ocean-going barge, with an outrigger. great idea, or terrible terrible idea?

[ijason]

greetings!

i've been keenly reading up on converted barges. particularly newly built ones done in a somewhat traditional style, the type of boat for motoring along canals in europe. i'm particularly interested in having a live-aboard boat, as i simply don't have the money to have both a boat and a house, and rather like the idea of being so mobile.

the tricky part - one of many - is that i'm greedy. and much like i don't have enough income for both a house and a boat, i don't have enough money for two boats; both an ocean going and a canal cruiser... but i want to be able to do both! of course, here's where reasonable folk would say "look, if you want a boat that will both be a live-aboard and a cruiser, you'll need to spend the money on a good cruiser". i agree this would be an ideal solution, but i've been thinking; what about attaching an out-rigger to a canal barge?

from looking at other threads here, i gather that the biggest problems in trying to sail a barge in any kind of rough weather is their tendencies to roll and suffer from other rude behavior due mostly to a shallow hull and lack of a keel. and my own opinion tells me that having a single large cavity in a boat makes for a heck of a flooding risk if you ever get a breech somewhere. i'm sure there are other reasons this is an entirely stupid idea to pursue, but that's what this forum is for!

so then, how do we feel about a "barge" ship and the open waters? i propose making it more sea-worthy by splitting the vessel into 4 separate compartments, each with a bulkhead and lockable water-proof door... between the main berth and salon/galley, between the salon/galley and the pilot-house, and between the pilot-house and a guess berth. this would add security against flooding, as well as significantly strengthen the ship and decrease the amount of twisting it should suffer from. i would also raise the bow and stern in a more schooner style to help in heavier waves. finally - perhaps most foolishly - i would employ a large outrigger. i figure that you could set hard mounting points in the side (line them up with the bulk-heads to prevent distortion and maximize load dispersal) of the boat and attach the outrigger. this would provide both stability, and extra room to store supplies or equipment only needed on open water.

with careful design, you could get the outrigger to fit into a shipping container of standard size, once detached from the barge, and have it trucked to whatever port you plan on leaving from. allowing you the convenience and cost-effectiveness of a live-aboard barge, but then the capacity to cross the ocean to tour another new land!

i've attached an extremely rough sketch to further illustrate

http://www.jasongoes.com/barge.jpg

[blackdaisies]

It looks like a proa like that, but not with the pointy ends on both pieces. If a proa works good on rough waters, this should make a barge better, but that would be an uneducated guess. Maybe one of those hot shot designers can answer you with technical jargon.

Concrete barges are very sea worth and heavy, so they hold up to rough water well. Look at the ones out in the ocean during those hurricanes, they had to ride them out, but those might be as big as a football field. It's the size that makes it resistant sometimes.

If the boat is flat bottomed, you might add on pointy ends with higher rocker, so the waves won't hit is so hard, then the ends would cut through them better. You're going to end up with a giant canoe no matter how you do it. Call it a canoe, sharpie, dory, all the same, but really they work on the oceans very well.

[ijason]

@blackdaisies. i would imagine a slight-V would be more sea-worthy than a completely flat bottom. i'll look into these proa's of yours :)

[robherc]

ijason:
According to most resources, a round-bottomed design would be a bit more efficient than a v-hull at displacement speeds (I HOPE you're not planning on propelling a barge to plane). Either way, it's your choice & I don't think the difference in efficiency there will make-or-break you on a project like this. :D

[ijason]

@rob. oh, good lord no - to the planing speed. i'm wholly unfamiliar with the differences of advantages between hull designs, beyond "anything is more stable in waves than a flat mono-hull" idea.

i recently ran across this picture, and have been loving the tjalk sailing barge design more and more. i wonder if the addition of an out-rigger and bulk-heads would make it seaworthy enough for occasional oceanic voyages?
http://www.jasongoes.com/tjalk-brw.jpg

[robherc]

