The lowest of the three bridges is the arched A27 road bridge. This appears on charts and in nautical almanacs as having a charted vertical clearance of 3.5 metres above the highest astronomical tide.
For an on-the-spot check when approaching Burseldon bridge there is an air-draft gauge on pile Z1, next to the training wall.
There are tide gauges at Crableck Beacon and at Swanwick Bend, near the bridge, which show the tide height above datum. Do not confuse this with the depth gauges on the maintenance piles which show the depth of water at that point.
Diagram of charted depths and clearance at Burseldon Bridge: