1883 The set of tides at half ebb and half flood
From the David Rumsey Collection.
HHA Tidal Surges
14AUG24 there was a surge, it built up very quickly as can be seen from the graph. Two stream measurements were made from a yacht taking the difference between STW and SOG. HHA Tide Data for the period here, times are BST. HW 0700 3.3m, LW 1245 1.4m, HW 1930 3.3m Range 1.85 average (neap …
Priming and Lagging
Each port has an ‘Establishment’, being the hour of the day (GMT) at which the High Tide occurs at the ‘Full and Change’ of the Moon. At Harich this is xxx. As the Moon moves through her quarters the time at which HW occurs changes. After the New Moon the Moon ‘waxes’ or enlarges through …
Log Calibration
A yacht’s log records the distance travelled through the water and, from that, derives speed (there are other types of log such as Doppler which work differently). Because the log wheel is subject to the marine environment, such as weed, it ought to be tested often and calibrated to be reliable. Many sailors are perhaps …
Elevation and Depth data
Also see Walton on the Naze tides – variation LIDAR is a Laser-based surveying technique that provides elevation data across a land area. There are various types of survey data that can be downloaded and then processed to show a given area. The raw data will include buildings and vehicles, this is the DSM version. …
Tides and Waves
A brief analysis of North Sea physics – in depth technical explanation of how the North Sea works including surges, wind, circulation and future climate change.
Air pressure, Sea Level and Surges
Standard air pressure at sea level is 1013 mb or Hectopascals, Changes in air pressure affect sea level, This effect has implications for the sailor since each A 10mb change in pressure results in a 0.1m opposite direction change in sea level which can be calculated easily. This is enough to make a difference at a river bar or marina entrance although any change should be within the safety margin allowed by the prudent sailor.
Walton on the Naze tides – variation
Also see Elevation and Depth data. Walton on the Naze is the standard port for our part of the East Coast despite the major port being Harwich. Times and heights are similar between the two ports but with Walton having slightly greater heights. Tide readings and tables for thirty years ahead are available from the …
GPS-GOTO vs CTS
It is easy when sailing to set the GPS system to GOTO waypoint and then steer to match the Bearing (BTW) with the Course over Ground (COG,) or set the autopilot to do so. Provided that Cross Track Error (XTE) is managed, and the course can be made, then the boat will travel directly to …
Commander William Hewett
1752 John Mount Sailing Directions
Tides by Full and Change
Tidal level at Woodbridge
Tide gauge (sometimes a bit on the drag) Highest level was 3.35 (2013?) 1953 the flooding reached up Cliff Road to the bend by the entrance to the Maybush car park. This is about 4.0m AOD (hard to be exact without measuring – lost OS BM on wall) which makes a height of tide of …
Tide and Wave predictions and data
Tide Predictions Harwich Haven Authority/Leisure produces annual tide tables as well as a tidal atlas. The tide does not turn at HW or LW anyway in Swimscapes Bay. The tidal stream turns to flood north about 4-4.5 hrs after HW and to ebb north about 1.5 hrs before the next HW. In time I’ll work …
Wrinkles in practical navigation by Captain S.T.S.Lecky
Squire Thornton Stratford Lecky , 1917 edition of Wrinkles, explains tides and instruments, lovely language.