space under floor for a fuel tank

[bob johnson]

I know I read one or two threads where guys mentioned adding a belly tank under their floor on their rebuilds.

i am considering that... i am not up that exact point yet.....but i want to keep my eye open for the right size tank...or at least if I caNT FIT A PERMANENT TANK, THEN WHAT EVER SIZE PORTABLES WILL FIT UNDER THE FLOOR.

SORRY ABOUT HITTING THE CAPS LOCK THERE!

I have a 1982 starcraft SS180.

the hull is about bare now, i got it stripped....id like to add the fuel tanks up front , to keep weight off the stern...

I am thinking of either trying to fit tanks up in the front under the step up in the floor or under the main floor right up near that step

I have seen tanks about 7-9" high down their centerline, and I have seen them ABOUT 25" wide....I dont have my stringers in yet...so I am not sure exactly what the width will be.

so i am asking...if anyone put a fuel tank under the floor in their 18 footer...what size was it?

I am also iunclined to use two portable tanks so it is easy to deal with bad or contaminated fuel easier if that condition arises.

The best scenario would be a center mounted tank at least 18 gallons with a filler lid on the gunnel...so i dont have to climb in the boat to fuel up.....

I am trying to leave as much open floor space as possible on this custom rebuild

thanks

bob

 

[barato2]

Re: space under floor for a fuel tank

Bob--

i'll jump in here since no one else has. i'm also installing bow tank into my 18' holiday to supplant the 18 gal stocker in stern. haven't even gotten the floors out yet but i have laid the tank up next to the hull and am pretty sure it will fit under floor....it's 19 gal alum, sort of modified wedge shape, from my engine donor boat. i might have to raise the center of floor to clear it but i don't thnk so. your plan is good one since it seems lots of people here want to move CG forward once they splash their boat.

 

[roscoe]

Re: space under floor for a fuel tank

Portable tanks under the floor would be a coast guard no-no.

Read your regs, follow the regs, do it safely.

 

[grzzzz]

Re: space under floor for a fuel tank

Bob
I installed an under deck tank when I restored my 66 Holiday 18.5 Starcraft. It went quite well. 18 gal. I am an engineer and recalculated the changes in CG and displacement changes. I tried to compensate for the now heavy 4 stroke kicker (90lbs)I put on, dual battery system I put in the back and now heavier women (I find as I get older) I take fishing. Moeler has a model that fits perfect. I bought it from the sponsor in this forum. The model number is FT1826. It fits nicely between the floor stringer, it comes with fuel gauge that hooks right up to existing vintage gauges. AND WORKS!!! The nozzles are at the front of the tank and angle nicely to the right front deck hmmm about a foot in front of the wind shield. I put the vent out on the boat side about 4 inches below the deck and the filler opening up on the deck. Easy to fill standing by the pump. The tank is up forward to where all the hoses are safe distance from you feet as driving. If you want I can get you some measurements but I say the front of the tank is about 3-4 feet from the front of the boat extending back hmmmm just short of mid deck. The tank shape about dictates how far forward you can go. It starts squeezing the tank. I just put tight cell foam under and around the tank to keep it off the boat bottom, stuffed as much of the Styrofoam I could to fill gaps, shot canned expando foam in cracks and crevices, shot a few lines of expando on the top of the tank and dropped down the flood, screwed it down as the expando was curing.

No way it is going anywhere. opsss Ran the fuel lines before all this down the center of the boat out to the engine well. That's kind of important....

As I calculated, the CG was close to the manufactures specs but things do change as the boating day goes by. Cooler contents are metabolized and expelled over board, women do go on diets each spring and than increase as summer goes by, fuel in consumed throughput the day, live well fills etc but I found it is balanced quite well.

Wish I could send you pics but I have never figured out how to do that on this site. I need to get my son over to help me. If you have any more questions ..let me know

Grzzzz

 

[bob johnson]

