The tabernacle holds the mast in place and allows it to pivot down to be stowed on the boom gallows when on the trailer.
It is made of 3/4" thick Douglas Fir.
My PocketShip must have a detachable tabernacle, in order to get the boat out of the garage due to door height restrictions.
The build manual states that this is fine, but recommends strengthening the sides by making them 1" thick.
So that's what I did.
I didn't think 3/4" timber would necessarily be strong enough for even a permanent fixture, so would have done this anyway.
I laminated a piece of 9mm ply to the pieces of wood provided for making the sides , as here.