I have used craft insure for a few yearrs, although I have yet to make a claim. I understand they are very reputable,but keep admin costs down by doing it all on line. There are real people there in case of need.
What are you insuring? I have used them in the past and had to make a claim, they were very helpful on the phone but the money took a while coming through. Have recently swapped to Newton Crum for my dinghy, no claims as yet though.
If it's a yacht (rather than a dinghy, try GJW Direct... we use them all the time and I use them for my own yacht.... very very good, very competitive and excellent when you make a claim (as I did when I snapped my rig whilst racing).
My old man insured his Sunseeker through them for several years. He made a claim almost immediately after starting the policy it was settled within a reasonable time.