CONTINUOUSWAVE

Complaints about Moeller 22-gallon on-deck fuel tank
[The material used to construct a Moeller 22-gallon on-deck fuel] tank [is not transparent]. [On the tank] there is a safe fill line, but to see when the level of fuel in the tank reaches the line is almost impossible. Periodically putting a yard stick into the Moeller 22-gallon on-deck fuel tank [in order to find the tank level] may work, but [that technique becomes] inconvenient [when the boat is underway] in three-foot seas.

Complaints about instrumentation on 170 MONTAUK
On the [170 MONTAUK boat on which this tank is installed there is] a gauge that does not have a fuel-flow monitor function. The gauge only provides [battery] voltage, [engine] temperature, and [engine run time] hours.

[Moderator's note: separated from another thread on a different topic.]

RaySmiley wrote:Periodically putting the yark stick into the Moeller 22-gallon on-deck fuel tank [in order to find the tank level] may work, but [that technique becomes] inconvenient [when the boat is underway in] three-foot seas.

When operating your 170 MONTAUK in three-foot seas, there probably will be so much sloshing of fuel in the Moeller 22-gallon fuel tank due to lack of any baffles inside the tank, that any indication of tank level from a float sensor will be showing a very variable tank level indication.

Requiring that you can obtain an accurate indication of FUEL REMAINING while the boat is underway in three-foot seas will probably need to NOT use any sort of in-tank level sender.

RaySmiley wrote:On the [170 MONTAUK boat on which this tank is installed there is] a gauge that does not have a fuel-flow monitor function.

My inference from your description is the gauge you mention is designed to monitor engine functions, and is not intended to perform a fuel management function.

For a fuel management function, you will find that most modern chart plotter devices with NMEA-2000 ports can be configured to infer a fuel tank level using the INDIRECT method of calculating fuel tank level based on fuel consumption as reported by a modern engine that sends NMEA-2000 data. Almost all modern outboard engines support NMEA-2000 data, with the only exception being engines from Mercury Marine. As long as the engine is not a Mercury, you should be able to connect the engine to a NMEA-2000 network and use a chart plotter to manage fuel without depending on having an in-tank level sender.

For advice on fuel tank level monitoring using the Indirect Method, read my article in REFERENCE at

Fuel Tank Level Measurement
https://continuouswave.com/whaler/refer ... Level.html

The Moeller 22-gallon tank was designed specifically for the Reversible Pilot Seat as used on the classic MONTAUK 17 hulls. It has been a popular choice for many years. On the c.2002 and newer 170 MONTAUK boats the original fuel tank set-up was two 6-gallon plastic on-deck tanks. The Moeller 22-gallon tank was a popular upgrade. If the Moeller 22-gallon tank is not to your liking you could look for a better solution for your particular situation.

Regarding alternate choices for on-deck fuel tanks, the first that comes to mind is to revert to using the original configuration of twin 6-gallons plastic fuel tanks. With this rigging you begin operating the boat with both tanks at full level and running off one of them, and as soon as all the usable fuel has been drawn off the first tank, you can change to the second tank with the confidence of knowing that it is a full tank. Both tanks are replenished to full at the next fuel stop, and the process begins anew.

More alternative on-deck fuel tank sources

In 2002—now 24-years-ago—Robert Schmidt wrote an excellent article about many then-available on-deck fuel tanks.

On Deck Fuel Tanks
https://continuouswave.com/whaler/refer ... lTank.html

But since then, the number of choices has reduced. There were two causes for this decline in market diversity of on-deck fuel tanks, and they were changes to the gasoline fuel itself and changes to regulations for marine on-deck fuel tanks; you can attribute both to the federal government policy.

The first change to occur in the early 2000's was the introduction of blending ethanol (an alcohol distilled from corn by farmers and subsidized by the federal government) with gasoline to act as an octane raising agent. While gasoline has always had the characteristic of a solvent, the mixture of ethanol, gasoline, and water created even more powerful solvents in the fuel tank. Non-metal fuel tanks constructed of fiberglass and resins were unable to withstand the solvent power of ethanol-gasoline blended fuel, resulting in the removal from the marketplace of a very popular marine fiberglass fuel tank made in Florida by Pate Plastics.

The next change was from the federal government and the Environmental Protection Agency, which decided that having removed practically every molecule of unburned gasoline from the emission of outboard engines through regulation, they turned their presumed authority to gasoline evaporating into the atmosphere from vented fuel tanks on boats. New regulations prohibited having open-to-atmosphere venting on portable or on-deck fuel tanks and required hoses carrying gasoline to have better containment of the gasoline from improved impermeability.

Several of the manufacturers of small-volume (and here I mean small sales volume) on-deck fuel tanks appear to have given up on trying to comply with the new federal regulations that governed their products, and just stopped making those fuel tanks.

The Moeller fuel tank was also affected by the new rules about evaporation from venting. All tanks were required to maintain a certain open space above the fuel in which vapors could collect. The result was the Moeller tank changed to become a 22-gallon tank with a maximum fill line from a 24-gallon tank, the loss of the 2-gallon capacity from the compliance with the new regulations. The tank fuel cap was changed to one that did not allow venting of gasoline vapor unless the pressure became excessive and put the structure of the fuel tank in jeopardy.

Whether or not there is another brand and model of fuel tank that will be superior to the Moeller tank is unknown to me. At one time—and here again I cannot be certain because I have not deeply investigated the present day market place—Moeller was able to offer its 22-gallon fuel tank in a version that was non-compliant with modern regulations, but only if it were to be used on a boat which was manufactured prior to effective date of the new regulations about closed cap and no venting.

I am really not in the market for a new on-deck fuel tank, so I have not made a study of what versions Moeller has to offer, so I will leave that inquiry in depth into the present day on-deck fuel tank market to someone with a greater interest in the outcome.