Not a problem being new to this, don’t put foam in the mast as it will absorb water and make righting your cat harder, cover every rivet or hole in the mast with silicone and make sure it’s water tight and that is better than foam as the foam only floats the mast due to the air inside it
Pardon the interruption for a new or different topic. My old boat was a Pacific Cat and it was super fine for sailing inland lakes in Texas although I know it was designed in California for salt water sailing off beaches. It had a lot of features that the later Hobies, tornadoes, etc didn't have including a solid deck instead of a tramp with wells in the hulls for your feet. It make sailing a cat much more comfortable. I know lots of new and younger sailors want to show off their speed and race, but I'd be happy with a small daysailor instead of making the jump to a full cruising cat. The cockpit in the hull variation doesn't make one a comfortable ride iMO. Any ideas or conversation?