Rehusa Channel

Wind Horse finds her way across the shallows to view gray whale mothers and babies in Rehusa Channel.

chart for Rehusa channel

At the south end of Magdelena Bay lies Rehusa Channel. This is a rarely visited part of Baja, which sees only the occasional panga with its crew of Mexican fisherman. It is a heavenly spot for watching gray whale moms and their babies. The only problem, as you can see above, is that it is tough to find your way across the shallows which divide Rehusa from Mag Bay.

The depths on the US chart above are in meters. Of course the chart is only a rough approximation of where things lie. You need to find your way through this maze.

Rehusa Channel chart vs. Google satellite image

Our new friends in the Mexican Navy indicated that the route shown on the chart should get us across. But then we always treat "local knowledge" with a healthy dose of skepticism. Speaking of local knowledge, here’s a Google satellite image of the area. The only problem here is we do not know the date of this photograph, and as it turns out, things have changed a lot since it was taken.

San Diegoa tidal cycle

When you work your way through shallow areas like this you want to be sure you are not doing it on a really high tide. If you were to get caught on that high tide, it might be a month before you got off. In our case we are on the lower high tide for this day. We timed our approach to an hour before high water, so that we’d have maximum depth, but still something left if we needed to float ourselves free. Wind was light. If the breeze had been strong towards the shallows, we would not have tried this (as the wind could have held us against any shallows on which we grounded).

The image above is the tidal cycle for San Diego, California for the day of our crossing. It just so happens that the coast of Baja is referenced here at almost the same time and height. The tidal data is from Nobeltec’s program.

Rehusa Channel: Shallow water

Although we now have SONAR, we still find a depth finder and visual navigation the best tools. It is amazing what your eye can pick out if you are looking. The only caveat is that you need good light, and the light needs to be preferably behind you, or at least on the side. In this case the sun was overhead and in front of us, so our ability to read the water depth was limited. Our track across the one shallow spot we encountered is shown above. We were down to 5 feet (1.5m) at this point, and turned to port back towards deeper looking water. That did the trick.

gray whales spy hopping in Rehusa Channel

The following three photos were taken with a 70-200mm zoom, at minimum zoom. The whales were so close we almost needed a shorter focal length lens. Gray whales were "spy hopping" everywhere we looked, once we got into the area. We were an obvious curiosity.

Gray whales in Rehusa ChannelBay, Mexico

This was a pretty good-sized whale, and with all those barnacles we assume it is a mom. It came right up alongside.

extreme close up with gray whales in Rehusa Channel

Here’s another visitor, again right alongside the hull.

gray whale breaching in Rehusa Channel, Mexico

Of course there was a lot of "breaching" going on. This whale breached three times in quick succession.

breaching gray whale in Rehusa Channel, Mexico

One of the factors that needs to be considered in Rehusa is where to anchor. We had a projected 25- to 30-knot northwesterly on its way, so we needed a protected spot.

choosing a spot to anchor

Using visual cues and sonar, we found this spot in the lee of the beach. The chart bears no resemblance to reality, but the track is useful for retracing our steps through what we know is deep water. The protection from the northwest wind is good, although there is some swell coming in from the ocean. You would not want to be here in southerly quadrant winds.

how to recognize a shoal

This is looking at a shoal spot, just after high water. If you look closely across the middle of the photo you can see an area with a different surface pattern. That is a clue that something is going on here. It could be shallow water, or a current shear. Either way, it is cause for caution.

how to recognize a shoal

The same area half way to low tide, now showing a nice disturbance.

using radar to choose an anchoring spot

This sort of surface turbulence will also show up on radar. In the image above, the surface break is clearly shown, starting at the outer edge of the second ring. The closer in targets are wavelets, i.e. sea clutter. Radar can be a great tool for this sort of work, but you need to be sure the sea and rain clutter, and gain settings are correct – otherwise the wave pattern for which you are looking may be masked.

using sonar to choose an anchoring spot

And then the sonar image. The top half of this is a horizontal slice, while the bottom is a vertical slice. In both cases the shallow water we see on the radar and with our eyes is clearly shown, although there is quite a bit of reflection from wave turbulence.

Rehusa Channel white caps and whale spouts

This is the breeze the next morning (you can see a whale spout in the foreground). It was blowing a steady 20 to 25 knots, too much to make whale watching fun, and the anchorage was better suited to more temperate conditions.

San Diego tidal cycle

The tidal range for today is a foot (30cm) less than yesterday during the daylight hours. But as we now have the sun behind us, and can clearly see the shallow spots, it is much easier to find our way staying in deeper water.

gray whales with tails up

Speaking of which, the gray whales are usually good markers for the deeper channels. They seem to need more draft than Wind Horse (she only requires 5 feet/1.5m). However, we saw several groups of grays in what appeared to be a head-down, tail-up position in shallow water. We think they might have been rubbing barnacles off their heads, but this is just a wild guess.

If the weather was settled we could see spending a week or more hanging out with the grays.

Post script: From time to time cruisers have discussed entering Magdelena Bay from the south, via Rehusa Channel. Our advice is – don’t. The whales and panga fishermen use shallow and narrow passes, but these break and are not in any way suited to even a shallow draft yacht.

Posted by Steve Dashew  (March 10, 2007)

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