Hi Patrick,
A bit random as it stands? Are you designing a kayak, or is this part of an ongoing discussion?
If this is a new topic you should instead look up the old debate, swede form versus fish form. This is a religious question, believers versus unbelievers and both will claim their preference is faster and more directionally stable. Some go faster backwards than forwards, but I won't say which.
From what I have read (and I'm no expert) the general agreement is the boat should be widest within 5% of either fore or aft of the midpoint, but not at the midpoint. To be clear, the calculations should be based not on the deck width, but on hull volume. Whether you go in or the other direction is often a question of: Do you need room for your feet or for you backside.
JohnK

Any opinions on where the widest part of the beam should be located?

: I looked at a top down picture of an NDK explorer and it appears to be widest
: where the front of the coaming is.