Using bladder tanks in the biges for extra fuel capacity ?

[Deleted User YDKXO]

the main issue is getting the tanks in there Mike, the door opening to the master cabin is only 47cm wide,
not to mention the steps making a 180° turn...

I understand that Bart but speaking personally, I would still try to find a way of using proper rigid tanks fitted with baffles rather than flexible tanks especially if you are considering mounting them forward where the movement of the boat is greater and the risk of leakage greater as a result. IMHO better to have 3 or 4 small rigid tanks properly constructed and installed with transfer pipes between each than a single flexible tank. Either way I would have thought that its worth at least talking to Tek Tanks who must have come across access problems many times before

 

[Deleted User YDKXO]

. If the delivery truck is pumping 200 litres a minute (that's what I get in Antibes) the main tanks fill pretty fast, and if the pipe to the bladders is too small so that the bladders do not fill fast enough you have that awkward job of asking the guy to wait, which may be ok but may not be if he is in a hurry. So it would be nice to have a big enough pipe. 3/4 BSP feel right

+1 The first time I filled up my previous boat from the starboard side I got a face full of diesel because the fuel wasn't transferring to the port tank as fast as I was filling the starboard tank plus the fact that the vents were partially blocked. I learnt my lesson after that

 

[vas]

I'm with Deleted User on this.

Shall I propose another thing then.
Bart, how about BUILDING tanks out of plywood, battens et al and line them with epoxy and mat using the hull side as the one "wall" of the tank?

I mean, the slanted hull is the one side, bow and aft sides can be bolted and then epoxied onto the stringers and you're left with building the freestanding side.
if you make them relatively shallow it will be easy to get in there and epoxy them properly making sure stresses and loads are at acceptable levels that grp can handle. Got to be careful with the fumes, but it's doable I can assure you
You could go about doing a dozen of these, using proper 3/4 fittings (could even go 1inch) daisy chain them on each side ending to the e/r on a smaller junction
box/day tank where from you can feed the main tanks via a pump or drive the engines directly (I guess you would start from them and then continue to the normal tanks). Could even have two separate fillers on deck level for them.

You could do two or three stringers at once, built the tank and after laying it with mat and epoxy you could use the stringers to secure baffles and sort out a lid (that I have to admit I've not got some clear idea on how it's going to be built but it should be possible)

anyway, just another possible solution to work on

cheers

V.

 

[jfm]

I'm with Deleted User on this.

Shall I propose another thing then.
Bart, how about BUILDING tanks out of plywood, battens et al and line them with epoxy and mat using the hull side as the one "wall" of the tank?

I mean, the slanted hull is the one side, bow and aft sides can be bolted and then epoxied onto the stringers and you're left with building the freestanding side.
if you make them relatively shallow it will be easy to get in there and epoxy them properly making sure stresses and loads are at acceptable levels that grp can handle. Got to be careful with the fumes, but it's doable I can assure you
You could go about doing a dozen of these, using proper 3/4 fittings (could even go 1inch) daisy chain them on each side ending to the e/r on a smaller junction
box/day tank where from you can feed the main tanks via a pump or drive the engines directly (I guess you would start from them and then continue to the normal tanks). Could even have two separate fillers on deck level for them.

You could do two or three stringers at once, built the tank and after laying it with mat and epoxy you could use the stringers to secure baffles and sort out a lid (that I have to admit I've not got some clear idea on how it's going to be built but it should be possible)

anyway, just another possible solution to work on

cheers

V.

This works. It is how Sunseeker build their tanks. But it is a heck of a job and you need to engineer a lid on the tanks. And then you have to find a route for tank vents etc. I prefer the bladder idea, with a suitable MO of having them empty most of the time. BTW, I thought Sunseeker hulls generally had no frames, only stringers, which is why they can do this easily (though I suppose you could put limber holes in frames anyway) - I'm happy to be corrected on that if someone knows better.

 

[Whopper]

My wakeboard boat has a c.350l "bag" in the center with a reversible jabsco pump. Granted it's for carrying water as ballast but it certainly doesn't leak and it is subjected to lots of movement. One thing, it's difficult to empty the entire contents completely.

