Hi Bill.

Things are going from strength to strength.
Participation in this topic increased from five to six.

Any comments are welcome.
Too bad not all of them have content. Not everyone can find something concrete in their trunk.

But they do what they can and we need to encourage them, next time they could do better, ahahahah!
The important thing is to participate, hahahaha!

I also understand that reading very long posts can be tiring for some.

To understand you have to read.

Much ado about nothing. Four words says a lot!
Lew
Florida 😴, USA

Hi Bill.

I don't know you personally but I know your work through the forum.
I look at them often because they are a school for me, I think I've run out of "likes" for your models.

I have great respect for your way of dynamic modeling and I admire your modesty and moderation in writing.
These characteristics make you an authoritative person in this forum, a few of your words weigh much more than many others.

For these reasons the phrase "Your hard work and diligence deserves a medal in not only this but other posts you share" is the medal itself for me.
I thank you for giving me this medal yourself when you said these words.

To many they may seem like rhetorical phrases but I am convinced of what I say because I was very struck by your commendable intent to lift me and JockScott up.
Your purpose is noble and probably reflects the person.

It's like you say! I'm not discouraged at all. I was just a little worried about JockScott, I didn't want some sentences to have mortified him.

I'm actually very happy that this topic (in my opinion with very interesting contents) has gone from only two participants to five.

I think that the worst that can happen in a forum is the absence of comments or the poverty of interventions; written silence is the death of the forum.
The forum is useful for spreading the knowledge and culture of modeling.

For these reasons I also welcome critical or very critical comments with great pleasure and interest, as long as they are respectful and not offensive. So far I have not read any offensive or disrespectful comments.
Unfortunately I can't grasp the nuances and all the words, perhaps I'm missing some subtle irony and it's a shame because I really like irony and the joking tone.

Thanks again for your valuable input.

Hi Roy.

Your posts are always full of anecdotes and information.
You are one of those modelers who would like to meet in person so that they can talk to you (in reality I would mostly listen to you).
You are a gold mine of skills and knowledge.

When someone writes a post they always expect your intervention sooner or later and if this doesn't happen they are disappointed.
On the topic of the anatomy of the ESC, you not only did not disappoint expectations but you gave a significant boost. You and JOHN.

You intervene on almost everything and you are one of the souls of this forum, one of the most active and lively ones, I'm just sorry that I can't always understand everything you write.
This is my limitation, certainly not your fault.

You wrote many interesting sentences in this post.

"Further calculation of the meta center gives you an idea of how violent or sluggish is the recovery of the boat as it rolls in the water.
A sluggish return to stability is useful for firing guns and a quick return is more for a sailing boat."
In fact, even passenger ships cannot return to stability too abruptly otherwise passengers would have serious seasickness problems. In Italy they say that the ship must not be too "hard".
On my model I have no passengers and I am looking for the most intense righting thrust. Furthermore, as you rightly say, it is a sailing ship.
Even warships need to have a softer return, it's just like you say.

"Much can be done by eye it depends if you like playing with numbers!
I don't do this anymore, I adjust an existing plan."
You've done it in the past, you don't have to prove anything today. You can enrich us with your anecdotes and advice.

"Nice to see that someone cares about the fundamentals."
I agree with you.
It's not my job because I do something else, but I'm an enthusiast and nothing stops me from reading many books on these topics, getting on some sailing boats, watching videos and talking to competent people.

Alessandro.
Your hard work and diligence deserves a medal in not only this but other posts you share.

I am sure that you are not,but don’t be discouraged by any perceived negativity shown in certain quarter's.
Keep up the good work…it’s how we all learn 👍👍🎅🎅
Regards
Bill

Hi back when I first got interested my first calculation was Simpsons 1st rule for estimating underwater volume. Not dissimilar to Allessandro's method.

Then calculate centre of buoyancy.
Then centre of gravity (i.e. dispersion of weight in the hull.) This not easy as in a model, by then it is a bit late!

Followed by altering underwater volumes to be in the same vertical plane as the c of g, and the boat floats on an even keel.

Keep c of b above c of g and you have a stable boat.

Further calculation of the meta centre gives you an idea of how violent or sluggish is the recovery of the boat as it rolls in the water.

A sluggish return to stability is useful for firing guns and a quick return is more for a sailing boat.

Much can be done by eye it depends if you like playing with numbers!

I don't do this anymore, I adjust an existing plan.

There are practical ways for instance if you cut out a silouette of the underwater hull from stout card, you can suspend it by a thread and draw a line where the thread crosses the card.
Choose a different suspension point and assuming they intersect, then where the intersection is, is the centre of buoyancy.

Nice to see that someone cares about the fundamentals.
Roy

Don't worry JockScott, we didn't waste any time.

The work was not useless at all, it was not futile.
Your questions were not trivial.

They would not have been futile and banal even if the results had been poor. Instead, the results were more than satisfactory, in my opinion.

If you want to make other comments or questions (also for any details on the water test), feel free to ask me, it will be my pleasure to answer you.

You will also try it in the ocean... fantastic!
I am even more interested in the developments of this tanker scale model.

Hi Alessandro, thank you for your comments.
As we went along with the clarification of various issues from the material I had given you, I was indeed wondering how much effort and time you invested in this project and if this was not stretching your patience and endurance. But since you diligently responded to all issues as they represented themselves, to stop now would have been disrespectful and rude on my part. So, for that I thank you for your comments in responds to RN's post as I had the notion, my part was conceived as 'leading you on to a trivial and somewhat futile attempt' of very little achievement. Therefore let's let it rest, you have achieved more than I could have imagined, until I can determine the true volume in a real test. It will be in fresh water. Later, when completion as progressed further down, I like to take it in the ocean to test the watertightness of the removable main deck.

