How to Layout Ship Structure

[@anuardelcastillo2627]

Thanks for the webinar! I learned a lot from it!!

[@nterry894100]

Well done.

[@cokeologist_artist3795]

I came here to learn about the design about designing a ship interior for my 3d modeling and I stayed for the utter previously unknown knowledge in this lecture. Well done

[@nterry894100]

I found this interesting Nick. I was particularly interested when the discussion turned to wood. These days MTC (Mass Timber Construction) is all the rage. The thing about engineered wood, using modern adhesives, is that you get much more consistent mechanical properties than you get with solid wood. It can also be laminated according to the intended direction of load, so parallel lamellae for vertical loads on a beam and cross laminated for sheets where strength in two directions is required. For boats I think that cold moulding with thin layers of wood, enhanced by the use of aramid fibre fabrics and epoxy is the bees knees. Once bulkheads and stringers are added, and these can be hollow plywood sections, then you get an extremely strong, light monocoque structure that is hard to beat. When all sealed in an epoxy envelope, the life of this vessel should be almost unlimited.

[@JennySusanti-u1q]

Hi Nick. Your videos are very good and informative. Will you do a video about materials? Which is best for 140ft trimerans aluminium or stainless steel?

[@DatawaveMarineSolutions]

This is on my list to a video like that. (But fair warning, I have a lot of videos on my list.)

[@jakhanis78]

When doing a side plan, front plan, and back plan of a ship. I noticed the vertical going from the bottom of the ship to the top of the ship. What is the measurement between line and how is that determined to help make the 3d model

[@FighterAceee94]

I'm curious what theory did you use to arrive at 0mm stiffener spacing. This is a problem I've tackled in my undergraduate thesis, optimizing the number of primary supporting members and stiffeners of a grillage structure. My solver algorithm bounds were set such that physically impossible solutions like that were ignored. Now as a classification society inspector, I'm aware there are several safeguards against such designs (attempting to use paper thin plates), besides the usual global and local strength criteria.

[@miguelcalvache706]

Same here, I'm really curious about your approach to came up with the 0 spacing result. Does that mean to have a thicker plate with no stiffeners? If that is the case, you would require a massive thick plate that weights way more than any panel. Or if is about optimizing the global cost, I think that when spacing is decreasing and getting close to 0, the amount of stiffeners will increase (even if they are smaller and "cheaper") and so the welding length to join them to the plate, which is very costly (man hours + filling wire + gases + equipment usage etc). Just to consider, but for all the rest thanks a lot, your videos are always very enriching for me. 👍👍👍

[@DatawaveMarineSolutions]

The 0 mm spacing was based on class society scantling calculations, optimizing for reduced weight only. I assumed flat bar stiffeners and maintained the required thickness / depth ratio. And then I ignored all the safeguards you mentioned. The final solution had plate that was wafer thin and flat bar stiffeners only a few mm apart, also wafer thin and only a few mm tall. Of course, this solution would never work in reality. And that was the point in the presentation. The theoretical equations allow this solution, but practical design recognizes that we get too small. The assumptions behind those theoretical equations no longer apply. Which is why the class societies have those practical safeguards.

[@DatawaveMarineSolutions]

@@miguelcalvache706 All correct. I optimized for weight, not cost. And I ignored weight of weld filler. So it's not a practical solution. But that was the point. I sometimes find that there are useful lessons to learn in the mental exercise of taking theoretical methods to their extreme. It's not about finding a useful solution. The more important point is to compare extreme theory against practical solution and learn from the comparison. In this case, it revealed that sandwich panels are a great solution . . . if we can only find a way to make them practical.

[@quartertwenty484]

@@DatawaveMarineSolutions I think the assumptions behind the scantling calculations fall apart somewhere well above 0 spacing but if the Class didn't specify a minimum it was because nobody would actually try it anyway. I'm guessing most people come at it like, given a particular plate thickness what does the spacing have to be?