A reversible pump plugged into the main tanks could be useful (if these are suitable to use with diesel?). Fill up the main tank, switch on the reversible pump to fill the bladder/bag. Refill main tank and once emptied sufficiently "reverse pump" the bladder contents back into the main tank?

I should add, my ballast tanks fill using the reversible pumps from the river/lakes. Once the tanks are full the overflows discharge any extra water back over the side (continuously if the pumps are left on). If my idea worked you would need such a discharge back into your main solid tanks (to prevent the bags bursting).

http://www.wakemakers.com/wakeboard-ballast-bags

 

[jfm]

If my idea worked you would need such a discharge back into your main solid tanks (to prevent the bags bursting).

I think in this case the bladders could fill by gravity so they only need to be able to cope safely with the 4m or so head of the main fuel tank plus its breather pipe
The pump would then be one way only, to transfer fuel from bladders to main tanks.

 

[BartW]

I think this idea could work well - I'm not as negative as some others on this! Of course metal tanks would be lovely but you just cannot retrofit them under cabin floors without smashing up the boat. A few extra thoughts:

1. Obviously you need bilge chambers that are smooth, and maybe lined in wetsuit material or something

2. You could have just one pipe going from engine room to the 4 (or any other number) of bladders, with a manifold near the bladders. The same pipe could fill the bladders and empty them. I expect they would fill by gravity and be emptied by a pump and of course you need the right valves etc to achieve that. Electric ball valves and an LED control station would be nice. The plumbing could be something like or 3/4 BSP, nothing big needed (but see 6 below)

3. Easy lift up hatches in the cabin floors would be nice so you can quickly see each bladder. You wont have gauges, so a flow counter would be nice then you know what you have transferred from the bladders

4. As a general modus operandi, I think I would pump the bladder fuel into the main ship tans as soon as there was space, ie as soon as the main tanks had 1500 litres of space. Hence, for 90% of the boat's hours and over winter etc, the bladders would be empty with no pressure in them. They would therefore suffer almost no chafe and wear/tear as the boat bounces on waves

5. Because of that, I think you would be fine putting them "too far forward" Bart. BA is a big ship and one tonne slightly too far forward for a few days is fine. Then you would empty the bladders within in a few days, starting with the furthest forward.

6. The fill pipe, from the main tank to the bladders, needs to be big enough size that it will fill the bladders in the time you have available when filling the boat. If the delivery truck is pumping 200 litres a minute (that's what I get in Antibes) the main tanks fill pretty fast, and if the pipe to the bladders is too small so that the bladders do not fill fast enough you have that awkward job of asking the guy to wait, which may be ok but may not be if he is in a hurry. So it would be nice to have a big enough pipe. 3/4 BSP feel right

Good luck with this

mmm, yes this idea becomes feasable, and a real plan,

1. OK

2. I would prefer to have the manifold in the engine room, because thats where I go looking for the level when refueling,
also I don't like to go donwstarirs in the cabins for this.
no big deal to bring 6 hoses to the E/R (I think) instead of one or two.

I don't feel the need then for electric vavlves, (for the 4 to 5 occcasions per season we are refuleing ) handvalves are good enough
(I would love to have electric valves on the seacocks, but thats another topic)

3. after a few tests fillings I think and I hope that we don't need to see the bladders, just a flow counter near the valves in the engine room might be sufficient ?

4. general modus of operandi, this is exactly how I had this in mind; empty the bladders as soon as I have enough space in the main tanks.

5. then I have 6 spaces available, I can plan for 6 extra tanks, thats more then 2000l extra !!!! (7500 l in total)
one position, the one under the master bed on P side, needs some more prep work during liftout / moving one seacock, and moving a few pipes, but all doable,
so I could start with just 4, but prepare everything for 6.

6. no worries about the filling speed, I usually fill at 100l/min, or sometimes even less,
long ago I had some spilleage when the filling rate was too high,
but nevertheless need a good size of pipes.

