I'd like to suggest that either ships be given some kind of station that converts raw cotton into repairs or that raw cotton be allowed as a material for repairing relevant ships. The reasoning for this is that right now cotton is in a weird place as a repair material. It's very easy to gather and carry there's no denying that. But sailing is an endurance sport and cotton costs cp whereas wood and ingots not only don't cost cp but they also can be found regularly when pillaging other vessels in pve.
The issue that emerges is that cotton is only really good for sudden bursts of need to repair. Because once the tailor has reached their cp limit that's it they're gassed and that's not hard to do when a lot of dedicated sailors will spend hours upon hours at sea. And so while the other materials might seem more cumbersome to store this also ends up being a minor setback at best when the benefit of that tradeoff is "You can repair as much as you want as often as you want so long as you brought materials". The reason I propose a station is mostly immersion, the idea would be that this is somewhere you take your cotton to pretend you're making sails without spending cp on requisite cloth crafts. Hence why the alternative to a station would just be allowing raw cotton to be used.