Self propelled barge design input

First off, let me thank you for your time reading this, and thank you for your input in advance.

A small bit about my project:
I have acquired a used dredge. I am removing the dredging equipment, and "refitting" it into a barge. Existing, as well as new, hull material is all 1/4" steel sheet. The barge is going to be for buoy, tackle, and sinker removal and installation. The barge is going to be used on a large inland lake and river-way. The waterway normally sees calm water, but can produce up to 4' swell at very close intervals (average lake depth is 18'). It is very reasonable to say this vessel will never see more than 2' swells.

The dredge is currently non-self propelled. It is my intention to find either a salvage cabin cruiser with twin I/O (stern drives), OR find (2) runabouts with identical stern drives to salvage for engine/drive train.

The dredge has a 12' beam, and the hull is 4' tall. Those dimensions will not be altered. Currently it is roughly 26' long. I will lengthen it to 32' overall, and add a rake to the bow. Inside the hull, I intend on adding (2) watertight bulkheads making (3) compartments. The stern compartment will house the engines, hydraulic pumps, and other machinery. The bow compartment (smallest) will be empty (I may add a hydraulic motor powered bow thruster in the future if need be). Midship compartment (the largest) will contain the fuel tanks and hydraulic tank. Each compartment will have a rain/weather proof access hatch. The stern access hatch, located above the engines, and yet inside the pilot house, will allow for easy access for engine maintenance.

At the stern of the barge, I intend on constructing a permanent helm with all the the vessel controls. I will add a pilot house that can be easily unbolted, and if need be, removed, yet still allowing the vessel to be fully functional.

I will be installing an AutoCrane 6006H boom crane approximately 6' behind the bow. This will allow the crane to lift, at its shortest reach, directly ahead of the bow, and still be able to pivot all the way back towards the pilot house. Remember this configuration - this comes more into play later...

The bodies of water I will be working in have a unique problem. They are connected via a lock. The lock has been closed due to an invasive species (round goby). Previously, a barge just traversed the lock from one body of water to the next. After the invasive was found, the lock was closed, with the exception of this twice a year barge traffic. (This barge installed the buoys on this now remote lake). When the barge would need to traverse the lock, they had to chemically treat the lock, killing EVERYthing in the lock. Let's not focus on that....that's another argument....

I intend to circumvent that problem.

Here's where it gets wild....

I want to take my 32'x12'x4' barge and make it "trailerable". Well, a trailer, as such, makes this cost prohibitive. So, I will make my barge itself into a trailer - almost an amphibious vehicle.

On the stern, I intend to mount an axle that can be lowered (for road use) and raised (while afloat). The axle will consist of a reinforced semi trailer axle. (2) hydraulic rams will raise and lower the axle. In the lowered position, there are (2) "blocks" that sit over the exposed cylinder rams (so the weight of the barge isn't resting on the hydraulics).

On the bow, I intend on having a "hitch" (lack of better terms). This hitch will go onto the 5th wheel of a semi tractor. A hydraulic ram (controlled by the semi's hydraulics) will hold the hitch up when it is free from the barge. To connect the hitch to the barge, the semi/hitch is backed into position, and pins inserted into the barge's connecting points. The hydraulic cylinder is then retracted, lifted manually, and hydraulically extended again to a third connecting point on the barge. Once connected, extending the ram further will raise the bow of the barge. The

To launch, the barge is backed into a launch ramp. The engines are started, and the axle is raised and pinned in the "up" position. The semi then lowers the bow of the barge, and disconnects the hitch.

Thoughts? Dreams? Aspirations?

 

If you are spending that much money on the project, you would be better off paying an engineer to do the calculations.

I note thats its already too wide for legal road transport without special permits.

I cant see anywhere where you have estimated the weight, the most important part of the equation.

 

I doubt the barge was designed to be supported only on the ends. You might have to consider how to prevent it from buckling in the center.
How far will it be towed, how often will it be towed and what are the conditions of the road?
Besides overwidth restrictions, there might be weight restrictions on the road. Or height restrictions.

