Not quite sure about this: I'm pretty certain that you can't withhold payment just because you didn't like what he wrote.

The surveyor is bound by guidelines that the Report should be a fair and accurate appraisal of the vessel as seen. If you were buying a boat, and he didn't report a defect that he'd found, you would quite rightly hang him out to dry. As this is an insurance survey, if you instruct him not to include known defects in the report, the insurance company could hold both you and the surveyor to account for misrepresenting the condition (and thereby the value) of the vessel.

By all means ask the surveyor to list those items which do not impact on the immediate safety and integrity of the vessel as "Advisory Notes" (which many surveyors do anyway for exactly the reasons given above), but I would strongly caution against any coercion over the content of the report.