steering gear repairs. Winter 2025

Last year was Provident’s centenary. To keep her sailing through the next hundred years will take continuing dedication and care.

With help from her friends we hope to do just that.

Our plan is, that every winter we will identify a particular area and give it some attention. We want these projects to be specific to an old boat, above and beyond regular maintenance.

Over the last winter we decided to have a good look at Provident’s steering mechanism which had become worn and a bit vague. From time to time we have heard a slightly odd noise coming from the area of the propellor. We’d already checked out the bearings that the prop shaft runs in and given them a clean bill of health. We wondered if the noise was something to do with the propeller causing vibration in worn steering linkages.

With this in mind we headed up to the yard at Corpach and hauled the boat out of the water to take a closer look.

On the way we asked Donald, the owner of the yard to come on board and have a listen to the noise. He diagnosed it as cavitation. This is where the propeller’s movement through the water forms tiny bubbles of steam. When we were out of the water we had a look at the prop. It’s a reasonably old lump of bronze and over the years has corroded a little. We decided to add a shaft anode. This is a lump of zinc bolted to the prop shaft. The idea is that the anode corrodes rather than the prop. We hope this will slow down any future corrosion.

While we were looking around this area of the boat we noticed that the propellor had cut a small groove in the rudder. The prop on Provi is set off to the starboard side. A steel bracket prevents the rudder from hitting the prop when on full lock to starboard. Or at least it’s meant to. We found that the bolts holding the bracket in place had become a bit elongated and the bracket had moved allowing the prop and rudder to make contact. We would need to do something about this.

We also examined the pintles. These are the steel brackets, a bit like hinges that hold the rudder to the hull. Two of these lintels lack bushings. We thought about trying to fit new bushes but the rudder and sternpost are slightly misaligned. This has probably been caused by movement in the timbers that make up the rudder which was replaced about a decade ago. Fixing this would be reasonably epic and sometimes the disruption caused by taking things apart causes more damage than the intended fix. We decided to keep an eye on this in future years.

Brixham trawlers were built to be robust and dependable. They were work boats. Stability was a necessity rather than a luxury. They were solid and simple. When she was launched Provident was steered with a substantial tiller. It would have required a fair amount of body strength to operate.

The stability and seaworthiness of these trawlers made them attractive candidates to be converted into pleasure boats as the age of trawling under sail came to an end.

In the thirties, Provident was converted into a “Trawler Yacht” by the yard of Morgan-Giles. As well as adding accommodation for people rather than nets, ice and fish, the steering mechanism was tamed by the addition of a steering wheel.

There are a few ways of connecting wheels to rudders. A method that is quite common on tiller conversions is a worm screw. A single shaft into which a left and right handed thread are cut, one at each end. A pair of nuts spin back and forth on the threads and some clever levers allow this mechanism to control the rudder even when operated by a human of ordinary strength.

These mechanisms have a definite elegance about them. It’s quite satisfying to watch as the circular motion of the shaft hauls the rudder-stock to port or starboard.

In order to preserve the steering mechanism, the threads and linkages need regular lubrication but even with good maintenance a century of wear takes a toll.

I’ve been told that the worm screw itself was replaced a few years ago. This would have been an interesting and challenging project and I understand the shaft that’s in use now was the second attempt.

The linkages though were worn and damaged. The holes in the end of the linking bars had become enlarged and one of the links had snapped. This apparently happened many years ago and had been repaired with a steel strap bolted in place. I stripped the contraption down to take a better look and found that a second linkage was fractured. If left alone there was a good chance it would break too. Closer examination of this whole system revealed that the bracket below the waterline had two functions. As well as protecting the prop from the rudder it was a steering stop that prevented the damaged leavers from bashing into a steel post when the rudder was hard to starboard.

The worn out and broken parts gave the steering a sloppy and vague feel. Steering an 85 ton boat with an offset prop is challenging enough anyway so we decided to sort this out.

The first thing to do was to re-do the rudder-stop-bracket. We fabricated a slightly heavier version and bolted it in place. Then had a think about the worm screw mechanism. Parts for 1930’s steering devices are not readily available. We would have to make new ones.

This would involve casting copies of the damaged levers and re-machining them to fit snuggly into the mechanism.

A few phone calls and a bit of research led us to Archibald Young Ltd. in Kirkintilloch. This is a bronze foundry run by Andrew Young. The company was founded by his grandfather who was himself a third generation foundry man. This seemed like a very good fit for Provi’.

Bronze uses moulds made by sand into which molten bronze, heated to over a thousand degrees is poured. It’s a fascinating process with all sorts of tiny details that make a difference. Even the angle of the mould makes a difference to the way the bronze fills the mould and cools down.

It was quite a small job for the foundry and it took a while for them to fit it into their busy schedule but with a few weeks before the start of the season we were told the castings were ready.

The mould for the new parts was made from the old ones. But before this could happen the old ones were modified to make them a little over sized. The new ones came without holes and without any straight or parallel surfaces.

The next steps were to create new surfaces and drill the new holes. The tricky thing was to figure out a datum. We did a bunch of measuring, made a few marks and mounted the parts up in a milling machine. The surfaces were then cut flat and true. The dial said it was flat to a fraction of a millimetre.

The holes were drilled with a boring bar. This is a tool with an adjustable cutting blade that can be set to just the right size. One of the trickiest bits in this process was clamping these very irregular shaped objects so they wouldn’t fly off during the work.

Eventually it was all done. We bolted the parts back together and it all worked perfectly. With a couple of days to spare we mounted it all back on board.

The revised linkages are fitted with more grease points so we can keep it all lubricated. We hope this new version will still be going strong for decades to come.

It felt good to know we could point the boat in the direction we wanted to again.

As a final touch we sanded down the wheel and gave it a fresh coat of varnish.

I’m writing this as we cruise down the sound of Mull on our first trip of 2025.

The steering feels different. Much more connected to the rudder and it feels good to have completed this interesting and complex task.

Massive thanks to the wonderful Friends of Provi for making this possible

Steve