Insurance cover/deductible: How can I reduce my deductible in the event of damage?

All of our boats have full insurance with a deductible of €2,000. If so desired, when you make a booking you can reduce this amount to €300, which adds 5% to the net hire price. We keep all our boats in perfect condition. Should damage be caused to a boat, it will be identified when the boat is handed back and documented in the hire contract. We of course have liability insurance that covers damage caused by the hirer, the cost of which is incorporated in the hire price.