We decided to start charging in advance for diesel fuel at set rates a couple of years ago.  We used to (like most operators still today) dip the tank when clients returned and charge accordingly, however this had its drawbacks for all parties.

It basically meant that we needed clients to return to base earlier, so that we had time to dip the tanks and take your money on site, which meant you had to come back to base on the Saturday evening.  We really wanted clients to get the most out of their holiday and stay out amongst the islands for the final night, returning on the Sunday morning, just in time to jump off the boat and into the waiting taxi - and this meant charging in advance for fuel so there was no messing around when clients came back in.

Of course some clients use more fuel than others, but it probably balances out over the years and gives you that vital final night out away from base!

Oh... and the number of clients returning at the end of the week having blown their last few euros on the their final meal was amazing...... cheques in the post guv...!