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.