preparing a tank calibration of a tug, need scantling of vessel

I have a doubt and can any one of you help me?...Am now preparing a tank calibration of a tug and am doing this first time..I collected all the details except one...Scantling of the vessel.I can complete if i get that bt i dnt knw how to get that value.can you plz explain what is scantling and how could we get that value

 

Scantlings is concerned, mainly but not only, the hull thickness, deck and bulkheads and the size of their reinforcements.
To perform the calibration of tanks do not need to know the boat scantlings.
When calculating the gross volume of each tank is normal deduce 3%, to take into account the thickness of partitions that form the tank and their reinforcements.

 

Are you asking about a tank test?

 

Hi,
That you yet have not the hull frame scantling means that you still make the initial phase of designing and a calibration of tanks is necessary only for accounts on intact stability and unsinkability. At this stage there is no necessity to know the frame inside the tank, but only location of molded lines transversal and longitudinal walls and platforms at the tanks.
But let's begin about ready computer model of the tow guessing that he is at you already. What it is necessary to make then?

 

After doing many stability books & tank capacities/ullage table I allow 5 percent for metal structure(95 percent permeability). For 'heavier' boats you might go to 93 percent)

 

actually am doing this in an excel format in which we only have to update Length of tank, length between draftmark,trim,transverse breadth of tank, distance from aft bulkhead to sound pipe, scantling correction....and after this updation i can get the whole value in each trim...so how can get the scantling value? is there any calculation for it?

 

The scantling correction to be applied is 97% (3% decrease of the calculated volume). JSL says he applies the 95% or 93%.
Ie, the net volume of the tank is the % you choose of calculated volume. What more do you need?
Maybe you should go over some concepts and terminology. Meanwhile, at your disposal if I can help.

 

The tank calibration is necessary before calculating the stability of the boat. First calculate the weights of the boat that define each load condition, calculate the floating balance, trim and, when these are acceptable, calculate the fulfillment of the stability criteria applicable to the ship.
Before calculating the stability you need, for example, to figure out whether or not a tank corrects by free surfaces.
There are no structural tanks and you don´t need to know the position of any ship bulkhead, however, must also be calibrated.
At no stage there is necessity to know the frame inside the tank. Normally tanks are calibrated without knowing the frames inside the tank.
Better not give opinions or advice that might confuse the OP

 

Thanks for all who replied me

 

I have another doubt.... Am now preparing a fireplan for a vessel of PRS classification society.My doubt is that there we are classifying the space partition and doors by A,B,C classes...what each classes mention for

 

The SOLAS has tables that clearly indicate the classification must give each space. All CS refer to SOLAS to this topic

 

Hi appusree888,
I think that sirs in the forum could not give you precise advice. Some from them are fast excited and become victims of the emotions rigidly convinced that only their opinion is the most correct. Even transfer to personal attack that is inadmissible for tolerable tone of the forum.
You in the beginning have not given the complete information. From for it my explanations touched to a situation about an initial phase of designing of a new tow. Now when it is clear that the question is update and repair of an old steel tow, I shall try to help you maximum precisely:
- Clearly that is not necessary to trouble about Lightship. Even if you where that will have inaccuracy in accounts in the extreme score when you will make Heeling test of the vessel will be exempted from any doubts. In fact you know that water is the accurate scales.
- But the problem with precise size of deadweight capacity very important because in the ultimate Stability booklet / which is necessarily corrected after Heeling test / it is necessary to indicate ultimate project sizes of the draft and the trim of the vessel for total displacement and if they exceed the booked sizes then usually project organization bears financial penalties for the benefit of the client. It is extremely important especially at cargo ships. At all river boats it too is extremely important from for limitations in the service draft.
It means that the maximum quantity of the fluid which can be filling in tanks necessary to calculate with maximum accuracy.
- What it is necessary to make?
Certainly in the initial phase when it is necessary to decide problems of the intact stability and unsinkability under Rules, it is possible to not trouble about the frame which to be inside theoretical volume of tanks. Too also there is no necessity to take into account that the thickness of some from walls too to enter in theoretical volume for the sake of molded lines of walls.
But in the ultimate phase of the working documentation all this should be taken into account.
How acted in Design bureau of Institute where I worked?
On available working drafts must take weights of all structural members / including and the brackets / were are in theoretical volume of the tank. To this sum it is necessary to add both the weight of the frame and the plating for walls of tanks included in volume. Then the total sum of the weight in t should be divide into specific gravity 7,85 t/m^3. It will be the unknown quantity sought for volume of the frame in m^3. We deduct her from the maximum theoretical volume and the volume is received pure /net/. It is not necessary to forget and about volume of angular welding which too sink the clear volume of the tank. It is taken into account to the following methods: we take the most often meeting template of two-way welds and we compute volume for 1 m. Then we discover a total length of all structural members welds and we multiply on volume of welds/1 m.
We multiply the clear volume of the tank on specific gravity of the fluid in the tank at operation and the maximum weight /100 %/ fluids which is received is possible to take in this tank. This maximum weight responds the high level of division of the measuring pipe. Then it is necessary to make a calibration and to improve indications of the graduated ullage foot at different levels.
If we would like to be absolutely precise, all aforesaid should be made for each tank. But we can and facilitate our work on the following method:
- For forepeak and after-peak ballast tanks unconditionally it is necessary to apply the above-stated method from for a particular frame in them.
- The remaining hull tanks can be shared into two groups - bottom and side. We shall make account for one bottom and one side tank on the specified method. The received percent for the frame is applied for remaining tanks.
This method is more precise in comparison about that colleagues offer / 5 % for all tanks / but all the same is approximate.

 

The method described by Rabah is great, almost perfect. I wonder, however, why not take into account the deformation of bulkheads.
My advice, and I do not despise anyone, is to take 95% or 97% of the gross volume of the tank, depending on the number of internal reinforcements and do not complicate your life. You sure do not need such precision.
Talking on damage stability IMO calls for applying a permeability of 96%.

 

Dear Tansl,
It is time to stop sneers. I shall not allow to concern with a sneer to the clear memory of all these excellent designers - shipbuilders with whom I worked, inclusively and projected a military vessel. Really you think that all of them are silly, but only you are the cleverest? And what you projected except for plastic motorboats? From your gallery we see only pictures and what is your sharing is not clear because all know that major vessel is impossible to project alone.

 

Rabah: What is wrong with taking into account the deformation of bulkheads?