Jerry, Just took another look at the old strongback that came out of A338.
It isn't straight across on the bottom as you might think because of the doorway to the forward stateroom. The original door was cased.
In fact the top liner of the opening is often the first indication that something is going on under the mast.
So the strong back definitely looks curved top and bottom - until I sighted along the bottom and saw that the mid part had been flattened (looks like with an AX) obviouisly to square the doorway.
I laminated my 'upgrade' and later decided that it would have been BETTER and SIMPLER to bandsaw the beam out of white oak. And so easy to make the slight chamfer along the top to snug the cabin top.
Commander's have a COMPRESSION POST.
My guess is that the fiberglass of the cabintop can be kept honest with a plain curved beam top and bottom. In other words I think you can skinny the beam depth as long as you still support the center with a post. I might make the beam a little WIDER - to make up for the cheat.
The beam on the Ariel is 4' long.
Not much to get bent even with a point load in the center.
In fact, bet there never has been an actual bent beam in any of our boats.
Yesterday's Alberg Assoc breakfast there was talk of the Triton's beam getting pressed down and the cabin sides getting pushed out!!! Could see the bulging! That just wouldn't happen with our cabins.
Making sure our shortie is married to the cabin top will imco cancel the remotest possibility of that happening in a Commander.
I'd make certain the center post cannot move.
Actually you could scroll into the beam a PAD in the center over the post, to fatten the beam there if you want to skinny it down. You'd do this all at the bandsaw, right? no gluing in anything extra.
That would remove any tendency to bend. In other words, leave the beam deep in the center but scroll out the sides to remove head bangers. Really round the edges, someone's going to head the beam anyway!
In a modern 'engineered' mast compression POST set up they'd probably just have a disk of some material under the mast - with no beam at all!!!!
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