When you dock up you need a crew member on certain points to throw lines onto the cleats on the docks (or bits/bolalrds for bigger boats) to tie up. Also, for anchoring, you need people manning the anchorline. I dont know of names but a crew would probably be locals so the type of names in the area (im unamiliar with south africa.)

Maybe the crew could be a bunch of badass Boers who are ex special something-or-others

For the boat, why not an aluminum-hulled 80-foot PT-type boat? You could replace the Alisson engines with desils, or for crazy speed, gas turbine engines. It would be large enough to fit everyone, small enough for 6 people (PT boats went to war with a crew of 13), though you might want to hire 3-4 crew so they can pick you up in a hurry if TSHF. FYI, most PT boats had 2x twin .50 cal mounts and a single 20mm cannon on the aft deck. You could put a single FN MAG/South African equivelent in place of the .50s and a .50cal in place of the 20mm. On the other hand, some PT boats were converted to gunboats and bristled with machine guns and light cannon. You might put a twin .50 mount like on Vietnam PBRs in the front deck.

Maybe have some local mariners be the crew types, doing line handling/ships maintenance. Have an ex navy or ship captain help on the bridge, and a few military types for security/be a ships officer type, liek relaying Johhny's orders among the crew.

I haven't gotten far into the story. I'm just now writing a scene where Greg is having breakfast (which consists of braaied boerewors and coffee thick with cream).

You can barely get essentials like medicine in Africa, so where is he going to get a luxury like cream?

There's this wonderful, magical animal called the goat. They produce milk and bleat excessively. He could get cream from the goat's milk.

I was thinking a goat as well. But then you have to feed it too.

Im thinking a 100 foot-range patrol boat would be good, can take heavy seas, crews usually around 15-25 depending on mission, powerful but manuverable and low enough draft for easy harbor access and good deck space or weapon platforms. For the story is it okay to take a few libverties (i wouldnt want to name you of a boat class with only ten made or one that wouldnt be sold/exported if you were going for the common surplus route)

Good idea. All I need is a mission for the mercenries. Any suggestions?