 

I forgot about the estimated weight. I figured the weight of the steel to construct a new hull of the same size, pilot house, bulk heads, interior framing (obviously not in my crude drawings), twin 7.4L mercruisers with bravos (doubt we will go that large) and crane and mounting structures would be just shy of 15k. So completely built, fueled, and geared I would say she would be under 9 tons.

Good point on permits, but we carry oversized load seasonal permit already. When the barge is on the road, it needs to be registered as well. I have that issue addressed as well.

Our fabrication and design company builds manure handling equipment. I have included a link to a video to a dumpster they build (this was a prototype, and now they build them twice as long, twice as wide). This will give you an idea of my axle / hitch configuration.

Heres the video:


(might have to copy paste that...not sure)

Samsam, you're right. The dredge is not designed to be supported by only the stern / bow. When the barge is lengthened, we will be adding longitudinal frame rails. These will also tie into the crane as well. During transport, the crane will be extended into a pocked just forward of the pilot house, thus adding to the structure as well.

The typical sinkers we will be dealing with are 1500 lbs. There are roughly 5 that are tripled up, due to current at their location (so, 4500lb total). The reason we positioned the crane 6' rearward of the bow, is so at the cranes shortest reach, it can access buoys from either side, or directly off the bow. Being at its shortest reach, the crane is well with its capacity to lift all sinkers, even the 4500 lb triples (there are 5 triples, and almost 100 1500lb singles). Due to the weight of the triples, it is our intention to lift those only off the bow. The 6006 crane can then extend and raise at the same time, never moving the buoy and tackle off the bow more than a few inches while lifting it completely out of the water. Once removed from the water, the buoy/tackle can be brought in above the deck, and hoisted rearward while being above the deck the entire time. So stability of the barge while "side picking" won't be a problem with the singles. I highly doubt there would be a problem "side picking" with the triples, but due to their location and current, I believe that they will need to be picked off the bow regardless.

Heres a 30' with a 5 ton crane, so it's been done before. I don't think this vessel is 12' beam either.

 

I forgot...road conditions....

This will get transported to the lake in the summer, remain in the water all summer, and removed in the fall. Our location is roughly 7 miles from the lake. There are various roads, in varous conditions that can be used to transport this. I have not rules out the concept of using a farm tractor to transport this (similar to the video pictured above). This would greatly change the hitch configuration (for the better), and drop road speed down to 20-25MPH.

 

The manual for the 6006H ( https://autocrane.us/wp-content/uploads/6006H-Hard-Wired-999945-0200.pdf ) crane says it's shortest reach is 9' 10" ( page 27 on pdf or page 2-4.0.0 in the manual) so there's that almost 10 foot of leverage from the center of a 12' barge. That's like 4' off the side of the barge.

The load chart ( page 116 or page 9-9.9.9 ) for 4,500 lbs. shows a boom angle of about 40 degrees with a boom tip height of about 9' off the deck. Then add the distance from the deck to the water, maybe 2' or so. The boom tilt would bring the load in to a little less than 8' from the pivot point of the crane.

So then you would have 4,500 lbs. leveraged about 8' horizontally and about 11' vertically on a 9,000 lb barge.

I have no expertise in all this, but it just seems somewhat iffy. Especially when you swing the load around from the bow to put the load behind the crane and the load is all leveraged off one bow corner or the other.

On pdf page 4 it says "A minimum G.V.W. of 14,500 lbs. is recommended for mounting the 6006H series cranes." Another site says the empty weight of a G.V.W. of that size is from 7,600 to 8,700 lbs. So with a barge weight of 9,00 lbs., you have that covered, but, all these numbers and load charts are based on having outriggers on the vehicle, which you obviously won't have. I have no idea how long the outriggers would be for this crane or how wide they would make the base compared to the 12' width of your barge.

Two more of my 'Thoughts? Dreams? Aspirations?' would be the WARNING! on page 3 to NEVER attempt to lift or drag a load from the side! The boom can fail far below its rated capacity. I do have expertise in overloading an I beam by a slight sideways force causing the beam to tip a very small amount and thereby transferring the load to the side of the beam which then crumpled like wet kittens. Any wave that rocked the barge while the crane was loaded could do the same thing.

