None. In fact, we probably owe some.

Our boats and sails are made of substances derived from fossil oil and its sinthesys release carbon (resins, paints, polyester, films, etc.), and others that require require heat from burning fossil fuels, also releasing carbon in the atmosphere (like metals, glass, carbon, etc.).

If you want to collect this type of credit, consider a wooden polynesian boat, built without nails, bolts or glue, with cotton sails and rigging. It is debited only for the trees cut to build it and for the natural fibers used.