Nab is an orang utan who lives on Noah's Island. He came to the Island following the wreck of the ship that was transporting him and the other zoo animals to another zoo.
Soon after arriving on the Island, Nab was appointed chief engineer by Noah due to his intelligence and ability to understand how the Firebowl worked. Since his appointment, he has always liked it when characters have addressed him as 'Chief Engineer', and has successfully steered the Island on many occasions, using the Fireball's power. His first assistant in the Firebowl is his adopted nephew Jasper (being a proboscis monkey, Jasper cannot be Nab's nephew by blood) and his second assistant is the Valve Rhino, who pushes a heavy stone to release lava into the ocean.
Nab often lacks self-confidence, especially when placed under pressure, and doesn't always believe that he is capable of operating the Firebowl safely. However, despite this, he always calculates accurately and manages to bring the Island to the desired destination. In the episode 'Rocco Hates Raffia', Nab also tried to work out how much raffia would be required to construct a chairlift, but he made a huge miscalculation on this occasion.
Even though orang utans are native to Borneo and Sumatra, Nab speaks with a thick Scottish accent. He seems to have a character reminiscent of 'Scotty' from Star Trek.