Gas Tank Under Foredeck?

Ben M

Ben M

Active member
My build has taken a turn with the recent purchase of a 15hp Evinrude. Hadn't planned on an outboard so soon, and certainly not one this strong. Fuel...

Motor weighs 75-ish pounds & a fuel tank adds an extra what....30-50lbs depending on size & fill level? Gonna booger up the trim in my pretty little boat! Haha...

I've seen people running their fuel tanks up under the foredeck to help with trim, but that makes me a little nervous. I'd be lying down in my boat, head maybe 18" from a gasoline tank, and a fuel line running down beside me to the motor. Lighting a cigar becomes a very dangerous proposition!! To say nothing of the fumes I might be breathing under the dodger. Idunno....

What do you think?

All this aside, there just is not a good place to put a tank in there without cutting a hatch or maybe a permanent tank with a fill cap. Maybe a 3gal tank would fit through the opening in the forward bulkhead to get under the foredeck, but anything else would either be in the cockpit with me, under my feet or something....
 
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Lighting a cigar becomes a very dangerous proposition!! To say nothing of the fumes I might be breathing under the dodger.
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Oh I agree, lighting a cigar is going to produce a variety of toxic fumes.

Simple solution to the prevention of breathing in toxic fumes,,,,,,,,,,,,,do not light up a cigar. Not lighting a cigar also removes the fire hazard.

As far as the issue of a fuel tank in the bow, most guys will build in a vented fuel compartment or use a permanent style tank that is vented to the outside.


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Lots of past posts on this forum about guys running fuel lines to bow-mounted tanks.

My advice--get a 3 gallon tank unless you are anticipating lots of long runs. You'll save space and weight.

In my 14' tin boat, I have a 3 gallon tank that I put well forward, though my fuel line is not long enough to mount it all the way up in the bow. Fuel line is on the floor of the boat and unprotected, and I've had no problems in 5+ years of use with this tank and line, despite using the boat while wearing metal cleated wading boots.

I'd move it farther forward if I could find a longer fuel line.

As for smoking in the boat, I don't think the location of your tank has any bearing on safety. No matter what you'll have lit smoking materials near your tank and fuel line.
 
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Lighting a cigar becomes a very dangerous proposition!! To say nothing of the fumes I might be breathing under the dodger.
Click to expand...
Oh I agree, lighting a cigar is going to produce a variety of toxic fumes.

Simple solution to the prevention of breathing in toxic fumes,,,,,,,,,,,,,do not light up a cigar.
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Click to expand...

Hahaha... Anyone who dares inhale one of those....whew! But I do like the flavor and the smell...I'll be sure to keep downwind of your position, good sir! :) I was, however, referring to the gas fumes from the can right by my ole noggin being trapped under the dodger. Haha...

Vented, sealed compartment for gas can...sounds like a pretty good idea, although there would still have to be a port for the fuel line to pass through the cockpit. And would probably require cutting a hatch in the deck on my boat...

Yeah, I guess my faithful cigar will just have to stay unlit if I'm to hunt a tiny duck boat with a gas motor on it in any fashion...

Is a 3 gal tank enough? An old 15 like this burns what....a gallon per hour of WOT? More? That's probably enough for all but the most ambitious trips I would tackle...Opinions? Experiences?
 
Good morning, Ben~

I used a Johnson 15 2-cycle for many years on my Sneakbox. I used a 3-gallon tank - stowed beneath the stern deck - and also carried a 1-gal emergency can. I seldom ran more than 3 miles from my launch site, but never ran out of gas.

Last year I moved a 6-gallon can forward of the cockpit on a South Bay Duckboat. It was kept in place by chocks fastened to the floorboards and some shock cord. (And, I later painted the tank with duckboat paint at the owner's request.)


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I lengthened the fuel line and protected it by running it through about 6 feet of 3/4-inch CVPC pipe. The pipe was snapped into a pair of standard pipe clips on the underside of the starboard deck.

Here is the post. The relevant portions are about 2/3 down this "epic" post.....


http://www.duckboats.net/cgi-bin/forum/gforum.cgi?post=272548;search_string=South%20Bay%20Spa;#272548



BTW: From your photos of the "run" on your vessel, I think that rocker will preclude any planing. I recommend you just find the sweet spot where the boat makes good progress but the engine is not laboring - and enjoy the comfortable, seaworthy ride. (Ideal propulsion would likely be a 6 HP with a flat-pitch prop.....)

