is adding a fuel tank 6ft aft of the bow on a 43ft monohull a bad idea?

[a64pilot]

You may want to consider bladders to store on deck.
When empty roll up and store, then when you no longer need them, sell them.
If I head for Sopac, I think I want two 50 gl turtle pacs on deck amidships.

However I have been told to be sure they are completely full, or empty, so size them no larger than your current Main tank.
Apparently a half full fuel bladder is tough to secure well. I’ve heard it described as like a drunk Walrus on deck

[Bill O]

Brann,
Yes, the extra tank will take up storage, but would have to say it's more difficult to find fuel than food (if that was intended use for the storage area).

Not loving the idea of the suggested turtle bags on deck. Each 50 gal bag would be approx. 400 lbs then mounted high on the boat. Not sure how easily it would be to secure them and in rough seas you could possibly lose them.

To me the forward fuel tank makes sense and would securely give you the added range needed for a Patagonia trip.

Bill O.

[KWISPEL]

Bladders are nice, if they are out of fuel, you can fit them under decks and fill them with helium. Super fast and dry front deck! http://www.cruisersforum.com/images/icons/icon3.gif

[boatman61]

The 31ft Longbow and its sisters have a 30gal water tank under the V berth.. so think you should be okay with double that.. 80gals I don't know.

[TrentePieds]

Quote: "If possible, I'd like to avoid storing jerrycans on the deck, which seems to me as downright dangerous in high latitudes, and adding an extra tank closer to the center of the boat would be at the expense of storage space ..."

I don't think there was any suggestion that you should keep you spare fuel on deck. Drums-on-deck was suggested only as a means of determining, without commitment to serious expense, what WOULD happen if you put 100 gallons (or any other quantity) of fuel under your V-berth.

A good figure for estimating weight of diesel fuel is 7 lbs/Gall. Thus, the equivalent of my weight in fuel is 25 gallons. As others have said, 100 gallons equals four medium size blokes. As Ann said, push through a chop with four blokes lashed down up forward. They can sit in the V-berth for the purpose, and you'll get a very good feel for how your particular boat will react.

Something you'll want to know is “how far would she go down by the head?”. Here is how you get a fix on it: Your LWL is, say, 40 feet. Your BWL (Beam on the Waterline) is, say, 11 feet. Thus the area of the “inscribing rectangle” is 440 sqft. Your “coefficient of waterline plane” is apt to be .65, so the area of the water line plane is 440 x .65 = 286 feet. Sea water in a tray of 286 feet area and 1 INCH deep would weigh 286/12 x 64 lbs = 1.525 lbs. Thus, to make her settle 1 inch on her lines you would need to add 1,525 lbs AT THE CENTRE OF GRAVITY.

Since you are talking about adding weight at the ends, there will be a “rocking horse” effect. For a rough fix on how much, just consider that 1,525 lbs added at the fore end will sink the bow FOUR TIMES as much as the same weight added at the CG would sink the whole boat. You are talking 750lbs rather than 1,500, so your bow may be expected to go down 2 inches (and your stern UP by 2”) when you put the four blokes in the V-berth. Do that, and check this “back of an envelope” calculation by simply using a measuring tape to measure the freeboard at the bow roller before and after adding the weight :-).

As others have said, you should use the fuel in tanks at the ends before you use fuel in midships tanks. As I see it, there is no reason at all that you shouldn't put a tank in the forepeak. Just remember to baffle it, and to make provision for easy cleaning of each compartment in it.

TP

[KWISPEL]

If they helium leaks in a emergency, they will thake your destress not so surious.

[boden36]

One thing to consider is that the effect will be variable and that you will have to cope with constant changes in trim as you fill and empty the tank.

Regards,
Richard

[KWISPEL]

My first post disappeared: If they are out of fuel, you can fill them with helium to keep the front nice and dry.

[a64pilot]

Why helium?
However helium is excellent for finding leaks, I’m a cave diver and we use it to find leaks in our dry suits. Helium is a smaller molecule and will leak when air won’t.

[KWISPEL]

It will lift the boat in the front, -> faster and dry in front (joke)

[boatman61]

Originally Posted by a64pilot

Why helium?
However helium is excellent for finding leaks, I’m a cave diver and we use it to find leaks in our dry suits. Helium is a smaller molecule and will leak when air won’t.

Plus.. you get to laugh hysterically when you have conversations..

[JPA Cate]

Originally Posted by Brann-

Well, I currently have around 100 gals, which is plenty for sailing in Europe, but I'm considering going to Patagonia, in which case I'll definitely need way more. It's not uncommon for boats sailing in those remote areas to have over 250gals of fuel in their tanks.

If possible, I'd like to avoid storing jerrycans on the deck, which seems to me as downright dangerous in high latitudes, and adding an extra tank closer to the center of the boat would be at the expense of storage space ...

Brann,

Would you be okay with a total of 250 gallons capacity?

If so, then you would only need 100 gals in the fwd tank, and that will save you a lot of weight. Keep it as far aft as you can. It IS way better to have the fuel safely below, in a baffled, cleanable tank, than in jerry jugs on deck, where one big greenie can take out the stanchions, lifelines, and jugs.... People do get away with it, but I think you are right to want to have the fuel below.

Another possibility not mentioned yet is, unless you're a center boarder, you might consider a keel tank. Seal the ballast with epoxy, and the remainder becomes a keel shaped tank. It is a little awkward with the dipstick--ours in in two joinable pieces, but, eh,voila!

@ A64: It is keeping the drunken walrus on board, and not breaking things that is the worry, plus having the weight high raises the center of gravity, affecting the total handling, and diminishing the self-righting given by the keel. We had some friends who bought a fuel bladder to load into their dinghy, and used the dinghy to go ashore for fuel, then pumped it with a transfer pump, from the dinghy, through a filter, and into their tanks. Doesn't increase fuel capacity, but ensures clean fuel from suspect sources.

A.

[DumnMad]

Originally Posted by Brann-

Well, I currently have around 100 gals, which is plenty for sailing in Europe, but I'm considering going to Patagonia, in which case I'll definitely need way more. It's not uncommon for boats sailing in those remote areas to have over 250gals of fuel in their tanks.

If possible, I'd like to avoid storing jerrycans on the deck, which seems to me as downright dangerous in high latitudes, and adding an extra tank closer to the center of the boat would be at the expense of storage space ...

May not be dangerous but I've seen jerry cans on deck split by breaking waves.

The extra fuel tank seems a great idea for a heavy boat like yours but have it well fastened down. Violent movement can occur up front.

[tinkrman69]

Is there no wind and time? What engine do you have?

[a64pilot]

Ann, if I do it, it will be 800 lbs or a little less, well distributed and pretty much center mass on the Boat. When full they aren’t so bad, and think 55 gl drum as to size, it’s not so big.
The Walrus comes in if you have one big bladder, half full.
It’s just a possibility at this point.