Hi JockScott.

Meanwhile, first of all, thanks for the appreciation.
I'm glad you are satisfied.

For me it wasn't work but fun. Furthermore, I refreshed and improved the knowledge (albeit little) I had about "Rhinoceros".

Your method provided a good result compared to the exact value (for the moment we can take the Rhinoceros result as the exact reference).

Your method may not be suitable for hulls different from yours, where you just need to remove obvious volumes (those triangles you were talking about).
I am referring to very tapered hulls with very different "waterlines". For example, it could not be applied to the hull of the model ship I am building or to many yachts I have seen in this forum.
Let's remember that the submerged hull of a supertanker is, most likely, the one that comes closest to the submerged prism.

However, I congratulate you because you have identified on your own, simply by observing, an effective and, above all, very simple method.
For this I admire you.
I am very much in agreement with you on this.

Regarding section 139, let me explain further. I don't want to mislead you.
It's not section 139 that has a problem.
The problem is that the number of ordinates in the drawing does not correspond to the one in the table, because number 83 is missing.
This meant that the alignment was wrong and I noticed it because the math never added up and the line (in the part marked by the red arrow) was not coherent.
However, it is a problem overcome and solved. It was just to give you a detailed report.

Section 169 is not a problem. There are no errors there. I didn't draw it because it's above the waterline, so it's not part of the submerged volume.


Don't worry about the time spent getting these results out for me it wasn't a hassle but fun.
I look forward to seeing the developments of your ship model.

P.S. Before putting it in the water, do not already set it up with all 32 kg. Leave a margin of four five kilograms but put at the last. But I think you've already thought about this.

By the way, will the launch be in the sea or in a lake?

Hi Doug. Thank you for your valuable and authoritative opinion.
Good morning to all modelers.

"Much Ado About Nothing" was also an extraordinary work.
I liked it a lot.
In reality, it is precisely this noise that we like.
We build models and talk about models. Isn't this a forum?
Furthermore, these topics are very closely linked to the naval techniques that interest us. We're on topic, I think.

I'm not even so sure that the "noise" is at all.
I have to say that in general I agree with you on the water tests.
I am the first to say that the practical test in water is the most truthful and the most useful.
I have written and reiterated it many times not only in this topic but also in others.
I always do it; I had also put some pictures on my ship model if I remember correctly. I attach them again.


However, there may be many reasons why a modeller wants to know (by calculating or estimating) his immersed volume, for example for simple fun (for the fun of it) or for actual necessity as in the case of JockScott's Deutschland Esso 1963.
His model does not fit into an ordinary bathtub (I think this is evident). So I preferred to give him some help.
For me, his request was a stimulus to take an interest in a problem and solve it.
In the end I'm the one who thanks him.

For me it's different, knowing what the displacement of my ship was, already in the design phase, before building it was essential and not useful, for obvious reasons.

You write that it takes two or three months. Allow me to disagree on this point.
The calculation can be done in a day and is very simple. Furthermore, the polynomial can be further simplified.
What occupied me the most was the design of Rhinoceros. JockScott would have loved to see it drawn in 3d and I did. For me it was a useful exercise.
It didn't take three months to do this, the actual work time I dedicated to it was relatively very little in truth. A good designer (unlike me) would take a moment.
The topic actually lasted quite a while. You're right about this.
There were actually a lot of messages between me and JockScott but it's my fault, I had to ask for a lot of explanations. Then we also dwelt on it.
But in the end I ask myself: "is this a problem?". In my opinion, the reasoning is the richness and strength of a forum.

I really admire those who create models in two months. Unfortunately, I'm not as good as them, I ask for indulgence, ahahahahah, but I'm very slow.

PS: Uncle Wiki says-
"The common non-SI metric unit of volume, the litre, is defined as one cubic decimetre, although, from 1901 to 1964, there was a slight difference between the two due to the litre being defined using the kilogram rather than the metre.
Markings of a ship's draft are shown in decimetres in most of the world."

Sooooo, this means that the average of the results given below, to whit 32.72dm³ equates to 32.72 litre, or 32.72kg of fresh water (at standard temp and pressure😉).
So what does this tell us? Damned if I know🤔 Our Christmas conundrum😁
I've long since forgotten how this all started (it spreads over two threads which I followed with bemusement), but it indicates a pretty big boat!
All lucid elucidations as to the benefit and practical use to the ship modeller of these results will be most gratefully received.
I'd also be intrigued to know how Alessandro would conduct the water test, that he mentions, to corroborate his results. Borrow Archimedes' bath perhaps😁😂🤣
"You reeker🙊" 'Hey, you don't smell so good either!🙊🙊'
Cheers All, Doug 😎

Amazing work indeed! Or is it much ado about nothing?
But to what end Jock? What will you now do with this result? How does it help you?
How long has all this taken? 2months, 3 months?
There are talented guys on this site who can build a hull, fit it out, finish in exquisite detail and maiden the completed vessel in 2 months.
Witness the recent Blog of a fabulous 'Typhoon' build for one.
Or the alacrity with which CashRC turns out his successful models😮

