Fitting longer fuel tank

[998cc]

All. I have a 1972 Gulstream runabout that needs a new fuel tank. The tank sits dead center of the boat under the floor in the V. The tank is flat on top and has a truncated vee shape for the bottom. The problem is the replacement tank found online that is closest to what I need is about 1-1/2 inches longer than I have room for due to placement of the wood cross beam.


After reading many posts here on reframing/repairing, it seems doable to relocate the frame, but I am posting to see if there are any major pitfalls to avoid or should I just go with a smaller tank. The stock tank is 28 gallons; the next step down that fits is 17 gallons which is a bit of a jump backward. My engine is a Mercruiser 165 Inline 6 with 2bbl carb.

Thanks.
998cc

 

[Woodonglass]

Re: Fitting longer fuel tank

What's your experience been with fuel in the past? Have you had issues where you've ran short on a "Day Outing " on the lake with the 28 gallon tank? Do you know what your Hourly fuel consumption rate is? I think that would be your main concern. If 17 Gallons will be enough for most of your usual outings then I recommend going with it. Are you certain you've exhausted all your resources for finding a larger tank that will fit? What's your measurements? What's wrong with the tank you have? Are you sure it can't be repaired? Have you heard of POR 15?

 

[alldodge]

Re: Fitting longer fuel tank

All. I have a 1972 Gulstream runabout that needs a new fuel tank. The tank sits dead center of the boat under the floor in the V. The tank is flat on top and has a truncated vee shape for the bottom. The problem is the replacement tank found online that is closest to what I need is about 1-1/2 inches longer than I have room for due to placement of the wood cross beam.


After reading many posts here on reframing/repairing, it seems doable to relocate the frame, but I am posting to see if there are any major pitfalls to avoid or should I just go with a smaller tank. The stock tank is 28 gallons; the next step down that fits is 17 gallons which is a bit of a jump backward. My engine is a Mercruiser 165 Inline 6 with 2bbl carb.

Thanks.
998cc

I take it you have not yet bought the tank? If this is correct, have you contacted anyone about a tank built to your specs. I had a water tank made for mine from a company in Texas and it wasn't that much more. Need to do some looking to find it, but there are several folks out their which can build you one.

 

[tpenfield]

Re: Fitting longer fuel tank

All. I have a 1972 Gulstream runabout that needs a new fuel tank. The tank sits dead center of the boat under the floor in the V. The tank is flat on top and has a truncated vee shape for the bottom. The problem is the replacement tank found online that is closest to what I need is about 1-1/2 inches longer than I have room for due to placement of the wood cross beam.


After reading many posts here on reframing/repairing, it seems doable to relocate the frame, but I am posting to see if there are any major pitfalls to avoid or should I just go with a smaller tank. The stock tank is 28 gallons; the next step down that fits is 17 gallons which is a bit of a jump backward. My engine is a Mercruiser 165 Inline 6 with 2bbl carb.

Thanks.
998cc

I would see if can get a similar capacity tank that has slightly different dimensions. Tell us a bit more about the space you have L x W x H and what tank you are planning on using. I see that Moeller has a 28 gallon 'belly' tank that is 49" long . . . they also have a 29 gallon tank that is shorter, but slightly wider. So, if you had some extra width, you might be able to use a wider/shorter tank.

Of course, those are plastic tanks, but if you are going aluminum, you may find the same sort of trade-offs.

 

[998cc]

Re: Fitting longer fuel tank

A lot of great questions, gentlemen.
Answers:

First off, I erred in the length dimension. The proposed replacement tank is actually 7+~ inches too long. The boat tank well measures 29-3/4"W 42"L. The depth depends on the rake of the vee but is roughly 8" at the point where the existing tank flattens at the base. The stated dimensions of the replacement tank are 49"L 24"W and 7.88" D. It's a Moeller 03258--likely the one tpenfield refers to.

1. Fuel consumption is a question mark. This is a new-to-me boat. I only have a few hours on the boat during a shakedown run after an engine rebuild, bellows, transom gasket and outdrive water pump replacement. I am currently running it on a 6 gallon topside tank.

2. The tank is aluminum and suffers from what I'll term as "metal cancer". It has areas of corrosion on the exterior sides where it is deeply pitted to the point that I don't trust it. Also, the dip tube was rolling around in the tank, and the threads on the fuel outlet are brittle and are failing. Yes, I am familiar with POR 15, Kreem and similar products having done a few British motorcycles over the years.

3. I doubt I have exhausted all resources, but the Moeller 03258 seems the best fit at this point even with the mods necessary, and the fuel fill stub, outlet and gauge sender are perfectly positioned to access the engine/bilge cover whereas the others I have seen look like they will be out in view after the cover is installed. :grumpy:

4. No, I have not purchased a tank yet. :joyous:

Thank you all.
998cc

 

[jbcurt00]

Re: Fitting longer fuel tank

If it's a new to you boat, I'd suggest some exploration to confirm everything is in good shape. No reason to remove decking, move a bulkhead & etc if there's no reason other then getting a stock tank to fit. On a 1972 boat, even if the previous owner (PO) claims to have done extensive work (unless extensive proof is offered via pix of the tear down & put back) don't expect all to be well below decks on a 40+yr old boat.

All may be well. If so, spend the extra to get a tank fab'd to fit your space & w/ all the fittings & hoses in the 'correct' spot...

If there is ANY cause for concern, or you've already pulled the deck, make slight changes to the structure & placement of bulkheads to fit a stock tank.

Be sure to note that there needs to be some space around replacement poly fuel tanks, for expansion............

Here's a site someone else @iboats posted:
Custom aluminum fuel tanks by SP Tanks

There are others, some posted @the forums.

