Mounting and securing fuel tanks??

BillD

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To ALL,

I've measured up the 25 T Jason for twin below deck fuel tanks. The boat had a single 35 gal fuel tank mounted on deck below the port side helm cabin windows. This tank is removed and headed to the aluminum scrap heap.

My original plan was a single stern tank in the 90-100 gallon range but after sea trialing and using the boat for 10+ hours I do NOT want to give up deck space to a fuel tank.

My plan is to have built 3/8s welded poly tanks rectangular 8' L X 17" Wide X 7" +- high tanks for a total of 49-50 gallons.

The hull is not flat or level over the length of the 8 feet where the tanks will sit. Is the proper way to build a level glass bed for each tank? Glass say 8 "pads" for the tank to rest on? Should I set the tanks so each follows the pitch of the flange?

The tanks will be manufactured by Triple M plastics in ME..same company that did Raider Ronnie's 28 BHM tanks.
I'll have the option of having mount strips or feet welded to the tanks.


Seems to me the tanks should be a whisker "nose up" with the boat @ rest.

I'll consult a builder or three but I figured I toss the question/s out to the forum.

Appreciated, Bill D
 

traditions

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I would build a flat bed for the tanks to sit on ,glassed in with the same pitch as the deck,with the fuel pick ups in the stern end.Do not put the return in the same place as the pick up unless you put pick up tubes on both . I would make glass tanks,but just my opinion.
 

Toolate

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Sounds shallow as hell (dont think you have any more space). Will you be able to mount a fuel gauge sender in a tank 7" deep?

Maybe just an inspection port so you can see the level through the tank walls.
 

Duke

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BillD

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I would build a flat bed for the tanks to sit on ,glassed in with the same pitch as the deck,with the fuel pick ups in the stern end.Do not put the return in the same place as the pick up unless you put pick up tubes on both . I would make glass tanks,but just my opinion.

Thanks,

Sounds shallow as hell (dont think you have any more space). Will you be able to mount a fuel gauge sender in a tank 7" deep?

Maybe just an inspection port so you can see the level through the tank walls.

No fuel gauge required, simple enough to track hours :)

The tanks sound too shallow. Say they are 1/4 full, you only have 1 3/4" of fuel in the tank. You pitch forward, down the front of a swell and you will uncover the suctions long enough to pick up air.

Good point !
 

Brooksie

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Tank aft N/G anyway; trim changes as you use fuel. Will they put a sump in the bottom for PU tube to go into? Have you considered taking the fuel off from the bottom. I have done this on both my boats and like it. You get more useable fuel from your tanks plus the water and gunk goes to the filters instead of laying in the bottom waiting for you to be between breakwaters. I will try to attach a diaghragm of my system.
If your engine is not self bleeding, consider making it so.

SEEKER FUEL 2.jpg
 
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BillD

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Tank aft N/G anyway; trim changes as you use fuel. Will they put a sump in the bottom for PU tube to go into? Have you considered taking the fuel off from the bottom. I have done this on both my boats and like it. You get more useable fuel from your tanks plus the water and gunk goes to the filters instead of laying in the bottom waiting for you to be between breakwaters. I will try to attach a diaghragm of my system.
If your engine is not self bleeding, consider making it so.

Thanks Brooksie
 

Tuna Pursuit

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Tank aft N/G anyway; trim changes as you use fuel. Will they put a sump in the bottom for PU tube to go into? Have you considered taking the fuel off from the bottom. I have done this on both my boats and like it. You get more useable fuel from your tanks plus the water and gunk goes to the filters instead of laying in the bottom waiting for you to be between breakwaters. I will try to attach a diaghragm of my system.
If your engine is not self bleeding, consider making it so.

You can't have a fitting anywhere but on top of the tank.
 

Keelboater

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Bill D - see if the manufacturer can install baffles in that long slender tank and possibly a trap near the pickup tube! That can prevent most of the sloshing as the level drops and space is created. Most plastic tanks are rotomolded and have no baffles. An 8' long tank with no baffles is asking for trouble in my book. It's about the forces created within the tank as well as it is about sucking air. I have built several aluminum tanks, all of which I installed baffles in. Good luck.
 

Toolate

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Any way you could make a tank the same size as your engine box's cross section and sit it right behind the motor box (like an extension to the box)? Think you were going to gain some space in your repower anyway.

Just thinking outside of the box a little. Tank would be out from under the deck and remain accessible which is nice.
 

Toolate

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I'll vote No on that,
Keep the moving liquids as low in the hull as possible

I would agree if it were 100 gals but the original tank was 35 which really weighs maybe 300 lbs? Like a guy sitting on your engine box all day. A big one. Just thinking out loud.

How much fuel do you need Bill?
 

CEShawn

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Not to bring this up again... but isnt there something about penetrations on the bottom of the tank not being allowed?

I also believe I started to go down this road and a welder turned me off on the idea...

Granted we do it on ships all the time, but do we ever see it elsewhere? I know boats have it but not enough seem to have it...
 

BillD

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Any way you could make a tank the same size as your engine box's cross section and sit it right behind the motor box (like an extension to the box)? Think you were going to gain some space in your repower anyway.

Just thinking outside of the box a little. Tank would be out from under the deck and remain accessible which is nice.

YIKES !!!!!! :confused::eek:
 

mudhake

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hey Bill, call me and I can tell you all about triple m tanks, because I have installed over 90 of their tanks. Steve.
 

Tuna Pursuit

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Not to bring this up again... but isnt there something about penetrations on the bottom of the tank not being allowed?

I also believe I started to go down this road and a welder turned me off on the idea...

Granted we do it on ships all the time, but do we ever see it elsewhere? I know boats have it but not enough seem to have it...

As far as I can see the regs state you shall not have a drain on the bottom of the tank. It doesn't specifically say no fittings or no penetrations but it does say all fittings must be easily accesible for inspection so anything on the bottom on most boats would not be easily accesible. Can you imagine a leak with a full tank? I would never put anything through the tank except on top.
 
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