Angle iron

[Mr Efficiency]

What on earth does that mean..?

It means a little angle section is going to flex a lot under load, and I don't see much structural SS work that allows for lots of flex.

 

[Ad Hoc]

It means a little angle section is going to flex a lot under load, ....

Define a lot, compared to what?

And now, you've gone from:

...I don't much like SS for any load bearing structure....

To:

.... I don't see much structural SS work that allows for lots of flex.

So which is it....you personally don't like it.... or....you personally don't see much of it being used?

And how is that a technical fact or what can or cannot be done with a material?

 

[Mr Efficiency]

Suffice to say, I would be looking for other remedies. SS makes great milk tankers, and many other things, but it is horses for courses, and if SS was a prime structural material for boats, there would be a few around, regardless of the cost, but they are as scarce as hen's teeth.

 

[Ad Hoc]

Suffice to say, I ...

Suffice to say then, that you're only offering your personal opine and no technical, or relevant facts, as the OP is asking for, in order to estimate the amount of deflection per load.
And that helps the OP .... how?

 

[fallguy]

This is a framework for a catamaran cockpit with floating panels that are removable. The floating panels will provide a resistance force that will help the iron. But I wanted to see if I could design the irons to be strong enough alone.

We built a modified crossmember with 2" leg 316 stainless irons that make a T as pictured. I used 304 in other places where it can be painted. The issue here is the 2" Tee is a little beefy for its connections. I can change the front angle easily to 2" irons with a weight penalty. The back angle is all custom fabbed with strapping.

I could also weld wings on the crossmember angles and extend the area of the loading. The strapping connections are already sized.

I can explain the drawing better. My son is going to try and model it to failure with a modeling program. But I am pretty sure my connecting points will bend as currently configured. So I will probably buy the 2" angle for the strap on the top of drawing. I apologize, in some haste, back pain..

 

[Mr Efficiency]

The fact that people stay away from making boats out of SS, in droves, isn't an opinion, it is a fact. He'd be better advised to seek other solutions, as a DIY man.

 

[fallguy]

The fact that people stay away from making boats out of SS, in droves, isn't an opinion, it is a fact. He'd be better advised to seek other solutions, as a DIY man.

It is just a cockpit support. I could have gone aluminum, but too thick to be equal strength.

This is a Wood's boat, but I am trying to make it a little more ready for fast 3 meter seas; just in case. The build is very solid and after making love to her building her for 3 years; I know her weaknesses eh?

 

[Mr Efficiency]

What does Richard say about the idea ? Or is the phone ringing out ?

 

[Ad Hoc]

The fact that people stay away from making boats out of SS, in droves, isn't an opinion, it is a fact....

That is a sociological fact not an engineering fact - which the OP is seeking!
Seems you are conflating the two very separate issues and do not understand their differences!

This is a framework for a catamaran cockpit with floating panels that are removable. ..

So, correct me if I am wrong. You have a single structural member ( a 2" tee) spanning the opening and you wish to calculate the deflection central/mid-span of that 2" Tee shown below:

 

[Mr Efficiency]

That is a sociological fact not an engineering fact - which the OP is seeking!

It is all of the above, and more, water finds it own level, the usefulness of SS for marine purposes has pretty well found its level, and aluminium is ahead by a ratio of 999 to 1 for non-cosmetic applications. Don't ask me for a source for that figure, lol !

 

[fallguy]

That is a sociological fact not an engineering fact - which the OP is seeking!
Seems you are conflating the two very separate issues and do not understand their differences!



So, correct me if I am wrong. You have a single structural member ( a 2" tee) spanning the opening and you wish to calculate the deflection central/mid-span of that 2" Tee shown below:

View attachment 154752

No.

We calculated the beam deflection already. The original tee was rated for 5" deflection. The 2" tee is rated for 5/8" or less under the 1500 pound figure.

We probably cheated a bit and likely treated the T as a single unit; despite it being welded. I digress.

What I am worried about are the endpoints deforming; not the crossmember, but where it mounts. I could be full of it. The panel moght balance it all out.

 

[fallguy]

It is all of the above, and more, water finds it own level, the usefulness of SS for marine purposes has pretty well found its level, and aluminium is ahead by a ratio of 999 to 1 for non-cosmetic applications. Don't ask me for a source for that figure, lol !

I was worried about corrosion and needing to supersize everything in aluminum.

 

[Mr Efficiency]

It just wouldn't have occurred to me to think SS for something like that, of course it is possible to do, and do successfully, but I think when most people think of stainless steel with boats, it is from the consideration of appearances, a SS rail is way more visually appealing than an alloy rail, that has weathered, and scratchy to run your hand along.

 

[Ad Hoc]

...What I am worried about are the endpoints deforming;...

Err ok. So, just to be 100% clear, you are only concerned about the connection of the long.t Tee to the 1.25x1.25" angle bar frame at its centre?
Here:

Is the 1.25" angle bar supported anywhere along its length, as it indictes a 52" span either side of this connection.

 

[fallguy]

Err ok. So, just to be 100% clear, you are only concerned about the connection of the long.t Tee to the 1.25x1.25" angle bar frame at its centre?
Here:
View attachment 154754

Is the 1.25" angle bar supported anywhere along its length, as it indictes a 52" span either side of this connection.

thank you

Yes. The 1.25" angle on the forward side is connected to another 1.25" angle. Those two angles also make a tee. The inside angle is bonded with mecjanical fastners 3/8-16 and 5200 to a 1.5" thick plywood backbone. The other 1.25" angle is connected with 3/8 fasteners on one foot centers plus a fastener each side of the cross member junction. The pic only had one black mark as the holes are not all done, yet. I just temp built it all.