Want to extend outboard motoring range with bladder tank

MrBill_FLL · Feb 4, 2013

check that closely.
when I cut my Vberth, the 'floor' was the top of the ballast tank (and never intended to support any weight. -it was thin and soft. I added 2 layers of mat and FG.

how much fuel are we talking about? and what happens if the ballast is empty, but the bladders are full, and you are bouncing thru a 3' chop?

can you stand on the top of the ballast? can you jump up and down?
again, doesn't someone make tanks that fit the 'stock' area in the 12-15 gal range? (before you go down this thorny path)

anchorclanker · Feb 4, 2013

MrBill_FLL said:
The shock loading of a bladder on a plane is nothing like could be seen on a boat.

I am struggling to comprehend where such a statement could come from.

anchorclanker · Feb 4, 2013

Bladders, at least the type used in aircraft, don't collapse as fuel is used. They are vented, and the top, or roof of the bladder, is suspended to the roof of the chamber by clips bonded to the bladder, which connect to clips attached to the roof of the chamber.

In an aircraft, a bladders purpose is to simply carry fuel in chambers within the wings structure that would otherwise leak like a sieve. Because the bladders are so expensive, in many cases bladders have been replaced by sealing the wing chamber with a flexible epoxy type sealant.

As others have asked/suggested, are there other, better places to carry fuel, what are your intentions, and why do you require so much? Modern fuel goes stale pretty fast. Having extra large tanks that arent full of fuel and being used on a regular basis is asking for trouble.

anchorclanker · Feb 4, 2013

Remember that fuel weighs less than water, and much less than sea water. Without containment the bladder will want to float inside the ballast tank. Its not just going to stay where you put it without boxing it in.

MrBill_FLL · Feb 4, 2013

moler or sceptor http://www.macgregorsailors.com/forum/viewtopic.php?f=9&t=18837&hilit=which+12+gallon+fuel+tank

http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=0A42QM23Q5HMWG8DAXPH

I think the bladder will be trouble.... if you already had 24gal in the access cubbys, I'd be more open to the bladder... but only a little. I assume this is for the DT trip?
I'd rather see you go to bimini than DT. at least you can buy fuel in bimini. and ice...

MrBill_FLL · Feb 4, 2013

there's the USCG reg's... to consider too... the compartment should be vented IIRC. probably sealed off from the cabin too.

it would be really bad if it smelled or leaked. it would make you sick.

what do you guess the nissan 50 burns at planning speed? 4-5 gal /hr?
so w/ 2) 12gal tanks maybe 5-6 hours. -but figure you can't use 100% of fuel in a tank.

I'd think the V berth is where you want the weight, for planning. If it were me, I'd move the foam, install a rectangular tank. maybe 2 in there.

+ we need to see some pic of the propane icebox.

anchorclanker · Feb 5, 2013

Dry Tortugas 2013 said:
Venting may be the only requirement.
Nissan probably burns that. How much better would a 4 cycle do?

Google says the 4 stroke 50HP Nissan burns 5.2 gal per hour. There is a lot of hype about 4 strokes, and a lot of BS about two strokes. 4 strokes do burn cleaner, but many late model 2 strokes can come very close to matching them. However, while a 4 stroke burns less fuel at lower power settings, at full power there is little difference in fuel economy between a 2 stroke and a 4 stroke.

Start comparing the complexities and weight of a four stroke, electronic fuel injection, fuel pumps, etc., Unless they were giving real sweet deals on a 4 stroke I would choose a 2 stroke. In fact (and especially), if I were leaving sight of land I would disable the oil injection system and run mixed fuel. When the OI system stops working, your motor locks up and your done.

MrBill_FLL · Feb 5, 2013

I'm not saying to REMOVE flotation, but relocate it. (compress the ~6 cubic feet into 4 cubic feet.)
or if you must remove some, replace with closed cell foam, or more styrofoam...

I was able to compress my blocks quite a bit... (but a different vintage boat).

I would bet you will find they just toss some blocks in there, (vs fit), and there is empty air space, that could hold more blocks/foam if you try...

anchorclanker · Feb 5, 2013

When you compress foam, it loses buoyancy relative to its density. One assumes the manufacturer added enough foam to keep the boat afloat, plus some extra. Compressing it to 2/3 its volume would cause it to have less flotation than cutting away 1/3 would cause, and in either case you could likely make the flotation useless in keeping the boat afloat should the cabin flood.

However. Many sailboats, especially larger ones, have no added buoyancy at all, and will in fact sink like a stone if the cabin fills. Rather than compressing it, it would be wiser to do some calculations (or contact the manufacturer) to calculate the total buoyancy. If you then decide you need the added space, rather than compress it, simply cut out the volume of foam for the space you need. The remainder will have greater buoyancy than it would otherwise have compressed to the same volume.

MrBill_FLL · Feb 5, 2013

good price..

You know, when the boats go down to Havana, they always say they're going to the Dry Tortugas... LOL.

Good Luck!

Oh compress iS the wrong word. fully occupy the cavity is a better description... its not full, you could fit more in there. especially if you go small, like foam peanuts.

Destiny 1 · Feb 10, 2013

I've sailed with the very system you are talking about all last season. I have a 35 gal. fuel tank in my water ballast tank. I've more than doubled my range. Helpful on remote Canadian Lakes. www.ballastplus.com

MrBill_FLL · Feb 11, 2013

how was the ballast plus installed? (DIY, or you bring it to them?) any pics of the opening? can you service/access the tank? or it was re-glassed?

Destiny 1 · Feb 11, 2013

I installed the Ballast Plus myself. Any qualified boat dealer should be able to install in half a day. The system includes a 8" x 14" fibreglass and lexin hatch to be fibreglassed to the ballast tank over the new opening. This will allow you to thoughly inspect the tank for glass shards. Mine took half hour, it was clean. Also allows for easy access for bag inspection and adding a fresh water bag or more fuel if desired.

MrBill_FLL · Feb 11, 2013

-very interesting....
I'd like to know more... website is just the 1 page and a contact in BC . any more pic's?

google and my searches have zip...

-some on Plastimo Flexible Water Tank, but nothing found on fuel. and nothing about putting it in the WB....

if it works it could make the Mac a cuban taxi....