It's funny you mention it, I've not been able to do it either, we use the shower spray lol
I know you have to open the tap in the engine bay for it it allow the sea water in but I've done this and despite pumping the handle it's never flushed. Sorry I can't be any more help. I've only had the boat since July so I'm still working out the bits.
Hi Steve, thank you so much. I do need help with the toilet. I can't seem to get it to pull water in from the ocean. When oumped the water goes down (I have to add water with a bucket). Any suggestions?