Jolodo,
Also consider using Sculpt-a-mold. I generally speaking, use it before adding plaster. I will be using foam, then plaster cloth, and finally sculp-a-mold when I begin my waterfront. Some skip using plaster cloth and just put the sculpt-a-mold directly on the foam. I probably will not use plaster at all for this project. Let us know what you decide and the results.
Dave