My portable fridge is not exactly noisy, but neither is it silent.
what you need volume wise depends more on how many people you have onboard for a transat. We run our 100L fridge with inbuilt 10L freezer, for all the stuff that doesn't squash easily. The 42L portable fridge has poor insulation so we use it as our warm fridge. Keeping it at circa 7/10degC puts less demand on the poor insulation and it perfect for keeping fruit and veg. Keeping all the fruit and veg together reduces how much stuff gets damaged.
Likewise. Easy for me to sleep with it on to be honest, and obviously you can position it somewhere on boat where you’ll hear it less.
My fridge freezer at home sounds like a diesel engine. I think we need a new one
Difference might be I don't sleep in the kitchen at home!
The OP initially said his installed fridge didn't feel as cold as the portable, it may just be because of it's volume and he hadn't run it for long enough with it filled or as you and I indicated the compressor may need regassing. However his boat is old probably 80s vintage and my experience says that builders then didn't bother very much with insulation or installation of cold boxes.
One can do some objective tests, like freezing a few 2 litre bottles of water and seeing how long they take to defrost, or running the fridge via an amp-hour meter.
