23' FUEL TANK SIZE

CJR · #1 02-11-2005, 07:32 AM

I AM GETTING READY TO REPLACE THE FUEL TANK ON MY 76/77
23 AND WAS WONDERING WHAT THE CAPICITY OF THE CURRENT
TANK IS? THE DIMENSIONS ARE 106X28X12 WHICH EQUALS APPROXIMATELY 154 GAL. BASED ON 231 CU.IN. PER GAL.
WITHOUT DEDUCTING FOR THE BAFFLES. I WOULD LIKE TO HAVE
A TANK WITH A CAPICITY OF 120 GAL. ANY HELP SOLVING
THIS QUESTION WOULD BE APPRECIATED. THANKS

Scott · #2 02-11-2005, 08:36 AM

Roughly a seven foot tank (84 x 28 x 12) would give you 120 gallons

Current capacity of a 2005 23 SeaCraft?? I think 135 gal

Thats a big tank you have there ... seems most of them in that time frame were in the 100 gal range (outboard)...

FELLOW-SHIP · #3 02-11-2005, 08:41 AM

I installed a 120 gal on my 76-77 CC SeaCraft a few years ago outside measurements were 84x28x12 that gives you 120 from the outside measurements and approx 118 inside true gal capacity. I fits perfect and balances the boat better as well. The back of my tank is located just approx 3” in front of where the stringers take that 90 degree turn to the port and starboard going forward to where the door on the CC opens. Which leaves you that big hatch in front of the CC Door still available for stuff. I also moved my live well forward from the transom to the area in the bilge behind the tank there the newer SeaCrafts have their live well. All in all it balanced out the boat and for me maid it more efficient for space. I paid approx $600 for the tank then re did the deck where the tank firs on and changed the hoses and fillers as well. On my 225 Yamaha EFI I have approx 250 to 300 miles range.
FellowShip [img]/images/graemlins/cool.gif[/img]

CJR · #4 02-11-2005, 08:54 AM

Scott,

Thanks for the response. I don't think my question was as clear as it couild have been. Question rephrased:
What is the capacity of my current tank? The gross volume 106x28x12)is approx. 154 gals., but the tank is baffled therefore the net volume is something less than the 154 gal. I am confident this is the original tank. I have been under the impression this tank had a usable capacity of 100 gals.,
but I would like to have this confirmed before I order a new tank.

Sleeto · #5 02-11-2005, 09:05 AM

Based on the formula of H" x W" x L" divided by 243 - yours is 146 gals.

CJR · #6 02-11-2005, 10:45 AM

Thanks All,

I was unaware that there was a big tank option. I have twin
150 EFI's with approx. 570 hrs. I will probably keep the same size tank or reduce it to96x28x12, which should give me plenty of fuel for my needs. Again thanks to all . This
is truly agreat forum.

ScottM · #7 02-11-2005, 09:18 AM

CJR,
The big tank option on the 23's was 144 gallons, so that is most likely the capacity of your tank if it's the original.

Scott · #8 02-11-2005, 09:28 AM

Well I’m guessing you have 4-5 baffles in that tank. So if they are all 1/8” thick that’s approximately ½”to 5/8” of space occupied by the baffles. I have been told by the builder here that 1” of tank length will buy me a bit more than a gallon capacity using 28” as the width and 12” as the height …So those baffles are taking up very little volume.

As far as your tank goes I certainly would think you should have more than a 100 usable gallons in a 154 gal tank. That’s a 1/3 of your capacity. That’s about 4” of fuel, 50 gallons, left in the tank when the boat is at rest or the tank is level (if the fuel pickups were that far off the bottom of the tank) and unless the boat is bow heavy causing fuel to pool forward away from the pickups.

What are you basing the useable volume on ?? That tank has such a huge surface area that its probably tricking your fuel gauge …each 1” of fuel in that tank is about 12-12.5 gallons. Do you have a fuel flow meter?