Q. would you pump the fuel from the bladders back through the filling pipe,
I was thinking to bring the filling pipe, from the pump to the top of the existing tanks, and fill it from the top, just like a normal filling.
what kind of pump would be suitable for this application ?

 

[BartW]

Shall I propose another thing then.
Bart, how about BUILDING tanks out of plywood, battens et al and line them with epoxy and mat using the hull side as the one "wall" of the tank?

I mean, the slanted hull is the one side, bow and aft sides can be bolted and then epoxied onto the stringers and you're left with building the freestanding side.
if you make them relatively shallow it will be easy to get in there and epoxy them properly making sure stresses and loads are at acceptable levels that grp can handle. Got to be careful with the fumes, but it's doable I can assure you
You could go about doing a dozen of these, using proper 3/4 fittings (could even go 1inch) daisy chain them on each side ending to the e/r on a smaller junction
box/day tank where from you can feed the main tanks via a pump or drive the engines directly (I guess you would start from them and then continue to the normal tanks). Could even have two separate fillers on deck level for them.

You could do two or three stringers at once, built the tank and after laying it with mat and epoxy you could use the stringers to secure baffles and sort out a lid (that I have to admit I've not got some clear idea on how it's going to be built but it should be possible)

anyway, just another possible solution to work on

cheers

V.

Good and feasable idea Vas !
the available space would be used at its maximum,
but some area's don't have good enough acces for doing that. unless a major rebuild.
and then also the hassle with acces hatch, and vent pipes, etc...

I have some other applications for epoxy coating, and would need some good advice on that,
but will come back later with my questions, tbc...

 

[BartW]

My wakeboard boat has a c.350l "bag" in the center with a reversible jabsco pump. Granted it's for carrying water as ballast but it certainly doesn't leak and it is subjected to lots of movement. One thing, it's difficult to empty the entire contents completely.

A reversible pump plugged into the main tanks could be useful (if these are suitable to use with diesel?). Fill up the main tank, switch on the reversible pump to fill the bladder/bag. Refill main tank and once emptied sufficiently "reverse pump" the bladder contents back into the main tank?

I should add, my ballast tanks fill using the reversible pumps from the river/lakes. Once the tanks are full the overflows discharge any extra water back over the side (continuously if the pumps are left on). If my idea worked you would need such a discharge back into your main solid tanks (to prevent the bags bursting).

http://www.wakemakers.com/wakeboard-ballast-bags

thanks wopper, good to hear a confirmation that this idea is used in practice
I'm afraid that these ballanst tanks can only be used for water, so we will search for the diesel specced versions

 

[BartW]

I would like to install extra tank capacity in our boat,
Is it a option to use flexible tanks in the bilges ?
I came across some solid models, that would fit in the available spaces,

http://www.imtra.com/collateral/documents/english-us/products/nauta_brochure.pdf
these have a brass connection for a pipe or a hose.

mmm
imtra is in US,
but the Nauta Bladders are made in France,
and the foil they use is made by Orca.com, formerly known as Pennel & Flipo,
and they have a factory in Belgium
and they have a booth @ metz
its on the visit list for tomorow

I'm still very serious about these bladder tanks
just a little doubt / a few practical questions ao about the "no vent hose" solution,

 

[AndieMac]

mmm
imtra is in US,
but the Nauta Bladders are made in France,
and the foil they use is made by Orca.com, formerly known as Pennel & Flipo,
and they have a factory in Belgium
and they have a booth @ metz
its on the visit list for tomorow

I'm still very serious about these bladder tanks
just a little doubt / a few practical questions ao about the "no vent hose" solution,

Report back when you have more info Bart, interested to hear more.

 

[BartW]

the Guy at Metz was not really helpfull, lots of words about safety and specification, but NO practical advice
got a full Nauta catalog, and a few names and adresses in Belgium and France for more info will continue my investigation about the Nauta bladders.

here some pics about one of the Bilge positions:

And a cross section :

This space is approx. 0.95m long between the two frames, 1.4m wide, and 0.6m high in the highest position.