I question the reasoning behind spending so much time on these abstruse calculations when the rest of us solve the essential problem, i.e. How much payload weight (drive train, batteries +) can my model carry and float to the Load Waterline at rest, in half an hour or so with a float/ballast test in the bath, paddling pool or swimming pool of our luckier plutocratic members!😉 With plastic or GRP hulls I simply pour in water until the hull settles correctly on the LWL. With wooden hulls I use lead balls, purchased from Krick in 1kg bottles. Advantage of water is that it is 'self trimming'😉 I then pour the water into a simple measuring glass.
Re Specific gravity/density: Living some 800km or so from the nearest sea water, and given that the variation of the SG of fresh water is a few digits some 5 or 6 places behind the decimal point, I simply convert the the measured ml into gm 1 to 1. Or pour into a jug on the kitchen scales.
Similarly I pour the lead balls into a bowl on the kitchen scale (tare weight of the bowl set to zero) and have a direct measurement of the payload capacity of my model.
'Bob's yer uncle and Fanny's yer aunt!'😁

Yours 'umbly, a simple electronics engineer,
Doug😎

Amazing work Alessandro. I will go over the details and your explanations later as I like to check for the apparent deviation of frame 139 in your pic. 6/8. Also the shape of frame 169 seems wrong as this is the last frame in the bow section which is entirely above the waterline and should not figure in the immersed calculation.
Meanwhile the final result is surprisingly close to my own very simple calculation by the volume of Length x Beam x draft and subtracting approximate 4 triangles for and aft at waterline level and 50% again for the aft triangle. This had given me 30.0 dm3.

In conclusion:

- 3d software method = 32.16 dm3
- mathematical/geometric method (without 3d software) = 32.2 dm3
- prismatic coefficient method =33.8 dm3.
- test in water = ?

The first data is absolutely precise (except for the missing part on the bow which I have not been able to reconstruct).
I think the missing part will be of the order of 73000 mm3, i.e. 0.073 dm3.

The water test should provide (barring errors) a value close to 32.2 dm3 (32.16 + 0.073).

Pay attention to the specific gravity of water when converting weights and volumes.

I'll try to put a video of the immersed volume.

... continuation of the previous message ...

Once I found the error I aligned all the sections correctly and started creating the surfaces on one side.

Creating the hull surface in a single solution by selecting all the curves at the same time was impossible. I couldn't do it with any command.

I created the surfaces between the sections and then joined them.
Having made the half hull, with the "mirror" command I created the other half and then joined them.

This work helped me practice and discover new things about the software.
I discovered that the mirror command introduces many errors, so I repeated all the work also on the right side and then joined them.

However, creating the volume by blending surfaces always failed.
Thanks to AndyN, I discovered the existence of the "show edge" command which shows all the unclosed edges between different surfaces.
After several attempts I understood how to "sew up" these edges and close the volume.

I will need these "discoveries" for my project. In fact, I intend to try to close the volume of that schooner too.

In the images you can see the immersed volume of your model and the result in mm3.
The submerged hull is missing a small portion at the bow that I couldn't complete because I didn't have the keel profile (you remember I asked you). However, it was a small flaw.

Once I obtained the precise volume I was able to compare the result obtained with Rhinoceros with what I described at the beginning of this topic.
I can state that the values are very close to each other, therefore we can consider it more than valid and certainly more precise than the prismatic coefficient method.

Therefore anyone who wants to estimate with an excellent degree of approximation the internal volume of his ship can perform this simple calculation:

Add all the products of the sections by the distances between them.
If you want to visually see what you are doing with this trivial mathematical calculation you can look at the Rhinoceros screens that show the individual volumes in green.
It is clear that this calculation is an approximation.

To make it even more precise I applied this:

sum of all (section in mm2 x distance between sections /2)


This is what comes out of it (I left all the steps so it's clear):


somma di tutte (sezione in mm2 x distanza fra le sezioni /2)



(sez. 2 x 41,67/2) = (5878 x 41,67/2) = (5878 x 20,835) = 122468 mm3
(sez. 3 x 41,67/2) = (9097 x 41,67/2) = (9097 x 20,835) = 189536

(sez. 3 x 43,71/2) = (9097 x 43,71/2) = (9097 x 21,855) = 198815
(sez. 4 x 43,71/2) = (13015 x 43,71/2) = (13015 x 21,855) = 284443

(sez. 4 x 41,14/2) = (13015 x 41,14/2) = (13015 x 20,57) = 267718
(sez. 5 x 41,14/2) = (16451 x 41,14/2) = (16451 x 20,57) = 338397

(sez. 5 x 89,33/2) = (16451 x 89,33/2) = (16451 x 44,665) = 734784
(sez. 6 x 89,33/2) = (21321 x 89,33/2) = (21321 x 44,665) = 917443

(sez. 6 x 86,06/2) = (21321 x 86,06/2) = (21321 x 43,03) = 917443
(sez. 7 x 86,06/2) = (23621 x 86,06/2) = (23621 x 43,03) = 1016411

(sez. 7 x 150,51/2) = (23621 x 150,51/2) = (23621 x 75,255) = 1777598
(sez. 8 x 150,51/2) = (24402 x 150,51/2) = (24402 x 75,255) = 1836372

(sez. 8 x 86,03/2) = (24402 x 86,03/2) = (24402 x 43,015) = 1049652
(sez. 9 x 86,03/2) = (24670 x 86,03/2) = (24670 x 43,015) = 1061180

(sez. 9 x 494,65/2) = (24670 x 494,65/2) = (24670 x 247,325) = 6101507
(sez. 11 x 494,65/2) = (24102 x 494,65/2) = (24102 x 247,325) = 5961027

