Gunwale Tanks - Good idea or Bad idea?

[Dyounge]

I’m in search of more storage space in my ‘69 GT160. I’d like to be able to use the relatively large space under the bow that is currently housing an 18gal fuel tank. I’d like to replace the big bow tank with dual 9gal gunwale tanks I found at https://miraxfuelproducts.com/gunwale-tanks/. Has anyone done this on an old Glastron. Assuming it will fit, will the hull handle it? Any other issues I should be aware of?

[Hyperacme]

Don't think it would be a problem.  Outboards like weight in stern.
Would you need a tube connecting both tanks together ? Balance tube ?

You could add two 50 lbs. sand bags and see how it works out, before buying & adding tanks.
With a light load of fuel (3 gals.) in bow tank or light load in portable tank in stern.

[hemi RT]

I’m in search of more storage space in my ‘69 GT160. I’d like to be able to use the relatively large space under the bow that is currently housing an 18gal fuel tank. I’d like to replace the big bow tank with dual 9gal gunwale tanks I found at https://miraxfuelproducts.com/gunwale-tanks/. Has anyone done this on an old Glastron. Assuming it will fit, will the hull handle it? Any other issues I should be aware of?

if both tanks do not drain evenly you are going to have a balance problem. Also depending on how far back the tanks are it may take longer to get up on the step. Also you will need 2 fill caps or a large hose going between both tanks so they fill in a reasonable amount of time plus 2 vents

[Plugcheck]

Sounds interesting, the balance part could be an issue to solve.  Any balance tube could also transfer if a list occurred.     At 10 gallons roughly, 80 lbs difference should not be an issue.  Maybe forgo the balance tube and use a two tank valve.  This could be manual or electric like some vehicles use for two tanks.  Two fuel gages maybe, or just use one till it reads half, then fully drain the other, then you have half to get home?  Any possibility of getting a form fitting tank up front that would provide more storage.

[Hyperacme]

Just some stuff to think about …

A 16 foot boat with 115 HP motor will get about 80 to 90 mile out of a 18 gal. tank.
Dave's CVX16 / Johnson 115 HP and my CV16 / Mariner 115 HP get about that running half to full throttle on a Mississippi river run.
Finding fuel on St.Croix and Miss. aren't a problem, but even with my 18 gal. tank I have to stop for fuel on a Miss. run.

I had a V-156 with two 6 gal. portable tanks, I would run one dry then switch to the other.
Not a big deal, except for two times …

First one ..  I ran out in front of a barge coming up stream. It was far enough away that after switching tanks I was back under way with plenty of time to get out of his way... BUT … it was close enough that I was pretty nervous and very happy motor started up fast ..
Another time I ran out around a marina and floated over to docks while changing tanks. Had to hold boat away from big cruiser's swim platform while changing tanks. 

For me … The convenience of my 18 gal. bow mounted tank out weighs the storage space.

[Dyounge]

Any possibility of getting a form fitting tank up front that would provide more storage.

I hadn't considered that, but a custom tank that fits tight to the hull and still leaves a large open area in the center is not a bad idea. Thanks!

[Dyounge]

I had a V-156 with two 6 gal. portable tanks, I would run one dry then switch to the other.
Not a big deal, except for two times …

First one ..  I ran out in front of a barge coming up stream. It was far enough away that after switching tanks I was back under way with plenty of time to get out of his way... BUT … it was close enough that I was pretty nervous and very happy motor started up fast ..
Another time I ran out around a marina and floated over to docks while changing tanks. Had to hold boat away from big cruiser's swim platform while changing tanks. 

For me … The convenience of my 18 gal. bow mounted tank out weighs the storage space.

Appreciate the heads up Gregg. If I do go this route, I will make sure they are T'd and the engine pulls from both tanks equally.

[Plugcheck]

I hadn't considered that, but a custom tank that fits tight to the hull and still leaves a large open area in the center is not a bad idea. Thanks!

       I'm really have no idea what the space behind the tank looks like, but its certainly possible to make a cardboard and tape box that fits it perfectly, then disassemble for a template to make a custom aluminum tank.    The old tank would have value, certain someone would be interested in purchasing if you go down the custom route.   Best time of season for this work as well.

[thedeuceman]

Ole Red built a custom fiberglass tank once, it was documented fairly well here somewhere


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[Hyperacme]

Fiberglas gas tank
http://forum.cgoamn.com/index.php?topic=3985.msg48378#msg48378

[Plugcheck]

     That fiberglass stuff is sure difficult to weld though... .....Did Red actually complete that tank?  there appears to be only one page to that link.   Anyway, I'm fond of aluminum for fuel, not saying glass wouldn't work, they make pressure tanks with spun glass.   I wonder if a glass box with a bladder might be an option?   I'm just scared of fuel in long term contact with glass.   Heck, long term contact with water ate the bottom of my boat, with gel coat and ablative coating.

[Plugcheck]

www.boydwelding.com/
Here is a company that will custom build an aluminum tank for any application.  Send them a drawing and they will quote a price.