These came up under a quick google search for:

Custom marine aluminum fuel tanks

Marine Fuel Tanks, Marine Holding Tanks and Marine Water Storage Tanks by Custom Marine Tanks LLC


Custom marine fuel tanks for recreational, commercial crafts, U.S. Coast Guard, aluminum, steel, stainless steel, Jersey Shore, NJ, New Jersey


Look around, you may find someone local that's qualified. Be sure to use a shop that certifies that the tank meets or exceeds the USCG standards for aluminum tanks INCLUDING a pressure test (3 or 5psi, I can't remember which, for 24hrs IIRC).....

Is Shingle Springs on the coast? If so, local shouldn't be hard to find..........

EDIT: Nope, local's probably not going to work. I can't count the number of times I've been thru there on 50 headed to Lake Tahoe, but never noticed the blip in the road..... 2010 Census has population doubled since 2000: 4500+/-.....

 

[tpenfield]

Re: Fitting longer fuel tank

998cc:

Thanks for the additional information. Depending on your budget, you could get an aluminum tank made locally, using the original tank as a reference. I did that with my F-242 a couple of years ago. It was a bit pricey, but also it was a big tank (90 gallons).

In terms of the tank dimensions, you want to shave a few inches off of the fuel bay dimensions as the tank should not come in contact with any of the structural parts of the boat (stringers, bulkheads, hull, etc)

Also, here on iBoats, they list an under deck tank that is 24 gallons that may be a decent match and gets you closer to your desired capacity.

Of course, the fittings are not laid out quite the same as the 28 gallon version . . .

If all else fails you could move the bulkhead to accommodate the larger tank, but expense and time-wise, you may be better to go the custom fab route.

I would also recommend reading up on marine tank installation (a la Google, etc), as needed, to determine your options and methods of installation.

 

[998cc]

Re: Fitting longer fuel tank

If it's a new to you boat, I'd suggest some exploration to confirm everything is in good shape. No reason to remove decking, move a bulkhead & etc if there's no reason other then getting a stock tank to fit. On a 1972 boat, even if the previous owner (PO) claims to have done extensive work (unless extensive proof is offered via pix of the tear down & put back) don't expect all to be well below decks on a 40+yr old boat.
SNIP>
EDIT: Nope, local's probably not going to work. I can't count the number of times I've been thru there on 50 headed to Lake Tahoe, but never noticed the blip in the road..... 2010 Census has population doubled since 2000: 4500+/-.....

The boat is new-to-me, but I have owned it since March. No work has been done to the boat—it was a “rescue” boat. The rear half of the floor deck is pretty soft and needs replacing. The front half seems pretty solid. Reframing does take time, but I don’t mind putting time in where I can save some cash. Realistically, the boat will not be worth what I have into it when it is all done, but that is not the point. I want a boat that is dependable and safe to operate and plan to keep it for about 10 years.
I will look around to see what a custom tank will cost. It may pencil out.

 

[jbcurt00]

Re: Fitting longer fuel tank

The boat is new-to-me, but I have owned it since March. No work has been done to the boat—it was a “rescue” boat. The rear half of the floor deck is pretty soft and needs replacing. The front half seems pretty solid. Reframing does take time, but I don’t mind putting time in where I can save some cash. Realistically, the boat will not be worth what I have into it when it is all done, but that is not the point. I want a boat that is dependable and safe to operate and plan to keep it for about 10 years.
I will look around to see what a custom tank will cost. It may pencil out.

I agree, completely w/ all that ^^^, particularly the safe & dependable part. If you spend $3K on a rebuild, it'll be brand new & better then ever. It'll also be significantly better then ANY $3K (& up) boat available for sale.

Good luck w/ it, looking forward to seeing some pix.

 

[998cc]

Re: Fitting longer fuel tank

998cc:

Thanks for the additional information. Depending on your budget, you could get an aluminum tank made locally, using the original tank as a reference. I did that with my F-242 a couple of years ago. It was a bit pricey, but also it was a big tank (90 gallons).

In terms of the tank dimensions, you want to shave a few inches off of the fuel bay dimensions as the tank should not come in contact with any of the structural parts of the boat (stringers, bulkheads, hull, etc)

Also, here on iBoats, they list an under deck tank that is 24 gallons that may be a decent match and gets you closer to your desired capacity.

Of course, the fittings are not laid out quite the same as the 28 gallon version . . .

If all else fails you could move the bulkhead to accommodate the larger tank, but expense and time-wise, you may be better to go the custom fab route.

I would also recommend reading up on marine tank installation (a la Google, etc), as needed, to determine your options and methods of installation.

I had not seen that tank; it does have possibilities. The only possible issue is the location of the gas gauge sender. Worst case scenario would be installing an access cover in the plywood deck. Thanks!!

 

[998cc]

Re: Fitting longer fuel tank

I agree, completely w/ all that ^^^, particularly the safe & dependable part. If you spend $3K on a rebuild, it'll be brand new & better then ever. It'll also be significantly better then ANY $3K (& up) boat available for sale.

Good luck w/ it, looking forward to seeing some pix.

Thanks for the vote of confidence, jb. here is a photo from about a month ago.

 

[Woodonglass]

Re: Fitting longer fuel tank

This might be of interest...
Aluminum Fuel Tanks

 

[998cc]

Re: Fitting longer fuel tank

All. Thanks for the links and advice. After weighing it all out, I have ordered the 49” tank. The location of the fuel stub, gauge sender, vent and fuel outlet more or less match the original tank’s configuration. I found Woodonglass’s stringer installation piece which will help immeasurably—thanks! This is a great forum!
Thanks to all.

998cc