Exhaust Repair

On boats, one thing just seems to lead to another. Here's how a corroded exhaust leak was discovered and patched aboard Vanishing Animal.

The week from January 27, to February 4, 2009 was warm, dry and windless across San Francisco Bay - a great time to strip some trim and apply 5 coats of varnish. Since varnishing had to be finished before 1400 each day, that left time to putter around the boat and do those maintenance chores that seem to get postponed when there's wind to go sailing.

Tackling the engine compartment one day, I discovered there was a light film of black on the alternator and the walls. It had been probably thirteen years since the engine belt had been replaced, and I had a spare, so I replaced it and cleaned up the forward end of the engine and the compartment.

Then I checked the freshwater cooling water reservoir, only to find it low. So I filled it up with water and antifreeze. But I was concerned that is was low and wondered if there was a leak. So, after filling the tank, I started the engine and crawled into the aft bunk to open the access hatch and look at the aft end of the engine and the heat exchanger. Though rusty in spots, it appeared to be dry.

When I put my hand in to feel around for any leaks, my hand was hit by a blast of hot air. It was coming from a small area of about 1/16th inch pinholes on the inside of the main exhaust pipe. My nose now also told me there were exhaust fumes, and these probably contributed to the light coating of soot in the engine compartment.

What to do now? Our daughter and grandchildren were arriving from Argentina in three days and we planned to include the boat in our activities. A trip to the boatyard wasn't going to fit.

Digging through my on-board repair supplies, I found a package of Syntho-Glass Instant Repair Resin Coated Cloth. It said it was water activated and sets "rock hard" in minutes. It also said, "Due to the high temperature resistance of Syntho-Glass, it is an excellent repair for exhaust systems, etc." It had a "Use Before date of Jan 1997. But, it sounded like it would work, and I sure didn't like the alternatives.

The package contained a 2" x 5' strip of impregnated fiberglass cloth. It came with a pair of synthetic gloves and the simple instructions to 1) clean and sand the area to be repaired, 2) don the gloves and soak the strip in water for 20 seconds, and 3) quickly apply the glass to the area, smoothing and working it until is sets up and loses it's initial tackiness. It said it would be fully hardened in approximately 30 minutes.

It seemed almost too simple to apply, but it went on easily, though I was concerned that I couldn't pull it totally tight around the pipe because of the overflow nozzle opposite the holes. It certainly seemed to be setting up - outdoor temperature was in the low 60s, and the engine compartment was probably in the mid 50s.

I left it to harden overnight and returned the next day to give it a try. As the engine heated up and water circulated into the exhaust system, a few bubbles popped up between the top two wraps of glass where there was only one layer. But, in about 15 minutes, and with a little massaging, the combination of water, heat and pressure sealed off even this little leak.

The following week we all got aboard and spent four hours under power showing the grandchildren the San Francisco Bay shoreline. When we got home, I took the pictures below. Where there were several layers of glass, the surface remained white, and where there was only one or two, the glass appears scorched, but doesn't leak. It sure saved the day for us!

I tried to get a replacement package at West Marine (where I most likely got it in the first place) but the Palo alto store has just closed, and the South San Francisco store doesn't carry it. I have contacted the company so see where I can get more -- I'll post the results when I get them: Neptune Research, Inc., 1683 Latham Road, West Palm Beach, FL 33409 Phone: 561-683-6992, www.neptuneresearch.com

Rick Van Mell Vanishing Animal 650-962-1515 vanmells@ix.netcom.com

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View from quarter berth
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A closer look
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Looking aft from cabin
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Front of package
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Back of package

(Click Pics for enlargement.)

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