(sez. 11 x 86,03/2) = (24102 x 86,03/2) = (24102 x 43,015) = 1036627
(sez. 12 x 86,03/2) = (23842 x 86,03/2) = (23842 x 43,015) = 1025563

(sez. 12 x 86,03/2) = (23842 x 86,03/2) = (23842 x 43,015) = 1025563
(sez. 13 x 86,03/2) = (22737 x 86,03/2) = (22737 x 43,015) = 978032

(sez. 13 x 86,02/2) = (22737 x 86,02/2) = (22737 x 43,01) = 977018
(sez. 14 x 86,02/2) = (20170 x 86,02/2) = (20170 x 43,01) = 867512

(sez. 14 x 84,19/2) = (20170 x 84,19/2) =(20170 x 42,095) = 849056
(sez. 15 x 84,19/2) = (16051 x 84,19/2) = (16051 x 42,095) = 675667

(sez. 15 x 82,32/2) = (16051 x 82,32/2) = (16051 x 41,16) = 660659
(sez. 16 x 82,32/2) = (10818 x 82,32/2) = (10818 x 41,16) = 445269

(sez. 16 x 41,16/2) = (10818 x 41,16/2) = (10818 x 20,58) = 222634
(sez. 17 x 41,16/2) = (7903 x 41,16/2) = (7903 x 20,58) = 162643

(sez. 17 x 45,23/2) = (7903 x 45,23/2) = (7903 x 22,615) = 178726
(sez. 18 x 45,23/2) = (4910 x 45,23/2) = (4910 x 22,615) = 111040

(sez. 18 x 40,66/2) = (4910 x 40,66/2) = (4910 x 20,33) = 99820
(sez. 19 x 40,66/2) = (1905 x 40,66/2) = (1905 x 20,33) = 38729

(sez. 19 x 40,67/2) = (1905 x 40,67/2) = (1905 x 20,335) = 38738
(sez. 20 x 40,67/2) = (772 x 40,67/2) = (772 x 20,335) = 15699

(sez. 20 x 40,67/2) = (772 x 40,67/2) = (772 x 20,335) = 15699
(sez. 21 x 40,67/2) = (65 x 40,67/2) = (65 x 20,335) = 1322



totale 32.200.810 mm3

32,2 dm3


You will notice that the value is very close to that detected with Rhinoceros, i.e. 32.16 dm3

Hi JockScott.
Good morning everyone.
I'll update you from the last stages of work to the results obtained.

After this explanation you will understand why I asked you to provide me directly with the distances between the ordinates.

After drawing all the immersed sections and calculating the areas, I aligned them along a line.
I positioned them at various distances with respect to a zero point following the table you provided me (first image attached).

As you can see, in the second attached image, the distances from the zero point (extrapolated from the table) are black.
The distances between the individual sections are instead colored green.
These distances are used to calculate the immersed volume even without the aid of any software.
To obtain them, simply carry out the appropriate subtractions from the dimensions in the table, or directly measure the distances between the sections from the model under construction.
The sections in the table are indicated by numbers that I have shown in red in the Rhinoceros drawing.

There is therefore a correspondence between the numbers in the table and the number of each section that I assigned starting from the bow and ending at the stern.
In this, you helped me a lot with the third image I attach, because I couldn't read the numbers.
The section numbers can be seen in the fourth and fifth attached images.

Since my intent was twofold, both to calculate the immersed volume without using Rhinoceros, and to calculate the immersed volume using Rhinoceros, I started to build the surface of the hull.

I open a parenthesis:
Rhinoceros software is not a real 3D modeling software like, for example, Fusion, Creo or Inventor. In fact, to create solids with Rhinoceros you have to start from the surfaces which are then joined, extruded, etc. etc. Exstruct is a very easy and intuitive command to execute. The union of surfaces, however, is very difficult because open edges are always created which prevent the formation and finalization of the solid.

To build the hull surfaces you need to build the curves first.
I therefore started drawing the curve that joins the edges of the sections and I realized that something was wrong.
If you look at the sixth image you can notice that the curve (in the part indicated by the red arrow) is not coherent.
Furthermore, the comparison between the odds never added up, there was always an error.
I spent a lot of time understanding where the problem was and in the end I found that section no. 83 (section no. 10 according to my numbering) was not shown in the table (see the last two attached images).
I had to change all the positions (ignoring section 10 which will no longer appear in subsequent layers of the drawing).


... goes on ...

It depends really how much accuracy someone wants in determining the displacement of the hull. I for one would be happy with 5% accuracy.
I am also quite intrigued to see the drawings by Rino of the hull in 3D.

Hi JockScott.
Good evening to all modelers.

I have achieved the desired results. After various obstacles and mistakes, we have what you wanted.

Just give me some time to rearrange the images and explanations to translate. I'll probably have to make more posts.

Now I can tell you the three results, compare them with each other and compare them with the test you will do in the water (if you want to do it):

- prismatic coefficient method (the result of which I already communicated to you)
- mathematical and geometric method that anyone can do (even without software)
-method with Rhinoceros.

For the latter I have to thank AndyN who some time ago gave me some very useful suggestions on the "Edge Tools" commands.

As for the second method, I can say that it is much more precise than the prismatic coefficient method (as I imagined) and, what is more important, is that everyone can learn and use it.
In fact I could open a summary and less dispersive topic to summarize it briefly.
Could it be useful in your opinion?

Hi JockScott.

Just to reassure you, I've started working on the case again.

Hi Alessandro looking forward to the result.

