Deck Barge

Hello everyone this is my first post here and I already need help. I am starting to build a deck barge 24' x 8' x 32" out of 5086 aluminum sheets. My questions is on what is needed for the stringers? I will be using the barge on a aquaculture farm in NC, the ride to the farm is only about 1/2 mile but there will be a winch on the barge and it will lift about 500lbs cages from both sides of the boat so it will be in the middle of the vessel. Any idea on what the stringers need to look like?

Thanks,
James

 

Hi Jimbob1

Welcome to the forum.

Unfortunately you wont get any decent replies, well, none that are going to help. Since structure is related to the weight/displacement of the boat as well as the general principal dimensions and speed. It is also dependent upon the scope/duty that the vessel shall perform and its environment. As such without knowing anything about the boat layout etc...it is impossible to say. What may be good for one boat may not be good for you, for various reasons. If you haven't done so already ready, I would suggest you contact a local NA to assist. Otherwise, you'll have to put up the plans on your thread so others can see what are the spans, the supports the duty etc etc, in order to provide you with any meaningful reply.

If you have no plans, then you do need help!

 

Thanks Ad Hoc. I do have plans in stp format that I can post in the morning. We will be running a 60hp outboard on the boat and speed is not important as the farm is very close to the area we offload. we will be lifting one cage at 500lbs and may have 5000lbs on the deack at anytime max. The barge will be 24'x8' on the top with only a 32" angle at the front all other sides are flat. All the sheet aluminum for the skin will be 1/4". it will be in saltwater everyday but in a protected basin that is only about one mile across and never has waves over 12" and most days is flat. I was thinking a box truss design.

 

Yes, post the plans you have and see what results you get. Also, a detailed description of the use/application is a 'must' so the NA understands what is needed.

 

I am curious why you chose aluminum for this. Heck I am curious why you aren't just buying a decommissioned barge. It would be a lot easier and cheaper to stick an outboard on a small barge then construct this from the ground up.

Just a quick search popped up http://www.maritimesales.com/RUB10.htm it's only 30', but comes complete with a crane, engine, generator, ect... All you would have to do it move it in place and remove the pile driver. Though that may come in useful for aquaculture as well.

 

Stumble,

We could use and old barge but a couple of things have lead us down this path.
1- The crane is just a jib crane frame with a windlass not a true crane.
2- Aluminum barges float in less water, we have about 78" of water at high but only 18" at low. when the weight is added every pound counts.
3- We have been working out of a 24 foot skiff but know if the top is flat that the water from the cages as we lift them will run off and the water from the washdown pumps can also run off.

here is a link to a youtube video of someone checking a cage, with the difference of the fact we use a windlass this is what we do. However we want to add our sorter to our vessel it is very light but takes up room that we will gain by no side and no taper on the sides.

http://www.youtube.com/watch?v=cAMP1qBTipA

I will post the drawings I have complete today.

 

If I was designing this rig, I'd pull the 500 pound cages through a hatch in on the boat's centerline, rather than over the side. As to scantlings, well any offering would be just guesses, so I'll resist, but it's not a difficult proposition for any designer.

 

Why build new...more expensive than you think.

Get one of these fiberglass jobs in shipwreck, bank repo, form...take a chainsaw to the cabin house, remove the rusted engine to use as a mooring anchor and you will have a nice barge

http://

 

Well getting some of the equipment shown on the deck and had to add 32" to the length. We have the aluminium sheets here from a tower tank job we did so the real cost to us will be in the stringers and i have no knowledge of how to figure the load or what they look like on barges. Ours will not carry much in the way of payload or be ocean going so i know that will affect the number and size of the stringers. I hope i attached the drawing correct if so you can see the long table we sort on, it will be on slides and move out about 24" to allow more room down the center. we cannot add to the width as NC has a 102" max trailer-able vessel and we move from farm to farm. I cannot pull the cages thru the center of the vessel but we did think of this up front by using a pontoon, the low water and cage height means we would hit the cages at low tide.

Thanks,
James

 

What alloy are those sheets? This is going in salt water right?

Do you have enough plate to make bulkheads/webframes? The alternative is to do all framing with angle and flat bar.

If the barge weighs 5000 pounds and you have 5000 pounds on the deck, she'll draw about 13" of (salt)water......

 

Tad,

The sheets I have are 5086 and yes it will be in saltwater. I draw in inventor and had the draft at 12-14" so glad to see you come up with the same number! The only real problem I have is I know nothing about how the Stringer/Bulkhead is layed out in barges. I was thinking the best way to build it was 3x3 angle at the seams and some type of truss support built from 2x2 angle. But I do not know how to figure the loads so I hoping someone had some idea of what is common. I have a Large shop with all the tools but need some help with the forces in work on the vessel. the crane is no problem I can spec it fine but have never built a barge or even looked inside one. hope this help with what I'm looking for.

Thanks,
James

 

If you are using in sea water make sure the alloy is marine grade (not industrial). Submit some sketches of your proposed framing layout so people can view and comment.
Also, make sure you comply with any applicable safety regs, or regulatory bodies,etc...

 

The 3 x 3 angle to the seams/corners? seams like a waste unless you want some extra abrasion resistance externaly or an easy fit up for deck plating to land on, maybe a corner weld & internal fillet would be enough, some unequal angle like maybe 4" x 2" by 1/4 or 3/16(just guessing) might be good transverse framing or use as longtitudinal stringers between transverse WT bulkheads, if this is a deck barge you need to build your way out of it before fitting the deck so there's minimal confined space work to interior(so a deck flange & maybe channel framing to plug weld the deck down). Maybe some appropriate to thickness folds could be nice if you have the equipment.
Jeff.

 

Don't think you want any stiffeners on the "seams" (assume you are referring to plate seams) as these should be welded inside and out.

The usual thing with barges is a series of watertight bulkheads running athwartships and one or two WT bulkheads running longitudinally. This barge is so small you might want to ignore WT bulkheads, or you may want them. A couple of transverse ones dividing the hull into thirds will be a good idea and not too much extra work. Usually these individual tanks will have a flush watertight manhole into each space, so you can get in there and inspect and weld (which will not be much fun, find a young eager beaver).

Between the WT bulkheads you'll have 2-3 (each tank, so perhaps 6-9 total) deep transverse web frames with cross bracing (truss) to support the deck. Then there will be a bunch of lighter longitudinal stiffeners on the top (deck) and bottom. The sides don't need much (because of the heavy 1/4" plt and only 32" span) and they can be channel welded on the outside as rub-rails. You may also have channel on the bottom outside to take wear when going aground.

 

Guys thanks for the help I will post the drawing in a few days and get your thoughts. Thanks again!