This is an interesting topic. I help Frank with the maintenance on Hayling Rescue. He is a one man band who offers 24/7 Rescue and Recovery in the Chichester Harbour and Hayling Bay area. He operates solely on donations and whatever he can get from Boatman work, cutting ropes from props, moving boats using his RIB and of course towing boats off that have gone aground or broken down.
It is nearly impossible to make a going concern from doing this sort of work as nobody wants to pay and because the RNLI don't charge, everyone expects these services to be provided for free! It is an astonishing situation!
I help out doing safety Boat and support stuff for events organised by Hayling Island Sailing Club using my own RIBs. The best I can expect in return is £25 per day for wear and tear plus fuel. You have to be careful where you charge more as you then move into commercial territory which will inevitably bring coding etc. I am advised that I could possibly charge up to £100 per day before crossing that line.
If you are thinking of offering safety cover with your RIB for club events, be aware that most clubs have virtually no budget for this as they invariably cock up the projected budget for an event that will often be arranged 2 years before the event takes place and to try and make the venue as attractive as possible to the class, they negotiate the lowest prices they can, leaving no flesh on the bone. There are emergency organisations that have come to light since last winter and all the flooding that may be interested in recruiting your services? SERVE ON
If you are considering going this sort of direction and haven\t bought a RIB yet, you might consider getting something with a Jetdrive as it is ideal in situations where people are in the water and if you help with floods and are travelling along flooded roads etc, wont have to worry about clouting the prop. The other bonus is the manouverability that a jet gives you, although they take some getting used to after a conventional leg and prop.
Good luck with your venture, I look forward to hearing more.