I'm not sure what a sail training charity is but a few ideas for fund raising:
-charity walks, with participation fee
-charity bike rides, with participation fee
-charity silent auctions
-mail shots to as many people you know and get hold of club mailing lists to mail to people you don't know.
-publicise in newspapers, newsletters etc
I have just completed a 70 mile bike ride for MS Research, my sixth year, and have raised over $20,000 over those years.
Now that I am retired, I can't go and bully my colleagues and subordinates, so I mail to about 400 people, get my picture and a little blurb in the local paper and always carry my pledge sheet. Hope that helps.
Prepare a quiz sheet with some reasonable questions, and not particularly good prizes. It's amazing how many people will pay their £2 for the sheet, and never send it back! This involves all your contacts selling a lot (maybe a little prize for the seller of the winning entry?)
Here's an idea - why not sail around the coast of the UK in a 14-foot dinghy, sailboard rigged, with only a mobile phone, setting yourself tasks such as a minimum number of coastguard rescues, several flares fired at ASR helicopters etc. etc....?
In all seriousness, I quite like the idea of a Treasure Cruise, not unlike car treasure hunts. For instance, aimed at a particular area popular with sailors, like... like... well, okay, like the Solent... clues could involve sailing to certain waypoints, locating transits and taking bearings, which are then decoded or collected on a sheet. It would probably take the whole weekend, and would naturally be sent out in advance to most competitors... at least the night before for latecomers to plan routes and overnight stops according to wind and tide....
It won't make anywhere near the whole amount, but will be fun to plan and organise... ten pounds per boat to enter?