Ok, just to be clear before I go on about this, I'm not a nutritionalist, and I'm probably the last person to talk to about 'good dieting' as I'm a chocoholic and eat ice cream like no tomorrow. I do try and go plant based, but it usually doesn't work and I compromise by being more vegetarian, even that route fails at times!
So, nutrition whilst swimming! I've tried to find general information about this topic and I must say, I gave up after a while. You could probably work a few things out for yourself, but a lot will depend on past experience, if any, and the swim you are taking part in. I'm pretty sure my stomach is nuclear proof as most things generally don't upset it, but I know a few people who have tried to used something like energy gels and they caused some unwanted results.
If I'm swimming an organised event, like a 10km swim, I tend to use the stuff they have on offer. I'm not fussy about having my own special concoctions made up. The event organisers tend to be sponsored by someone and they use their energy drinks, gels and chews etc. Smaller swims, I tend not to bother. I don't swim fast, so I'm not burning through my energy reserves.
For longer endurance swims, like my 6 hour qualifier, 1 and 2 way Windermere swims I use a mix of energy drink, Torq, and solid foods like bananas, peaches and some gel blocks for the end of my swim. I try to keep it simple, mainly for my support team as they don't need to be messing about at each feed.
For my 2 way Windermere swim my feeding pattern was simple too. First feed was at 90 minutes, 2nd at 70 minutes and then all other feeds at 40 minutes. I found 40 minutes to be a good gap between feeds as it wasn't too short nor was it too long. I also couldn't easily try to work out how long I had been swimming for.
One thing to be aware of, when picking solid food make sure it is easy to swallow. The last thing you need is to be chewing on something for a minute, trying to swim and risking choking. I've tried things like dried dates and Soreen bread and have had to spit them out - a waste of food and no energy taken on board.
In the future I want to get away from the energy drink powders and start to explore more natural foods, but I will need a lot more understanding of what things can be used as a substitute.