Modification to 12 gallon tanks on a Mac26X

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OverEasy
Admiral
Posts: 2012
Joined: Mon Sep 28, 2020 11:16 am
Sailboat: MacGregor 26X
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Modification to 12 gallon tanks on a Mac26X

Post by OverEasy »

It was suggested that we share our experience in modifying our 2001 Mac26X to incorporate a pair of 12 gallon Moeller fuel tanks.

Our objective is to prepare Over Easy and ourselves for extended cruising of the Atlantic Intra-Coastal Waterway in 2022.

Given the remoteness, narrowness and lengths of many of the waterways we feel that a good portion will be done motoring rather than sailing. There are also tides and river currents to contend with. An adage from my flying days says one of the most useless things in life is fuel not with you when you need it.

Over Easy came with 2 serviceable 9 gallon tanks and we wanted to improve upon that. After looking and evaluating additional auxiliary tanks we decided it would be better for us to accomplish that with a pair of new 12 gallon tanks. We felt it a was neater, cleaner, less obtrusive and easier to use option to pursue.

The Moeller low profile 12 gallon tanks fit within the existing fuel locker cubbies on our Mac26X. The flanged opening width was our only preliminary limitation.

We also didn’t want to be pulling out the tanks to open vents and refuel so we decided to add rectangular top hatches to the benches over the cubbies.

Widening of the cubbie flange pending was accomplished using a Ryobi 18V cordless trim router with a carbide laminate edge trim bit with a slightly oversized roller bearing. This helped keep us from inadvertently crashing into the cubbie side walls as we trimmed back the flange width. We left the top and bottomcubbie flanges alone as the vertical opening was already sufficient to fit the tanks.

We will latter dress the exposed fiberglass flange edge exposed with touch-up gel coat.

We decided upon a pair of nice large rectangular non-locking tool-free hatches for easy access to each of the tanks though the cockpit benches. The hatches selected appear to be strong enough to stand upon if need be ( we already have done so several times), low profile without sharp edges or protrusions so the are comfortable to sit upon, textured for grip. Given the fuel cubbies are open to the cockpit and the tank surfaces are sloped to cockpit center we were not concerned with having a hard latch, locks, etc. The hatches have a roller detent closure and a lift lever handle to facilitate easy toolless access from the helm seat. The opening allows easy access for institutional refueling, tank gauges, line connection and vent.

We centered the hatches over the cubbies and outboard toward the port and starboard at the edge of the bench diamond pattern texture but still parallel to the bench edges. We laid out the openings to be cut with blue painters tape. Holes though the bench surface into the cubbies (through a channel reinforcement of about 2 inches thick) with a drill at the corners were made. Cutting was done with a Ryobi 18v jigsaw and a long down stroke cut blade that we expected would be of limited use afterwards ( fiberglass is tough on non-carbide blades). This Bosch blade held in there to complete the cutout for both hatches but was useless afterwards. Blade cost was about $1.50 and a good investment.

After dry fitting the hatches and demurring the edges we found the the original manufacture of the interior ceiling piece within the cubbies had over a 1/2 gap all around the interior at the cubby wall interface. This had allowed wasps into the bench reinforcement thickness as evidenced by a couple nests found on each side. We chose to seal up all the edges with water proof expanding foam as well as all the channels exposed in cutting the hatch holes. The hatches mounting screw holes were predrilled undersize.

Before finally mounting of the hatches the perimeter of the hatch was trimmed into the blue painters tape and the interior portions were removed leaving the exterior portion in place. Then an appropriate bead of marine sealant was applied to the under flange of the hatch and it was then mounted and screwed in place ensuring an adequate squeeze out of sealant around the outer perimeter. This was left alone for 2 days to set the adhesive. A sharp trim knife was used to trim the sealant at the perimeter of the flange. The excess sealant was then removed by pulling up the remaining perimeter blue tape making a nice neat installation.

Photos below:

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So much for our modification to install a pair of 12 gallon low profile Moeller fuel tanks.
Still to be done is the installation of a true 4 way (Tank A/Tank B/ Tanks A&B/Off) and an inline spin-on fuel filter/water separator.

Total man hours was roughly 4 hours (5 if you include lunch :D :D ) so far.

We like what we have accomplished so far and feel comfortable with using it.
We would definitely do this again to increase our fuel capacity and make it more convenient for what we plan to do now and in the future.

Hope this post has been helpful to those interested in making this modification.
Best Regards from Over Easy!

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Starscream
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Sailboat: MacGregor 26X
Location: Montreal, Quebec. 2002 26X - Suzi DF90A

Re: Modification to 12 gallon tanks on a Mac26X

Post by Starscream »

OverEasy wrote: Fri Mar 26, 2021 11:16 pm It was suggested that we share our experience in modifying our 2001 Mac26X to incorporate a pair of 12 gallon Moeller fuel...
Hey Over Easy can you recommend a thread sealer for the fuel line fitting where it threads into the tank?

