For anyone who orders a ticket through the Archive Shop in Lydney High Street, opposite Tesco's, will be giving a percentage of the price to the 614 (Lydney) Air Training Corps.
"The date for your diary is Friday July 12," said ATC committee chairman Ruth Barber.
"It's a fantastic day out and a wonderful experience to cruise down the River Severn."
The Balmoral, built in 1949, is licensed for 800 passengers and has heated lounges, a dining saloon, bars and an open deck.
She leaves Lydney Dock at 9.30am and cruises down river past Chepstow and under the two Severn crossings. Going on down the Somerset coast she reaches Ilfracombe in Devon at 3.30pm, landing passengers and starting back at 5.30pm. She docks at Penarth at 8.15pm for a coach ride back to Lydney.
Tickets at £23.95 adult, £21.95 senior citizens and £12 children are available by ringing Mrs Barber on 01594 825047 as well as at the Archive Shop.
Lydney ATC treasurer Vicky Burgum said: "We are very excited about this trip. Most people don't realise that the ATC is funded by volunteer civilian committees like ourselves.
"We have to raise most of the money to fund activities and outings for the young men and women of the Forest of Dean who come to Lydney ATC."