[EDIT]: There is a TL;DR at the end now.
Healing potions for players and boards to repair ships on the fly could potentially reduce the amount of time spent retreating and waiting for natural regeneration in between fights.
Instead of up to a minute or more for your health, you could spend a few seconds drinking a potion, then go right back into the fight immediately. Of course, there’s always the issue of keeping it balanced, so I would suggest limiting the amount of potions you can carry to 3, and each one would heal around 60% health (just a suggested amount, could be more or less). The cost of buying potions and boards would scale with your level, and they would not be tradable (no alt cheese). There would also be a risk involved in using them. In order to even attempt to drink one, you would need to be standing on solid ground, and hold perfectly still for a few seconds (on a ship, the ship can be moving as long as you aren’t doing anything else like walking or attacking). If your animation gets interrupted by an attack (a direct attack, so not a cloud, puddle or DOT), you would not be able to finish drinking it, and the potion would not be consumed from your inventory. One last thing, if this healing rate is still too much, an additional cooldown could be applied after a potion is consumed (though I doubt it would be necessary).
Boards would work in a similar way as potions: requiring you to be still, standing on your ship, and not taking damage for the duration of the animation (again, only impact damage would stop you). The animation would likely consist of you bending down or kneeling and then hammering a board into the floor. This would likely restore the same percentage of hp for your ship no matter how much it has (I’d say 30%), but the more hp is has, the longer the animation would play for. In other words, tanky ships would be more difficult to repair while in combat. I would also suggest limiting who can repair your ship, due to large teams of players potentially all having their own boards to use. For that reason, it would be best if only the owner of the ship could repair it.
TL;DR: Potions for players and boards for ships. Potions heal you 60%, boards heal your ship 30%. You can only hold 3 of each, using them can be interrupted by getting hit, and the price to buy them scales with your level.
Possible questions you may have
Q: Would this lead to players in pvp always running away to heal?
A: Unlikely, since they would need to get far enough away where you couldn’t stop them from using the potions, which would basically end the fight either way, and you could also heal yourself when they run so it goes both ways.
Q: Wouldn’t this make healing magic useless?
A: No, because healing magic will probably work more quickly, and without the potential for interruption (or at least one of those two possibilities). Although, I suppose it’s a bit too early to consider how that will work.
Q: Wouldn’t this invalidate getting your boat repaired at a shipyard?
A: No, because boards would only be a temporary fix, as they don’t heal as much as potions, and you’ll run out of them pretty quickly if you try to rely on them too much. In other words, they could be just enough to get you back safely (if used right) but you’ll still need to return to the shipyard at some point.
Q: Why not just have the potions and boards be sold for a flat rate? Why do their prices need to scale with your level?
A: These are the kinds of items that would be stay useful for the entire game. Due to their immense usefulness, it would be unwise to let players get to a point where they can spend practically nothing to get them. It would also not work to just make them super expensive, as lower-level players would miss out.
Q: Why would clouds and puddles not stop players from healing?
A: If a players is to be stopped from healing, it should be done via a direct action. Filling the battlefield with clouds and puddles leads to plenty of automatic damage, but there’s no impact there that pushes them out of the drinking animation.
Q: Wouldn’t this ruin boss fights?
A: One, the bosses wouldn’t give you too much of a break, so its already a big risk to stop moving for a few seconds. Two, even if they did pause long enough, you can only heal a few times (you can only carry a few potions, maybe 3 at once). Three, if that healing is too overpowered (which I doubt) it could simply be made so that you can’t heal while near a boss (a lore-based excuse for that would be that the situation is too tense for you to drink a potion).
If you have any other questions, feel free to ask.