Re: Boat insurance for environmental cleanup?
I might be able to shed some light on the topic. I happen to be an environmental engineer who works for an insurance company that underwrites environmental damages.
Environmental liability insurance typically classifies damage in two ways: 1.) sudden and accidental, and; 2.) gradual release. All policies should cover sudden & accidental (i.e., hit a rock, sink, sudden parts failure). However, a gradual release from a leaking system MAY be excluded in some policies. This is based on the fact that this coverage derived from leaking underground storage tanks at service stations where an owner suspected a leak but didn't do anything about it because it would interrupt business. The tricky thing about this type of claim involving a non-commercial boat from an insurer's perspective is proving the leak was gradual - which from an engineering perspective is close to impossible and really not worth the hassle as these are all small claim items.
Having worked on spill response claims in water (from Marina's leaking gas tanks), I can tell you the cleanup costs are typically minimal. The largest "in water" claim I worked on actually involved a tanker trunk of milk overturning adjacent a trout stream. 9,000 gallons of fresh milk entered the stream, which created a high biological oxygen demand environment and thus a fish kill (trout are very sensitive to water conditions). Cost about $1M for a bunch of milk!
Hope this helps.
Ben