Simply changes weather type after spending some time in a boat.
Boat Thunder – Enhance Your Ocean Adventures!
Looking to add more excitement to your boat journeys in Minecraft? Boat Thunderstorm is the perfect mod for you! This mod triggers a (vanilla) thunderstorm after the player has been sitting in a boat for a while. It introduces a new level of unpredictability, making long boat trips more thrilling and immersive.

You can run this mod on both Client and Server side.
No! Only dedicated server needs to have mod installed, other players can join without mod installed. This includes singleplayer worlds connected with LAN or Essentials etc. where only host needs mod installed.
There is a uncommon chance that boats or ships from different mods will trigger thunder because my mod checks for vanilla boats, only way is if devs made them a part of Boat class.
I might make compatibility with other modded ships at some point, but don't expect it in near future.
No incompatibilities to current date by my knowledge. No dependencies either, just put the jar file in mods folder.
It was created in Eclipse IDE.