Mast Compression Fix on Cal 28

Coming down with boatheimers?

It's possible the casting has broken free of it's hull shell bond, but it wouldn't move very far. The liner on the other hand can move quite a bit, depending on which hull shell bonds have broken.

 

I really don't think it is the liner that is moving. The table is bonded to the keel and the table is what moves. I will take a look at how and where the liner is bonded to the hull, and what condition that tabbing is in, anyway.

 

This project is now at the top of the list and underway.

I have cutout a section of the fiberglass liner to gain access to where the stainless steel horizontal beam will lay. I have also installed a temporary strut and removed the original vertical beam. It is clear to me that the replacement vertical beam will have to be bolted to the main bulkhead, similar to how the original was laminated in place.

The next step is to size and fab both the horizontal and vertical beams. The horizontal beam will be a sheetmetal weldment, boxed in on all sides with a few webs in the middle. I am trying to get a sense of required material thickness. I created an FEA, 1/8" wall thickness, 5000 lb load in the center, fixed at the corners. Deflection at center was about .06 in, stress looks reasonable except locally, where the part was 'fixed'. What kind of load should I be designing for? (load and safety factor, I suppose)

Also, looking at the beam. I am planning on using a 2"x2" stainless square tube, length is 57". Using Euler buckling, I found that with a .25" wall thickness, the beam will buckle at ~80000lbs. .187" buckles at 66000 and .125 buckles at 48000lb. But.... I am going to be bolting the bulkhead to beam along one face, and plan to drill and tap the beam, so I'd like more than an 1/8" of thread. I am thinking .187 wall thickness.

I have a couple more pictures, maybe I can post them later today.

How do you think I should go about sizing material thickness of both horizontal and vertical beams?

 

Thanks for all the good ideas on this thread. I've just bought a 1964 Cal 28, hull #68 and will be reinforcing the deck and compression strut. I'll be glad to share ideas with anyone still working on this. Cheers, TK