TOPIC: Any idea what this is? (shot in the dark)

I just bought an old tri-hull skiff (definitely from the 60s). No idea who made it. Any thoughts? I got to work rpairing a few worn spots and removing a crude, rotten old plywood gunwale that a previous owner had stuck on there with a bunch of bolts. Covered with layers of old paint, they were no picnic to get outta there. Many thanks!

I should say - there's no evidence of a HIN anywhere on this boat. I did look closely. Hoping someone might recognize the distinctive curved line on the side of the hull. Thanks!