Since we’ve been sitting here now for literally 3 weeks, it seems like a good time to explain how we do our weather routing! That way you can understand, sort of, why we haven’t crossed to the Bahamas yet (to tell the truth, I’m not quite sure I understand – is this type of strong weather typical for this time of year!?). Read about our previous experience with crossing the Gulf Stream here!

What’s Comfortable

First we’ve got to talk about what’s comfortable. This is different for every one, and it’s different for catamarans vs monohulls, but there are some basics about the direction of the wind and waves that makes a huge difference.

In “following seas,” which is pretty much anything aft of the beam (waves coming from the direction of any of the blue arrows), the waves gently lift us up and then we slide down them. Very comfortable. Steep seas are less so, we might pick up some serious speed surfing down a wave, but following seas are always the best!

In “beam seas” (purple arrow) we get some weird side to side motion. Okay in flatter seas, pretty jarring in steep seas.

Anything forward of that can be rough. With waves coming at us, they’re hitting us more frequently so unless they are gentle sloping waves, we’re crashing up one side then falling off the other. The closer to the red arrow, the worse they are. This is called “bashing.”

For wind direction, pretty much anything is comfortable, but if the wind is coming right at us (red arrow) we can’t sail. Our no-sail zone includes about 60° on either side of the red arrow.

Gulf Stream

There are four factors we have to take into account when planning our crossing. The first one is the Gulf Stream, and it’s a constant, so we only need to look at it once. It changes a little bit, but not much. Since this is a strong current, if there is opposing wind it can create a big, steep swell. Conventional wisdom – and every guidebook – says don’t ever cross the Gulf Stream if there is any northerly component to the wind because of how rough the waves can get.

Since the current will carry us slightly northward, we have to point a little bit south for the crossing. Our path will go straight east, but we’ll actually be sailing southeast. The takeaway here is that if there is a southeast wind, we’ll be going straight into the wind.

The other factors for planning are the wind, the waves, and the time period that we’ll be crossing. The time period doesn’t vary too much, our crossing will take about 14 hours and we want to arrive in daylight, which means we can leave the inlet here anytime between 9pm and 2am. Then we’ll look at the wind and wave forecast for that time period – we need good crossing weather for an entire night and day in order to consider it. We also look at the weather on either side of that, because if there’s strong weather before or after our crossing, there’s a chance it may arrive early or something.

Wind and Waves

We’ve had very strong wind here for a couple weeks. Strong wind kicks up big waves, so even if we had a day of calm wind right now, it will take about 24 hours (give or take) for the waves to flatten out enough. Ideally, we want wind from the West or South, we want following or flat seas, and while we’re at it we might as well get a unicorn and some blinker fluid and a few other things that don’t exist.

We subscribe to PredictWind for our weather routing, the app doesn’t work well but it connects with our offshore hotspot (IridiumGo), and it has a couple other features like creating an actual route based on our specific data. The route is more important for longer trips offshore. For our purposes here, I’ll be using screenshots from windy.com because it’s easy to use, it’s based on the same weather files, it’s visually appealing, and it’s usually my starting point. If windy looks good, I’ll do the actual planning using PredictWind. After that we’ll keep checking the weather frequently until we leave to ensure nothing has changed. Super important disclaimer: we are NOT experts. We’ve been offshore less than 10 times. We have learned a thing or two about weather routing but we’re still figuring things out!

Alright, I’m writing this Thursday night so let’s look at the weather offshore right now!

Yeah, it’s a shitshow out there. I’m glad we’re safely at anchor. For the record, this is what tonight’s forecast looked like when I checked it a week ago – I thought this might be a crossing opportunity but that calm disappeared!

The potential opportunity I see on the horizon is next Tuesday (12/31) so let’s start with Sunday and look at the weather leading up to that. Here’s Sunday at noon.

Southeast wind, so we’d be going straight into a strong wind. Not great. Windy shows the wave direction, it doesn’t show up quite as obviously in the screenshot but seas are also on the nose, and 5 ft waves in a 6 second period (the period is the time from the top of one wave to the top of the next wave) are big and steep. I am 100% not interested.

Let’s move on to Monday.

A south wind, that’s totally doable! Those waves though…those are still pretty steep seas, and almost on the nose. We could sail, but we’d be bashing and it would be very uncomfortable. The boat could handle it, I’m still not interested.

Okay, so what’s Tuesday look like?

Oooh, this is interesting. Here’s where I really start to take a closer look at our weather routing. The wind is about dead and the seas are pretty flat. Yes, that’s a north wind, but it’s basically nonexistent. On windy, I’ll start at 9pm, hit the play button, and watch the screen for both the wind and the waves carefully. It starts out as a 12-kt south wind, then dies down as it clocks around to the north. We might be able to start out sailing and then motor the rest of the way. The seas are 3 ft / 5 sec, which is pretty flat, and they only get flatter.

Now I’ve got something to keep an eye on. It’s four days out so there’s still plenty of time for things to shift. The weather seems to hold until Weds afternoon when the seas get steep again, so this is a longer period of calm than I’ve seen lately. At this point I will check windy daily, if the forecast holds we’ll check windy and PredictWind and carefully discuss our plan. We want to make sure we’re choosing a good option, and not just taking the best bad option because we’re antsy to leave. We’d prefer to sail, of course, but I’ve been watching the weather carefully for weeks now and it doesn’t take much to build a steep swell out there, so if I have flat seas for 24 hours, I’ll take it!

Other Notes

If you’re into different weather models, you’ll notice in the bottom right corner of windy you can toggle between different models. The GFS tends to underpredict the wave height and I don’t ever want to be caught in bigger waves than I planned so I always look at the Euro model for waves. I’ve found things to be pretty accurate for the next 24 hours, beyond that they can shift a little. I don’t care to do more than one overnight without having the ability to check the weather, we now have a way to check weather when we’re offshore!

There are a lot more layers on windy than just wind, waves, and current. I’ll do a quick check of the rain layer just to make sure we don’t have any storms on the horizon. When we were doing our little offshore hops in November we checked the temperature religiously, offshore temperatures are usually much more steady, and the Gulf Stream helped keep it warmer offshore!

I think that’s a pretty good overview of our weather routing. We’re doing short trips and we’re never too far from land so it’s certainly not as intense as crossing oceans. The animations on windy and PredictWind are probably the only nuance I haven’t captured here, it’s much easier to see how the wind and waves can shift when looking at the actual programs.

As long as the waves look comfortable and the wind looks sailable, we’re ready to go! If there are any questions I’d be happy to answer, or if anyone has any better programs I’d love to try something new!