To be honest, there's not much to go on. There are a number of small craft in the picture, most of which are unlikely to be internationally registered or classed, making positive identification very difficult. The only thing I can say is that the vessel in the centre seems to be some sort of fishing vessel, whilst the vessel on the left appears to be a former oilfield supply boat, probably US-built.
I would say the vessel in the centre is a fishing boat. The two craft to the right of of the photo appear to be landing craft of sorts. The larger one is probably involved in some sort of construction work as there is a large crane on deck. To be honest, I was not sure which "unknown vessel" you were referring to given that there are several in the photo.