Chinese river ship launch failure

As an engineer of Eversafe Marine which is the best marine engineering company in China I want to say something of airbag ship launching.

Marine airbags are invented by Chinese and untill today only Chinese can manufacture these bags. A simple reason caused this, marine airbags are mostly made by hands. Anyway there are some accessorial instruments to help people to make bags easier.

There are standards of Chinese marine airbags. The first one (CB/T3795-1996) is the industry standard issued in 1996. Recently ,maybe only this month, the ISO standard (ISO 14409:2011) was issued.
http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=54715

The working pressure (safe pressure) and bursting pressure of airbags are different for different diameters airbags.

For our airbag with 1.5 m diameter, its working and burst pressure can reach 2.5bar and 7 bar respectively. For 1 m diameter airbag, 4 bar working pressure is ok.

How to calculate airbag ship launching, please refer to http://www.eversafe-marine.com/technology.aspx. Even the page is too simple it can offer some figures of airbag launching.

 

Thank you Coolmike. I just wanted to say that my earlier flippant post was meant to refer to the original vid from the OP. The post by Angel immediately prior to mine shows a terrific example of engineering art. (the big ship launch). A quick question for you. Do the bags use a knitted reinforcement or wound reinforcement like a bias tire. I'm still trying to get these things to behave on paper. And welcome to the forum.

 

Bloody ugly boat. Only appropriate place for it is on the bottom....

 

Marine bags have some plies, generally there are 6 plies of reinforcement and one seal layer. Reinforcement material used in bags is often called synthetic tire cord, as same as polyamide fibre which is pressed with rubbers to form a reinforcement layer. Hope it helps.

 

A proposal for the moderator: how about merging the two threads, this one and the http://www.boatdesign.net/forums/open-discussion/chinese-river-ship-launch-failure-40153.html ?
There's an interesting discussion going on over there too - it's a pitty to keep good things dispersed, imho... If Brian@BNE agrees, of course.

 

Sure, no problem!

 

Yes, good idea to merge. But due to the late merge a lot of posts now seems to be out of context to each other as the merge mixed the posts of the two threads due to time sequence of posting.

When the Moderator saw and posted that there were two threads about the same topic that would have been the best time for the merge as there was only the opening post in the first thread then.

Well, the good thing is this could be a learning opportunity for the next time

Cheers,
Angel

 

Sorry about that Angel. Unfortunately there's no option to reorder posts when merging threads so the posts questioning the 2.6m figure which referenced the other thread title might appear a bit odd ordered chronologically. Sorry about that. Still I think it reads OK.

 

Regarding post #19 I would like to add that the airbags were not the problem but the sollution to an earlier failed launch attempt which made the vessel sit on the slipway on broken sledges with inclinations in two directions . . . . .

See the links in that post how the Chinese solved that problem in the EU . . . . .

OK, Romania but that's EU too

Cheers,
Angel

 

Thanks, Angel,
We also did some works for Belgium EXMAR.

 

Nice to hear Mike

 

Need Help

COOLMIKE, learned that you are well experienced in ship launching area as a seniour engineer in EVERSAFE MARINE, i would like to ask you to help me out on one matter as regards ship lauching with air bags at the bottom. Case is like this, one overseas client of mine is establishing one shipbuilding yard, and he is very interested in this particularly cost-effec genius Chinese way of launching, but they have no ideas of this technology which is very new to them. And they are planning to send some engineers to consult with some ship-laucing companies and observe at a few launching cases, i think if your company agrees to assist in this case, it'd be great. Also they would like to study this special ship-launching technology wit air bags before they come to China, do you have some English documents to help me? for example, ISO 14409:2011 PDF? If you have this would be helping a lot.

Pls send me a messeage to raysing83@gmail.com if you have anything at hand to help me.

Thanks in advance.

 

I took over a project for the owners that out grew the original intended design in Dubai sand boat yard that when finished I used airbags to launch the 38m 280ton Dhow motor yacht.

The only options I had were either sliding 3m long 25mm thick steel plate under the hull as runway for multiple wheeled carriers or airbags.

The beach had a 5:1 gradient to the yard only the bags could manage. The bags were Evergreen China supplied by Iranian company.

Launch was ulcer making calibre but eventually successful.

 

Thanks, watchkeeper. 5:1 gradient is quite a big slope angle for airbags launching. Considering yacht doesn't have a wide flat bottom your launch is a little difficult. You still stay in China? You may come over for a drinking, Evergreen Maritime is our group company the leading manufacturer of airbags which is often called sausage or balloons.

Rayniac ,I have sent you the ISO 14409 file and waiting for your further demands.

 

this what i am here for !!

Oh no its the same kind of boat that we are making but ours is 25 mtrs not 32 mtrs !!!!!
I think i will leave china before it goes in the water !!

When i first saw the design sketchs i could not believe what i was seeing!!!
its like nothing i seen before !!
As time has gone on and we are progressing further with this project more and more stupid mindless things keep coming to light !!
The hull construction is prehistoric and mind blowingly backward !! i spent quite a few hours pondering what to do with the glass lay up to improve stiffness and make a little thicker but not tread on the designers toes to hard !!. Note improve and not go overboard !!
Using better glass was the way i went and slightly changing the foam stringer construction to make it easyer and quicker and leave less room for the bad worknamship and error that could and would happen .
Stringer construction and strength is only as good as the glass is assembled so there are small things you can do to improve quite a bit and not be noticed by inexsperianced people from outside the industry . simply changing glass materials is the first one!, not glassing completely with one piece of glass but joining it on the top so it builds twice the thickness is another and a few other little things all added together almost adds 1/3 extra strength to that seemingly innocent looking PU foam stringer !!. I am now working on a central internal keel that will serve to give longtudinal stability and also be able to support the floor inside the main cabin that will have to have a series of lift out glass foam glass floor panels as there is very little room under the floors for anything specially fuel tanks and water and gray water tanks that will need to be fitted some where !! GLASS tanks are and will not be a option so dont think about it !! this is china !! All the glass has been ordered this morning and the ball will start to roll very soon !!.

I have already posted pictures just need to find them !! as time goes by i will up date again and again !!!!.