gypsy, about 1 min 51 s.
High water 1.90 m at 09:25. Roller depth 7.1 m. Scope 7.00:1.
Modelled swing 67.7 m fits inside the entered 80.0 m clearance. This does not prove the anchorage is safe.
Plan view · anchor fixed at high tide
Low-tide swing circle
The rode is set for high water. As the water falls, its horizontal projection grows; the outer radius also includes the forward bridle reach and the boat’s length overall.
- Solid: low-water outer sweep
- Dashed: high-water outer sweep
- Dotted: entered clearance limit
- Low-water outer radius
- 67.7 m
- High-water outer radius
- 67.5 m
- High-to-low radial increase
- 0.2 m
- Horizontal reach · low water
- 49.4 m
- Horizontal reach · high water
- 49.2 m
- Maximum cross-circle span
- 135.4 m
- Full-circle travel
- 425.3 m
- Working rode
- 49.7 m
- Low-water swing ratio
- 8.98:1
- High-water roller depth
- 7.1 m
Horizontal reach + bridle forward reach + LOA
Same working rode; shorter horizontal projection
At 5.5 m roller-to-seabed depth
At 7.1 m roller-to-seabed depth
2 × low-water radius
Only if the vessel completes a full 360° swing
High-water scope rode; not the outer swing radius
Horizontal reach ÷ 5.5 m roller-to-seabed depth
Modelled clearance fits
The low-water circle is within the entered 80.0 m limit. This is not proof of safety.
Wind and current determine the boat’s actual track. This geometric model assumes the anchor holds; it does not establish holding, predict a track, or prove safe clearance. Tide values are entered by you—there is no live tide feed.
Annual predictions · Pittwater
Load BOM tides
Sand Point (Pittwater) · Lowest Astronomical Tide datum · Australia/Sydney time.
The added full day gives a conservative high/low extrema envelope for planning, not an exactly 24-hour set. Confirm the relevant extrema against the intended stay and check local conditions with the skipper.
Imported 2026/2027 annual predictions for Sand Point only; these are not live observed water levels.
BOM-derived product notice and full disclaimer
Copyright Commonwealth of Australia / Bureau of Meteorology. This AllSail product imports the Bureau’s 2026 and 2027 annual predictions for Sand Point (Pittwater) only. It is not a live feed of observed water levels and does not represent other stations.
The extra full local day is included as a conservative high/low extrema envelope; it is not exactly 24 hours. Confirm predictions, local conditions, and suitability for the intended stay with the skipper.
This product is based on Bureau of Meteorology information that has subsequently been modified. The Bureau does not necessarily support or endorse, or have any connection with, the product. In respect of that part of the information which is sourced from the Bureau, and to the maximum extent permitted by law: (i) The Bureau makes no representation and gives no warranty of any kind whether express, implied, statutory or otherwise in respect to the availability, accuracy, currency, completeness, quality or reliability of the information or that the information will be fit for any particular purpose or will not infringe any third party Intellectual Property rights; and (ii) the Bureau's liability for any loss, damage, cost or expense resulting from use of, or reliance on, the information is entirely excluded.
Working chain is scope times chart depth, plus the highest tide of the stay, plus the height of the bow roller. The bridle loop is extra chain. It is not scope.