I have a fortress anchor and have had no issues with it penetrating the bottom. Bottom penetration is not so much a function of weight as anchor design. That being said, I couple he anchor with 100'' of chain plus 150'' of rope. Perhaps you could stopover at a place where you can tie up to a dock or a mooring. Another option would be to get a 2nd anchor and set two for the night for a little piece of mind. Where are you going from-to? Depending on the boat size and wind, 65 miles is do-able in 1 day.