Crew were tasked just before midday when the Vos Sentinel was struggling to locate a fast rescue craft that it had dispatched in the foggy weather as part of an exercise north of Lerwick.
The craft was found off Wadbister by the Lerwick Port Authority vessel Knab, with all crew on board safe and well.
The lifeboat was tasked again on its way back into Lerwick to come to the aid of a 14-metre yacht which was having problems off Bressay.
The Kimluan, which had three people on board, had become wound up in its own ropes.
The lifeboat towed the yacht into Lerwick’s small boats harbour by around 2pm.
Coxswain Darren Harcus said: “We were pleased to be able to assist in both the search and tow-in this afternoon, thankfully with both ending with successful outcomes.
“The wind has been increasing this afternoon and the crew on both vessels did the right thing in calling the coastguard and asking for assistance as soon as they realised they needed it. Our volunteer crew are always available to respond to 24 hours a day.”