HI there
Langebaan has some good spots for cob....locals call it "die lyn"...close to Geelbek. If you launch your boat at Langebaan, travel to the left of the Lagoon, past the yaught club. "Spreeuwalle" is also good for cob but you are going to burn quite a bit of fuel to get there. "Spreeuwalle " is to the right...toward Saldanha if you launch at Langebaan. White stump on the other hand can be caught basically anywhere in the Lagoon but the best spot in my opinion is about 200m straight ahead toward the Island after you have launched. If you have proper tackle you can actually cast that far from the beach. If yiu want to I can try and get the GPS coordinates from my father in law for the cob spots.
Cheers,
Morné