Recap on taking your boat under objects such as bridges.
- Know what your vessels AIR DRAFT is
- Approx 36 – 42 ft Sailing Yacht is 40-50 ft – 13 – 16 Meters
- Northam Bridge has a clearance of 4.2 (METERS)
- This figure is measured from HAT (Highest Astronomical Tide) and represents the smallest clearance you’ll likely ever have.
- The range of tide locally makes a large difference. (if HAT is 7.5m then when the height of tide is 1.0m we have 4.2 +6.5 = 11.7 meters of clearance)
- This is the greatest high water height possible and is rare in most areas and greater than MHWS. (Mean High Water Springs)
- For a Motor vessel with an AIR DRAFT as high as 5 or 6 Meters, this is a realistic bridge to pass under where as a yacht this would be unrealistic without dropping the mast.
- A 12m tall yacht would require the HEIGHT OF TIDE to FALL by 8m and would only allow 0.2m room for error + the HAT bonus.
Extreme measure can be taken to reduce you vessels AIR DRAFT as seen in figure 2. We don’t recommend this approach!