fleshing coyotes

I've been having some trouble doing a good job of getting the fat off of my coyote hides. I use a semi dull knife and try to scape it off with some success but their is still alot to get off. what other way is there to do a good job? How long should this process take? do I need a special board to scrape on? Any info would help. I've caught about 20 coyotes this year and have been trying to learn how to properly take care of the hides. I usually wash them as well an want to know if I should scape them before or after washing or when they are partially dried?