Re: 1981 Islander Bahama 30 Topping Lift
This kind of thing isn't really 'boat specific'... it can be whatever you want it to be.
"wired to the backstay" sounds like a temporary pennant that supports the boom when you're not sailing. It's not as good as a real topping lift because it's not very effective when you want to support the boom while reefing.
A fixed topping lift from the masthead to end of boom, with a short adjustment tackle at the boom end works well, or the TL can be run to the masthead, down the mast and aft to the cockpit for easier adjustment. Either option requires a trip to the masthead to set it up (to add a block or shackle for the lift) if it's not already there.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)