I bought a tandem version in May, 2015. My wife and I took it on Ross Lake, a remote 25 mile long fijord like lake in North Cascades National Park. It is a wilderness lake with no car-access, so it's remoteness makes challenges more serious. Eight miles into our maiden voyage, a hairline stress fracture formed at the base of one of the three small ribs which make up the mating surfaces for the joining system. Cold water began pooling in my wife's cockpit soaking her and her gear.
No glue, resin, or adhesive sticks to the polypropylene material (believe me, I've tried more than half a dozen things), so I tried heating a knife in the flames of my pack stove and then tried to melt/weld a piece of plastic milk carton into the hairline fracture. This slowed the leak, but since the plastic jug was a different material than the boat, the weld never really took. We limped along, bailing the pooling water for 4 days before heading home early.
I contacted Point65N and they immediately sent me a replacement module for no charge. In the meantime, thinking our original leak was an isolated manufacturing quirk, I ordered a second tandem module to use for carrying gear on another extended trip on Ross Lake.
Four weeks later we set out again, this time with the kayak configured as a tandem, plus one extra module in the middle for gear. We were to paddle about 60 mile during the course of a week on Ross Lake. On the 4th day, another module developed a new hairline fracture --once again at the base of one of the the 3 small ribs mentioned above. This time, I had 3 different types of glue and was able to do temporary repairs that enabled us to complete our trip, even though the repairs were not permanent because nothing adheres permanently to polypropylene.
The boat modules are always stored in a shed, lying flat on shelves, so the stress only occurs while using the boat in water. Counting my original tandem module, and the replacement tandem module Point65N sent me, and the extra tandem module I purchased to carry gear, I have a total of three tandem modules. When you add the bow and stern modules, I own a total of 5 modules.
In the summer of 2016, I took my daughter to Ross Lake (a favorite spot), using the "gear module" as a tandem for her. This was only the third time we have used the kayak. This time, we didn't use an extra module for gear since two of the tandem modules had leaking hairline fractures. On the second day of this third trip, both my daughter's module and my module developed the familiar hairline fractures. I used JB Plastic Weld to make temporary repairs, but we cut that trip short because of the leaking modules.
After the first, original fracture, Point65N told me I should not carry the boat with the modules connected, but should always assemble it at the water to avoid causing stress to the joints. They also told me not to leave gear in the boat modules while carrying them by themselves. We have always followed their instructions so as not to create undo stress. Furthermore, I weigh 165 lbs, my wife weighs 140 lbs, and our daughter weighs 110 lbs, so the modules have not been over loaded.
Rather than throw $2,000 out the window, I am learning to plastic weld using heat and plastic welding rods made of the same material as the boat. So far, I have welded 4 hairline fractures and then added reinforcement plastic in those same areas to make them stronger. I intend to plastic weld reinforcement to each small rib in hopes that will prevent fractures on the ones that haven't fractured yet. This means plastic weld reinforcing on a total of 15 small ribs (3 per module).
Over the last 2.5 years, I have sent more than 20 emails to Point65N. They have only responded twice. In their second and last response, they told me that plastic welding was the only way to repair the fractures and they promised they would send me plastic rod that could be used for my boat. Eight months and four emails from me later, they still have not responded or sent the promised welding rod. I hunted down the repair rods I am using, from another source.
It is probably worth noting that after less than two years, Point65N discontinued the Martini GTE and replaced it with a modular kayak that utilises a different sort of connection. I take that to be their unspoken acknowledgement that the original was poorly engineered. I know this much, 4 out of 5 of my modules developed hairline fractures.
The concept is great, and for the miles we were able to use the kayak, it performed well.