Hi JockScott, and cheers to all modelers.

I started working again, corrected some mistakes I was making and in a few days I will give you the results.

Hi JockScott, there are few that have big bathtubs for your ship or private pools, hahahahaha.

You can buy a small inflatable paddling pool, but if it's just for this reason it's a waste of money.

Interesting method for the bow. I've never used it.
I do everything with strips, never used the bread and butter method, but I'm self-dictated.

I greatly admire those who, like you, master more than one construction method.

No worries about if you can't do it right away. There is no rush.
Construction was quite simple. Straight Bottom plate, frames throughout and stern and bow bread and butter.
It won't see water till next year as the model is 1.74mtrs long and my bathtub is not big enough.

Hi JockScott.

I'm completing the table with the information you gave me. The numbers didn't add up, now I've deciphered the numbers I wasn't reading with the new photo.

However, I will send you all the tables and drawings of Rhinoceros with the measurements so you too can check if I have made mistakes.
We are almost at the end now.
To be clear, here are three images of what I'm doing.

I don't know if I'll be able to use Rhinoceros in these five days because I have to go away for work, it's one thing to write messages with my cell phone, I can do that anywhere, it's another thing to draw on the PC. But I don't think you're in a hurry.

I wanted the thicknesses of the frames and the spaces between the frames because I always prefer to take measurements directly on the model itself. Even for electrical matters I don't just rely on the data provided but I do direct tests where I can.
But in this regard now a doubt arises in my mind, perhaps I have taken a construction method as obvious.
A question out of pure curiosity because it has nothing to do with the calculations we are doing: How did you make the hull?
Could you send me a photo showing the inside of the hull?
I was probably off track.

Conclusions.
1. Prism method: done.
2. Multiplication method: we are almost completing it, it is almost finished.
3. Method with Rhinoceros: If you want me to try to draw the surface of the hull entirely on the PC, I need at least the bow and the measurements on it.

Then it will be fun and interesting to compare the results of the three methods with the result of the water test. The only one to tell us the absolute truth.

In theory, method two should be more precise than number one and method three more precise than number two.

I am not sure what it is you still need as I have posted everything you need to have.
1. frame drawings. You may have trouble reading frame numbers on the drawing. I have hand written the number hopefully now easier to identify on another photo
2. the frame distance diagram. They look very clear to me and are the original measurements from the plan converted to 1:150 (2nd column)
3. The measurements between frames are always centre on centre and therefore there is no thickness to consider.
Hope this helps

Hi JockScott.

These measurements are not useful to me because I have no references, furthermore I cannot read many numbers on the photo of the sections (even by enlarging the image).

Please take measurements from section to section with a ruler or caliper (whichever you prefer) directly on your model if you cannot do so on your project.

Please fill in this table. It's very easy. Do it without any rush when you have time.

Distance between section 1 and 2 = mm _______
Distance between section 2 and 3 = mm _______
Distance between section 3 and 4 = mm _______
Distance between section 4 and 5 = mm _______
Distance between section 5 and 6 = mm _______
...
Distance between section 20 and 21 = mm _______

single frame thickness = _________

I'm attaching an image to help you understand what I mean and what I need.

I ask you for this small effort because I could take all the measurements in the table and, only after a long work, realize an error. Instead, with the measures taken directly by you, we won't be able to make mistakes and we will still have further feedback.

If it helps you, I post another picture of the schedule for the frame distances. "0" is the rudder shaft. Distances are back (-) to stern and forward to bow. Hope this helps.

Hi JockScott.

I don't understood the whole post well.

The photo of the stern alone, without the measurements printed on it, is not useful to me.

In reference to the distances between the sections, could you explain them, please?

I mean, for example:

Distance between sections 1 and 2 = ? mm

Distance between sections 2 and 3 = ? mm

Distance between sections 3 and 4 = ? mm

Etc. etc.

Please write them all down, there are only 20 anyway.

Hi Alessandro
That looks pretty impressive. The stern profile is shown in the photograph. As before measurements to waterline. The lines from keel to waterline incl rudder needs to be copied as you did for the frames. For the bow there is little recess from the waterline down, so I won't bother with a copy. The rest of the hull is flat.
I have posted the frames distances in my first post together with the frame drawing. If you need more info please let me know.

Hi JockScott and hello to all the modelers on the forum.

I found all the dipped section areas for your 1:150 scale model of the 1963 Deutschland ESSO.

The numbers are printed on the sections themselves in the photos I attach.

The same results could have been achieved even without Rhinoceros with the method I explained to you a few posts ago.
If you use graph paper it is even easier and more precise. However, I have now used Rhinoceros.

The next step is to calculate the immersed volume.
To do this I need precise measurements of the distances between one frame and another.

To avoid errors of interpretation, send me photos of the entire keel.
I know you may not be able to do a single scan.
It doesn't matter, you can send me more images, as long as they have measurements on them.

With the keel and the information I asked you for, I can also try to draw the immersed surface and volume of the hull.
In this case I could provide you with an even more precise value.

Hi Alessandro,
thank you for your kind words. I did start a topic under the title "my dream project" from the time (2years!!) I started on it and continue as a building blog. The progress is slow due to other activities and I have given myself 10 yrs to final completion. I know with my little practical experience it is a daunting undertaking but I am striving to achieve as close to "museum quality" as possible and hoping to draw on this site's vast knowledge. I will rename the title with the next post (relevant progress).

Fo'c's'le - the English word for what in German is called the "Back", the raised forward or bow section.

Hi JockScott.

