DIY Garmin GPS holder

I happen to have a Garmin Nuvi 500 for a boat with naval maps. Decided to put it on a Spark too, so I ordered a second holder from Garmin. Fixed the holder to the hatch with stainless steel bolts (forget the std sticker or the vacuum system on a marine kit if you don't want to lose the GPS). The pivot is the weak point in the holder if you hit the unit with your knee etc. and don't want to lose the GPS so I secured the holder to the leg with a fishing wire. Works.