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Discussion Starter · #1 · (Edited)
I would like to have a fast sailboat, with a lot of above-deck living-space, that rides flat. I think I want a cat or symetric hull tri. I'd also like to be able to "beach" it and unload cargo, like an LST (Landing Ship Tank). I don't want to spend 5 years building it.

My idea is to take an existing barge, like the kind some builders use for houseboats and weld some pontoons onto it, then flip it back upright and put it back in the water. If I want any complex curves, I can build these up a little at a time, with wire-mesh bondo and glass, for the final shape. For living quarters, I could bolt-on a container, or two, or three, then add and subtract metal as needed. I could even build up freeboard that way and add a landing ramp to offload vehicles, tents, supplies, etc. Finally, I can add some kind of sail-plan and improvised engines, for when there's no wind. A couple of outboard motors could be used at the bow, as bow thrusters, steered remotely, without cutting holes in the hulls, etc.

This could be a complete off-grid solution, with solar, water-maker, etc.

If the vessel turns out to be very large, I could just sail it in close to shore, at high-tide and offload cargo, etc at low tide. I could even add retractable feet, to keep the vessel level, at low tide.

I think this can be done economically and quickly (less than a year). I'm not sure what it would look like (complete frankenboat monster) or how heavy it would be (heavy as 4 hecks, but mitigatable). I'm not sure what kind of sail-plan would work either. I've been thinking ketch-rigged, with a mast before and after the container or maybe a dual crab-claw arrangement, on each side (this would definitely be the ugliest boat in the world, a total offense to the senses).

Any opinion? (i'm, no doubt, going to burn in hell for this suggestion. i'll apologize now.)

Oh yeah, I can hardly wait to get lynched at the yacht-club, when I park this sea-hag, next to million dollar cats.
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Ok, I'll bite. The closest thing I am aware of, but in the monohull design is a Dutch Sailing Barge. Designed for shallow water, and possible to beach.

Something you are proposing would definitely fall into the "Franken" category, right now I am not sure how it could be done, that would work well, and I cannot imagine it being anything close to fast. All the barges I have seen have been plumb bow, or maybe a 45 degree bevel across the width of the bow. Just sheer horsepower to move it.

I'd love to be proven wrong...
 

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So... LST... are you going for the whole deployable landing platform concept for an ATV or motorcycle?, or you just want to be able to beach it and offload your grill. I can't imagine a ketch rigged barge with pontoons would sail particularly well... might do ok dead down-wind in a gale.
 

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This approach doesn't make any sense to me.

If you want a steel catamaran, what's the point in the barge? Weld up two high volume hulls. Then weld a steel deck over the hulls. It would be a fraction of the weight of using a barge and no more work. I have been involved in a build like this. The hulls were manufactured away from the water, trucked to the water then the hulls and deck were attached at the water, then superstructure built onto the steel deck, boat came to 86 ft long, 33 ft beam and a couple hundred GRT.

The boat will be too heavy to be fast, I think that's a given.
 

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Now that I have recovered from the spit-take of my mid-morning coffee, I will try to address this with some seriousness.
I would like to have a fast sailboat, with a lot of above-deck living-space, that rides flat. I think I want a cat or symmetric hull tri. I'd also like to be able to "beach" it and unload cargo, like an LST (Landing Ship Tank).
To begin with, if you want a shoal draft boat that sails pretty fast, has shallow draft, and a lot of above deck space, and sails flat, then you are generally heading the right direction with a catamaran. The rest of the building technique makes less than zero sense. To sail decently and have a reasonable degree of safety, Catamarans need to be reasonably light in weight. The construction method would need to avoid adding unnecessary weight. The problem with your 'found object' approach is that none of the components are properly engineered for loads that they will be dealing with. The net result is that you would be trying to weave the necessary structure through the ;as-built' components. Pretty quickly that would wipe out any time and money savings.

You would be way ahead of the game building this out of aluminum if you are a good welder, or out of glass over plywood if you are not a good welder. In either case someone would need to properly engineer the structural components that form the deck and deckhouse, and that tie the hulls together along with the connections between the deck and the hulls. The forces on a 60 foot multihull are very large. Building a 60 foot properly engineered multihull is time consuming and expensive no matter how you do it, Building one that is badly engineered and having it sink, is wildly more expensive.

I suggest that you consider using a stock plan and adapting the deck layout to your needs. While I am not a big fan of Wharram's designs, his work is closest to what you are looking for in terms of being quick and inexpensive to build. This design would make a pretty good starting point for what you are considering. Pahi 63 Self-Build Boat Plans | James Wharram Designs

If the vessel turns out to be very large, I could just sail it in close to shore, at high-tide and offload cargo, etc at low tide. I could even add retractable feet, to keep the vessel level, at low tide.
If you designed the boat with a fair amount of 'rocker' (curvature to the bottom of the hull when seen from the side) then the bow should be shallow enough to get onto a beach, and a section of deck could be hinged to allow boarding vehicles onto a beach.

