I was taught that geriatrics - nowadays rebadged as care of the elderly - can be summed up as paying attention to eyes, ears, teeth and feet. How does this work on a boat? Older people constantly loose stuff, particularly their glasses. So carry a couple of pairs of reading spectacles from Boots, not so good for spotting buoys but OK for reading charts (or two older people could share reading glasses). Can’t do much about hearing aids, the older people will have to look after their own or be deaf to the skipper’s orders, or at least pretend to be deaf. Can’t do much about false teeth either, but these are not easily lost although they can be - and have been - vomited overboard. As for chiropody, get it sorted before the cruise, and if you can’t bend down to put your shoes and boots on bring a long shoe horn.
But there are at least three other things to worry about: getting on and off the boat, the prostate, and constipation.
Of course warn any crew about slippery pontoons in the wet, but older people don’t much like leaping from the deck, rather they prefer to step down backwards, so the skipper’s parking skills are important. Getting in and out of the dinghy can however be a real problem because so often the older person simply cannot bend their knees and hips enough to step up on to the side deck, or even up over those scoop things on the back of more modern boats. So get a suitable boarding ladder and sort out hand holds where necessary. If really stuck, cruise from pontoon to pontoon.
As for the prostate, make sure that the worst affected males have a bunk close to the heads or with easy access to the deck at night, but don’t let them do a Robert Maxwell and fall off the back – hold on to the boat with one hand and you know what with the other. Another tip for day time in the cockpit and night time use, is the plastic milk or other plastic bottle with a suitably sized (and sanded) hole cut in the side near the top – regular, medium, large and outsize (known as the Penton piss pot). Just occasionally there may be a real medical emergency when the afflicted male goes into acute and very painful retention of urine ie the bladder fills and fills, but the prostate gets in the way of the urinary outflow which then stops. Unfortunately the kidneys do not stop making urine and so the bladder goes on filling, and filling. Get help quick or take a urinary catheter with you to temporarily relieve the situation.
Constipation is best dealt with by prevention – plenty of fresh fruit and veg, prunes and so on. I hesitate to suggest you carry some surgical gloves for a manual evacuation but sometimes needs must. Otherwise retire to the heads with a good book and keep trying.
Finally, wear a lifejacket, hold on to the boat with at least one hand whatever you are doing (balance deteriorates with age, I know), and invest in an electric windlass, and even electric winches when you are really old.
In other words, adapt, and don't stop sailing. Like the 92 year old I met in 2012 at the Kip Boat Show, no reason to stop he reckoned.