Yes, mounting a fitting to a plastic sea kayak deck is pretty easy.... place, drill, seal and bolt.!

The reason however i am writing this Instructable, is that i really dislike any thing metal and potentially "sharp" protruding into my kayak cockpit or hatch space, waiting to "bite me" during the perils of kayaking.. ( wet exits or blind hand sweeps...)

So..... while i was installing this fitting i, found a great way ( completely accidentally ) to cover up these potentially sharpie bits.... just laying around in my shed...

Image (a) My finished GPS mount on deck

Step 1: Parts Required

What i used:

Garmin GPS Marine mount (2 parts-deck mount & GPS mount)
Three stainless steel bolts (length to suit plastic kayak deck+ 10 mm)
Three stainless steel washers
Three stainless steel Nylock nuts
2 x Spanners to fit the bold and nut
Three Weather seals(the secret ingredients = Image (d))
Sealant
Rag with clean up fluid(suit the sealant clean up requirements)

Step 2: Placement

First i put some consideration into the optimum position for the GPS fitting.(so that it was both easy to read and i could reach the keypad with ease from my position in the cockpit)
This resulted in the "optimum position" being right over the top of the cockpit, and thus the stainless bolts would protrude in the cockpit - away from the legs - but there was always the potential for "snaggyness" in the wet exit's that don't go to plan......

So, i placed the mount

Drilled the holes
Tested the bolts
Removed the mount and layed a ring of sealant around the extreme outside of the three holes
Replaced the mount with the holes lined up, and put a dolup of sealant into the countersink spots on the mount
Pushed the bolts through.....Image (C)

Step 3: The Secret Useful Extra...

Image (D)

Then on the inside of the cock pit,;

First place the stainless steel washer on the bolt
Then slide a "Weather seal" up the bolt (with the little cup facing down as shown)
Then the stainless steel Nylock nut
Tighten the nut up against the weather seal and washer.
Fold the cap over the bolt end and push until it locks in place.....
Repeat for all bolts

Hey presto - a nice safe end on the bolts, as seen here in Image (E) - the completed installation