Usually, watercraft over 15 years old are required to have a survey, and an updated survey is due every 5 years from there. A survey amounts to an appraisal of the boat which determines its condition and value. Insurance companies use this for market valuation in the event of a total loss.
If there are items of disrepair on the boat survey, the insurance company may require repairs in order to receive insurance.
Depending on these items, more often a boat survey is required. If you have a recent boat survey, typically this can be used as part of the boat insurance quote process.