I carry a spare Mirage drive on my AI's, but my TI already has a second drive and the space to store a spare is more of a premium on the TI.
I have a good stainless pliers mounted on my PFD as well as a titanium knife, both have proven useful and low maintenance. All other tools and parts are either in the rear hatch deep gear bucket sealed, or in my ditch bag. Steel tools do rust quickly. I found I had to rinse and oil all of them each time I opened my sealed plastic "tool box", so more stainless ones are being procured and kept in the rear hatch bucket with most of the rudder pins.
A Kayak pump is at the top of my recommended tool list for any kayak.
Maui is a great place to sail, and even more fun sailing with others like Geoff!
- - - - - Hobie Island Sailing since 2006 - - - - - 2011 & 2015? Hobie AIs and a 2012 TI