User:Vincecate/Pipe Spar

Looking at Red Hawk Spar and thinking about using standard pipes to make a spar.

Lets look at [1]36" sched-40 stainless steel pipe]. This is probably 0.375 inch thick. The density of stainless steel is about 8000 Kg/m^3 or 8 grams/cc. At 36 inches diameter it is about 287 cm in circumference. If we have a pipe 150 meters long this is 8*287*150*100=34440000 grams or 34,440 Kg. Stainless costs around $5/Kg with a pipe being a bit more than this.

If we have 20 meters above water we have 130 meters underwater. Displacement for 3 foot diameter pipe is 1.5*1.5*3.141592 = 7.069 per linear foot. With 426.5 feet underwater and each cubic foot of water is 60 lbs, then 7.06858200 * 426.5 * 60 = 180885 lbs or 180885/2.2= 82,220 Kg.

After taking out the weight of the pipe, we have 82,220-34,440= 47,780 Kg for ballast and living space. If we use half for ballast then we have 47780/2 = 23,890 Kg for living space.