Anyone retrofitted an inernal fule tank into a boat

Charlie S and Titan

Charlie S and Titan

Well-known member
In my throes of looking at new boats I realized that I am pretty happy with mine now and would like to try to "spruce it up some" rather than spend lots of money I don't have on a new hull.

No matter what I do, I'd have to spend at least $7K to "upgrade" into a new version of the same boat. That just doesn't make financial sense when I am very happy with the have a boat I like. Besides the only way I could do it is to go into debt and my wife is (wisely) against that proposition.

One thing I don't like about my boat is the fact the the original owner deleted the internal tank option. A 6 gal portable tank eats up a lot of deck space that I'd like back.

What I am wondering is whether anyone here has retrofitted an internal fuel tank into a boat? If so, can I pick your brain? How did you do it? Where'd you get your tank and fittings?

The factory tanks are under the floor, but I am wondering if custom tank sized to fit in the bow storage might be a better (less destructive) use of space. I see that some manufacturers (like Hewescraft) put their tanks in the bow which also helps with weight distribution.

I am in the planning stages of what I will do next summer and want to see if it is possible or reasonable to retrofit one into the boat.

Other than that, I'm thinking about having a friend in the body shop business hit the inside with grey flecked Zolotone and painting the outside with FME med open water grey. That'll make it just about perfect for me.

Thanks,
Charlie
 
most "internal tanks" are larger than (6) gallons and that can result in a lot of wt. in the bow of the boat that can't be relocated to "trim" the boat.....under the floor boards in the big flat tanks distributes the weight over a bigger footprint ensuring a better trim while keeping the COG as low as possible.....not to mention saving the valuable "dry storage" area in the bow that you lose.....

As a good friend likes to say...."if you are going to be a Bear, BE A GRIZZLY"....and do it right by going back to the underfloor tanks....

Steve
 
Great point. I think the one this boat should've come with is 19 gallons. That's something like 152 pounds plus the tank. It'd be better to have it in the belly to help with center of gravity. That being said it is a lot more invasive surgery. Not insurmountable, since I've rebuilt the floor on a similar boat before, but is is definitely a lot more work. Do you think it is reasonable to assume the underfloor structure is the same on boats with tank delete? If so, I may just be best off buying the pieces from lund.

Charlie
 
Four Stroke became the "normal" power plant on boats and I "think" that a lot of the reason they are now forward like that is to offset the heavier wt of the motor...I know Gregg Kurz has the bow mounted fuel tanks on his AlumaWeld but in that application he didn't lose the bow storage....plus on a Jet its a good thing to have wt in the bow, both for the hole shot and running shallow.....

My "guess" is that if there is an underfloor option on the hull you have that the easiest thing to do is to buy the parts the factory would have used.....I'd pull the floor boards up and compare that to a drawing that a dealer would have of the rib locations befroe buying the tanks though....

Steve
 
I'm kind of against built in tanks. Of course, if you use your boat ALOT, then having a 19 or 20 gallon tank is great. I worry about condensation and plugging of the vents on them. I like to actually see what I have left on fuel and be able to dump 3 or 4 gallons if it is bad..then clean the tank. If you are cautious, and don't fill it so it sits for months, wunnerful.
 
Are the old tanks still under the floor? If so, replacement, as in finding replacements & fittings should be easy since you will have somethign to compare to.
As far as tanks & parts, most builders use standard size tanks & finding a replacement should not be hard. Also, most good marine stores will have all the fittings & plumbing you need as well as being able to order tanks.
One thing to remember is that if you don't already, once permanently install a tank, you have to have a fire extinguisher on board.
 
Okay,

Here's the story right from Lund. They never had a belly tank option in the Alaskan 18 in 1999. I was wrong about the "tank delete" (so much for trusting what the seller tells you...).

Fortunately I got ahold of a super knowledgable guy in the Technical department. They didn't even offer a belly tank option in this boat. The spacing of the underfloor cross supports does not allow enough roof for anything (the cross braces are spaced ever 12" he tells me, plus the depth is pretty shallow). The newer hulls have a completely different under floor support system that accommodates a tank.

What they did offer back then as an option was a side mount tank that went in one of the rod lockers. The part (Lund p/n 590013) is no longer available though. He suggested that I see if I can measure the dimensions and see if I can get a similar tank from a marine store...

So, I need to put my thinking cap on. Maybe I can make that work.

