Zipped/folding mattress - comfort?

[magictime]

We're looking at getting a mattress custom made for our boat and one option obviously is to have a zipped 'hinge' so that the mattress can fold back on itself during the day and be pushed out of the way, then be extended to full width at night - potentially letting us fit a 150cm mattress on a 120cm bed base. I'm basically wondering where best to put the zip - the most obvious options being a quarter of the way in on the under-gunwale side (leaving me sleeping right on top of the join), or straight down the middle so that you basically have two zipped-together single mattresses (which might make it easier to get at the under-bed storage, but might also look a bit ugly by leaving a foot or so of the bed base exposed when in 'daytime' mode). Any thoughts? Am I right to be concerned about comfort levels if the zip ran right down my side of the bed?

[Sea Dog]

1 hour ago, magictime said:

Am I right to be concerned about comfort levels if the zip ran right down my side of the bed?

Probably, but what if it ran down the other side?

Edited March 6, 2018 by Sea Dog
Changed autocorrect's "of" back to my" if"!

[magictime]

She'd have to lump it!

[MHS]

For a bed running along the length of the boat, I would definitely go down the middle. 

Our cross-bed has the split 70/30 which is great. The join is behind your knees, so you don’t notice it. 

[OldGoat]

We had two 2' 3" mattresses made (initially to make it easier to get them in the boat!) in case we might need extra space in the forward cabin. Never had problems with the 'join' in many years. Now we have a mattress protector to lock the two together and make the firm mattress seem a bit softer.

[Bunny]

we have 2 mattress toppers , dont notice the join . Bunny 

[Neil Smith]

In our caravan it hinges on the middle so no problem, you could put a vallace sheet on first to hide the edge of the bed.

Neil.

[magictime]

Interesting that most people seem to favour the zip running straight down the middle. I think of the 'standard' design being something like this, with a fairly narrow section that drops into place when the bed is made up - but where the person on the inside of the bed must end up lying on the join: