The Misses Robertson of Kintail and her volunteer crew launched just after 5pm and made their way across Peterhead Bay to the Princess Royal Jetty at the ASCO offshore supply base.
On arrival, two crew members were put onshore and led to the bridge by the local coastguard rescue teams.
On arriving at the bridge, they immediately began the RNLI Casualty Care process, relaying all information to the Coxswain.
The team decided that the best course of action was to reposition The Misses Robertson of Kintail alongside the vessel.
With assistance from the coastguard rescue teams and Scottish Fire and Rescue Service, the casualty was transferred to the ALB for forwarding to the hospital via sea.
On arriving in Aberdeen Harbour at 8pm, a doctor was at the quayside to perform another assessment on the casualty.
They were then transferred to the Scottish Ambulance Service and onwards to Aberdeen Royal Infirmary.
Commenting on the incident, crew member Michael Ritchie said: “As soon as we launched, crew member Craig Aird and I made our casualty care equipment ready and when we reached the location, made our way to the casualty and took over from the local coastal rescue team.
"We assessed the situation and realised we could not resolve the patient's health issue.
"We therefore deemed it necessary to get the casualty to Aberdeen Royal Infirmary quickly.
"We stabilised the patient, transferred them to the Peterhead Lifeboat, continued our observations, and kept the casualty stable until we reached Aberdeen harbour and moved the care to the Scottish ambulance service,” he added.
Volunteer duty Coxswain Pat Davidson said: “Again I want to praise my fellow crew for what was the second medical emergency in as many days where the team dealt with the casualties in the most professional manner.
“Everyone at Peterhead RNLI wishes a speedy recovery to the person concerned.”