Good call. The cheap Chinese eBay units are certainly not marine grade. They may work for a while, or they may not. For me, it's worth fixing it right the first time and then forgetting about it. I just think about whether I want to waste time messing with it every few seasons, or use it without worrying about failure.
Blue Sea is one of the foremost marine electrical component manufacturers. Their rigorous testing methods are noted in their reliability of their products (and cost). They do list 9-32VDC as their range, which is even wider than the Carling. You can't really go wrong with either Blue Sea or Carling.
That being said, it's great that somebody posted an alternative unit, the Carling model, but, unfortunately, the Carling is inferior to the Blue Sea unit bracketracer posted in nearly every performance metric. And, with the units being about the same price, the Blue Sea 1039 is a clear winner in comparison.
First, the Carling unit has an output of 3.15A, or only 1.57A per port. The Blue Sea is at 4.8A total, which is 2.4A per port, enough power to charge larger devices, some at quick charge levels, such as an iPad or other tablet/phablet.
Second, the Blue Sea unit has intelligent device recognition capability, which allow more devices (phone/tablet/etc) to draw power in their quick charge modes and pull the full amperage. The Carling unit does not have any device recognition listed, or any Qualcomm protocol. The Carling unit will never quick charge a device.
Third, the mounting depth of the Blue Sea unit is far shallower than the Carling. The Blue Sea only requires 1.83" of mounting depth from the face of the panel. The Carling requires 3.33", nearly double! That's huge. Someone without a lot of headspace behind their mounting panel may not be able to fit the Carling unit. Blue Sea's form factor is more compact.
Fourth, the parasitic draw (unused draw) of the Blue Sea is slightly lower at 1.0mA, versus 1.5mA for the Carling. Nearly negligible, but worth noting.
Fifth (subjective), the rubber cover on the Blue Sea seems like it may be easier to use than the spring loaded doors on the Carling, the Blue Sea also may allow easier one-handed plug in. Carling typically requires two hands, one to hold the door open, the other to insert the plug.
