You talking about rainbows on the water brings up a fond memory.
One year at Wish a Fish - one special needs boy was telling us about the rainbow he saw. That day was clear - no rainbows in the sky to be seen.
It took some doing but he finally explained to us he saw the rainbow the boat made when it went across a wake and threw water.
Every time my boat throws water and makes a rainbow - I recall that day.
Sounds like you were upfront with your charter - but being fishermen - they just had to go. Amazed Capt. John could cook in choppy seas but guess if he spills it - he has a good mate to clean it up.