...on insurance...

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Being a fairly sensible sort of bloke, I will be insuring my Ribcraft in the usual manner for messing about with boats.
However, if I were to start using my boat commercially, do I need to upgrade my current insurance to cover all eventualities, or upgrade my current insurance to cover commercial use AND get another policy to cover indemnity/3rd person liability for the commercial company etc etc etc.
Would this be a fairly standard thing, or does it depend on what you are doing with the RIB? Or does it depend on the insurance company?
Sorry if the question is a bit dumb - doing some planning and want to get it right......(especially the risk assesments/safety and the money...)
Dylan...