We finished glassing down and sanding the electromagnet mount on the bottom of the sub. This pics shows one being tested. The 40 pound weight is being held in place by the electromagnet. I wanted a sphere for the drop weight so it would roll off the hull if the sub was upside down. Kettlebell weights are prefect for the job. They are spherical, come in all sizes, are iron that the magnet really likes and they even have a handy handle!
Brilliant!