Dee Caffari struggles in currents off Cape of Good Hope but the wind is in her favour 31/3/06

Date30 March at 2344
PositionS37° 1’/ E29° 49′

With regards to the local topography of the seabed and the currents in this area, this approach to The Cape of Good Hope is fascinating as well as being extremely frustrating.

The Agulhas Current runs down the east coast of South Africa and reaches speeds between two and five knots. It is a warm water current and in parts the sea surface temperature reaches as high as 26 degrees. Therefore, if you get it right you can sit in a bath like conveyor belt to the corner. If life were that easy then everyone would be doing it.

Just when I am so close to getting a break and a small token of something helping me on my way, we also have to consider the currents movements and the seabed. As we close the continental shelf there is an increase in seamounts, plateaus and ridges on the ocean’s seabed. These all have an effect on the waves in the area and also influence the flow of the current. The current therefore unfortunately doesn’t just flow in a straight line. Eddies are formed and counter currents occur.

Today I have had winds increase to 30 knots as the high pressure slid east away from us making progress good, or so I thought. I have been pushing Aviva quite hard. The water has been relatively flat and we have been reaching with the wind on our starboard beam. The boat speed has rarely dropped below 9 knots all day and has often been over 10 knots. I was pleased until I saw the speed over the ground on the GPS. It was showing a good four knots slower than my boat speed. How depressing! It seems that we have found a counter current from a back eddy and as we have been sailing west, it has been flowing east. There are a number of these around and I just have to sail fast through them until I find myself in the true current going in the right direction again.

The sea surface temperature should illustrate the strength of the current. When we are in the strongest flow the temperature will go up. Again with the ocean varying in depth so much this creates pockets of cold water. Just today alone in the space of five hours the sea surface temperature had dropped from 22 degrees to just 16 degrees. Similarly it returned back to 20 degrees in only three hours.

These temperatures and fast flowing water attract a great deal of marine life. In addition to whales and dolphins, there are often sharks, so now is not the time for a quick dip, no matter how warm the sea temperature gets. As we closed the coastline last year, we also saw seals and penguins. So far I haven’t seen any marine life, just my bird buddies keeping me company, but I shall keep my eyes peeled.

I am being very fortunate to have reaching conditions as I round the Cape. You can only imagine that warm fast flowing body of water meeting a westerly gale at the continental shelf and the results that it can create. It would create a huge wind against current scenario with short, steep, breaking waves and no shelter. At last maybe my luck is turning

Dee and Aviva