building or modifying barges

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I'm going to be doing some work on one of a buddy's barges, basically because he's kind of in a jam. I'm a decent welder but I know nothing about barge construction. I'll try to post pics in a few minutes of what I'm starting with. Basically, he's got two pontoons about 4' diameter by 60' long. The barge will end up being about 30' wide. I haven't seen any of it yet, just going off a phone conversation and a couple pics emailed to me. Right now, the two pontoons are joined by a small beam at either end. The plan is to weld I-beam ( 24"?) between the pontoons every 10' and 1'4" plate on top and bottom of the beams. Then a crane will be positioned somewhere on it but I haven't got the specifics from him yet.The barge will end up with a small crane on it with fuel tanks, storage boxes, welder, etc. He builds docks, bulkheads, boathouses, concrete docks, etc.I don't have a specific question. I'm just curious if anyone here has any experience with this type of thing and can offer any advice or point me to a website that will be helpful. Pics appreciated as well.Thanks.Always looking for another old VW, especially in the southeast.
Reply:i'm not sure if this will help..but..my nextdoor neighbor has a aluminum pontoon boat..the deck was welded to the top of the floats and there was a wood deck on it...but after awhile the welds started to break on top from too much flexing..i took it to where i used to work and welded 4 "x" braces between the tanks..top of left to bottom of right..then top of right to bottom left..duh..every 2 feet or so..granted what your about to dive into is way bigger...but the neighbors boat is good and strong now.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Yes, the 30x60 is a bit bigger but that's good info. This same guy has a couple of small pontoon barges made from old party boats. One of them needs a hole in the pontoon fixed. What if the best way to do this? I don't have a tig but I will buy a spool gun for my Lincoln 255 soon. I've used a spool gun on a Miller 185 to repair a john boat once before.Always looking for another old VW, especially in the southeast.
Reply:i know little about migging aluminum... and not afraid to admit it..oh well..i cant help you there...but i will tig it anyday......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:No problem. It sounds like your mig is like my tig. I can do it but I'm not going to brag about it. I'm planning on buying a tig within the next 18 months, I'll hit you up for advise then. Your work looks great.Always looking for another old VW, especially in the southeast.
Reply:The connection from crossmember to pontoon wall is critical.  If your buddy has some extra pontoon pipe material you might cut some sections to put on the pontoon to double the thickness where the beams connect to the pontoon.  Four foot diameter will not float a great amount of weight.  If the floats are almost totally submerged then the cross members will have to be as high as possible on the pontoons.  Are the pontoons chambered?  If one pontoon develops a corrosion hole it could cause a sinking unless each pontoon is divided up.  Most of the units I have been involved with have been for supporting docking fenders or just plain floating steel pontoon docks.  We sometimes filled them with foam block before welding closed.  That way the thing can be corroded big time and still float.   I inclined to think that your friend will need three steel pontoons instead of two if he wants it to carry any weight.  That or five foot plus diameters.  Drop me a line and I could send you some private pics.QUOTE=bugdust] Basically, he's got two pontoons about 4' diameter by 60' long. The barge will end up being about 30' wide. snipI don't have a specific question. I'm just curious if anyone here has any experience with this type of thing and can offer any advice or point me to a website that will be helpful. Pics appreciated as well.Thanks.[/QUOTE]
Reply:The connection from crossmember to pontoon wall is critical.  If your buddy has some extra pontoon pipe material you might cut some sections to put on the pontoon to double the thickness where the beams connect to the pontoon.  Four foot diameter will not float a great amount of weight.  If the floats are almost totally submerged then the cross members will have to be as high as possible on the pontoons.  Are the pontoons chambered?  If one pontoon develops a corrosion hole it could cause a sinking unless each pontoon is divided up.  Most of the units I have been involved with have been for supporting docking fenders or just plain floating steel pontoon docks.  We sometimes filled them with foam block before welding closed.  That way the thing can be corroded big time and still float.   I inclined to think that your friend will need three steel pontoons instead of two if he wants it to carry any weight.  That or five foot plus diameters.  Drop me a line and I could send you some private pics.QUOTE=bugdust] Basically, he's got two pontoons about 4' diameter by 60' long. The barge will end up being about 30' wide. snipI don't have a specific question. I'm just curious if anyone here has any experience with this type of thing and can offer any advice or point me to a website that will be helpful. Pics appreciated as well.Thanks.[/QUOTE]
Reply:I have a few pics here: http:http://smg.photobucket.com/albu...t69/Welding///The loose plan is to weld the I-beams to the pontoons. I have thought about putting a scab between them like you suggest. I don't know if he has any material but I may be able to get some plate bent at work. The pontoons are made from old tanks that have had one end cut off then another tank welded to it so they are compartmentalized. (phew!) The I-beam is 24" I think, have to check. There will be solid plate on top and bottom so in effect it will be it's own support. I was thinking that where the crane sits I would double up the plate and use some slot/plug welds to hold it, plus weld the perimeter.Like I said, this is the loose plan without having seen it in person and not being familiar with barges at all.Any pics or ideas can be sent to [email protected]. Please put barge in the tag line.Thanks again.Always looking for another old VW, especially in the southeast.
Reply:I get 48,000 pound displacement for one pontoon in salt water.  ( 4 foot diameter. 60 feet long)So 24 tons on two pontoons would get you half submerged
Reply:This may help.http://www.shopfloortalk.com/forums/...t=pontoon+boat
Reply:Originally Posted by TEKThis may help.http://www.shopfloortalk.com/forums/...t=pontoon+boat