Marine Surveyors Langkawi, Phuket, SE Asia
If the boat is in the water then the onboard inspection and sea trial will take place and then the vessel will be lifted for underwater inspection. This lift needs to be organised prior to the survey and any cost for this is a client expense. If in the water ideally the bottom and prop should not be too fouled as this will affect performance.
If the vessel is already out of the water the process is reversed and this has the benefit of a clean hull for the sea trials. For some research have a look at the link for the ebook shown below. Marine Electrics Made Simple.