[@saeedh2742]

Hello. I hope you are fine. The topic of your thesis is very interesting for me. I have many questions about grillage and I don't really know its calculations. For example, how can I determine which support is appropriate when two longitudinal and transverse girders cross each other? fixed or simply supported . I would be grateful if you could either give me your thesis to read or give me an article or suggestion if you have any...thanks a lot.

[@saeedh2742]

Hello, dear Nick. Thank you very much for this webinar. You did a great job. This webinar was very useful and interesting for me. but I have many questions about grillage and I don't really know its calculations. For example, how can I determine which support is appropriate when two longitudinal and transverse beams cross each other? Bold or simple. Thank you for explaining or making a video about this. If you have an article or suggestion, please give me... Thank you very much

[@DatawaveMarineSolutions]

That is a common problem. As we get to larger structure, there is no clear "supporting" body. As you said, this leads to a grillage analysis where all beams combine for total strength. Funny part, I have never done a grillage analysis. I believe that with the abundance of FEA software these days, it's more common to just go to a full FEA anytime you need a grillage analysis. For example, it is very common that major ship designs will include a Global FEA model. This is where we model all the major beams and bulkheads in the ship (ignoring the small stiffeners) and check the structure. The main goal is to ensure the stresses all distribute well, avoiding any large concentrations.

[@saeedh2742]

@@DatawaveMarineSolutions You are completely right. But I came across this point in the scantling that when the floors meet the side girders of the same size in a ship with a single bottom, can a side girder be a support for floor? Or should I say better, can the floor span be the distance between two side girder?

[@Sbiper]

The cutaway section looks to me like its from a modernized WW1 battleship, the bulging and several vertical bulkheads behind the bulging all look like early (1920's) torpedo defense's to me. The sloped structure called 'R' is probably the main belt armor, sloping it was popular in the early 1900's to increase its effectiveness against (non plunging) hits, like the way WW2 tanks started to have sloped armor.

[@DatawaveMarineSolutions]

Good deduction. The original photo was from the midship section of the HMS Royal Sovereign, circa 1936. Here was the original photo source: W. Authors, "HMS Royal Sovereign, midship section," Wikimedia Commons, 1936. [Online]. Available: commons.wikimedia.org/wiki/File:HMS_Royal_Sovereign,_midship_section_(Warships_To-day,_1936).jpg. [Accessed 9 Feb 2023].

[@sailorguy9288]

Wonderul video

[@michaelsalting1987]

1. the aeroplane Lancaster have skot and stringlers aligned 45 degree, the roder and highroder screv the rear end of the plane. You have propellerblade and roder also. 2. You use I or H steel, what about J steel, lower weight is the result. 3. Thank you.😊

[@matthewmillar3804]

How do you balance strength and flexibility? A ship needs to flex over waves, but how do you figure the correct flexibility and proper ship strength? Is too much flexibility a bad thing?

[@DatawaveMarineSolutions]

Yes, too much flexibility can be a bad thing. Too much flexibility means the plates bend more, leading to early fatigue failure. On the global ship scale, too much flexibility means the ship constantly bends and twists. Now we aren't driving a straight hull through the water, but some bendy, curving mess. To balance this, the key is adding more strength. But critically, we have to add strength in a balanced manner. Make the entire structure stronger, not just one or two critical joints. Modern FEA tools help with this a lot.

[@GlenCychosz]

The laminate panels seem like they would be susceptible to undetected internal corrosion.

[@DatawaveMarineSolutions]

You are correct. Although the panels are theoretically sealed, inspection is an ongoing concern. Many of them use a polymer foam for the core, which eliminates corrosion from the interior.

[@quartertwenty484]

Ultrasound should still work.

[@weatheranddarkness]

@@quartertwenty484 how good/portable is the kind of ultrasound kit available for such mobile inspections at such depths?

[@sigungajoshua6149]

@@DatawaveMarineSolutionsAnodized ?

[@AnthonAlifonce]

Well.