Sea has always been a little jank. The current version of sea feels a bit unwieldy and there have been some changes(That I have not played with) to attempt to fix it. I'm not talking about corsair today, I'm talking about everything with AOE or rampant firendly fire at sea, primarily Duck, Torpedo Boat, claymore.
Ducks are an awkward unit to use enmass because in shallow depth or even on land they suffer from the same issues as pyro, hitting themselves from the back. Like 2 weeks ago there was this game where Godde had a warlord but an aly of mine tried to snipe it with ducks. they did good damage, but every time they fired like 3-5 ducks would die to friendlyfire, and linemove can only work so well when you have like 30 of them and their range is so short.
Torpedo boats are listed as a raider but I feel their utility is more anti-sub as they trade favorably against seawolfs and have some AOE that helps against underwater swarms of ducks, seawolfs, or scallops. but the AOE is also a curse, because in shallow watters when they get in some nasty mix of goodies and baddies together they will friendly fire with their AOE killing themselves and their allies along with their enemies. this can happen frequently because their range is so short and the range of the things they counter is so short, so they'll collide very easily when fighting.
Claymore is a good anti sub weappon, and a good anti sea wepon overall. It hits a target and does massive damage in a big AOE after a delay. it has more range than underwater units. it can kite them and kill them. but it seems to have resistance to it's own damage. I've tried countering them by peeling one unit off and charging it straight into a claymore ball, but the claymores don't die to just that, sometimes it feels like they still have over half HP. This is incredibly frustrating to play against, maybey because I should be building some other unit like rocket ships and outranging them. but with 1200 HP and good movespeed it's a war of attrition I don't feel like investing into considering that mistrals are runied by subs. Claymore having some kind of anti-FF where as these other units don't feels really punishing.