looking to build a cargo barge approx 8 x 30

[F350layinglow]

Good day .
I am looking to build a cargo barge approx 8 x 30 with a carry weight of 18000 lbs used to move equipment and supplies in a smaller lake so will need with the least amount of draft as possible. Would like it to use a outboard motor . Would anyone have plans for this ?

Thanks chris

 

[bajansailor]

Welcome to the Forum F350.

Re your proposed dimensions, 8' is rather narrow for a length of 30' - even if your barge is literally a rectangular block in shape, then a cargo weight of 18,000 lbs that is distributed uniformly will sink that block by approx 14.5".
And this is before you start to think about the effect on stability, which will be significant.

Here is a link to a long running thread by @DogCavalry about a barge that he wanted to build - it had to be capable of transporting a load of 13,000 lbs (5,000 lbs less than your barge) - have a look through this thread and see what you think.
Barge to carry a single pick-up truck https://www.boatdesign.net/threads/barge-to-carry-a-single-pick-up-truck.68396/

Here is another thread about a small work barge - @Rumars makes a very good point re have a look around to see if there are any old motor boat hulls available locally that are reasonably cheap - even if you have to re-fit it, it will still cost less than building a new boat.
Material choice for twin hull barge/work pontoon https://www.boatdesign.net/threads/material-choice-for-twin-hull-barge-work-pontoon.68702/

 

[F350layinglow]

Thank you for the replies.

I would like wider but 8ft is the widest without getting a oversize permit in ontario. I will be building 3.5 hours away from the lake . What would be the longest length and maximum payload I could go with 8ft wide ? I am new to boat/barge building.

 

[kapnD]

Outboard motors are ill suited to slow, heavy craft.

 

[bajansailor]

@F350layinglow can you tell us a bit more about the lake where you will be using this barge?
How large is it? Is it large enough to get rough if the wind is blowing for a while?
If you do get waves on the lake, the barge will have to be able to cope with these.
Once you get the barge to the lake, will it stay there permanently, or will you have to bring it home on the roads every winter?
If it can stay there permanently, then you could perhaps build a catamaran barge in sections, and disassemble it for transport to the lake, and then re-assemble it again.

Edit - how difficult would it be to get a wide load / oversize permit - and how wide are you able to go with a 'standard' permit?

 

[F350layinglow]

It is a small fresh water lake that does not see any sort of rough waters. The barge would stay at the lake . When I am done building I would be using it for transport back and forth of passengers and weekend supplies .

 

[F350layinglow]

8.5 ft is regulation with oversize permit to 12ft but than I have the issue of getting on a trailer. Most tilt anf loads are 8.5 ft

 

[fallguy]

8x30x1’ is 240 cuft of water at 62.4 pounds is 14,976 pounds.

The barge weight is a factor and the bow needs an angle and the barge needs freeboard. You are either going to go wider or longer to get to the beach.

 

[BlueBell]

Chris, have you looked for a used barge for sale in your area?
There may even be one that's already at your lake...

Did you look at similar threads on this Forum?

 

[F350layinglow]

8x30x1’ is 240 cuft of water at 62.4 pounds is 14,976 pounds.

The barge weight is a factor and the bow needs an angle and the barge needs freeboard. You are either going to go wider or longer to get to the beach.

Sorry for my ignorance, are you saying that 8x30x1 ft would carry 14,976 lbs? Or is that buoyancy , 14976 minus the weight of the boat gives you carry capacity

 

[F350layinglow]

Chris, have you looked for a used barge for sale in your area?
There may even be one that's already at your lake...

Did you look at similar threads on this Forum?

Yes I have, there is nothing within my province that I have found as of yet.

 

[bajansailor]

It might be useful if you join this Facebook group about Trailerable work barges, and you could also ask for opinions there?
https://www.facebook.com/groups/1752048448544094/

Sorry for my ignorance, are you saying that 8x30x1 ft would carry 14,976 lbs? Or is that buoyancy , 14976 minus the weight of the boat gives you carry capacity

The 14,976 lbs is the displacement of a 30' x 8' rectangular barge floating at a draft of 1' in fresh water.
If the barge is heavier than this, then the draft will be more.
If your barge does happen to coincidentally weigh this amount, and you then add a uniformly distributed cargo of 18,000 lbs, then you will sink it by approx 14.5", giving you a total draft of 26.5".
You will need to have a reasonable amount of freeboard - if the total depth of the rectangular barge is say 4', then your freeboard will be a bit less than 2' (which is not a lot really).
And you still have the issue of stability to consider - especially if it is a deck barge, with all of the the cargo loaded on the deck, rather than inside the hull.

Be aware though that a 30' x 8' x 4' rectangular brick is not going to be the easiest thing to push through the water, so you then ideally want to have some shape / flare at each end to reduce the resistance.

 

[bajansailor]

8.5 ft is regulation with oversize permit to 12ft but than I have the issue of getting on a trailer. Most tilt anf loads are 8.5 ft

If you build a 30' catamaran that is 12' wide then you should be able to transport it on a standard low loader trailer? Although you will then need a truck to tow it.

If your catamaran has two rectangular hulls that are each 4' wide, and an overall beam of 12', then you should not have any issues with stability, and the draft will still increase by 14.5" if you add a cargo of 18,000 lbs to the barge.

 

[F350layinglow]

I would thank to thank everyone for the responses.
I have another question, I found a bardge that is 20x8 that I am told is rated for 10 tonne. I need to float my 28ft travel trailer over to the property, the landing gear to rear axel is 18ft so it will fit on the bardge. Would centre of gravity be a problem? How do I calculate if it would be safe to float over?

 

[bajansailor]

What is the hull depth of your 20' x 8' barge?

How much does your 28' travel trailer weigh, approximately?
Do you have a photo of it that you can post, to show how high it is?

Fresh water weighs approx 62 lbs per cubic foot.
If you load 10 tons (22,400 lbs) uniformly on your 20' x 8' barge, then the draft will be 2.2'.
But if the centre of gravity of the trailer is fairly high, then your stability might be a bit fraught.