John Hanrahan

John, I received an email via SeaKnots regarding your issue with your fridge and freezer power consumption. I too have a 2008 43 and have done quite a bit to maximize both units efficiency. Note that we live aboard and cruise so it's critical both work well for us.
Not sure how each of your compressors are using that much power. Your friend is right they typically use 3 to 3.5 AHRs each. The only way I can imagine seeing that kind of amp draw is if the variable speed setting on the freezer is set to 3500 RPMs. If you haven't done so already I would have both running and take note of the amp draw. Then using the thermostat control shut one of them off. Take another reading and make note of it. Then turn that unit back on and the other off taking yet another reading. If it's the freezer drawing excessive amps then check for a small circuit pwb on the side of the controller mounted on the back of the compressor. Hopefully you have the manual for the compressor in your owners book. There should be a drawing that indicates which terminals produce the different RPMs. The lower the rpm the lower the amp draw but also the unit won't cool as well. Keep in mind the freezer isn't the same as what we have in a house. They're not as well insulated and as a result run more consuming amps. Between both units you should be seeing an average 3 amps per hour.
There are other things you can do to help efficiency. Make sure you keep the compressor coils clean. You'll have to remove the wood grills that cover each to gain access. I use a small paint brush to reach in and remove the dust that builds up.
We've also place a plastic coated wire rack apx 1" high in the bottom of the freezer. This allows better air flow which results in food on the bottom freezing properly.
Defrost both the fridge and freezer whenever necessary. Heavy frost reduces efficiency which causes the compressor to run longer.
Try to keep air space between food and the walls of the fridge. Again better airflow equals better cooling.
We also keep ice cube trays in the fridge's freezer. Plus we keep synthetic ice cube sheets in the top of the freezer. They're 9x12 sheets we bought online. They come flat and you soak them in water then freeze them. We rotate them in and out of a cooler we keep produce in.
Sorry if I've thrown too much info at you. Let me know what questions you have. If you want to we can talk live. Let me know and I'll share my cell number.
Mike

John hopefully you'll get this response. We're cutrently in Guana Cay it moving between. Here Treasure Cay and Hopetown over the next week as our daughter is flying in for a week this Friday. After she leaves we plan on hanging in Hopetown for a few weeks. After that it'll be northbound. My Bahama cell is 242-458-7770
Mike