A new exhaust system requires miles of expensive hose.
A new exhaust system requires miles of expensive hose.

Exhausting All Hope!

I’m exhausted by my marine exhaust system – or rather the engineering and construction thereof. I thought it would be dead simple – which was both dead-wrong and dead-stupid. I honestly thought I’d re-power my Amphitrite 43 in a lazy day or two while smiling the entire time. Sure, there’d be some small technical issues – just enough to add spice to the project.

Take my exhaust system as a convenient example: my new M92B Perkins would fart and pee, and I’d conveniently convey those gases and fluids over the side via a rubber hose. Wrong!

Nothing is simple or cheap or straightforward when it comes to a boat.

For instance, there are four separate hoses leaking/oozing/spitting/dribbling raw water and/or gases from my new engine. That’s a lot of hoses and a lot of holes and a lot of money, honey.

If you balk, the marine engineers whisper the dreaded word ‘back pressure’ and make you burst into tears. What is back pressure? I’m really not too sure. I initially thought it was – while repowering – resistance to pumping massive amounts of money into the marine economy like a fire hose, but I was wrong.

It is the force it takes to move air through a tube.

Air is pretty light stuff, right? But, evidently, this is a heavy subject – so heavy, it can considerably lighten up a credit card.

For example, my ketch weighs 30,000 pounds and I have just purchased a 1,000-pound diesel to push it into the face of giant waves at 7 knots while burning up the last of the warming planet’s carbon resources… all of which my Perkins is guaranteed to do. But, alas, my new powerful engine doesn’t have enough energy left over to, say, float a feather through a rubber hose. Strange, eh?

The first inkling I was in trouble came when I was informed that I’d have to change my two-inch exhaust over to three inches. “Nutt’n to it,” reassured my marine engineer.

My second shock was sticker shock: three-inch hose wasn’t 33 percent more expensive than two-inch hose – it was many times more. Plus, I had to change my exhaust through-hull and, of course, my seacock. Ditto, my raw water intake as well.

In fact, I had to change everything.

Why? Because I invited a boatload of marine exhaust system experts aboard, and they very carefully and conscientiously examined each link of my existing exhaust system. Their conclusion was simple and swift: since my present exhaust system had worked flawlessly for 32 years and countless ocean voyages, it was crap and would have to replaced entirely.

“Okay,” I said glumly, “that sounds logical.”

If you can’t handle a ‘brain-storming’ session like this, do NOT repower your vessel!

I’ve found that experts are experts – mostly at scaring you. They know that as your bowels loosen in fright, so do your purse strings. Fear sells. Always has; always will.

“Did you know that a single teaspoon of saltwater can cripple the mightiest, most expensive diesel in the world?” they kept asking me.

I did. I do. I always will!

I was so freaked out about the possibility of a single water molecule getting within a nautical mile of my new diesel – I agreed to the ultra-expensive Cape Horn Exhaust option.

This means, basically, if I’m sailing along in a hurricane and on the exact opposite side of the world is a huge earthquake… and two giant tsunamis rush around the world in opposite directions and meet back up at my vessel at great speed and with huge force at precisely the wrong time… just as my vessel is getting hit by a rogue wave and a Russian meteor… during a severe rain squall… and solar eclipse… while pitchpoling… during the Second Coming… well, I won’t get a drop of saltwater backed up into my engine. WHEW!

Here’s a brief history lesson on marine propulsion: engines started out being cooled by seawater. This, evidently, was too simple and cheap. So they added a second ‘freshwater’ cooling system – in the hopes that twin systems would double profitability. They were right. To up the ante, they started using a lot of crappy aluminum in engines – knowing it would deteriorate faster than you could say, “replace zinc daily!” Realizing that there was no end to the gullibility of the well-heeled marine consumer, the engine manufacturers (no matter how small and chemically adverse) then started marketing an engine-specific ultra expensive XLC (Extended Life Coolant) which was dyed different colors to further exploit their fish … er, their loyal customers.

Hard to believe?

Sure. But it’s true. Many formerly respected manufactures of diesel engines now hint your warranty might be void if you have the unmitigated gall to use an ‘unlicensed’ coolant of a different color.

Can you remember when engine manufacturers wanted their customers to be able to buy the correct fluids to keep their engines running dependably – regardless of post-purchase profit?

I can. Barely.

Nowadays, if you buy a new diesel and blow a hose, you’re suppose to call Dockwise and ship your vessel back to the engine manufacturer to have your coolant refilled. The engine manufacturer used to spend their time actually building engines. Now they spend their day laughing (all the way to the bank) while slapping barely-dry labels on their ‘exclusive’ coolant.

Sailboats are odd transportation devices. Their engines are often below the water line. They occasionally heel in excess of 45 degrees. Waves smack them with massive force. They pitch. They roll. Sometimes, they even flip!

Saltwater really is evil. Yes, it really is plotting against you and your inboard diesel. Yes, eternal vigilance is the real price of dependable propulsion upon the high seas.

The sad reality: 90 percent of all premature marine diesel failures are directly related to improper exhaust engineering. Numerous engine manufacturers go to great lengths to accurately inform their customers – my favorite outreach being Northern Light’s DON’T DROWN ME booklet (which has been the Bible for many generations of gen/set installers).

And, as much as I bitch about the Extended Life Coolant gaff, it certainly is nice to only replace your coolant every five years. Today’s modern diesels are, admittedly, remarkably dependable. Example: while my new M92B is about the same weight and size as my previous diesel (a FOUR-154) and burns about the same amount of fuel, it produces about 33 percent more power.

I’m going eight knots plus at 2100 RPM. And my four liter engine sounds like it is just loafing along, which it is. All of this makes even a professional complainer such as myself happy. The cost of operation is lower, too. I’m only required to change my oil and filter every 500 hundred hours – a five-fold advantage.

Of course, the first thing any knowledgeable boater does when they crank up their diesel engine is check to make sure seawater is spurting out the exhaust. But now, when I glance at my exhaust, I don’t see water disappearing into the harbor. I see hundred dollar bills. Yes, I have nightmares of seawater silently invading my engine – all sound-tracked by the “swish, swish, gurgle, vomit” of the modern, temperamental, high-end exhaust.

But everything on a modern boat is a trade-off, and today’s diesels are smaller, lighter, and more powerful – and more dependable. I take the bitter with the sweet, and having a brand new diesel in my boat is sweet indeed!

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