Thank you very much for the compliment.
Addressing these topics is always stimulating and fun. For me it is a pleasure.

My hope is that someone else (perhaps someone who has worked in this field) will join the discussion by adding information and/or corrections.

Allow me to give you some advice:
You are building a very large and demanding model (I admire your work) so it's fine to insert photos here and there but why don't you open a topic from scratch to describe the 1963 Esso Deutschland in 1:150 scale?
This model deserves its own topic, in my opinion.

Consider this message a brief aside; in the next message I hope to send you all the areas of the sections.


P.S.
fo'c's'el. ?????

Hi Alessandro
You did some fantastic work on the calculation and I thank you for your efforts. I agree with your determination of the values leading to the final result and I can confirm I had come to 0.030cbm 30kgs when I did my rough calculation. I basically just calculated the cube of LxWxDraft and deducted 4 triangles to allow for bow and stern. Ofcourse I couldn't make allowance for the hull curvatures where seemingly the 10% difference comes from.
Another interesting point: your 2. diagram does not include the bow bulwark in the LOA which accounts for the difference between my calculation of the original and what it is described.
Nonetheless a very interesting experience for me what the rhino program can do and see the schematic drawings of my model which I will download and include in my collection for this project.
Meanwhile there is some progress on my model with the final bottom paint applied. Next stage are the 2 waterlines and corresponding color scheme and main decks with decks for poop and fo'c's'el.

Hi JockScott.

To understand better, I divide the topic into separate sections again.

PREMISE
1. MANAGEMENT OF THE PHOTO WITH THE SECTIONS TO BE CALCULATED.
2. CALCULATIONS OF IMMERSED SECTIONS.
3. APPROPRIATE CLARIFICATIONS ON THE LENGTHS OF THE SHIP
(IT'S NOT A LESSON, IT'S ONLY USED TO UNDERSTAND BETTER).
4. OTHER IMMERSED VOLUME CALCULATION SYSTEMS.
6. CONCLUSIONS


PREMISE
I'm not an expert in the nautical sector, I'm just an enthusiast who likes to read about these topics.


1. MANAGEMENT OF THE PHOTO WITH THE SECTIONS TO BE CALCULATED.

The new image is slightly better but still has many alignment errors.
It does not matter. If you have scanned with a scanner (and not a photo with a camera or mobile phone) it is not up to you, so you can't do anything about it.
We'll carry on anyway.


2. CALCULATIONS OF IMMERSED SECTIONS.

First I will measure all the immersed sections and I will write them in the next post.
Check, please, if I have numbered the frames correctly. (See first image attached).
I'm 21.
Logically I will not consider the first frame because it is above the waterline and does not have an immersed part.


3. APPROPRIATE CLARIFICATIONS ON THE LENGTHS OF THE SHIP
(IT'S NOT A LESSON, IT'S ONLY USED TO UNDERSTAND BETTER).

Length between perpendiculars LPP: is the distance between forward and perpendicular back. It is a conventional measurement that characterizes a ship very well: in fact it does not take into account the thrust of the bow and stern and is therefore used for this purpose resistance to motion and structural strength.
Waterline Length LWL: This is the length of the waterline figure.
Overall length LOA: it is the maximum longitudinal dimension of the vessel comprising each appendix.
(see the second attached image)



4. OTHER IMMERSED VOLUME CALCULATION SYSTEMS.

For further feedback, I will inform you of how many kg your immersed volume is, following the prismatic coefficient method (except for errors on my part, logically).

According to my calculations, the immersed volume with a waterline of 97 mm from the keel and with a waterline length, LWL of 1715 mm is 33.8 dm3.
We approximate 1 dm3 of water = 1 kg (even if this is not the case)
therefore approximately 33.8 kg.


That's how:

The immersed prism has a height of 97 mm, a width of 254 mm and a depth of 1715 mm, therefore its volume is 42,254,170 mm3
42,254 cm3
42.254 dm3
Approximately 42.254 kg (remember that one liter-dm3 of water does not weigh exactly 1 kg)
Rhinoceros confirms this simple multiplication (see the third attached image).

If you remember, in previous posts, thanks to the ratio between the main immersed section and the rectangle circumscribed to it, we had found a ratio of 0.9899.
The ratio turns out to be 12195/12319 = 0.9899.
This value was very close to the value of 0.997.

In the table on the row corresponding to this type of ship (large tanker) the prismatic coefficient (C B) is 0.802.

Applying the inverse formula of the prismatic coefficient:
C B = ∇/BTL
∇=C B x BTL

where BTL is the volume of the submerged parallelepiped.

we have ∇= 0.802 x 42.254 = 33.8877 dm3


5. DEUTCHLAND ESSO DATA 1963

I did an internet search to get the data on this tanker.
I found some photos. I attach some of them.

In reality, what I would have liked to have is the displacement (D) at full load, in order to apply the correct scaling factor and obtain further data on the immersed volume to compare with the others.
Unfortunately, as you can see, the full load displacement data is missing from the image relating to the ship's data.

We have the DWT of 94556 tonnes.
But DWT does not correspond to displacement (D)
Deadweight tonnage (also known as deadweight; abbreviated to DWT, D.W.T., d.w.t., or dwt) or tons deadweight (DWT) is a measure of how much weight a ship can carry. It is the sum of the weights of cargo, fuel, fresh water, ballast water, provisions, passengers, and crew. (from Wikipedia)

Not even the ton = 54,440 tons is very useful to us.

