Imagine you’ve taken your sailboat out on a three-hour tour. The day begins, and you’re happy on your boat. The wind is in your sails.
And then suddenly, it isn’t.
The shore is four nautical miles away, and a storm is brewing. The crew is feeling slightly disgruntled. You go to turn on the engine, and you discover you don’t have enough fuel to return to shore.
Sailors who understand gas mileage and fuel consumption won’t ever have this problem. Here’s what you need to know.
The Constants
Units of Measure |
|
| Your engine’s horsepower | hp |
| How much fuel you have on board | gallons |
| How fast your sailboat can go | nautical miles/hour |
| How efficient the fuel consumption is | pounds/horsepower |
| How much the fuel weighs | pounds/gallon |
The Constants Aboard the Sea Shanti
Units of Measure |
|
| Your engine’s horsepower | 40 hp |
| How much fuel you have on board | 60 gallons |
| How fast your sailboat can go | 5 nautical miles/hour |
| How efficient the fuel consumption is | .4 pounds/horsepower |
| How much the fuel weighs | 7.2 pounds/gallon |
The Formulas
How many gallons of fuel does the Sea Shanti use per hour?
The Formula
Gallons per hour = (Specific Fuel Consumption X Horsepower)/Fuel Specific Weight
GPH = (.4*40)/7.2 = 2.22 GPH
How long can we travel on the Sea Shanti’s fuel supplies?
The Formula
Travel Time = Gallons per hour X Gallons of Fuel Onboard
Travel Time = 2.22*60 = 133.2 hours
How far can we travel on the Sea Shanti’s fuel supplies?
The Formula
Total Distance = Time Traveled X Average Sailboat Speed Motoring
Total Distance = 133.2*5 = 666 nautical miles
BONUS: How many days can we travel on the Sea Shanti’s fuel supplies?
The Formula
Number of Days = Travel Time in Hours/Number of Hours in the Day
Number of Days = 133.2\24 = 5.55 days
In Conclusion
If you’re going to be a sailor, you’ve got to learn the risks and how to deal with them. Sometimes that involves math, a fate more terrifying than sirens.
I do find math a bit terrifying 🙂 We’ve never been in the position where we didn’t have enough diesel to get to a safe harbor. Not sure I ever want to experience running out.
This was math that we conned our poor teenager into doing when he was asking questions about our travel plans. Fain actually wrote this. (I just hadn’t had a chance to add him to the blog users yet. He’s there now!) I can’t say as I fully follow it all, but it was cool to watch him figure it out. 🙂
Neaubeard, infamous pirate and now what appears to be a budding mathematician.
Indeed! Otherwise, how will he know we’re divvying up the booty equally as all good pirates should?