Need a refresher on v berth cushions

[jojo]

So I lay the foam on the fabric and trace for the top plate and then flip the foam and trace the bottom plate. Am I adding seam allowance? The cushions are about 5.5 ft long and 3 ft wide at the widest point. Where am I making my hash marks, since the top and bottom plates are different sizes? Also. Is there anything special to know about the boxing, or am I just cutting the proper length?  Thanks in advance. I do these so infrequently that I'm unsure of myself.

[MinUph]

Jojo,
  When we do these I cut the foam a bit oversized but not a full inch unless they are getting wrapped. As for the boxing the straight sides of the cushion the boxing is normal. Where the bevel meets in front and rear the boxing will be angled. I make them a bit long and adjust when sewing them on and making notches on the top corner and bottom corner of the boxing, sew it together and then finish sewing the boxing on. Just like when ending a normal boxing.

[jojo]

Thanks Paul. What about alignment marks? There are notches and curves, and since the top plate is bigger than the bottom plate, I fear I'll have a twisted cushion in the end. Should I just find the centers on eac of the plates?

[Darren Henry]

I often make alignment marks right on the foam and then transfer to the top and bottom plates and boxing.

[MinUph]

Thanks Paul. What about alignment marks? There are notches and curves, and since the top plate is bigger than the bottom plate, I fear I'll have a twisted cushion in the end. Should I just find the centers on eac of the plates?

Centers help and then just line up the corners and stretch it in place you need to sit back a little to get the stretch out then hold it at a workable length, sew some and do it again.

[65Buick]

Interesting. I hadn't heard of these so I had to look up what they are. Does look challenging.

[Mike]

I will ad to paul the boxing along the hull side following the curve of the hull will be slightly "c" curve  shaped