However, a model oil tanker with a DWT of 94556 tonnes, in 1:150 scale, gives me a DWT of around 28 kg.

We don't need the DWT but we can see that 28 kg is consistent with the displacement (D) of approximately 33 kg obtained with the prism rule.



6. CONCLUSIONS

According to the prism method, the immersed volume with a waterline of 97 mm from the keel and with a waterline length, LWL of 1715 mm is 33.8 dm3.

In the next post I will send the surfaces of all the immersed sections.

No requests for further information at the moment.

Hi JockScott, you're welcome.
The day after tomorrow I can already tell you something.

Yes Alessandro it is 171.5cm. Sorry for the error.

171.5 cm or 1715 mm. Right?
Was it a 171.5 mm error?

Hi Alessandro
I am quite impressed. You managed to adjust the diagram to 1:150 scale as the measurements you quoted are correct. I have also now attached a scanned copy of the diagram. You also managed to detect a flaw in my copy of the frame diagram. When copying for the lines of frames I simply cut out the respective frame and folded the paper down the centre. Later I realized it was off by 1 or 2 mm. But I reasoned the difference would be too small and would be negated after the hull was planked and sanded.
Re. Immersed volume calculation. I am not sure if I understand fully CM = A M/BT and to determine co-efficient 8.02 but this gets too technical and not relevant to understand the principal of the volume calculation.
Name is Esso Deutschland blt 1963. I don't know actual displacement as I don't know light displacement.
Conclusion. Some margin of error is not important as I want to know what your rhino can do to determine the displacement. For length of Waterline take the frame dims as per my frame distance table less Back extension (from LOA at bow to frame 169) and ~ 6mm of the poop ext where the stern recesses above the waterline =171.5mm.
You will notice while original LOA was listed as 260.9meters, my table shows for 1:150 1753mm, off by 1.4mm or 2.0 meters from the original.
This may be due to my estimated distance from the 1:200 scale and/or if the bow bulwark is included on the original or not.
As one last comment: I have made a very rough calculation at the early stages of my built of what the full displacement of my model would need to be. Curious how much I was off.

Hi JockScott.

Last night I managed to spend a few minutes on Rhinoceros. Tonight I can't.

To try not to cause confusion, I will divide the discussion into sections.

1. PREVIOUS QUESTIONS.
2. MANAGEMENT OF THE PHOTO WITH THE SECTIONS TO BE CALCULATED.
3. CALCULATIONS OF IMMERSED SECTIONS.
4. OTHER IMMERSED VOLUME CALCULATION SYSTEMS.
5. DIFFERENT WATERLINES ON OIL TANKERS.
6. CONCLUSIONS


1. PREVIOUS QUESTIONS.

In my last post I asked you: "Send me these measurements please: From the keel to line number 4 (see blue line in the attached photo). From the keel to the number 2 line."

Maybe I didn't ask the question well, so I ask you to look at the first attached image and tell me if the measurements are exact.

From the keel up to number 2 you measure approximately 105 millimetres?
From the keel up to number 4 you measure approximately 66 millimetres?



2. MANAGEMENT OF THE PHOTO WITH THE SECTIONS TO BE CALCULATED.

I could have done the section calculations with any image and then redo all the proportion calculations.

Instead, I preferred to work on a drawing that already has the same dimensions as yours.

Last night I managed to scale the photo using only the width data (i.e. 254 mm).

Look at the second photo.

As you can see, there are some small errors in the image. It is probably a photograph and not a scanner.
They are small errors but the error multiplies as you do calculations.
As you can see, the width of the stern is slightly different from that of the bow. Scaling the image according to the width of the stern (left side 127 mm), the stern (on the right side) is approximately 128 mm.
This is because the image is slightly rotated. The photo frame axis and the drawing axis are offset by 0.7 degrees. (see second and third attached images)
This phase shift also has repercussions on the waterline.
I plotted the waterline at 97mm. As you can see, it doesn't coincide perfectly with the line you reported. There is a small rib of almost 3 mm (see the fourth attached photo).



3. CALCULATIONS OF IMMERSED SECTIONS.

There is no difficulty in calculating the area of the immersed sections.

If you want, I can continue with your image but subsequent calculations could be affected by these errors, or I wait for you to send me an image taken with a scanner at maximum resolution (via email).


4. OTHER IMMERSED VOLUME CALCULATION SYSTEMS.

Thanks to the results we have obtained so far, if you tell me what the waterline length (LWL) of your model is, I can find a value for the immersed volume.

In this way, without giving up the method we are following, we will be able to have further feedback.

If you look at photo no. 5 attached, you will see that I traced the profile of the main half section and calculated the area.

The area of the master half section is 12195 mm2.
The circumscribed rectangle is 127 x 97 mm = 12319 mm2

The relationship between these two areas is defined as follows:

Midship Coefficient - CM
The fineness coefficient of the main section is, similarly, obtained as the ratio between the area of the main section,
referring to a particular dive (AM) and the area of the circumscribed rectangle having as sides the width of the ship (B) and the
draft (T), according to the relationship:
CM = A M /BT
see photo no. 6 attached.

The ratio turns out to be 12195/12319 = 0.9899

The closest data is 0.997 and refers to a large tanker (large tanker 76000 tons. DWT)
See the seventh photo attached.

Consequently the prismatic coefficient of this vessel could be (taking the data from this table) 0.802.

If you tell me how much the waterline length is I can calculate the volume of the prism and with the coefficient of 8.02 I can estimate the immersed volume.
C B = ∇/BTL

See the eighth photo attached.

