I'd suspect the battery. Just because it's brand new doesn't mean that it's fully charged. I'd also make sure that the cables and connections ane tight and clean. You can add a waterproofing spray such as Boeshield T-9 to the connections (adds a sticky was-base to waterproof the connections, but the formula is electrically friendly - I have great success with it).
I'd be more concerned with the flooding of your hull though. You could try an automatic bilgepump, but that can be drain to the battery. Have you checked your trim of the boat? Maybe your keeping too much heavy gear towards the stern so she can't clear her scuppers? -Call the manufacturer ASAP. Good luck!