The garment is amazing when used complete. If you wish to wear the garment without the cap be prepared to get wet. They use similar tubing to IV lines. Next time you're at a hospital maybe bring the cap along and test my theory. The other side of this problem is the garment itself requires the cap to fully function. As the lines to the cap are approximately through the middle of your back, the cap completing the piping to the other half of the garment.
Also... the chin strap is annoying, I'll probably cut it off and have it altered to a velcro strap if needed accessory.