OK...to sum up, besides boat & trailer we have:

PFDs (with attached knife & whistle)
rash guards
wet suits
sail box
beach wheels (if trailer launching not an option)
righting line
harnesses
gloves
footwear
Boat US membership
cellular phone
VHF radio
dry bag(s)
spare parts (shackles, rings, wire, duct tape, etc.)

...and beer.

Probably better also include:

multi-tool
flashlight
batteries

Anything else?