Actual fuel usage in a '72, 36' Hatteras

[aah924]

I was reading somewhere, and can't remember where, about someone who had an early 70's Hatteras, with the original 150 gallon tanks but had on about 110 usable gallons. Is this actually true? I run about 12 hours roundtrip, while offshore fishing, and burn about 145 gallons, 75 port side and 70 starbord side, total and the gauges are in the 1/4 tank area. I think that the gauges are original, and don't work accurately. I'm concerned about how many actual usable gallons that I have. Does anyone have any info. on this? Is this info. that Hatteras may have on file?

[jim rosenthal]

It owuld be difficult to come up with an answer for your particular boat, but here are some items that may be of use:
-the tanks are rectangular with flat bottoms; what governs how much fuel you can pull out of them is how far down the pickup tube reaches (within an inch or so of the bottom) and how the tank is baffled. Hatteras may be able to tell you something about that. Since these tanks don't have cleanout ports, it is hard to tell how tall the baffles are off the tank floor. As the boats run slightly bow-up, it is probably safe to assume that most of the pooled fuel as the tank approaches empty would be at the rear of the tank, which is more or less where the pickup tube is.
-the pickup tubes can develop leaks and holes which interfere with their function (see Dave Sommers' post last year). As long as they are not leaking and not blocked or corroded, you should be able to use most of the fuel out of the tank.
-my gauges, which are the mechanical float ones that you view through the aft deck, read "3/4" at full. They are not accurate, but they are consistent and agree from side to side. (so I suppose when they read 'empty' I have a 1/4 tank left each side, but I don't let it get that far.
-in 1972 the tank capacity was enlarged in these boats, I think. You may actually have 300 gallons of fuel space. Tom Slane or Sams' would know this. For offshore running the big tanks are a definite plus. One of the boats Tom did over was refit with a 375 gallon capacity, but located differently, a valuable criticism of the original design.

[GCombos]

When I bought my 36. Order the replacement magnetic gauge face units from Sams Marine. Both now operate well and are just barely off from one another other.

I consider the last 25% as an emergency reserve only.