Here are two scetches with bladders inside this space


In this first one, the hose fitting is on top, with a long hose so that it can move easily when filling or emptying the bladder.

My idea is to have a slightly bigger sized bladder then the available space, so that it can take the shape of the available space, and use the available volume at its maximum.
With Marine ply its quite easy to make that vertical supporting plate, and some floor wedges…

The red layer, could be a foam like we use in Flightcases, for protecting sensitive equipment.
We have this available in a not too soft version, mats of 1m x 2m and 10mm thickness.
simply cut sheets with a Stanley knife, that fit on the bottom and against the frame sides, on the surfaces that are not smooth or have sharp edges.

In this second scetch, the flange is on the bottom,

I rather like the idea of no vent opening, so that tank will inflate / deflate when filling / emptying with fuel.
but
I’m in doubt about the positioning of the fitting; in the Nauta catalog they advice to place that on top,
I’m afraid that with this postion, we won’t be able to empty the bladder completely.
the second solution with the fitting on the bottom, would be more efficient for emptying the bladder almost completely.
With this solution I’m not sure if there is no risc of damaging the fitting & hose, with the weight of the filled bladder on top.

 

[newWave]

The following may all be rubish, but just thinking out loud to offer a different insight into the problem.

1) For your second solution, I would suggest a plywood support under the flange so that the weight of the fuel does not rupture the bladder on the flange.
Additionally I would try to smoothen out the stringers as each fold is a potentional rupture point. This means losing quite some volume if you flatten the entire area with a single sheet of ply.

2) Do these bladers have straps attached so you can secure the top and bottom to avoid having those chafe each other when empty ?

3) Would it be possible to put two bladders on top of each other ? One filled with fuel and the other connected to a compressor (or an air tank) that way the air bladder would expand and push the fuel out of the bottom bladder.
Additionally movement of the fuel bladder would be restricted by the air bladder.

If you decide to but the flange on top, you might put the air bladder on the bottom, which gives extra protection to the fuel bladder, though you would need more pressure to inflate the air bladder so depends on how much the bladder can take.


As I said just trowing up a few balls.

 

[rafiki_]

the Guy at Metz was not really helpfull, lots of words about safety and specification, but NO practical advice
got a full Nauta catalog, and a few names and adresses in Belgium and France for more info will continue my investigation about the Nauta bladders.

here some pics about one of the Bilge positions:

And a cross section :

This space is approx. 0.95m long between the two frames, 1.4m wide, and 0.6m high in the highest position.



Here are two scetches with bladders inside this space


In this first one, the hose fitting is on top, with a long hose so that it can move easily when filling or emptying the bladder.

My idea is to have a slightly bigger sized bladder then the available space, so that it can take the shape of the available space, and use the available volume at its maximum.
With Marine ply its quite easy to make that vertical supporting plate, and some floor wedges…

The red layer, could be a foam like we use in Flightcases, for protecting sensitive equipment.
We have this available in a not too soft version, mats of 1m x 2m and 10mm thickness.
simply cut sheets with a Stanley knife, that fit on the bottom and against the frame sides, on the surfaces that are not smooth or have sharp edges.

In this second scetch, the flange is on the bottom,

I rather like the idea of no vent opening, so that tank will inflate / deflate when filling / emptying with fuel.
but
I’m in doubt about the positioning of the fitting; in the Nauta catalog they advice to place that on top,
I’m afraid that with this postion, we won’t be able to empty the bladder completely.
the second solution with the fitting on the bottom, would be more efficient for emptying the bladder almost completely.
With this solution I’m not sure if there is no risc of damaging the fitting & hose, with the weight of the filled bladder on top.

Bart, if it were me, I would try to fill in the gaps between the stringers to reduce the opportunity for the bladder to chafe. You will also need to carefully at the lift pump spec if you are not having a vent in the bladder too.

