The Shamrock is a different hull, similar to the Aquasport, but with a full keel that is glass filled to prevent damage to the running gear. The front is similar to a pre-72 Aqua, but it has a semi-V deadrise like later models, and, once again, has that full keel. The Shamrock WAC looks just like the Aquasport above the waterline, but again has the Shamrock hull underneath. Don't know about Seamark, but I doubt if Coburn would have sold the mold for the 19-1 or 22-2. However, there were a few builders that made molds of Aquasports and ran copies of them in the 60s and 70s. Usually somewhat under the radar or with just enough changes to keep away from a lawsuit. You would need to see a Seamark out of the water to know if it had Aqua heritage.
I agree SB. Great post/comparative pics Jess. The bow is different. The Seamark is higher. And less raked to the stern. Seamark sharper as SB noted. Certainly a difference regarding the prow lines, at least per the pics.Maybe the take-off/rip off was from a 19-1? Or totally NOT from our lineage/pedigree/purity? We may need to call in a super-sleuth.