I don't even know if any marine engines could use VMSPC which plugs into the diagnostic port of the engine computer. I've used it on both a Detroit 8v92TA and series 60 in my motorhomes and liked having access to all of the engine parameters. It has a database of many engines. It gives you the ability on a win doze laptop to build custom gauges, alarms and also diagnostic info. I also used the fuel tank minder and found it very accurate down to a gallon or 2 on fillups of 150 gallons or more. It does get speed readings from the engine and gives an accurate mpg but don't think that would work on a boat. But it would give you gallons/hour and might help in finding the most economical speed.
Anyone using VMSPC?