Thanks,
Charlie

Carl, I have a marine extinguisher in the boat. I think it is a Coast Guard requirement for boats this size.
 
Charlie, westmarine.com They have a bunch of tanks and hardware. Kinda spendy but it is hard to walk away from a burning boat. yuukk Good luck. BTW I hope to build in a tank into my next last boat.
 
assuming I'm not grossly incorrect.....

for some reason I seem to remeber it being on the same side as the console which would seem to be exactly opposite of where I would have thought it would go since on the opposite side from the side mounted console it would trim out better.....might be wrong in the recollection on that though....

I've never had any issues with "contaminated fuel" like Lee worries about....Hell until this year I never ever ever used anything to stabilize my fuel in the off season, (like Stabil), or to condition my fuel, (like Seafoam), like everyone seems to recommend here....and not only have I never ever ever used them I'mve never ever ever had any issues with starting or running........based on that built in fuel tanks on a boat are a plus to me....

The above said I've always wondered WHAT fuels breaks down into after the first thirty days as so many people say here.....does it break down into mayonaise or something and I just haven't seen it? I mean I have a vehicle in Florida that gets run exactly one week a year, 10 days at the most.....when I park it when I leave Florida after Christmas I'll turn the key, close the door and leave it....parked outside....next to my Brother In Laws house.....every year up till this one, and we'll know about this year tomorrow, the car will fire off before draining the battery, and that fuel, without additives, having had 355 days to "break down" will run that motor like a top....

So I have to ask, are additives worth the $$ they cost or are they just hype for gear heads? Oh, and BTW, based on the recommendations of this site this year I actually added Sea Foam to the fuel on my 15hp Johnson, a motor that has started within 3 pulls in October after not having been run since the previous January and you know what happened? The frigging fuel line inside the cowling split, leaked like a sieve, spewed fuel into my favorite piece of water in the World and cost me $200.00 to get fixed?......Coincidence? Harrummph....

Steve
 
Steve, I too have never ever put stabil or any "conditioners" in any motor I have ever owned. The only time I ever saw any problem was on a Honda 90 that had set for ....years...there was a jelly like crud in the float bowl. That's the only time I had seen fuel break down. That gas would have been regular "leaded" gas back in the 60's. I think some of the new alcohol based fuels are more troublesome. I use Seafoam for keeping carbon buildup in the motor to a minimum, not as a stabilizer...but it's supposed to do that too. The biggest problem with fuel tanks is condensation and the bigger, the more prone to it I would guess. Refined oil(gasoline) has a bunch of additives in it and I guess they seperate out and a lot of them evaporate. I've had to dis-assemble carbs on 2 stroke snow throwers to clean stuff out but I think it was the oil that had been mixed with the gas and somehow the gas part had evaporated out of the float bowl. Bad gas shows up in 2 strokes worse than 4 strokes and I see it recommended to use "bad" gas in your car to get rid of it instead of dumping it out back.
 
Steve

Consider your self lucky that you have not had any bad fuel problems. But if you do, you might think it is a motor problem rather than a fuel problem, like other people. With out stabilizer in the fuel it with begin to make a varnish that likes to plug up the passages in your carb. When you think you have run the carb dry and out fuel, there will always be a little left over. If you have some left in a tank that has sat around for awhile, it will degrade to give you poor running performance and again you may think it is a motor problem. Also, the fuel left over in a fuel line or any where else that will hold fuel can give you a potential problem. It is to easy to think that since you have had no problems, you never will. This thinking will come back to haunt you some day and I hope it is not in a remote place or in the middle of a big lake.

Charlie

You should ask the tech. you talked with to find out if there is a need to meet COG reg. about venting if tank is in closed compartment. Like Lee, I would rather have potable tanks when possible. I would rather see that expensive fuel go into my truck that have it sit around in a boat tank. If you can modify under a seat or some place to stow the tank or extra tank to give good trim, you could use the locker for other storage. Also, I can see if you have long runs to make and use more that a 6 gal. a lot, a bigger tank makes sense. Either way, what you like best is what counts. Besides, if you show your wife that it did not cost as much as you thought you can spend some on her to keep an even keel around your house.

.
 
My boat was light on the front end to start with so I went to a welding shop and had an aluminum tank built to lay into the v close to the bow and fit between the ribs.
I was shooting for 18 gallon but they ended up building one that held 24 gal. Their math skills were a little rusty but they built a good tank and I've never regretted it.