I could bolt-on a container, or two, or three, then add and subtract metal as needed.
Having explored container structures, containers are pretty heavy and are hard to adapt to the kind of use that you are considering. You would be better off from a time, weight and money standpoint building a simple superstructure either in glass over wood or aluminum.

I'm not sure what kind of sail-plan would work either. I've been thinking ketch-rigged, with a mast before and after the container or maybe a dual crab-claw arrangement, on each side (this would definitely be the ugliest boat in the world, a total offense to the senses).
Crab claws are expensive to build for a large boat and reefing really isn't an option. Ketch rigs tend to be slow and expensive to build and maintain, but the low center of effort might make sense for what you are contemplating,.

Any opinion? (i'm, no doubt, going to burn in hell for this suggestion. i'll apologize now.)
You really want an opinion? Seriously, this is all a very silly set of ideas. I suggest that you read up on how multihulls and boats in general, are designed and built. You will see why.

Jeff
 
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Discussion Starter · #8 · (Edited)
Now that I have recovered from the spit-take of my mid-morning coffee, I will try to address this with some seriousness.

To begin with, if you want a shoal draft boat that sails pretty fast, has shallow draft, and a lot of above deck space, and sails flat, then you are generally heading the right direction with a catamaran. The rest of the building technique makes less than zero sense. To sail decently and have a reasonable degree of safety, Catamarans need to be reasonably light in weight. The construction method would need to avoid adding unnecessary weight. The problem with your 'found object' approach is that none of the components are properly engineered for loads that they will be dealing with. The net result is that you would be trying to weave the necessary structure through the ;as-built' components. Pretty quickly that would wipe out any time and money savings.

You would be way ahead of the game building this out of aluminum if you are a good welder, or out of glass over plywood if you are not a good welder. In either case someone would need to properly engineer the structural components that form the deck and deckhouse, and that tie the hulls together along with the connections between the deck and the hulls. The forces on a 60 foot multihull are very large. Building a 60 foot properly engineered multihull is time consuming and expensive no matter how you do it, Building one that is badly engineered and having it sink, is wildly more expensive.

I suggest that you consider using a stock plan and adapting the deck layout to your needs. While I am not a big fan of Wharram's designs, his work is closest to what you are looking for in terms of being quick and inexpensive to build. This design would make a pretty good starting point for what you are considering. Pahi 63 Self-Build Boat Plans | James Wharram Designs

If you designed the boat with a fair amount of 'rocker' (curvature to the bottom of the hull when seen from the side) then the bow should be shallow enough to get onto a beach, and a section of deck could be hinged to allow boarding vehicles onto a beach.

Having explored container structures, containers are pretty heavy and are hard to adapt to the kind of use that you are considering. You would be better off from a time, weight and money standpoint building a simple superstructure either in glass over wood or aluminum.

Crab claws are expensive to build for a large boat and reefing really isn't an option. Ketch rigs tend to be slow and expensive to build and maintain, but the low center of effort might make sense for what you are contemplating,.

You really want an opinion? Seriously, this is all a very silly set of ideas. I suggest that you read up on how multihulls and boats in general, are designed and built. You will see why.

Jeff
Thanks very much for the reply.

I'm trying to imagine a found object approach that will work. Sometimes, close enough is good enough. I've seen some amazing unorthodox designs coming out of Indonesia and the Philippines that have left me breathless.



Thank you for helping with my brainstorming. I know what capabilities I want and I'm trying to find a way to package them in a single vessel. You obviously know what you're talking about and suggested some very good material choices.

I think my literary approach was intended to make the desired features visible in a single unit, rather than be a viable design concept. You are correct, the ideas as expressed are silly, if constructed as described;However, I've seen plenty of barges and I'm really just thinking of an available platform that won't need much modification and will already float on its own. A barge was the first thing I thought of. Some of them are pretty sturdy.

I tend to innovate in several disciplines and this is part of my creative process. Thanks for indulging me.

Cheers

PS, I think I should build a model of what I descriped in my original post; so, I can have something to share and laugh at.

Complete with dragons painted on the sails.

Oh BTW, I'm an expert with a JBWELD-er. Stong as steel, and won't corrode.
 

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Discussion Starter · #9 · (Edited)
have been involved in a build like this. The hulls were manufactured away from the water, trucked to the water then the hulls and deck were attached at the water, then superstructure built onto the steel deck, boat came to 86 ft long, 33 ft beam and a couple hundred GRT.
Really? Images?🤩😍🤩

The whole barge thing is a found object approach, that will likely still be seaworthy, after its initial value has depreciated considerably. It's also something I can just repurpose as a platform for a houseboat, if I change my mind about the build.

