Sorry to hear of your exhaust hose issue. They are a maintenance item, and if it is 35 years old, I would guess way past due. I have seen those hoses delaminate, usually from overheating.
Quick story. When I first got our boat, I installed an exhaust temperature overheat alarm (Borel) on the hose just after the shower head where the water is injected. The next summer, that alarm kept sounding. I had 2 different mechanics have a look at it to determine why the hose was overheating (I confirmed it with an IR gun). Neither one was sure, and their guesses were (to me) all over the map. I was sure that it had to be the exhaust elbow, as all other engine temps were well within spec. Turns out I was right, my elbow had corroded through in a few spots on the inside and it was not visible at all. Glad I installed that alarm, as if this issue had gone on, I could have "sucked" water into my turbo or even the exhaust manifold. I also caught the issue before the hose suffered any visual damage. My hose was rated for 200 degrees F, and I was seeing spots of 220 degrees.
I would guess that your hose problem could be just "old age", but I suggest you check out your cooling system, especially your exhaust elbow to ensure no issues there. By the way, my elbow did not show any problem visually until I took it to the radiator shop for a good cleaning. Then the holes (very small) were visible. Even the "shower spray" looked good when I used the garden hose to supply the water on the dock. It needs to be cleaned to be sure.
I am not an expert on this, but this is my experience.