Owning a large boat for the inland waterways of France does not need to be an expensive affair. 

A canal barge is a usually iron hulled with a steel superstructure and very little woodwork outside except for doors, hatches and handrails. When the boat is based on the canals and a long way from any maritime influences, maintenance of the outside is minimal with some painting to be done every year. The only major item could be a wooden wheelhouse found on some boats, and this has to be regularily varnished due to the effects of the sun and rain (boatowners will know what I am talking about!). 

The barge should be hauled every four years for cleaning and repainting the hull with a tar based paint. Four years may seem long but it is not necessary to do this more frequently. 

Insurance companies in France generally base their rates on the value of the boat. For a barge of a value of 100,000 euros the premium would be about around 1% of the value of the boat for a good coverage. This may be slightly more for boats around 50,000 euros and slightly less over 150,000 euros. 

Most barges and canal boats over 10 years old will not be expected to depreciate in value if maintained in good condition. If they are not maintained they may depreciate rapidly as with all boats. 

In France there is a system for paying to travel on the canals. This is payable for the period that you are travelling and not when you are moored. At present for any barge over 60 m2 (length X beam) the rate is 259 euros for 30 days of travel ( not necessarily consecutive days) or 426 euros for the whole years unlimited travel.

In Belgium there is a minimal tax of a few dollars and Holland nothing at all. 

In general most moorings along the route are free of charge except for private marinas like ours where there is a rate of under 10 euros for the night. This will be more in Paris. If you leave your boat in a marina then the rates vary but should not exceed 1,500 euros for the year. 

For a 20 meter barge costing 100,000 euros and paying cash i.e. no finance costs 

Annual maintenance 1.000 euros
Mooring 1.500 euros
Depreciation  0 euros
Insurance 1,000 euros
Canal dues  300  euros
Put aside for 4 yearly hauling  800  euros
Total 4.600 euros

Affordable boating!!