Your approach is clearly the winner; and, is an example of how such a vessel should be built. Seriously, I want to see what you did, especially how you joined the hulls and built the deck. I also want the design to be modular; so, that I can reconfigure it as a work boat, and-or sail it with just a biminy. Then I can build my dream living module, on shore, then just lay it on the deck and bolt it down, when I'm done. The crab-claw concept, is to keep the center of effort low, to aid stability, make it easier to handle by myself and keep the deck free of clutter, in case I want to carry cargo or machinery.

In a perfect world, the best metal would be HSLA-steel w 2-3% copper. That would arrest corrosion and make barnacle clearance easy-peasy.

My present plan is to brainstorm how cheaply I can build something, that will solve most of the same problems as a 60ft cat and also serve as a work and cargo platform, for a fraction of the cost, possible combining found-object and-or new construction methodologies.
 

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Discussion Starter · #10 ·
So... LST... are you going for the whole deployable landing platform concept for an ATV or motorcycle?, or you just want to be able to beach it and offload your grill. I can't imagine a ketch rigged barge with pontoons would sail particularly well... might do ok dead down-wind in a gale.
I only sail during gales ;-)

ATV, motorcycle, wall-tent, construction supplies, light-machinery, etc. Yup, sounds right. Also, "ocassional" consignment-carry. Why should all these yachts, sailing the world, "not" be carrying "some" commercial items. Uber for yachts sounds like a great idea. I'll run the whole operation, including dispatching, from my laptop.

*Legitimate use case. Suppose, I want to buy some Crimean-war swords and uniforms from Europe, or "any" kind of military surplus or collectibles, I can't ship them by air. These items are completely inert, but are now considered hazmat, under some ludicrous UN rules. I guess they want to make sure none of the peasants can obtain such things, without great difficulty, or cost, or to drive the price up. They must be shipped by sea only. Suppose, I go pick some of these things up myself, or consign. You don't need a whole container-ship for this kind of traffic.

Seriously though, I'm trying to put all these capabilities into one package, DIY, on the cheap. This is my initial vision. I suspect, it's more metaphorical than real; but, at least I've been able to image something, that will combine all of these features and actually still be able to move.
 

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Discussion Starter · #11 ·
Ok, I'll bite. The closest thing I am aware of, but in the monohull design is a Dutch Sailing Barge. Designed for shallow water, and possible to beach.

Something you are proposing would definitely fall into the "Franken" category, right now I am not sure how it could be done, that would work well, and I cannot imagine it being anything close to fast. All the barges I have seen have been plumb bow, or maybe a 45 degree bevel across the width of the bow. Just sheer horsepower to move it.

I'd love to be proven wrong...
I've seen these. I like them. I'm thinking more like a flat bottomed barge, with 45% angle bow. This certainly wouldn't be ideal. I'm trying to solve the problems of a large living platform, flat ride, cargo load-offload without needing a dedicated pier, while also being able to serve as a work platform, for the lowest possible investment. In fact, I think I prefer this approach; because, I might want to do it again, if I can get it to work.
 

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Really? Images????
I don't have many photos of the construction process, I do but they are on an old phone. I grabbed this one off Youtube.

This is by no means found object boats, she is a mutli million dollar build. But, the geography of the area prevented conventional ship yard techniques, so the boat had to be built in place as described above. In this pic the superstructure is being built onto the deck. Built of steel. I skippered her for over a year, good boat.
Vehicle Window Snow Machine Winter
 

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The above project was one of the coolest projects that I was a part of. The catamaran was built on a marine railway so it could be launched in the spring and recovered in the fall and hauled up above the ice flows for the winter. Their were a bunch of experts brought in by the company, a bunch of engineering experts and naval Architects to over see the construction of both the marine railway and the boats themselves.

The boats would be operating in an area of strong river currents, 2 identical catamarans and a 70 ft jet boat for emergency towing. The boats could each be shunted onto the marine railway.

That's how the pros build a big custom catamaran. Pretty fun stuff.
 

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Discussion Starter · #14 · (Edited)
That's sexy as hell. I'd love to take part in something like that someday. Knocks my socks off.

I've also been looking at pontoon boats, like the kind people take their families fishing in, with the big outboards. I like the utility of it; but, I'd like to figure-out how something like that could be driven by sail, for unlimted distance open-water cruising. I'm also thinking about how I could make a sail driven vessel, with the utility of a flatbed truck, that could be configured for multiple roles. The deck space would need to be kept clear while underway; but, most sailplans cover the deck. So, what's the solution? I've been looking at trawling boats for a while, and can't help thinking that that dual masted arrangement could somehow be configured into a sailplan, while keeping the deck clear. That's why I've been thinking about crab-claw sails. If semi junk-rigged, it might even be possible to reef. Also, trawling masts, are big enough, and way over-engineered to carry sail. It might be slow as heck; but multirole, with commercial potential, here we come.

As a found object, I've also been thinking about an LPG-cylinder as a pontoon. People have made submarines out of these and the pontoons on those fishing boats, I previously described, are pretty fat. They still move plenty fast, even as trimarans.

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