Latitude is a geographic coordinate that specifies the north-south position of a point on the Earth’s surface (thanks, Wikipedia!).
They are the lines that run parallel and horizontally around the earth starting at the equator (0 degrees) and moving towards the poles (90 degrees). Each degree of latitude is broken down further into minutes (60 minutes in a degree) and seconds (60 seconds in a minute).
Each degree of latitude is approximately 69 miles, which is almost exactly 60 nautical miles. As a side note, I get asked often what the difference is between a mile and a nautical mile. A nautical mile is 1.15 miles. This conversion traces its start back to long before the compass was commonplace on vessels. By the 1600’s, mariners used a log (literally – a log) to measure their speed. They would tie the log to a long line with knots spaced 48 feet apart and wound around a reel. To measure the vessel’s speed, the mariners would throw the log over the stern of the boat and start a 30-second sandglass. The number of knots that ran out in those 30 seconds offered the ship’s speed (we still talk about speed in knots). Spacing the knots at 48 feet was practical back then because it was 8 fathoms and therefore easily divisible, but it makes a nautical mile 6,080 feet instead of the landlubber’s mile of 5,280 feet. (This information came primarily from a wonderful book called Compass: A story of Exploration and Innovation by Alan Gurney.)
60 nautical miles to a degree of latitude makes my math easy. It means each minute of latitude is equivalent to 1 nautical mile. It’s good this math is easy, because I do it a lot on Halcyon.
Before we leave on a passage, I look at the latitude (and longitude) of our next destination. As we sail south, I can calculate how far we have to go and how long it will take based on our current position. Alternatively, when I know how many miles we have to travel, it’s easy to determine what our new latitude will be when we arrive. Yes, we have many devices that do this math for us – but those night watches are long and tequila makes my brain mushy ☺
So in an effort to de-mushify my brain, here are some latitude-themed statistics about our adventure so far.
Seattle is at 48 degrees north (hence the name of the awesome sailing rag I write for). That means it is 48 degrees and approximately 2,880 nautical miles north of the equator.
When we left Seattle, we went north – as far as the north end of Vancouver Island. We reached 51 degrees north before turning south around Cape Scott. That means we traveled about 180 miles north (but also nearly 300 miles west) on our way around the Island.
We are currently in Cabo San Lucas, which is at 23 degrees north. That means we have dropped 28 degrees and 1,680 miles towards the equator.
It also means we are more than half way to Ecuador. We’ve been gone 3 ½ months and we are already half way down our projected coastal cruising!
From that, I can deduce that we need to slow down. On one hand, cruising by definition is slow; we travel at 6 nautical miles per hour. That 1,680 miles, if sailed in a straight line, would take 280 hours or 12 straight days at that speed. But on the other hand, we have spent more time on the move than we have spent exploring the places we find along the way.
That’s changing. We stayed in front of the bad NW weather, collected and deposited crew, and made our flights. We have nothing else on the calendar until our visas kick us out of Mexico in 5 months. That’s 5 months to explore the next 9 degrees of latitude.
And I’m looking forward to it.