It was time to replace the original Tempo low-profile tanks and I went with 2 Scepter 9 Gal. They don't quite fit vertically, and required a cut-out in the cubby fiberglass for the gauge and cap threads.

The marine store said use Teflon tape but the internet tells me not to. I bought some Permatex thread sealer but on the tube it says in caps: NOT FOR USE ON PLASTIC PARTS. So now I'm not sure what to use.

The original tanks had some sort of red thread sealer. I can't quite clean it all out of the threads, and I'm wondering if I should just buy new ones. The new Scepter tanks aren't actually compatible with the Evinrude connector: when screwing it in the connector prong contacts the tank. It can be forced, but leaves a little gouge in the tank plastic. Stupid.
OverEasy
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Joined: Mon Sep 28, 2020 11:16 am
Sailboat: MacGregor 26X
Location: NH & SC

Re: Modification to 12 gallon tanks on a Mac26X

Post by OverEasy »

Hi Starscream!

Here what I do know:

—> Yes, WHITE Teflon ISN’T for fuel applications. The WHITE version WILL DEGENERATE in the presence of hydrocarbons.

——>>There is a YELLOW version of Teflon tape that is for hydrocarbon gases use like natural gas and propane that might be a better match for gasoline type fuels.

Teflon tape comes in a variety of types for specific use applications.
Some are listed below:
> White: used on NPT threads up to 3/8 inch
> Yellow: used on NPT threads 1/2 inch to 2 inch, often labeled "gas tape"
> Pink: used on NPT threads 1/2 inch to 2 inch, safe for potable water
> Green: oil-free PTFE used on oxygen lines and some specific medical gasses
> Gray: contains nickel, anti-seizing, anti-galling and anti-corrosion, used for stainless pipes
> Copper: contains copper granules and is certified as a thread lubricant but not a sealer

Just a note of caution might be valuable as most people think of PTFE, or Teflon tape, is a benign product.

“Hazards”
Overuse or misapplication of thread seal tape may be a hazard. Excess application of tape can prevent mating threads from fully engaging, reducing the shear point of the threads. Combining thread seal tape with a pipe dope compound can also overload threads. Also, internal overhangs of loose material may constrict a joint or slough off and form a foreign body that could jam a valve seat. Therefore, use of tape as a thread sealant is generally not considered appropriate in fluid power (hydraulic) systems. Overheating and subsequent decomposition of Teflon can produce perfluoroisobutene which is 10 times as toxic as phosgene. Inhalation of even a minute amount can be fatal.

The aspect of plastic compatibility is new to me but worth checking out further but I suspect it has to do with the physical stress exerted on the plastic component threads which may cause an over stress to occur and crack the component. This is especially true if the plastic component is the female threaded one.

Typically on plastic applications I personally try to use “gas rated thread compound” rather than a Teflon tape to avoid the issue. IF I do use a Teflon tape I make sure that I DO NOT EXCEED 2 layers (I typically would start with 1 layer first) of tape AND I very carefully tighten any fittings to avoid the potential of over stress yet make sure that the joint is sealed, ESPECIALLY when I would be working on any fuel system.

I will try and chase this down with some of my former life contacts and see what their thoughts are on the subject. If I get back anything of use I’ll try and post a follow-up.

Hope this helps some.

Best Regards, Over Easy

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Starscream
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Re: Modification to 12 gallon tanks on a Mac26X

Post by Starscream »

Thanks OverEasy,

Your reply put me on the track of this product:

https://www.oateycanada.com/product/mas ... nge-t-tape

It's available at Home Depot for about 7 bucks cdn, is approved for gasoline and plastic. I'm ordering some now.
OverEasy
Admiral
Posts: 2012
Joined: Mon Sep 28, 2020 11:16 am
Sailboat: MacGregor 26X
Location: NH & SC

Re: Modification to 12 gallon tanks on a Mac26X

Post by OverEasy »

That’s Fantastic!👍

:) Orange.... I need to add that to the list and my toolbox! :)

I appreciate your sharing this!
Thank you!
OverEasy
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Joined: Mon Sep 28, 2020 11:16 am
Sailboat: MacGregor 26X
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Re: Modification to 12 gallon tanks on a Mac26X

Post by OverEasy »

Hi All

Something that we didn’t know about new Marine Portable Fuel Tanks:

Post by Jimmyt » Sun Apr 18, 2021 7:48 pm

New tanks should allow vent in, but don't vent out - my understanding. Emissions reduction strategy. Check this article. If you have an old motor and a new tank, you may need to add a component to reduce flooding...

https://www.westmarine.com/WestAdvisor/ ... Components

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Thanks again JimmyT!
You were dead on with your suggestion as far as our fuel system! We did a test of sorts today with one of our new tanks and our engine. Sure enough the tank with the vent open pressurized and flooded the engine!

