BCF is just one outlet "Salt Away" dispenser is usually available from - about $70. Salt Away product reputed to be very good stuff but some may differ - its not cheap. Google it to find out more.

I went one step further and installed a petrol pressure washer on the front of my trailer with a soap injector to wash my boat down. Works a treat! Boats also to big to fit in the DIY car washes.

 Jesus that looks like something off the set of Mad Max

Sorta looks like it's got a face haha 

 i use a weed and feed bottle (once emptied of coarse). Works perfectly. 

Put a bit of soap in then top up with water. 

 I used to do the reused boat wash pack same as weed and feed pack but found a hortex insect and fertiliser dispenser at Bunnings you don't need to pre mix the detergent as you can adjust the mix on the top of the gun. They aren't cheap but they're a bit easier to use with trigger action, mine would be 5 or 6 years old and works a treat  Use it on the boat and the cars

 Have a look at a product called Salt-away. It's sold at BCF and other outlets.

i think this is probably what you saw.

it dispenses a soapy substance and then you can move the lever and it will rinse the soap off.

I have one and it works a treat but is a little on the expensive side....... my kids bought it for me.

cheers

 Try googling a product called Ausaca Ezy Jet

Company is Vic based but may have WA distributor

I bought one from Bunnings about 2 years on clearance for $5.00 , wished I had bought a few spares

Has a jar that you fill with liquid soap and then connect to a hose , I use mine on my boat , works awesome

Cheers Katman

 I Use a Hydro Foamer with boat wash and wax ,soap comes out like shaving cream and hangs on the boat which saves a shit load of cleaning then just hose off