You'd better believe it! In short, the screened hole in the base keeps vapors from entering the distributor and in turn keeps sparks from getting out into your gaseous engine room. The distributor cap must be of the non-vented type for the same reason. Fire prevention is obvious, especially in a boat!
The marine advance curve is usually different than cars as marine engines are operated at up to 100% of cars doing the same work at 20%, due to water resistance, of course. Marine engines are normally fully advanced around 2500 to 3500 RPMs, even though top RPM will be greater.
The vacuum advance canister is eliminated on modern marine engines as it's just not necessary to have two types of advance for the operating reasons above. Removing it leaves a void in the distributor housing that must be plugged airtight for reasons above.
What about boarding inspections at sea or lake? You forget to put in the drain plug, or many of the reasons below. The USCG or Sheriff can legally confiscate your vessel and passengers if at least five things are not legal for marine use: the distributor, fuel pump, alternator (generator), carburetor and flame arrester (air cleaner).
Check out aaamarine.com selection of marine distributors to keep your boat running safely while also getting top-tier performance!