Yep...I did it (twice)
The original mattress foams in my B361 were an uncomforable joke. So, my first (cheap) attempt at comfort was to order a California King sized piece of 4" Memory foam from overstocks.com. I cut this with an electric bread knife to go on top of the old foams and then sewed a new cover that fit over it all. Total cost...about $250. It was a huge improvement.
Then, we spent the night on a friends boat that had a custom Tempurpedic installed and were LOVED it. So, I went to same local dealer that made his and had one made for my boat. It was hideously expensive ($1,400 for the V berth) but wow is it comfortable. It truly makes out weekends luxurious.
By the way, the original foams were split vertically (fore and aft) to allow access to the storage under the V berth. On my first attempt, I changed this to be split side to side (athwartship). This was an imrovement, but I still didn't like having a split in the mattress. So, when I had the new one made I didn't have it split at all. It fit in the boat just fine and I can still get under it to access the locker. I don't go in there very often anyway. I have an ATN storm jib stored there along with extra sheets.
Hope this helps,
Agaliha
