A six-hour charter is not six hours of fishing. Two of them can be spent steaming out and back, and the reviews that say “we barely fished” are almost always a run-time problem rather than a fish problem. Subtracting the run from the charter turns a vague promise into a number you can print.
A six-hour trip 22 miles out at 22 knots spends two hours running — four hours with lines in the water, not six.
The example
Three trips off the same dock, each to a different set of numbers.
| A | B | C | D | E | F | G | |
|---|---|---|---|---|---|---|---|
| 1 | Trip | Charter hrs | Miles out | Knots | Run hrs | Fishing hrs | % fishing |
| 2 | Half day | 4 | 9 | 18 | 1.0 | 3.0 | 75.0% |
| 3 | Three-quarter | 6 | 22 | 22 | 2.0 | 4.0 | 66.7% |
| 4 | Full day | 8 | 30 | 20 | 3.0 | 5.0 | 62.5% |
The formula
Run time first, because the captain already knows it:
How it works
Four things happen here:
C2/D2is the one-way run in hours. Distance in nautical miles over speed in knots gives hours directly — that is what a knot is, and it is the reason to keep both columns in the same unit family.2*because the boat has to come back. Quoting a one-way run is the most common way a charter over-promises.B2-E2is the fishing window. This is the honest number for the website and the phone call.MAX(0,...)guards the edge case: if the run exceeds the charter, the answer is zero hours, not a negative, and the trip needs to be longer or the spot needs to be closer.
Divide fishing hours by charter hours for a share. Anything under about 60% is a trip that should either be sold longer or run closer to home.
Try it: interactive demo
Enter the charter length, the distance to the grounds and your cruising speed.
Variations
Charter length for a target fishing time
Rearrange when the customer says they want four hours of fishing. Add the round-trip run to the target and you have the trip to sell.
How far out you can afford to go
Solve for distance instead: how far can the boat run and still leave the promised fishing time on the clock?
Pitfalls & errors
Cruising speed on the way home is not always cruising speed on the way out. A head sea, a following sea, or a heavier boat all change it — if the return leg is reliably slower, use two speed columns instead of doubling one.
Add setup time as its own deduction. Rigging, chumming, and finding the mark can eat twenty minutes at each stop, and it is not run time and not fishing time.
Do not mix statute miles with knots. A knot is one nautical mile per hour; feeding statute miles into the same formula understates the run by about 15%, which is a whole half-hour on a long trip.
Practice workbook
Frequently asked questions
Should I advertise charter hours or fishing hours?
How do I handle a trip with two or three stops?
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