Looking for a manufacturer that makes a backrest that I could attach to the end of my flybridge bench seat so you had the ability to lean against it and keep from sliding off the benchseat. I've seen something similar on some Viking yachts and there's is removeable. __________________
Most of them are just made out of SS tubing with a padded and upholstered back piece mounted to it. Then it slips into recessed tube holders. Like small diameter rod holders. Or in some cases they use rod holders if the diameter of the tubing is big enough. Anybody who bends tubing could make that part and a good upholstery shop should be able to make the back rest piece.
I own an upholstery shop and as Bill mentioned, any decent shop should be able to create it and have it match existing upholstery.
Most sportfishers now install some custom made receiver cups that hold the backrest off the helm chair. It has to be made to fit whatever brand is installed but can work for all of them and usually is set up to have the backrest lean either forward for riding or aft for bait watching. Some also buy an extra backrest for the bench seat. All of the aliminum fabricators have made these and know what works for which chair manufacturer. Another option, if you didn't want to stow the helm backrest is to use rod holders like the well-known leaning post manufacturer (starts with an "A") and make a dedicated seatback.