Seadog
I made it myself out of white melamine and two pine strips down the centre. The pine loosens up after a while, so a hardwood could be better or some 2020 aluminium extrusion with tee slots. Check that out on eBay.
I am thinking on what do do so I can make a gantry, maybe waterline maker better, but have not worked it through yet
Cheers
Geoff