Derrick Mayoleth in Wisconsin has a very long-running and interesting website. He also owns a very nice sparkle purple Rockpool Alaw Bach sectional sea kayak, which he used to circumnavigate Puerto Rico in 2008. It's similar to the white Rockpool pictured above. He is an accomplished paddler and roller, and an instructor. Derrick ran an eductional piece, titled "bits and pieces", answering my query about sectional take-apart sea kayaks. Here is a link to his site, and the many comments that followed his well-experienced observations. Be certain to peruse his entire website; it's full of information and entertaining insights on life.
No, this is not a kayak chop shop for stolen parts to be reformed into a Frankenstein boat. One major advantage of sectional sea kayaks is the ability to easily take the kayak inside for repairs and modifications. The middle cockpit section tends to be where the most mods come into play. Here I am adding a minicell backband to my Aquanuat LV, and I am vacuuming out and adding new rubber washers to the Nordkapp. They will then both be polished. All in the livingroom.
Here are the front of the cockpit section (the part that interfaces with the bow segment) for two Valley sea kayaks: the uppermost photo is a 2008 Valley Aquanaut LV and the bottom photo is a 2005 Valley Nordkapp. Both feature male interlocking pieces and rubber gaskets around the edge. What is different about the two kayaks is the bolt placement. The Aquanuat LV (top) has the two lower bolts placed to the sides, and not directly midline. The Nordkapp (bottom) has the bottom bolt placed right in the midline, at the v-bottom of the kayak. When I test paddled the Nordkapp, the lower bolt area allowed water to leak into the boat; the outside waterline was above the level of the lowest bolt. This would be less likely with the Aquanuat LV configuration.
I replaced the rubber washer (see prior post about rubber washers) in the lower bolt to see if this will provide for dryness. If not, then I will consider some form of modification to the outer rubber gasket. Should that also fail, leaving the lower bolt out (i.e. connecting with only three bolts instead of four) and filling the hole with removeable silicone would be mandatory.
Clip hull 3-piece kayaks, of course, have watertight sections as the clips are on the outside of the hull. Examples would be Rockpool and NDK boats. More on those later.