Structural configurations?

[ringoo83]

Forgive me my bad English

I want to know from engineering point view, why were longitudinals attached to the stiffeners of this bulkhead, they are not attached in other BHDs….what would happen if they were not attached?

How longitudinals should be attached to collision BHD in small high speed craft…a lot of welding will be done and more stress will be resulted…?

[Ad Hoc]

2 reasons.

1) TO stiffen the WTB. Without stiffening any head of water would deform/buckle/ the plate and lead to immediate failure.

2) Whether the long.t stiffeners on hull are continuous or intercostal (between WTBs), the stiffening on the WTB is best to 'connect' to other structure for providing a load path and to reduce stress concentrations.

[ringoo83]

Thank you Ad Hoc,

Could you please explain that in formulas or graphics, I mean the load path & stress concentration.

As you see in the middle of the first pic, the stiffeners on the center are bended, why are not kept straight?

Any answer regarding my second question how to end the long.t on small Collision BHD (2nd pic)?

Thanks

[Ad Hoc]

Originally Posted by ringoo83

Could you please explain that in formulas or graphics, I mean the load path & stress concentration.

This looks like an actual current build/project??..if so:-

You should consult the designer, as that is their job.

There are plenty of ways to finish the stiffeners, again, you should consult with the designer.

[Willallison]

Ringoo.... As AH has noted, it's always poor practice to terminate a stiffener by simply butting it up against an otherwise unsupported panel. There should always be a path to transfer the load to another member, regardless of the siz e of vessel.
In many instances this isn't done. That doesn't make it good practice, of course, but so often the smaller boats are so overbuilt that the builders get away with it. But then one also regularly sees stress cracks in them too...
Am I correct in assuming that one of these is your own boat, or that you have designed one of them?

[ringoo83]

Ad Hoc, Willallison

I'm not designing .... I'm very interested in HSC, unfortunately I collected alot of structural pics for aluminum HSC, and I'm confused because of the variety of the structures and construction methods. what I'm trying to do is to understand the 1st principles of HSC structural design. you would say that I have to study naval architecture or whatever... since I don't have time to do that, I have nothing to do but asking the professional people like you.

Hope you can share me some of your experience...if you can advise me to websites or books where I can find information about HSC structures..I'll highly appreciate that..

[Ad Hoc]

Originally Posted by ringoo83

I'm not designing .... I'm very interested in HSC, unfortunately I collected alot of structural pics for aluminum HSC, and I'm confused because of the variety of the structures and construction methods. what I'm trying to do is to understand the 1st principles of HSC structural design.

The more boats you look at the more questions you shall have....each boat with each designer, depending upon their training and experience, and of course the capability of the yard and the budget for the build, will yield different structural arrangements.

Notwithstanding that, the basics are not that difficult. BUT, you do need a back ground in either naval architecture and/or structural design. 1st principals etc requires understanding things like: stress concentrations, load paths, fatigue, fabrication etc all these aspects and many more which are all taken into consideration when performing structural analysis and then design. It is not possible to give "one liners" as a reply when so many factors are involved. The required depth of understanding is significant once you go deeper than scratching the surface.

To continue in your interest, just read up on any RINA, FAST, SNAME or similar publications of their conference proceedings on all things HSC related. There are many out there.