I used the big 4 X 8 sheets of insulation foam boards. They are semi flexible to give you the curve you need. I spray painted them using some fading techniques and then used a wide sharpie to draw lines for the seperate board look. The mast is PVC pipe and the sail is a tan sheet that I cut holes in for cannon ball holes. Take black spray paint and quickly shoot the sides of the holes so it gives it the burned through look. Tear the sail to give it a tattered look. The crows nest is a laundry basket spray painted brown. The bow is an 8ft gutter downspout spray pained to match and I stuck a foam skull on the end. Thats the basics.. dress it up with ropes etc...
The lighting is a red light stuck within the ship facing up into the sail. In front of the ship are blue lights shining on the ship itself. The trick with lighting (anything) is to never let them see the source of the light. I also had a fog machine with a chiller that blew fog out and you couldnt really see the bottom of the ship as the fog laid low. I had strobes hooked through a lightining machine synced to thunder also.
To stand the 18 ft mast I used 8 inch pvc, with a 6 inch slid into it for sturdiness. (lost my first one in wind) To stand it up, i sledged a fence post. One of those green metal post/stakes for wire fences into the ground. Slid the pole over it. The roped it in all directions to the ground from half way up. I also roped the horizontal piece from the sides.
This should get you started....