I've never used stabilizer.
I put in an inline fuel filter/water separator normally used for an inboard motor. Every year before using the boat I drain the fuel into my truck and put a new filter on.

I've gone 14 years without any carburetor problems at all using the same motor, (94 Mercury 2 stroke 60hp.)

Mike
 
Steve,

Odd that it is on the same side as the console. I never thought to even ask - I just assumed. I'd have guessed that that would make the boat tip even more in that direction than it already did if put on the console side. My gut tells me to put it on the other side to balance out the weight of the driver and console (that is the side I put my portable tank on). Maybe I should call Brian back.

Mike,

Who'd you use for fabrication? A local welding shop, not some mail order marine place? How'd that work out? Any special treatement necessary? What grade/thickness of aluminum?

Did you just tell them what you wanted and drop the boat off for construction, or did you make templates or a prototype and give them the prototype?

The alaskan sits bow high as it is, so maybe it wouldn't be so bad to add some extra ballast to the bow? I don't really use that storage all that much except as a place to stow a throwable PFD. Then again, the factory side trunk option idea is probably worth copying, they must've put some engineering thought into it?

I believe either way will involve custom fabrication - the side trunks are an odd shape due to the angle of the sheer (? - whatever you call the side wall of the boat). Of course I'll look at the off the shelf options, but they are not cheap - probably nearly as cost effective to have one made up and have it fit the space properly.

Thanks,
Charlie
 
Charlie,

I've seen Alaskans that have a custom-built compartment in the rear of the boat for a portable tank, battery, and storage. Have you already ruled out a simple solution like that?

Rick
 
Rick,

I haven't ruled anything out yet. I'm still in the "noodling it over" stage.

Can you tell me more about what this compartment looks like and is made of? No chance you have a picture is there?

Thanks,
Charlie
 
Sorry, no picture. I just tried doing a pot-head drawing ala Harker, but just managed to smear ink all over the screen.

What I've seen in the Alaskan is just a plywood box built across the rear with separate compartments for the gas tank and the battery, and a cover that goes over the whole thing forming a bench. Probably about 18"-24" deep. The same carpet that's on the floor covers the box so that it looks like an integral part of the boat.

As I recall, I've only seen them on tiller models--the switches for the bilge pump etc. were located on the front of the box.

Rick
 
Steve-

The console is starboard with a storage locker and the fuel tank is port (I now have Bill's boat). I'm actually trying to figure out the size of the tank (20' Lund Alaskan, 1996) 'cause I'm switching to a 2 stroke (the 4 stroke had a heart-stroke) and need to know how much oil to add to the mix (beats $8-9k for a new motor, the 2 stroke runs like a top).


And between Bill & I this thing got to have used more fuel than most people's cars!! hehe No problems with condensation (has a water separator & never had water come out yet)...
 
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Paul,

Thanks!

My understanding is that the late 90's and very early 2000's Alaskan 20' had an 18 gallon tank. They switched over to a 27 gallon tank later. This is just what I've read though, so no guarantees.

Any chance you'd be willing to take some pictures for me? Of the tank location and the fill and vent setup?

Moeller has a side tank that is designed for this sort of application, but it is too deep (17 7/8" plus another 2.5" for the fill pipe). I wish I could find a NOS Lund tank, but odds are I'm going to have one fabbed up out of aluminum. Not the end of the world, but probably more pricy.

There are several places I could put a tank, the side locker, the two small square anchor lockers or under the bow. The stock location in the side locker would be best from the perspective of being the least used space with the easiest routing of lines.

The side locker is 7" wide at the base and 10" wide at the top, one surface is vertical and the other follows the angle of the sheer. I have 36" of length if I want to preserve the use of the side locker, somewhat longer if I am willing to sacrifice stowage space.

Where did you (or Bill) mount the fuel/water separator, filter?

Or I could just keep running the 6 gal tank, which is the cheapest option, but I am a pain in the neck, so I'll probably do it the hard way.

Thanks!

Charlie
 
Charlie-

I've got some pics of it when I dismantled it, I'll see if I can dig 'em up.

The water separator is mounted on the front of the splashwell. I'm going to install a board to beef it up a bit though.

Hit up the various fishing websites and ask around for a OEM tank. Odds are there are more fishermen using these boats and there's gotta be a junkyard somewhere or one sitting in someone's yard gathering moss.

paul
 
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