I don't think there are any operators running direct from Sattahip, all the diving in that area is based from a small fishing town at Samae San, 10 min's drive away. Ray Divers is the only operator actually based in the town, right next to a pier and their boat, Thai owned and well run. Not been on their boat for some time, customers are predominantly Thai's from Bangkok at weekends, but I do believe the boat is available every day subject to demand. I have heard over the years lots of criticism of this outfit, generally emanating from their farrang run competitors around Pattaya who try to discredit them to justify their much higher prices. DO NOT LISTEN TO ANY OF IT. Standards are at least as good as what you will get from any of the Pattaya shops and far superior to many, the main difference is that they do not operate a pick up / drop off service, but dare say if you don't have your own transport they would organise something for you, particularly if there are a few in your club?
Other than that all the other boats in the area are operated by the Pattaya shops who will transport you from Pattaya to Samae San, about 30-40 minute drive, Tread carefully. Real Divers based in Jomtien would be my choice.