February 16, 2016

Think hard about gasoline

WHEN THE DREADED day comes, and your old auxiliary engine finally decides to head for the great scrapyard in the sky, what are you going to replace it with? There’s almost complete agreement these days. You’ve got to get a new diesel, right?

But why a diesel? It’s not necessarily the right choice for everyone who owns a good old boat. In fact, it’s more of a fashion than a logical choice. There’s much to be said for modern gas engines with fuel injection and solid-state ignition.

The most popular reason given for choosing a replacement diesel is that it’s safer. But sailors who own diesels mostly cook with propane gas, which can blow a boat to pieces just as easily as gasoline can.

A gas engine is cheaper, smoother, and more powerful than a diesel of the same weight. It’s easier to crank, easier to repair, even for an amateur, easier to remove from the boat, and much quieter in action.

Gasoline engines in cars are designed to run about 3,000 hours, or 100,000 miles before they need an overhaul. Now, the average boat owner logs 200 engine hours a year, so, if you maintain it faithfully, it would take nearly 15 years before a gas engine needed an overhaul.

As for safety — your nose is very good at sniffing out very small concentrations of gasoline. Together with a bilge blower, run for five minutes before every start, it will virtually eliminate the chances of a surprise explosion.

So, when the time comes to replace your auxiliary motor, don’t be stampeded into diesel. Gasoline engines have been used in small boats for many decades. Consider their advantages very carefully before you make your choice.

Today’s Thought
To some will come a time when change
Itself is beauty, if not heaven.
—E. A. Robinson, Llewellyn and the Tree

Notice outside a muffler shop:
“No appointment necessary. We heard you coming.”

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)


Don P. said...

O.K., I'll bite.
The longer I have a diesel the less charmed I am with it.
All the gas engines I've seen are meant for high speed planing hulls.
Do you know of any sources for small marine gas engines suitable to a 30 ft sailboat? Say 10-25 hp?

John Vigor said...

Don, here's a website that compares gas engines with diesel.
This article is meant for power boats mainly. These days your choices for smaller gas engines are limited. Ford used to make marinized car engines, Watermota for instance, but I think now you'd have to look at a restored Atomic 4 engine. If you Google Atomic 4, or Moyer Marine,you'll find suppliers of this well-known gasoline power plant that was original equipment for many thousands of boats of your size. It's 30 hp and has a good reputation. See also:
And you can hand-crank it!
John V.

Don P said...

Thanks John,
As a sail type I forget that sometimes your posts are power boat related. Having reviewed the options for repowering a sailboat I suspect the future will probably be electric motors. Battery technology has a little way to go first though. Some of the newer sailboats now have dedicated compartments for portable generators. All part of the process of evolution I guess

wil van Londen said...

What about electrical propulsion?
If my old Yanmar is end of life I would replace it with a TORQEEDO electric motor. These guys are making very nice outboards, inboards and pod motors for the same price as a diesel engine. No more smell of diesel in the cabin!