Method
How the numbers are worked out
Simple, written down, and checkable with a calculator. The site uses no outside prices: every dollar figure comes from you.
Owning
Total cost of owning over the years you keep the boat = value lost (price minus your resale estimate) + loan interest paid while you own it + one-time extras + yearly fixed costs × years + running costs.
Running costs = days out per year × years × (engine hours per day × gallons per hour × fuel price + other costs per day).
Loan interest uses the standard monthly payment: payment = loan × r / (1 − (1 + r)−n), where r is the APR divided by 12 and n the term in months (0% APR: loan ÷ n). Interest paid in the first m months = payment × m − (loan − balance after m months). If the loan runs longer than you keep the boat, the balance left is paid from the sale price; it is not counted again.
Loan principal is not counted as a cost: it buys the boat, and what you lose of it is already in "value lost".
Four ways, one formula
Each option is a fixed amount per year plus an amount per day out:
- Own: (value lost + interest + one-time extras) ÷ years + yearly fixed costs; per day: fuel and day costs.
- Rent: nothing per year; per day: the day rate, plus fuel if the renter pays it, plus other day costs.
- Club: joining fee ÷ years + 12 × monthly dues; per day: fuel if members pay it, plus other day costs.
- Share: owning's yearly amount ÷ number of partners; per day: your own fuel and day costs.
Cost per day out = cost per year ÷ days per year. Cost per engine hour = cost per day ÷ hours per day.
Break-even days
Owning and another option cost the same at d days a year when own-per-year + own-per-day × d = other-per-year + other-per-day × d, so d = (own-per-year − other-per-year) ÷ (other-per-day − own-per-day). Above d, owning costs less. If owning never catches up within 365 days, the planner says so.
What it leaves out
- Inflation, investment returns on the money you would otherwise keep, and tax effects.
- Repairs nobody plans for. Put a figure in your service budget if you want to allow for them.
- How much you value having the boat whenever you want it. That part is yours to weigh.
Season Ledger
Days out counts each date once, however many trips you log on it. Cost per day out = everything spent ÷ days out; cost per engine hour = everything spent ÷ hours logged. Plan against actual compares what you have spent with the yearly cost you planned, and your days out with the days you planned.