 

[BartW]

As I said just trowing up a few balls.

thats why I post this here you know, thanks for your contributions and the wild idea's ;-)

1) For your second solution, I would suggest a plywood support under the flange so that the weight of the fuel does not rupture the bladder on the flange.

yes that was my aim, but not very clear in the pic,
even then I'm not quite sure if the flange must /can be supported, etc...
the manual say's specifically that the fittings may not be installed on the bottom of the tank

2) Do these bladers have straps attached so you can secure the top and bottom to avoid having those chafe each other when empty ?

some models do have provisions for straps,
all models have reinforced mounting eyes on the corners that I wanted to use to keep the tank('s) in position with straps,
but as the tank size would be bigger then the available space, I thought that the movement and shaving of the tanks would'nt be a big issue,
also the foam protection on all sides

3) Would it be possible to put two bladders on top of each other ? One filled with fuel and the other connected to a compressor (or an air tank) that way the air bladder would expand and push the fuel out of the bottom bladder.
Additionally movement of the fuel bladder would be restricted by the air bladder.

I don't see the need for that,
there is no vent opening, so the tanks will be sucked empty, and get completely empty and flat ... ?

 

[BartW]

You will also need to carefully at the lift pump spec if you are not having a vent in the bladder too.

many pump types / makes to choose from at Metz,
a DC cetrifugal pump, with a capacity of approx 100l/min, with a 1" hose connection, 18m head,
and can be used in two directions, for emtying, and for quicker then gravity filling....


at the moment my fuel tank is half filled (approx 3000l) so I could easytly try this out with one or two bladder tanks.

I'm thinking towards Jfm's sugestion to place the manifold, taps and pump command, centrally under the floor between the cabins,
so that I can controll and check everything from there.
and just one hose going to the E/R - main fuel tanks.

 

[vas]

OK, I'm completely out of context, but you'll probably find that the sprayrails (or however you call the hull chines) co-inside with the stringers (which sort of makes sense...). That's what I found out once I ripped the port side hull plywood on MiToS

Not much to contribute on the discussion other than I generally don't like it. If you start building false floor for the bladders (which must be seriously strong not to crack and fkup the bladders) then you might as well forget it and get down to building proper grp tanks in situ.

cheers

V.

 

[jfm]

Bart I still like this idea. I like your first picture. I like the way you have dealt with the stringers by NOT bridging across them and only making "wedges". The 10 mm foam will deal with the chafe, as will ( very important) a MO where you always empty the bladders as soon as possible (as discussed above) so the total hours cruising with heavy bladders is kept quite small ( the opposite of my MO!). IMHO the fill connection should be at the top as in your first picture. The weight of the full bladder on the pipe connection feels bad to me. You will need a clever design of pick up pipe of course

Regarding the pumps, will the centrifugal pump self prime on air? You wouldn't expect it to. This is obviously important.

Overall I like this project. I appreciate the benefits of extra range and for a retrofit I think this idea is good ( in the hands of a smart captain who understands the system well ie you Bart!!)

I think you should also put the 10mm anti chafe foam under the cabin floor, ie on the "ceiling" of the space that encloses the bladder.

 

[nauticalnomad]

I had bladder tanks for fuel and id never have them again.. They were airtight but always smelt of diesel.. The diesel seeps out of the cap and the vapours escape..
They although are stated as airtight and dont leak.. From personal preference they would always smell of diesel..and always had seepage around the filler cap.. I pressure tested them and they held air at 1.2 times the recommended pressure.. I then fill them back up with diesel and again.. seepage around the caps that used to lay flat in the hull.. To fix this i sold the boat!

 

[MapisM]

I must say that I didn't think about that, but you are raising a very, very good point.
Not that I have any first hand experience with these tanks, but I do know how persistent diesel smell can be.
There was an almost invisible leak from a fuel filter when I bought my boat back in 2000, immediately fixed.
Long story short, after several attempts to find other leaks elsewhere in the following years, I just accepted to live with some smell - heck, it's an e/r, after all.
I can't positively say that it completely disappeared by now, after almost a decade and a half.
It surely isn't so obvious anymore, but according to swmbo, whose olfaction is better than mine, it's still perceivable... :ambivalence: