Sally enjoys canoeing but fatigues fairly easily due to Multiple Sclerosis. It is possible that simply pairing Sally with a strong partner would give Sally the option to paddle less strenuously and rest when she needs to. The technique Sally uses will also make a difference. If Sally pulls the paddle blade slowly it will create less turbulence and require less effort. An effective seating position will help maximize Sally's strength.
Some people modify canoe seats to provide back support.
Sally might consider support for the canoe seat. Since the canoes belong to Center Activities it is more plausible to use seat support which is removable. One possibility is using folding camping chairs, such those manufactured by Crazy Creek or Thermarest. For more info go to Crazy Creek Paddle Selection For individuals, such as Sally, who have decreased arm strength the weight or shape of the paddle may make a difference. Although Center Activities only has one variety of paddles it might be helpful to look in the community for a lighter weight , longer paddle or a bent shaft paddle .