Hmmmm...depends on what margin of safety you're comfortable with...as does every sing other "seaworthy" design. There is no set definition of "seaworthy"... it eventually just boils down to what each person feels is the "acceptable risk."
Myself, I prefer a boat that has at least SOME positive buoyancy (which is why I LOVE cored-composite, and wood/glass construction methods) for when the s&*# really hits the fan, and loads of freeboard to keep the s&*# out of the fan under most circumstances. If I have those 2 things, I can feel safer with other things that might terrify others; meanwhile, designs (especially in steel or concrete) that others feel very safe in, I personally would tend to avoid, because they don't have my "safety blanket" of positive buoyancy.
Decide what defines "seaworthy" for you, and go from there. The most important thing is that YOU feel safe (and are in control) in your boat, and that you have a great time! :D

[ijason]

@rob. actually, positive buoyancy was something i was trying to figure in to making a steel barge more seaworthy. by designing in bulk-heads that split the ship into 3 separate compartments (4 if you count the pilot-house) you could conceivably take on a substantial amount of water while not relying on your ship being dry to stay above water. i fear to think of the engineering required to make the ship strong enough to stay afloat with one of the compartments filled.

i was also thinking, often these ships have a cabin space that is a foot or two more narrow than the outside hull; giving you a deck you can walk all the way around on. perhaps you could stick a foot and a half of foam into the cavity between the cabin wall, and the hull wall. it would mean sacrificing the space for recessed shelving or stowage, but would possibly be enough to give you at least neutral buoyancy. what do you think?

[robherc]

I think that sounds like a LOT of $$$ spent on foam, but it'd make me, personally, feel a bit more comfortable about being in the boat.

[ijason]

@rob. maybe it would be more economical to seal off that cavity (between cabin interior and outer hull) with the same structural steel as the rest of the ship. no need for foam if you're trapping air, right?

[PAR]

Starting with a steel barge as your base, you'll not save much money over the full cost of a completed project. I'm not sure of the size you're thinking about, but I'd guess around 40'. The cost of the bare hull will account for only about 10% of the total effort and cost for the project.

The image you show is of a very shapely hull form, though called a barge, a very purpose built vessel that can carry quite a load, sail like, well a barge and not even remotely blue water capable.

Considering the current markets, you could pick up a fine sea going hull, for pennies on the dollar and convert it to whatever you want, rather then attempt to make a sow's ear into a silk purse.

What happens if the boats rolls away from the outrigger?

[yipster]

becouse i'm dutch i dont have to like dutch barges and tjalks rite?
yet your quest reminded me of some some of Michael kasten's designs
http://www.kastenmarine.com/pennywise_above_aft_transp.gif
http://www.kastenmarine.com/pwrcataboveaft.jpg

[ijason]

@par. pardon my ignorance on how outriggers work, but i presumed that they prevented rolling TOWARDS the outrigger because the ship is rigidly connected and the buoyancy of the outrigger would stop that motion. while an outrigger prevents rolling AWAY from the outrigger by itself being quite heavy, and being out on the end of a boom ads even more mechanical leverage.

???
is this not so?

[PAR]

In small, light weight craft this is somewhat true, but not in lager vessels. There aren't any container ships, tanker, freighters, naval ships, cruise liners, etc. employing this particular innovation.

In small craft the "linkage" of the outrigger to the main hull is a difficult engineering problem, but can be over come. In larger craft, we just don't have materials that can accept the loads that would be imposed in some sea states, on this outrigger (and keep weights reasonable), not to mention the vast difference in sea conditions from main hull to outrigger.

Picture a healthy swell, say 20', with breaking, wind topped waves of around 10'. Now, your on a quartering sea course and the outrigger encounters a trough, but the main hull is climbing a swell. The boat rolls to the outrigger, then it encounters the next wave or back side of the swell. It's buried with the boat rolled toward it and now you've got to wonder how strong your welds are as the outrigger acts like a submarine through the swell. It shouldn't take long to literal rip something like this right off it's mounts.

In small craft, where you can really control the weight, plus the strength to weight ratio is fairly high, the same situation would cause the attachments some strain, but they can be made stout enough to survive. This is because it's light enough to "cork" over most everything it encounters and the sea state is generally much less demanding on the structure.

Your barge has a very high initial stability, but not so much in ultimate stability. You could cut the barge down the centerline and make a cat out if it, but again, it will just have high initial stability, with the prospect of an unrecoverable capsize very possible in blue water.

The bottom line is leverage. You need to have enough to right the boat. There's only a few ways to do this and the fatter or wider a boat is, the more difficult to generate these positive ultimate stability figures.