14 June 2019

First Big Steel Job

Meeting the remarkable Australian cruising couple, Neil and Ley Langford, last year really opened our eyes to the possibility of DIY steelwork. They showed us all around their beautiful steel boat Crystal Blues, and then showed us pictures of the many, many steel jobs that they had done over the years.

"That's the beauty of steel boats," they said. "If you wonder if something is rusting, just cut her open and look. You can always weld her shut again."

They had done just that several times, to fix tanks and other things. No need for that kind of work on Petronella, but there was one steel job that I had on the schedule for our St. Mary's haul out. Thanks to the Langford's example and encouragement, I was sure we could tackle it.

Cutting out the Engine Vent Assembly
The problem was in Petronella's engine vents. Behind each of the four holes above was a steel elbow, to which were attached flexible air ducts. Three of these elbows were rusted clean through. If we were to take a wave over the stern and fill the cockpit footwell, water would gush through these holes onto the top of the engine and into the bilge. This was unlikely to happen, but since we were preparing Petronella for her 12th Atlantic crossing, fixing this problem was near the top of my to-do list.

My plan was to cut out the whole vent assembly, and then have a welder fabricate a new one. The first problem was to cut it out in such a confined space.

My jigsaw, equipped with a metal cutting blade, made short work of two sides, but it was too large to get to the other two sides. I tried several tools, including a bare hacksaw blade, but the guys in the yard recommended an oscillating multi-tool. I'd seen these in hardware stores, but had no idea how they worked. Turns out, they work pretty well at cutting steel in confined spots. It is easy to burn out the rather expensive blades, but once I backed off and let the blade do the cutting (always a good idea with a cutting tool), it worked great.


My new favorite tool
In the pic below, you can see the problem clearly: three of the vents were rusted through. One so badly that it literally broke off when I tried to disconnect the vent hose!

It was definitely time to replace them!

The old vent assembly
Here is the hole left behind, with all the rust and dirt created by the cutting cleaned up. A bit ragged, but I was glad that part of the job was done.

The resulting hole in the footwell

So, I gave the old vent assembly to Rocky at St. Mary's so he could fabricate a new one. Meanwhile, I wanted to clean up some of the rusty bits you can see in the photo above, prior to painting the area.

I set about this job relieved that I had had the nerve to tackle this project and that a major problem would soon be fixed.

Air-powered needle gun
Neil had recommended we buy an air-powered needle gun last summer. I'd immediately bought one, but this was the first time I'd used it. A needle gun is the ultimate tool for chipping rust and old paint off steel. The yard had a compressor, so I grabbed the opportunity to give it a try.

It worked great, and I discovered that the needle gun was also good for opening cans. As in 'can of worms'.

What the needle gun revealed..
After a minute or two blasting away at the small line of rust in the footwell, I soon discovered a big surprise: the joint between the floor and back wall of the footwell was rusted through in several places. Someone had caulked these holes with some sort of silicon goop, but the goop was loose and the holes were no longer effectively patched.

What happens when you don't look (or paint) under the footwell floorboards for a few years.

I found this depressing, and at the same time thrilling. Since buying Petronella, Helena and I have been on a quest to cure all leaks. Water, diesel, anti-freeze, or whatever. In this quest, we had replaced a leaky water pump, replaced several old hoses in the cooling system, and replaced the engine injector fuel lines. This eliminated most of the leaks and nasty diesel smells, but there was still a persistent slow leak that did not seem to correlate with motoring or rain storms or any other potential source of the leak.

I was convinced we had a leaky water tank, but I had put different colored dye into each tank and waited for colored water to appear in the bilge. Nope. Not trace of dye. Just clear water.

I'd nearly given up in despair, but seeing these holes rusted through in the footwell seemed like an Ah-Ha! moment if there ever was one. I never would have suspected the footwell was leaking, but because I'd had the nerve to fix the engine vent, and furthermore took an obsessive approach to prepping the hole for painting, I'd uncovered what could be the source of our sneaky leak.

Repairing the holes with epoxy and fiberglass.
I set about the footwell with the needle gun with a vengeance, and soon discovered several other rusted-through holes that had been also patched with silicon. I soon had all these old patches out, and the rusty areas thoroughly prepped with the needle gun and rust converter. After consulting with both Rocky and Howdy Baily, we all agreed the best way to fix the holes was with epoxy and fiberglass.

The floor of the footwell had been removable to provide access to the engine, but this had probably helped cause the problem in the first place. We agreed that when Petronella needed re-powering in the (hopefully) distant future, that would be the time to cut out the whole footwell and replace it with a new one.

For now, fiberglass would make the footwell truly waterproof and strong enough for whatever we threw at it (or into it.)

The new vent assembly
The new vent assembly arrived, and we set about prepping it for painting and installation.

We had had the assembly built 3/4" larger, all around, so that it could be bolted over the hole, rather than welded in. This was because Rocky was worried about welding over the engine compartment, with its risk of fire.

Eventually, it was time to bolt it in.  We reattached the vent hoses with new hose clamps (the old ones were rusted badly) and bedded it down with 4200.

Bolting the new assembly into place
And here it is, job done. The footwell could use one or two more coats of paint to 'finish' the job, but we ran out of time in St. Mary's. We will get to that whenever it stops raining and warms up here in the North.

Job done
We took these pictures back in St. Mary, but I haven't wanted to declare victory over our leak until today. The leak was just too elusive and random for me to trust that the footwell had been the ultimate source, at least until we had been leak-free for a whole month. It had been so maddening that we hadn't been able to correlate the leak to rain, or running the engine or any other potential source of water. I now believe that the leak had correlated to the taking of cockpit showers! Not that we tracked these, so we never made the connection.

Since we nearly always have our awning up when it rains, we never got much water in the cockpit from rain storms. But when we decided to shower in the cockpit, we would often dump several gallons of fresh water into the cockpit. That's where the water had been coming from.

So, a mystery that had stumped us for 2 years was finally solved. Our bilges are now dry and Petronella is as watertight as she was when launched in 1976. It's a good feeling.

Thank you, Neil and Ley, for showing us the way. I hope you are doing well wherever your travels have taken you.


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1 comment:

  1. Hello John, Congratulations on your new found skills! The needle gun IS a marvellous “investigative” tool. It’s the epitome of non-destructive testing on a steel boat. Anything sound and solid is not effected, anything weak and inadequate is immediately obvious. By the way, welding over the engine would not have been a problem, I would have found another welder ...... and made that vent from 316 stainless. In a complex part like that, the design and fabrication labour far exceeds the materials cost - using stainless won’t change the price much at all. In fact it can save you money, as the need for protective coatings is minimised. Cheers, Neil

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