Boston Whaler boats typically use a fuel tank level gauge that is magnetically coupled to a mechanical lever float arm. See
http://continuouswave.com/whaler/refere ... #fuelGaugefor more information on the fuel tank level gauge.
I don't know what you are referencing by "three types" of tank level gauges.
On the chance that your 1993 Boston Whaler 16 SL has an electrical fuel tank level sender, it most likely has a rheostat with the standard resistance range used in the USA. Quoting myself:
Historically in the USA a standard has come into use for the fluid tank level sender to provide a variable resistance in a range from 33-Ohms when the tank is full to 240-Ohms when the tank in empty.
Source:
http://continuouswave.com/whaler/reference/fluidTankLevelNMEA2000.htmlI recommend you call Boston Whaler customer service and inquire with them about the particulars of the fuel tank level gauge used on a 1993 Boston Whaler 16 SL boat. The fine folks at Boston Whaler customer service will be able to give you the best and most reliable information about that particular boat model and year.