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The vent valve on the new tanks held pressure just “fine”. :o :o

There is a function on the vent cap though to “relieve” the built up pressure which is to depress the top of the open vent valve if anyone is interested.

We have already ordered the Fuel Demand Valve from West Marine to add to our fuel system.

Again JimmyT, U-r-da-best!
Thanks! For making this a non-event for us!👍

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svscott
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Re: Modification to 12 gallon tanks on a Mac26X

Post by svscott »

My old 3 gallon gas tank fittings are sealed with standard white Teflon tape and have been since before I acquired it. I still need to buy and install the fuel line fittings for the pair of 9 gallon tanks I'm installing in the X.
I'll buy the orange tape and use it to rework the 3 gallon tank's fittings and also for the 9 gallon tank fittings. Without reading this, I would've just (incorrectly) used the standard white Teflon tape I have in the plumbing parts bin.
1987 26D - Three Hour Tour; 1998 26X - to be named
OverEasy
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Re: Modification to 12 gallon tanks on a Mac26X

Post by OverEasy »

Attached is the rough schematic of our fuel system as installed.

We have 2 each 12 gallon Moeller low profile fuel tanks. One on each side.
We modified the fuel cubbys by enlarging the openings and adding through hatches pin the benches to access them for refueling and to check fuel quantity. These work like a charm!

We treat these fuel tanks as rather permanent ( have you ever carried filled 12 gallon fuel tanks? :o :? :| ) and refuel in place.
This works at the refueling dock and also when the boat is on the trailer.

We don’t use any spray less quick disconnects on our system except at the engine.
All fittings are direct connect to the fuel lines which are 3/8 ID.
We have a primer bulb sized for 3/8 ID tubing which gives a better prime per pump than the 1/4 ID variety and are less prone to fouling.

Routing is from each tank to a 3 way selector valve ( Tank A or Tank B or Tank C) then to the fuel filter separator then to the primer bulb and then to the engine. These are all mounted on a PVC Board located on the aft face on the starboard side wall behind the swing seat. The selector valve and prime bulb are just below the top surface within easy reach when seated or when standing. The fuel filter/ separator is viewable when seated by looking over the back of the seat.

The Tank C port is a “TBD” at this time to allow for an additional 3rd auxiliary tank to be added for longer motoring passages when needed in the future traveling plans.

This PVC Board was fabricated and assembled at home and then brought to the boat to be mounted with 4 each 1/4-20 SST screws with washers and lock washers to the 4 Well Nuts. Alignment of the holes into the aft face wall of the boat was a snap by being able to use the predrilled 1/4 diameter holes in the PVC Board. These were then the pilot holes to drill the Well Nut holes in the boat.

The Final holes were drilled tight fit to the Well Nuts which were inserted with a small bit of 5200 Adhesive in the holes and the back flange of the Well Nuts. (NO LOCKTITE)

Once in place the fuel lines were attached and clamped.

Fuel flow to the engine was very improved and the convince of just reaching over and turning the selector valve to the desired tank is a breeze compared to fussing about down below one’s knees struggling with disconnecting/re-connecting fuel tanks. Far safer too as the helmsman’s attention is not divided away from navigation. The prime bulb is readily at hand and always vertically orientated as it should be to work properly.

We will be at the boat this weekend and we will take a couple pictures of the installation.

Note:
We left the fuel line deliberately long as we are planning on adding some additional modifications to our aft deck/motor well area in the future. The extra lengths will allow some latitude to position things.

Regards,
Over Easy
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OverEasy
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Posts: 2012
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Re: Modification to 12 gallon tanks on a Mac26X

Post by OverEasy »

Installation photos of Fuel Selector/Primer-Bulb/FDV/Filter-Separator Panel.


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Hope this helps.
It works for us. :) :)

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Jimmyt
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Re: Modification to 12 gallon tanks on a Mac26X

Post by Jimmyt »

Looks great!
Jimmyt
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Cruising Waters: Mobile Bay, Western Shore, Fowl River
OverEasy
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Re: Modification to 12 gallon tanks on a Mac26X

Post by OverEasy »

NOTE:
I inadvertently omitted the Fuel Demand Valve (FDV) from the scheatic diagram.
The FDV is a pressure regulator to prevent solar heating pressurization of the fuel system due to solar hating of the new vapor compliant sealed fuel tanks that only vent vacuum not vapor pressure.

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The FDV is located after the fuel tank selector and the filter/separator.

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