They are no longer being made. That was the original product before it became Navman. Standard Horizon specialise in
Radio communication and
GPS now and are no longer made in NZ.
When you say a "propellor" is this a paddle
wheel?? If yes, Airmar make the paddlewheels and you can find a lot of info on their site. I got a paddle
wheel for the SL50 via finding the info on Airmar's site and then
buying the required model paddle wheel off Ebay.