Bowtubes and the USCG

You surely remember the broken lumber A-frame shown recently here on the 42 daycharter cat.  The owner chose to replace and update with a standard alloy tube and wire system.
My worst fears about MSC came true.
I submitted the stock, stamped, original plan sheet to MSC.  I also submitted an 2017 version with the same section properties or better.  Keys Rigging submitted the proposed with extra strength on all items.
It was rejected. They wanted the calculations also.  Done. Those were rejected until I would explain how I did my calculations. They did not have a standard to aim for. In fact I was asked to explain what the relevant factors were.  It has been almost 2 weeks of back and forth now. My fear that nothing that was settled “law” before, is now.
I have probably done a hundred of these, and I bet Keys Rigging has done that many also, or more.
I also get the feeling that they are stressed and angry at MSC. Maybe Trump chaos has hit there also.
This is one part of why no postings last week. Deadlines also. Next week will be better I’m sure.

23′ Trimaran Update

I finally got the first run of modeling the updated 23 daysail trimaran. Version B will have ama rudders and the even hotter version C will have foils. It is a developed plywood/epoxy unit with core vacuum bagged onto the flat surfaces needing that. And carbon fiber where it helps. At around 360 kg lightship weight, it can be built for around $5000 us in construction materials. The connecting beams should be carbon mast sections. The camper version comes next.