Re: looking for past or present owners of 1970 through 73 cal 27s
So you have an "in hull" mount already - that means you can service/remove the transducer while afloat.. Odds are its a 200kHz transducer so all you'll need is a compatible head. Most signet transducers have some red on them.. Round cutout would point to Signet or Standard Horizon (from that era)
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)