Chart height is not always correct. A friend of mine hit a 75 ft high cable with a 70 ft mast close to Hilton Head. It was a Spring high tide and the temperature was close to 100. Luckily all he lost was his VHF antenna, not high carbon fiber mast or hislife.
An number of years ago a small Oday hit a power line; the crew jumped off the water and were electrocuted.