You are responsible for the boat even if a professional skipper is present.
While some companies will not ask you for a deposit, others will ask you for one, as you are financially responsible for the boat as the contract holder.
The deposit also covers minor damage to the boat, such as lost cushions, cigarette marks and other minor damage to the boat's equipment.
Guarantee buyback insurance is therefore useful in many cases where a deposit is required by the charter company.