What is the name of your tanker?
How much was the actual displacement?



5. DIFFERENT WATERLINES ON OIL TANKERS.

You asked me:
"You mentioned the big difference of loaded to unloaded waterline typical for tankers. Where did you see that?"

I'll answer you with the last two photos. Perhaps they are clearer than a text.
Otherwise we'll talk about it again.
Do you understand what I mean?



6. CONCLUSIONS

Jock tell me if you can send me an image via email, taken with a scanner at maximum resolution or I will continue the calculations with the photo I already have.

Tell me what the lenght waterline, LWL is (not the overall length, LOA).

Hi JockScott.

Yes. Something gets lost in the translations but it's a problem that can be overcome.

Tonight, if I can, I'll start working with Rhinoceros.

Send me these measurements please: From the keel to line number 4 (see blue line in the attached photo).
From the keel to the number 2 line.

Then I'll tell you why.

P.S. Then I'll send you some photos for the discussion of the water lines at full load and not.

Alessandro here is the water line marked in red on the frame diagram.
I think some thoughts and comments are getting lost in the translation. The green line measurements you wanted me to make seem to refer to the beam which is as I mentioned 254mm. each side on the diagram would be as you mentioned correctly 127mm. Was there anything else you would have wanted me relay to you? For volume calculation purpose of course they will have to be doubled. I hope this will give you all data required for the Rhino to do his job.
You mentioned the big difference of loaded to unloaded waterline typical for tankers. Where did you see that?

Hi JockScott, I'm waiting for Monday.

"We are getting somewhere". She takes it one step at a time.
It is useful that everyone understands well what we are doing, so anyone can express their opinion, correct us if we are wrong, give us information we don't know.

"Also you asked for the green lines for the Hinterschiff but I will include the lines also for the Vorschiff. Without that it would only be half what you need." Okay Jock but I believe that the line of the Hinterschiff will be the same as that of the Vorschiff, otherwise the ship would be asymmetrical.
I actually need the total for the green line. I expect the green line to be 127mm (254/2).
I don't need the internal segments to create the sections (I'll trace those) but to get further feedback. I need to understand if the photo has undergone deformations.
That's fine though, the more information you give me the better.

"You see the waterline on the left (Hinterschiff) as multiple lines which is 97mm from keel." No, I don't know what the water line is; for this reason I asked you to point it out to me on the drawing.
On my photo I can't detect 97mm from the keel like you could on your drawing.
This is precisely the first problem we have to face.
I need to resize the photo drawing to your original drawing.
I hypothesized line 4 but only a hypothesis to be able to start drawing something.
Put a red arrow above the photo (you can use the free Paint program to do this) indicating the waterline you want to use as a reference for the calculations we will make.
Or, if you prefer, place a red line (e.g. with Paint) superimposed exactly on the waterline of your drawing.

Now, the next step will be to bring the image I have back to the size of your project, so I'll wait for Monday.

One important thing I forgot:
The type of ship you are building has a very big difference between the fully loaded waterline and the unloaded waterline.
The 97 mm refers to full load, do you know?

We are getting somewhere. I can give you the measurements as you asked for and I will have for you not before Monday but I thought the rhino will read the frame lines and calculate the area. Also you asked for the green lines for the Hinterschiff but I will include the lines also for the Vorschiff. Without that would only be half what you need.
The lines you see on the drawing was for the wood boards when I did the bread-and-butter method. You see the waterline on the left (Hinterschiff) as multiple lines which is 97mm from keel. The beam of 254mm I thought I should give you as a reference so you can enlarge the drawing to fit the 1:150 scale. Hope this answers part of your questions.

Hi JockScott.

Good news.
I was able to import the image you gave me into Rhinoceros and can work with it.

You no longer need to use a square and pencil.
I think I understood that you didn't really want it, ahahahahahah.


So, look at the first two images of the first test:
1. I imported the drawing (I haven't scaled it yet, I can't do that yet without more information).
2. I drew the outline of the submerged section on the second bow frame.
3. I created the surface.
4. I asked Rhinoceros to calculate the surface area. Everything works ok.

Logically the data is not reliable because I have to scale it.
I also chose a float line at random.
Instead we should establish it with certainty and precision.

For this reason I ask you to do some simple things.
1. Take your original 1:150 scale project (not photo) and measure the segments (green lines) you see in the third photo. Try to be as precise as possible and give me the results in millimeters. It would be better, if you can, for me to put the numbers directly on the image.
2. Mark the position of the water line as in the fourth image I attach. It could be higher or lower than the blu line I hypothesized.
I want to be sure and understand where the 97 mm of the keel and the 254 mm of width that you told me are marked.

If you don't want to ruin the project, use a photocopy.

If I wasn't clear or I got something wrong, tell me.

I'll open a parenthesis: Now I'm working with the image I downloaded from the forum but it's really bad.
It's certainly not your fault, but the images are reduced to be managed by the forum; we see them anyway but they lose quality.
I'm not a computer expert (in fact if I compared myself to someone who writes a letter I would be writing: "dearest friend") but I think it's like this.
So as soon as you can send me the original scan file (at maximum resolution) of the project via email, so the file remains of good quality.
Pdf, jpeg, png, tiff whatever you want.


I think we could do it.

Hi JockScott.

Here is the list of file types that Rhinoceros can export in the attached images.

I recently picked up Rhinoceros and in my free time I was designing the lifeboats I need.
I'm stopping to see if I can get your sections back to Rhinoceros.
I'm trying but a file (at least pdf would be better).