Painting the hull and deck of PT-109.

I recently purchased the PT-109 PT Boat by Revell, but the instructions are very vague! It doesn't say what color to paint the Hull & Deck? I figured that you would paint it either dark grey or light Grey? Probably dark grey, because it's showing in the picture of the model, that the lower half of the Hull is lighter then the top! If someone has an idea or opinion about what color it should be painted, I would really appreciate it! Thank you.