Cachalot Whales relentlessly and agressively hunt down any player ridden ship from the mod SmallShips, these ships usually have a large hp pool, can be repaired, have an inventory and are generally a larger investment. As of now (Forge, latest 1.20.1 Version of AlexsMobs), the whales will always oneshot the ships, probably due to them inheriting traits of vanilla boats.

Could this be fixed on your end? Can you add a bandaid solution of a blacklist for entities the whale shouldnt aggressively attack?

@RainbowSaber Cachalot Whales are neutral until attacked, and they tend to try and follow peacefully behind or alongside players in boats. Unfortunately, by default Small Ships deal collision damage to entities, which is aggroing the whales. If you go into the SmallShips config and change the option shipGeneralCollisionDamage to zero, this will prevent the ships from dealing damage to entities they collide with, and the whales won't have any reason to attack the ships. You probably don't need this option on anyway unless you're doing PvP and ramming other players' ships.

Interestingly, the Cachalot Whale is actually present in the Small Ships default config, as a member of the blacklist of entities that are not allowed to get on board a ship and occupy a seat, so the Small Ships mod author seems to be aware of Alex's whales.

Thats a quality answer, I greatly appreciate the effort you put into this, however I believe that it would be preferred to have an explicit exception for the whales boat instakilling behaviour so that the mods work as intended out of the box. In theory I think both ramming whales with ships to damage them AND whales attacking ships, threatening to break them is interesting gameplay that adds tension to ship journeys.