Some tidal streams around the UK are relatively strong and are therefore the major consideration when planning a trip. The level of the sea rises and falls as the tidal currents flow around the coast, resulting in two high tides and two low tides approximately every 25 hours. Your trip can be faster or slower, and the sea conditions will be affected by the tide.
Note – Highest Astronomical Tide (‘HAT’) is replacing MHWS as the reference level for clearances – e.g. bridges and overhead electrical cables – as this represents the ‘worst case’ high tide and therefore the least clearance. Many charts though still reference these clearances to MHWS. Be careful to check the chart.