Re: space under floor for a fuel tank

Bob
I installed an under deck tank when I restored my 66 Holiday 18.5 Starcraft. It went quite well. 18 gal. I am an engineer and recalculated the changes in CG and displacement changes. I tried to compensate for the now heavy 4 stroke kicker (90lbs)I put on, dual battery system I put in the back and now heavier women (I find as I get older) I take fishing. Moeler has a model that fits perfect. I bought it from the sponsor in this forum. The model number is FT1826. It fits nicely between the floor stringer, it comes with fuel gauge that hooks right up to existing vintage gauges. AND WORKS!!! The nozzles are at the front of the tank and angle nicely to the right front deck hmmm about a foot in front of the wind shield. I put the vent out on the boat side about 4 inches below the deck and the filler opening up on the deck. Easy to fill standing by the pump. The tank is up forward to where all the hoses are safe distance from you feet as driving. If you want I can get you some measurements but I say the front of the tank is about 3-4 feet from the front of the boat extending back hmmmm just short of mid deck. The tank shape about dictates how far forward you can go. It starts squeezing the tank. I just put tight cell foam under and around the tank to keep it off the boat bottom, stuffed as much of the Styrofoam I could to fill gaps, shot canned expando foam in cracks and crevices, shot a few lines of expando on the top of the tank and dropped down the flood, screwed it down as the expando was curing.

No way it is going anywhere. opsss Ran the fuel lines before all this down the center of the boat out to the engine well. That's kind of important....

As I calculated, the CG was close to the manufactures specs but things do change as the boating day goes by. Cooler contents are metabolized and expelled over board, women do go on diets each spring and than increase as summer goes by, fuel in consumed throughput the day, live well fills etc but I found it is balanced quite well.

Wish I could send you pics but I have never figured out how to do that on this site. I need to get my son over to help me. If you have any more questions ..let me know

Grzzzz

yeah I would love to see the pictures... I think i would make a hatch that allows access to the tank...i keep thinking I dont want to tear up the whole floor to pull the gas tank... I was also thinking in the first 1/3 of the boat, and Ill put my dual batteries under the console( one single side console is all i will use)

this is the site i load my pictures from

http://tinypic.com/index.php

you can see where to browse then "open" and it jumps to one of three fields..i think i copy the second field down..and then i go and paste in my box right next to where i am typing...very easy...they have a little test you need to go through so a coputer system wont automatically load pictures..

but its easy...i use 15" monitor as the size i use and it works great


bob

 

[grzzzz]

Re: space under floor for a fuel tank

Frankly Bob, I don't ever plan on seeing it again in my life time. Maybe a bit optimistic?? You will have to pull the floor anyway, or I assume you already did. You will have to lay the plywood side to side so just pulling the first 4X5' piece will about expose the entire tank for removal. I think you might have "strength" problems with a hatch. Those stringers are only about an inch maybe inch and a half wide. Not much support there and there will only be about the same space left between the tank and floor. But it does fit nicely. As if made for it. I put my batteries up in the bow. I found I was way back heavy because of the added weight of the 4 cycle kicker motor. I have no consoles, boxed seating ...... nothing except a pedestal seat for driving. Passengers set on folding camp chairs. They can move them any place they want to set and I fold them up to store when not in use. I LOVE the open deck space.

I will work on pics this weekend.

Grzzzz

 

[bob johnson]

Re: space under floor for a fuel tank

Frankly Bob, I don't ever plan on seeing it again in my life time. Maybe a bit optimistic?? You will have to pull the floor anyway, or I assume you already did. You will have to lay the plywood side to side so just pulling the first 4X5' piece will about expose the entire tank for removal. I think you might have "strength" problems with a hatch. Those stringers are only about an inch maybe inch and a half wide. Not much support there and there will only be about the same space left between the tank and floor. But it does fit nicely. As if made for it. I put my batteries up in the bow. I found I was way back heavy because of the added weight of the 4 cycle kicker motor. I have no consoles, boxed seating ...... nothing except a pedestal seat for driving. Passengers set on folding camp chairs. They can move them any place they want to set and I fold them up to store when not in use. I LOVE the open deck space.

I will work on pics this weekend.

Grzzzz

thanks for the reply.... I may be installing side cross braces and skip using the stringers... I ll add drops to give support about in the area where the stringers would have been....if i use 2" wide X 2" angle Ill have an inch of tip to support my plywood front to back and the whole width of the crossbeams from side to side... I am thinking 2 foot apart, id have a super strong floor and I can frame in a hatch. or worse comes to worse i pull up the front section of floor if need be... rivets drill out easy... i wont be using any carpet on my floor.

