Mod to 12 gal tanks on a Mac26X

Original Post by OverEasy » Sat Mar 27, 2021 2:16 am


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.

Although Over Easy came with 2 serviceable 9 gallon tanks and we decided it would be better for us to go with a pair of new Moeller low profile 12 gallon tanks fitting within the existing fuel locker cubbies on our Mac26X. (The flanged opening width was our only preliminary limitation.) We felt it a was neater/cleaner/ streamlined/easier-to-use option to pursue.

We added rectangular top hatches to the benches over the cubbies. As we didn’t want to be pulling out the tanks to open vents and refuel.

Widening of the cubbie flange was accomplished using a trim router with a carbide laminate edge trim bit with a slightly oversized roller bearing to keep us from inadvertently crashing into the cubbie side walls as we trimmed back the flange width. We left the top & bottom cubby flanges alone as the vertical opening was already sufficient to fit the tanks.

We used a pair of large rectangular non-locking tool-free hatches for easy tank access though the cockpit benches. The hatches selected are strong enough to stand upon if need be, are low profile without sharp edges or protrusions, 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. The hatches have a roller detent closure and a lift lever handle to facilitate easy access from the helm seat. The opening allows easy access for in-situ refueling.

We centered the hatches over the cubbies and outboard but still parallel to the bench edges. We laid out the openings to be cut with blue painters tape. Holes were drilled though the bench surface into the cubbies (2” thick channel reinforcement) at the corners were made. Cutting was done with a Ryobi 18v jigsaw and a long down stroke cut blade ( fiberglass is tough on non-carbide blades).

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

Before finally mounting of the hatches an appropriate bead of marine sealant was applied to the under flange of the hatch 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.

Our installation was completed with a true 3- way (Tank A/Tank B/Off), an inline spin-on fuel filter/water separator, a fuel pressure relief (FPV) & a primer bulb.

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 ease of use.

Hope this post has been helpful to those interested in making this modification.

UPDATE 05/12/2024:

I finally got around to remembering to take a couple of better photos of our fuel selector/FPV/filter/separator/bulb panel set-up on the boat. I should have done it earlier an’ jus’ ever got-a-round-tuit :D :D

This is now our third season with this set-up and it’s been working out great for us…everything easily falls to hand in use, is easily checked and easily serviced. 8) 8)

As you can see the selector is where one can see it from just about anywhere in the cockpit and reach it from the helm seat.
The primer bulb is also readily at hand form the helm seat by just reaching over the seat back.
The filter water separator visual bowl is large enough to contain any water collected without needing to be addressed on an immediate crisis basis and is easily checked/serviced(drained) at the start or end of any trips when we raise/lower the engine. (As we try to exclusively use ethanol-free marine fuel we haven’t found any water accumulation at all. Only early on when we couldn’t get anything but regular automotive fuel did we find any errant water droplets… but they were easy to see and drain into a cup for proper disposal.)

Best Regards from Over Easy!

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