New Fuel Tank installation, pre 1980 Double Eagle 190.

[Kilwinning]

Morning
Had a new belly mount fuel tank built, (3/16” with 4 baffles welded 90 to length of tank). same as old one.
Old one was foamed in place which helped support the tank. Trying to get away from the foam
But supporting tank is proving difficult with the shape of the bottom of boat, I’m thinking with the tank sitting on the top of centre stringer, which is 2- 1/2” in dia (I could make it a little wider but have limited height left so have to watch what I do there as well)
and building up sides of stringer with coosa board so tank is supported on both sides, that it should be adequate, it would also be bolted down , looking for ideas on what others have done. Or would my plan place to much stress on tank.
Thanks Kilwinning.

 

[Inchebe]

Interested in others experience here too, as I am re-installing my tank soon. (76 DE)

In my case the original tank was only supported in the front and back buy two small pieces of wood glassed into the hull (see attached ) the bow piece being higher than the stern piece by about 1/2". they appeared to be original installations

there was also 2 pieces of used conveyor bely there ... not sure if that was original

but that was it for a similar sized tank

in terms of movement, there was a wood spacer at the bow and the beams going over the tank and under the deck were flush with the tank, holding it in place.

have not decided what I will do for the re-install, don't feel the 2 blocks are enough so will beef it up, but keen to hear any thoughts.

 

[Rayvon]

You should try to support the length of the tank fore and aft with 2 stringers with the stern lower for the fuel pickup.Glassed in and gelcoated.A rubber piece on top is good but don't use any fasteners to hold it down,use Sikaflex.Your tank should fasten to the sides of your outside stringers,not on top.I don't like water anywhere around the tank,so I have bulkheads fore and aft ,a tank coffin.

 

[Kilwinning]

Thanks Rayvon
That’s my plan, I will have tank enclosed with bulkheads fore and aft, with a drain plug on bilge end. I was going to paint it with interprotect 2000e, but I’m using coal tar epoxy instead, I’m using thickened epoxy to stick some coosa to sides of stringers for my mounts to attach too. Just need to figure out how to get more support under tank
I can’t raise tank much at all or I won’t get my supply hose on, so I’ll have to get creative.

 

[Rayvon]

Make a plywood piece the shape of your tank (V bottom) and use that to see how high your stringers need to be front and back.Probably only 1 or 2" high to give bottom clearance.

 

[Kilwinning]

My filler hose goes through stringer, and all my fittings are on top of tank , I had to reduce height of tank by one inch already to get my filler hose to go through stringer, I had thought about doing what you suggested but with 1/8 aluminum plate, something I’ll explore more
All good suggestions
Thanks.

 

[Inchebe]

My filler hose goes through stringer, and all my fittings are on top of tank , I had to reduce height of tank by one inch already to get my filler hose to go through stringer, I had thought about doing what you suggested but with 1/8 aluminum plate, something I’ll explore more
All good suggestions
Thanks.

Not sure where you are with your build, however I am in the process of re-routing the filler hose through the bilge and filler cap on the stern. This is how the new DE's are configured .... No more going through the stringer and it opens up deck space options

 

[seachicken]

Not sure where you are with your build, however I am in the process of re-routing the filler hose through the bilge and filler cap on the stern. This is how the new DE's are configured .... No more going through the stringer and it opens up deck space option

And way easier to dump fuel in from a Jerry can when the boat is in the water...

 

[Kilwinning]

Mine is a regular belly tank , built to original dimensions, although we extended the tank the full length of the coffin and all fittings on top, the original came out the side , that’s why we have the tight fit. I would need to see pictures to visualize that fuel tank arrangement, I just hung a new 200 hp merc on the back yesterday. So I think I’m past making any major changes , whatever I do I’ll post my mounting arrangement
I do appreciate all the ideas
Thanks.

 

[Chinookslayer]

Doesn't the fuel gurgle when filling from the stern? I had a stern fill on a 400 litre tank on my last boat. I don't know how many times I got sprayed in the face when fueling at the marine dock. One thing I did learn was getting my kids to go to the bow of the boat to shift some weight that tended to help.

 

[Inchebe]

Any thoughts on what to use to lining between the Aluminum tank and the structural support, my research is saying options such as
- Closed cell neoprene tape
- Reinforced plastic with 5200 / 4200
- Foam

My current thinking is the neoprene ... for context the tank will sit off the hull, on a series of wooden shelves which have been glassed in place. the tank area would need to have 3 inches of water before any water was permanently in touch with the tank. I feel it needs a small amount of soft cushioning between the fiberglass and the tank - I am unable to bolt it in position.

Reinforced plastic / HDPE etc. would seen to offer little cushioning but is inert

Foam seems to be a massive no from most pundits

Anything / Option I am missing?

 

[Inchebe]

Doesn't the fuel gurgle when filling from the stern? I had a stern fill on a 400 litre tank on my last boat. I don't know how many times I got sprayed in the face when fueling at the marine dock. One thing I did learn was getting my kids to go to the bow of the boat to shift some weight that tended to help.

I guess that's a valid issue, but I think the additional deck optionality for me anyway wins here