Voyage planning is the second best part of this whole living on a boat thing. The West River Sailing Club cruising fleet plans a number of outings each year. They're a great way to learn about the best spots on the bay. And meet up with friends.
Dropping anchor in a new place is the best part of this living on a boat thing. Having friends from the sailing club is a bonus. (Rafting up is work. Anchoring separately and dinghying around is a lot more fun.)
This year's Memorial Day cruise is planned for Drum Point and Granary Creek. It's up the Wye River and the Wye East River. I had to spend some quality time with charts and Google Earth to figure out where it was.
After my search, I checked with the club members to confirm, and was pleased to know I found the right one. The Bay has a million Back Creeks, Mill Creeks, and Dividing Creeks, so you always need to check to see if you've found the right Drum Point and Granary Creek. And confirm it.
Here's a screen shot showing three possible legs for the weekend (plus maybe some of the following week.)
On the left, if you squint, you can see Herring Bay. We're starting from Herrington Harbour North, obscured by the black menu bar.
Drum Point is on the top right. OpenCPN provides a super-handy summary table of details.
This gives me a really accurate picture of each leg's time, distance, and bearing. The bearing tells me where to steer. The ETE is the estimated time enroute. The first line shows that it will take 24M 51S to get from the dock to the mouth of Herring Bay going 6 knots.
The departure time defaults to Right Now, which I don't like. I don't leave the computer running when we're under way. It's a power hog, and it's fragile. I copy OpenCPN's GPX file to the chart plotter and navigate with that. (An iPad is first backup; iPhone is second backup; computer is third backup.)
The ETA column seems to be a timestamp and a summary, like "(MoTwilight)". I think that's morning twilight. I mostly see "(Daytime)" in the ETA column. I think it's there to help when you're using UTC and need to know what this means locally.
The "MoTwilight" is confusing. There are three tiers of twilight: astronomical, nautical, and civil. Astronomical twilight is too dark for most things, but not dark enough for astronomers. Nautical twilight is when you can discern shore vs. water and almost nothing else. Civil twilight is when you have trip-and-fall hazards and streetlights are used to avoid lawsuits. Since "Mo" doesn't fit those well, I'll assume "Morning."
(If I was super anal-retentive, I'd break the very first leg into two legs: the part before the seawall which we cover at about 4kn and the part outside the seawall where we can ramp it up to 6 kn. This would add about 2m 30s to the sum of the ETE's. But. We're not flying an airplane here, this all happens at boat speed: we have plenty of time to figure out where we are and what part of our navigation went wrong. And we can trivially circle or drop anchor to work it out.)
This summary can be pasted into a spreadsheet, but not all spreadsheets can parse the fancy-format text values. I do some pre-processing in Python to strip out the formatting and make it easier to paste.
I also use the route summary to estimate the fuel consumption. Assume 1.5 gallons per hour when motor-sailing. The worst case is 6 gallons for this part of the trip.
All of this is much easier than CA's job of provisioning for a trip. Food. Water. Beer. Guest Towels. Beer. There's a ton of details to make a happy voyage. CA keeps detailed inventory of consumables. I just plan routes.
The Rest of the Trip
There are two other routes shown on the overview image. One is from Drum Point around Tilghman Island to Cambridge. That's a relatively long trip — 40 miles — which can be a solid 7 hours of motoring (or motor-sailing.) Ideally, the wind would be benign and we could run down the Bay under jib and jigger. Even a close reach over to Herring Bay and back would be better than a head-to-wind slog.
The other route shown is a route we've used before between Herring Bay and Cambridge. It's included only to make sure I have the full round-trip mileage of 92.7 nautical miles if we decide to visit Cambridge. And the full round-trip elapsed time of 15H 27M.
The whole outing could burn as much as 23 gallons of fuel, so, I may to take on some more fuel along the way. Cambridge has nice marinas, so I think I'll wait until I get there.
We're looking forward to getting off the dock. The jobs are mostly done. The planning is underway. It's time to drop the anchor in a new place.
Update 27 May 2021
SAT NE winds 10 to 15 kt with gusts to 20 kt. Waves 2 ft. Showers likely.
SAT NIGHT NE winds 10 to 15 kt with gusts to 20 kt. Waves 2 ft. Showers likely.
SUN NE winds 10 to 15 kt. Waves 1 to 2 ft. A chance of showers.
This doesn't seem too bad. What'a got folks concerned is this tidbit in the discussion:
Small craft advisories possible Sunday
The preliminary forecast isn't trustworthy too far in the future, and this point suggests caution. https://www.weather.gov/lwx/marine has the full discussion with other scary notes about SCA (Small Craft Advisories.)