I've got a sterngear repair job on at the moment which is demanding a bit of ingenuity. My solution involves a bronze bearing (commercial bronze (330?)) passing through a flange, for which I propose to use 15mm stainless plate. The bronze is 3" OD, 50mm bore, reducing to 70mm OD at a shoulder where it passes through the plate. I propose to silver solder the two together, I may also add a (bronze) reinforcing sleeve over the 3" dia, also silver soldered to both the bronze & the plate. Anyone care to comment on the viability of this. It will spend its life under (usually fresh) water? I have to admit I've never silver soldered stainless, but the price I was quoted for a slab of bronze to do the job was a bit alarming!
The job is to repair the propellor shaft bearing on a Dutch sailing barge, which was motorised probably in the 1930's. The construction, at least by UK norms, is very unusual. The stern tube is encased in a hollow steel 'fin' at the stern of the vessel, is over 4 feet long, and appears to consist of one piece of a fairly hard white metal tube with no support other than a cement grout which fills the 'fin'. I had assumed there was a steel or bronze tube around the white metal, but there's nothing but the cement! This was clearly done as a 'once only' job to see the life of the vessel out, but after probably 60+ years it's worn out :-(
I've made up a boring bar, the first foot to be a snug fit in the worn bearing, with an adjustable hss cutter behind, and a 3mt spigot on the other end to be driven by a 2-man portable drill, so as to cut out hopefully about 6" of the old bearing. I successfully removed about 2" this afternoon, establishing that the method works, before it was time to pack up.This will be replaced by the bronze, which will also project 4" behind the stern 'post' & give a reasonable length of bearing. The stainless flange will be secured with 4 bolts to an existing steel 'box' on the sternpost (rear of the 'fin'). I have been wondering about some sort of a resin grout to fill any void between the bronze & the concrete. Anything like that will have to be fairly fluid, & injected through a modest sized hole in the steelwork. which can later be plugged. Anyone any suggestions for a suitable material? Ordinary resin as used for glassfibre work might be good enough?
Cheers Tim Tim Leech Dutton Dry-Dock
Traditional & Modern canal craft repairs