All the best,

SJS
 
I have a 15hp Johnson, 1978 motor. 3 gal tank up under the fore deck. Mine is a displacement hull. Glass over cedar. I run the gas line down through the cockpit and out over the combing. I don't like putting more holes in my boat than I have to and especially on the rear deck. I redid the boat in 1995 and smoked till last year. Never blew up. I just closed the vent when gunning.
 
I have a 15hp Johnson, 1978 motor. 3 gal tank up under the fore deck. Mine is a displacement hull. Glass over cedar. I run the gas line down through the cockpit and out over the combing. I don't like putting more holes in my boat than I have to and especially on the rear deck. I redid the boat in 1995 and smoked till last year. Never blew up. I just closed the vent when gunning.
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Hey Kurt, since Mr Sanford believes my hull won't plane, and you have a 15 on a displacement hull....how has that worked out for you?

Thanks for your advice, Steve. I've never felt like I really need to go fast on cold water in the dark anyway...displacement hulls seem like the safest way to go for duck hunting anyway...
 
I don't plane at all.....I plow. I went from a 9.9 to the 15. Once I did the switch I needed goggles as I was able to obtain a blistering 11kts. Seriously, it is a trade off. My boat was a sailer I found in a barn left to rot. totally redid it. Rows like a dream and I set it so I can carry about 75 decoys. I hunt the bay and have never felt unsafe in the boat. But plane?.......never....was never made to do it.
 
The old school formula for fuel consumption on those motors was very simple. Move the decimal point one to the left and you have gal/ hr. at WOT. A 15 should use about a gal & 1/2 per hour wide open. I might add that I demonstrated this one morning with my 25, a very long walk in chest waders. I use 2- 3 gal tanks on my Broadbill with a 25 Evinrude
 
I put a 6 gallon moeller bow tank under the deck in my duckboss 15. the only time I have an issue with fumes is when I over fill the tank. The nice thing about this fairly new tank is the triangular shape allows it to fit further up in the bow. I also cut a 4" hole in the front deck and put a round cover directly above the fill so I can fill the gas tank without removing it from the bow.
 
Brilliant idea Shawn! Might you PM me some pics of your set-up and access hole? I think I'd like to do this modification to my DuckBoss15.

Did you glass the tank in?

Thanks in advance!
 
Mike, I did not glass the tank in. I used 5200 and glued a piece if decking(not sure of the specie) that is very rot resistant. One in the front and one in the notch in the back of the tank. On each I put a bungee ring so I could hold the tank down. I set the tank in place and drilled a pilot hole from the center of the tank fill up through the deck. I used a 4" deck plate setting it up to make sure it would sit flat an then I drilled the four inch hole in the deck and installed the plate with 5200 and screws. When I need t fill the tank I drop an long oil funnel directly into the tanks fill and pour from outside the boat. You do have to use care not to overfill the tank, but my etec has never used 6 gallons of fuel in a single day so I never fill to the top.
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Not the best picture, but you can see the deck plate in the corner of the walk on front deck in front of the blind. I had some better pictures but they got lost in my last phone. I will try to send you some in the next few days.
 
Shawn,
Thanks for the picture! I like where you placed the 4" deck hatch. Since you've placed it there have there been any instances of cracking? We use the front of my boat a LOT to come and go in the marshes. Hence the concern.

I was considering putting something like this near the bow and above my highest set of handles. My concern with the 'keyed' caps is that they jam with ice and muck and may possibly damage waders. This one, with the plastic rim, may not damage waders and hopefully not jam with ice/mud.
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There is also a curved metal fill cap that might lay more readily along the curve of my boat. Although, I am QUITE concerned the pictured model would easily jam.
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Your thoughts? Suggestions?

Anyone else have some ideas or suggestions?
 
The tank I used under my deck is actually an above deck tank and has no means to attach this type of fill. I have not had any issues with walking on the fore deck, and I weight 250lbs. There is good structure there and I used a hole saw to make a perfectly round hole.
 
I hunt a south bay and mounted a large tank in the bow for those longer trips to in a new area. Use a 3 gal in the stern for local creek hunting. Both are removable, used steve sanfords design. Always have a 2gal spare in the truck for top offs.
 
Brings to mind the day I was hunting with a friend in his boat and after the morning action had died down he was taking breakfast orders. Great!! Then I looked back into the "kitchen" and saw the Colman stove perched slap damn on top of the gas tank. No explosion but I suggested a different spot for the stove. All's well that ends well I guess.
 
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