Canadian Yachting Special Feature: Dinghies and Davits Spring 2020 - 8

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Figure 3: Valiant 40 Stem Fitting

ing partner wanted to be able to use
the dinghy more, so we left our
15hp engine at home and took an
8hp - 2-stroke outboard. First of
all, it was lighter and easier to pull
up onto the motor mount on the
stern rail. The engine performed
flawlessly. (OK it was a little smoky
being a 2-stroke!)
Two things happened during the
trip. Even alone in the dinghy, I
could not get it on a plane and
Mary never took the inflatable out
on her own. Now, I am a proponent
of being able to plane for a couple
of reasons. First, when Sojourn is at
anchor and we are a mile or two
away in town or at a marina - we
sometimes want to get back to the
boat quickly before the weather
changes or the sun sets. Second, 2
adults, groceries and laundry slow
the boat down even more. If you
add waves to the mix, then you can
be in for a slow and wet boat ride.
8

Dinghie s & Davi t s

Of course, this is why we carry foul
weather gear. When you have a real
cruising emergency (like you are
out of ice or beer) you need to get
there and back quickly. (Remember
I said a cruising emergency - not a
boating emergency!)
Review how you use your boat
and make the decision based on
your actual cruising practices. There
are many proponents for a smaller,
lighter outboard. If you are still not
sure, see if someone will loan you a
higher-powered outboard for a week
cruise and see for yourself.
If your choice lands on the
slower side of the equation, there
are two options to consider in the
2 to 10 hp range - electric and
propane. While these are not new,
they have both developed significantly over the past few years.
Talking with Ed Learne of Bridge
Yachts in Port Dover, we discussed
the ongoing development of the

Torqueedo electric motor for
dinghies. Of the four lines in their
outboard models, Torqueedo produces models with 2, 4 and 10
equivalent horse power in both remote and tiller versions.
According to Torqueedo's website, "Standardization of power is
nothing new. It goes back to James
Watt, who defined horsepower in
the 18th century to demonstrate
the performance of his steam engine. Since then, it has been measured uniformly in HP or, in honour
of its inventor, in watts." Referring
back to Figure. 1, my 3.1-meter inflatable is rated for a maximum 15
hp or 11.2 kW (kilowatts).
"... The most meaningful performance indicator of a drive system is propulsive power, which
indicates the performance actually
delivered by the motor to move
the boat, taking all losses, including
propeller losses, into account ...
The propulsive power of a gas
outboard with 4 HP shaft power,
for example, is just 1 HP. How can
the differences in efficiency levels
of different types of motor be
measured? We'll shed some light
on them." (Torqueedo.com > Technology) [Figure 2 Torqueedo
Power Equivalent]
In addition to all of this, the
Torqueedo Cruise comes with built
in Information Screen which includes all of the operating information a boater could need.
And then there is propane. The
first benefit of propane is that most
cruising sailors already have
propane on the boat and are able to
eliminate one fuel from the boat.
No gasoline - no ethanol. In addition, propane fueled engines burn
cleaner (up to 30% fewer emissions) and they require less maintenance. All key considerations when
cruising far from home. And the
weight? The Tohatsu 5 HP / 3.7
kW propane outboard has the same
power rating as the Mercury
Propane and Sail Power (gasoline)
engines and all three weigh the
same - 59.5 lbs or 21.2 kg. I had
SPRING 2020

http://www.Torqueedo.com

Canadian Yachting Special Feature: Dinghies and Davits Spring 2020

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