- emergency radio, emergency beacon, signal mirror
- iphone, waterproof or in a waterproof container
- signal whistle
- bright LED safety light & headlamp if you are on the water after dark or before light
- Sham-wow is better and more multi-functional than a big sponge, IMHO
- sun block
Several items of rare but important use can be vacuum packed and stowed out of the way to keep them together in a minimized size package and protected from salt water. The corner of the plastic pack outside the vacuum seal can be punched with a hole for a string or clip.
Rarely used items can all be tossed together in a dry bag or tupperware or vacuum sealed master-pack, stuffed away in the hull out of the way. Make it retrievable with a piece of paracord fastened within reach. My bilge pump was always rolling around in my hull somewhere. It's now on a string fastened near the hatch between my legs and easy to retrieve.
Live and learn