The other thought would be to contact the crane company or to read something like this to see what "different engineering considerations for lifts made by any crane secured to a barge." Mobile Crane On Barges Part 1 | MOF Company (Subic), Inc. http://www.mof-subic.com/heavy-lift-topic/mobile-crane-barges-part-1

No idea where part 2 is, that might be handy to read also.

I was on the deck when this thing collapsed and ever since I have not especially liked being around when cranes are lifting. Unexpected things happen very fast, and once the little thing sets the big thing in motion there is no turning back.

 

I'll throw in my favourite "gotcha"

Whos going to insure (or provide an approved survey permit) a machine like that, without an engineering certificate ?

You are going to need to professional help.

 

I wonder the same thing because it is a complicated and dangerous "machine"

 

The only large and easily "roadable" barges I've seen are of such a design that they can be dismantled. Swedish army, engineering, used to have alloy sections for building bridges (floating). They were made to be attached to each other thus allowing the engineers to build a floating bridge of the length and width necessary. These have become quite popular among for instance salvage divers as each section is narrow enough to be road legal without special permit. They are also rather light.

I would suggest that you consider a similar design, perhaps you can modify your current barge? I'm not sure how often you'll have to move your barge on the road but if it's something that will only happen on rare occasions the trouble of dismantling the barge will not be a big concern. And on the other hand, if you do move the barge a lot the time of dismantling it might yet prove to be more economic as moving something heavy and big tends to be rather expensive.

I'm also curious to know why you need it to be self propellant? Cheaper, easier and lighter would be to push it, and you'll have a tender boat with you all the time too.

I recommend legs to anchor the barge to the bottom. Since you say that it'll be operated in shallow waters this is a very good feature which makes to job easier, safer, more precise and reduces stress on the material.

While a crane is nice perhaps consider something like in the picture? Very good at handling heavy stuff, not to mention very reliable and not sensitive to the rocking of the barge. When the barge moves the load on the crane will increase which in turn means that the crane must be of a significantly higher capacity than what you're planning on lifting, I'd recommend at least a 2:1 factor or chances are you can't use it for what you intended (or even having to experience that the crane lowers whatever you're lifting because the over pressure protection cut in, potentially in the worst and/or most dangerous moment).

 

Then again, here's a 30 x 13 barge that claims "There is ample reserve buoyancy to carry six to eight tons and the derrick and its falls are designed to lift seven tons with a large factor of safety to spare."
That doesn't actually make any warranties or claims about what you can safely lift while floating (or how to do it) but it strongly implies you can lift seven tons and set it on deck. So, maybe two and a half tons are well within the capabilities of the OPs barge.

The mast is approximately 15' high above the deck and the boom is about 23' long.

This must work, Atkins was a serious designer and all, but without any lateral boom control it seems that it would be easy to lose control of the load. A little tilt one way or the other and the load would sway that direction, amplifying the tilting effect exponentially.



http://www.atkinboatplans.com/Misc/images/Giant-2.gif


Giant
A 30' Derrick Barge
By William Atkin

A Floating Derrick

Wherever there are ships and boats, large or small, floating derricks are needed because boats will sink in deep water now and then, and means must be available to re-float them; heavy moorings, and light, must be laid and re-laid; pilings hoisted from hard packed sand and clay; heavy masts and spars stepped and lifted out of boats; and many another operation of similar character performed as seasons afloat come and go.

Our Giant is a 30-foot over all by 13-foot beam scow, its draft being about 1 foot. Sides are straight and stand vertical, bottom is flat and the ends cut under somewhat to ease the work of towing. A pair of ample white oak guard rails extend all around the hull, one at the edge of the deck, the other 15 inches below. Half a dozen old automobile shoes would make good fenders.

There is enough room on the deck to land two Star boats or a couple of Wee Scots, a small cruiser or a small auxiliary. There is ample reserve buoyancy to carry six to eight tons and the derrick and its falls are designed to lift seven tons with a large factor of safety to spare.

Atkin & Co. - Giant http://www.atkinboatplans.com/Misc/Giant.html

 

First you should check whether trailering the barge between locations will be acceptable to the authorities in charge of goby quarantine. For example authorities may be concerned goby eggs will adhere to your barge or adult fish will be able to survive in a water intake or similar.