Here are the wave predictions from OPC for the Atlantic (most of these long ones with long periods in the tropics are swells). Dakar at 15N, is just off the chart in the bottom right. The boat will have NE wind waves from the trades, riding on top of these swells. Very roughly speaking, anything we see that is below 7 or 8s will be wind waves, and the longer waves are swells from storms well north of them. Also the shorter period waves will not have much fetch behind them, whereas you will see the swell patterns clearly emanating from distant sources.
We have more specific data we will add here shortly. They are about to get underway, so we have to get this stuff together in the next week or so. If all works as planned, these data should be updated automatically every day. We shall see.