Mainship 430 Aft Cabin fuel capacity

[TJ Sprocket]

I recently had problems with my generator stopping with UV message. We were getting below 1/4 tank fuel levels according to the gauges so I wondered whether it was something to do with getting starved of fuel depending on the depth of the pick up for the generator was in the tank. By the time I got back to my slip, the tanks were showing almost E empty, and the generator wouldn't run at all. Based on my log, I should have only used approximately 400 gallons, with therefore still 100 gallons remaining with a 500 gallon capacity. The tanks sounded empty when I tapped on them, so I was worried I'd used much more fuel than I expected. I got filled up, which only took 390 gallons. The generator then ran perfectly. Now I'm beginning to wonder whether the capacity is actually 500 gallons as published, or closer to 400 gallons. I saw one online spec that said it was only 350 gallons, but I know it's more, obviously.
Does anyone have experience on what the capacity actually is for a late model 430 Aft Cabin?

 

[porman]

I don't think I've ever let ours get too far below 1/4. I have wondered how far the generator pickup goes in the tank.

 

[Shrew]

The generator pickup tube in the tank is not as long as the engine pickup tube. This prevents you from running the tank empty on the genny and not being able to get home. You can at least fire up the main and hopefully limp to a fuel station.

 

[TJ Sprocket]

Yep, I agree on the generator fuel tube not being as deep as for the engines. It just seems too conservative to have it starve the generator when there are still over 100 gals of diesel in the tanks (assuming 500 gal capacity).

 

[ranger58sb]

Does anyone have experience on what the capacity actually is for a late model 430 Aft Cabin?

If you can get to the tank, there may be a label. Mainship may have used units from Florida Marine Tanks, Inc.

If it IS an FMT product but you can't get close enough to read the label very well, FMT will likely have records.

-Chris

 

[TJ Sprocket]

I just measured the fuel tanks. Approx 28x28x73”=114500 cu in = 495 gals.
So there we have it. So now the question is why could I only get 390 gals during a fill up when the gauges said Empty and the generator had stopped working a few hours of run time ago???

 

[ranger58sb]

Can't speak to generator issue, although your point about the dip tube not extending as far as dip tubes for the mains could be on target. I've read that's not uncommon.

But as to 390 gallons... gauges, especially some gauges, may or may not be in the same ball park, let alone be accurate. And some systems intentionally build in a reserve. And then if they're analog gauges, judging what it means when Mickey's hand is on the E may take running out of fuel once, just to see.

Also, if your fuel senders are adjustable (some are), they may be out of adjustment.

And... the shape of the tank impacts how the sender works. For example, in a cubical tank, the sender float could well be at a different point (sending a different resistance in Ohms) than it is in your tank... even with the same volume of fuel in each tank. (There are some gauges that can sort-of deal with that, and which have some calibration capability to adjust for tank shapes.)

-Chris

 

[TJ Sprocket]

I did notice that once I’d filled the port tank (to where I could here the vent gurgling) and then went to fill the starboard tank, that by the time the starboard tank was full, the port tank had transferred some contents across also, so it was now reading about 1/8 less than Full. I guess that could account for maybe 50 gallons or so? In that case, the generator was beginning to get starved with something like 50-70 gallons remaining which is probably what they were aiming for with the idea of not allowing the generator to run the tanks empty. For practical purposes, I’ll just keep the tanks filled above 1/4 and be ok with it.

 

[Captain Ron D]

T.J. You may want to check your math on the LXWXH calculation for the cubic inches per tank. 28 X 28 X 73 = 57,232 Cubic Inches, not 114,500 !!!
57,232/231 (CUBIC INCHES IN A GALLON) = 247.75 GALLONS !!!
Captain Ron D.

 

[TJ Sprocket]

Capt. Ron: yes, that was the number for both tanks. I'd missed the 2x in the formula. Thx.