Ill lay rubber or spray rubber on my painted sealed plywood floor layed in sections that can be pulled up on their own at any time... Ill trim between with t molding to keep debris and water from trying to go down..

i want the water in the boat to run all the way to the back before it drops into the bilge...if possible..

keeps the small opening under the boats ribs from clogging....i bet there isnt 3/32 nds" of a gap under those ribs, for water to drain to the back of the boat!!

bob

 

[grzzzz]

Re: space under floor for a fuel tank



Bob, here is the first layout to find best spot. If I have this figured out I will send more of the finished product of my 66 Starcraft under floor installation

Grzzzz

 

[bob johnson]

Re: space under floor for a fuel tank

I bought a nice looking aluminum gas tank near me...but alas...its too big...its a 53 gallon tank from a Bayliner Capri. its 10" high in the middle...but it was only $20!!!

Ill just hang onto it for a future project maybe.

where you put your tank is exactly where i would like to put mine...

bob

 

[grzzzz]

Re: space under floor for a fuel tank

I bought an AL tank too! I even attempted to cut it down to size. What a waste of time. Took it to a couple of ..so called professional welders and still leaked. Tried and tried to seal it up till I finally lost all confidence in it not leaking and could no way feel good about covering it up under deck. This poly tank was about $300 but fits nicely where I needed it. As I wrote earlier the filler and vent hoses went nicely to the upper deck and upper side. Make sure you use USCG approved hoses. It will be stenciled on the hose. If the water cops suspect you have altered your boat and inspect it they will look for the USCG stencil. They did on mine last spring.

I ordered a camera a couple weeks ago. Now that I know how to post pics, as soon as it come I will send you pics of the hose installation.

Grzzzz

 

[barato2]

Re: space under floor for a fuel tank

that's pretty wild on the waterfuzz inspecting your fuel hoses! sounds like they were REALLY looking for some bidness. was that here in NM?

 

[grzzzz]

Re: space under floor for a fuel tank

Yep..... at Abique lake north of Santa Fe hmmm about 60 miles. It just started off as a mussel check (that are at every lake the past 2 years) then they started looking at my mods. Went right for the gas tank and fuel lines. They said they were very surprised to find the GC approved hoses. It is a common mistake they say many make.

Grzzz

 

[barato2]

Re: space under floor for a fuel tank

many apparently have a lower concern for avoiding third degree burns than you and i. ironic since the correct stuff isn't much more expensive for the 3 feet or so you'll need than whatever they use (radiator hose in the case of my Starchief).

that said, this smacks of gummint operatives trying to make some stats to justify funding..........and it's easier to inspect fishermen at Abiquiu than to try to stop the drunk Texan jetskiers at da Butte.

 

[barato2]

Re: space under floor for a fuel tank

now that i have the floor out of the Holiday, it looks like i'll only have to cut off the front 2' or so of the stringers to drop the tank in, and then it appears to fit nicely. got some 2x2 alum angle to rivet lengthwise to ribs to make up any longitudinal stiffness i lose....i think Bob was right, the stringers might add a lttle structural stiffness but it can't be much

 

[bob johnson]

Re: space under floor for a fuel tank

what will support your floor in that 2' you cut from the stringers?? the top of the gas tank?

the tank i found fits between the stringers... but it holds 53 gallons...thats too much for me.... Id like a 28-30 gallon tank.

bob

 

[grzzzz]

Re: space under floor for a fuel tank

Bob,
If you look at the pic I sent, the moeller tank (FT1826) I put in fits nicely without any cutting. Yes, it was about $300 but is CG approved, 18gal, inlets and out lets point right where you need them, give you about 2" clearance between tank and deck, comes with sending unit that wires right up to our old gauge...... 53 gals!!!!! Fill it at the marina and the fuel will be worth more than the boat!!!

The piece of mind you have with a new tank buried under the deck may be worth the cash!! Just my thoughts from one that has been down your road you are about to travel.

Grzzzz

 

[jasoutside]

Re: space under floor for a fuel tank

Just for brainstorming purposes...

I put a 28 (aft side) and a 33 (bow side) gal sub deck...

The 28 came from a cut up and properly disposed of glasser. The 33 I picked up off craigslist for 50 bux if memory serves me.

 

[barato2]

Re: space under floor for a fuel tank

Bob--
no, just going to move the cut off sections of stringers slightly outboard, bend the "Z" shape as needed to get the right floor height, and rivet em back in. will probably also end up reinforcing things with lateral members once i get everything fit in place

 

[jbcurt00]

Re: space under floor for a fuel tank

This seems like a good place to leave this about installing an aluminum permanent tank

I would avoid using styrofoam & spray foam under the deck, near the fuel tank, and under the deck.

 

[barato2]

Re: space under floor for a fuel tank

jb--thanks for posting that. learned sevl things i didn't know there.