+1
That's what astronauts are using on the ISS.

check out a book called 'The Naked Warrior' for really tough effective workout without any equipment at all.

I'm in the fitness industry and have tried all the 'modern' fitness gear, bands, balls, bells, tubes, programs, etc.

Based on a sailboat I would recommend TRX. I have used this product on a regular basis and recommend it.

Standard disclaimer applys

I'm not sure the actual method you use matters much. The biggest cause of failure is that people don't keep at it. And one of the biggest reasons is they are impatient and then, trying to make it work faster, they work it too hard and injure themselves and/or get too sore to continue. Once they give up for a day or two the equipment stays in the closet thereafter.