This is part of a collective, consecutive, fast set of A Series of Errands for Lucky.
Mission: Sneak onto a rivals boat and non harmful sabotage
If caught can try and dive in/jump and swim away (Athletics DC 10 and Stealth DC 15)
Get on the boat by Stealth DC 25, or Athletics DC 12 (swim) + Athletics DC 14 (climb) + Stealth DC 15
Find something suitable non-critical to sabotage (Perception DC 17); Hide something that will hurt a sailor (but not permanently) at just the right time as a message (Sleight of Hand DC 14; failure means the crew finds it before it happens and sabotage will not work)
Get off the boat without being seen [same as getting on in reverse)
Reward: 50 silver + expenses; if Sleight of Hand passed get an extra 50 silvers