If you are involved in a nighttime collision and have non-USCG certified bulb/fixture combinations in use, you will likely be found at fault. You may also not be covered by your insurance because you were using uncertified fixtures. Is it really worth it? The Aqua Signal Series 32 fixtures aren't all that expensive, and USCG Certified.
I don't think this is necessarily true. It is certainly something that will likely to be claimed by "the other guy" and his lawyers, or the state, but if you can show that your arrangement meets the USCG criteria, you should be fine. The installation is what matters, and it says so when you read the fine print on a USCG certified fixture. The only USCG certified installations are on OEM boats. If you have a CG certified fixture and it's not OEM to the boat, you no longer have a CG certified installation and the onus is still on you to prove that the installation meets the requirements.
I would agree the the burden of proof and the amount of testing you will have to do (in the night time collision situation) increases if you don't use CG certified fixtures.
Most insurance policies that I've heard of regarding denial of coverage due to lighting fixtures, require you to use the OEM fixtures, for the above reason. So, unless your boat is <10 years old and you are simply replacing your LED bulbs, you are likely out of luck if you insurance has one of these clauses. I don't think that's the case for most here.
I would be interested in hearing about any case where someone was found at fault specifically because they were not using USCG certified lighting fixtures (regardless of installation, or any other factors). Cases where one of the boaters is an off-duty sheriff's deputy do not