Boating and Sailing.pdf - Moja ladja

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Part 1: Getting Started in Boating
What Props Are Made Of
The materials used in making props are a compromise between durability, performance,
and price. Props are usually made out of one of the following:
◆ Aluminum
◆ Stainless steel
◆ Bronze
◆ Plastic
Let’s take a look at each of these materials in more detail.
Light, Cheap, and Bendable—Aluminum Props
Chances are that your first boat will come rigged with an aluminum prop. Aluminum is
not the best prop material, but it is one of the cheapest, and that’s the reason you see it on
most package rigs designated “entry-level” or “value-priced.”
But, as I must occasionally remind my wife, just because something is inexpensive doesn’t
mean it’s bad. (She in turn reminds me that “cheap” is not a synonym for “good.”) Prices
range from as little as $45 for an aluminum prop fitted to 6–10-horse motors up to about
$150 for props matched to the larger V6 outboards in stern drives. For the right application,
aluminum is just fine. Used on engines with moderate horsepower in areas where
bottom contact is unlikely, it’s the most common prop material, and survival can be
good—as long as you don’t hit bottom, an aluminum prop can last for as long as you keep
your boat.
Where you may hit rocks, shell bars, or even hard sand, an aluminum prop will soon
begin to look a bit worse for the wear. Those dings and bent blades greatly reduce performance
and can also create vibration that can ruin the lower-unit seals or bearings. Also,
aluminum props don’t have the required stiffness in thinner castings to give maximum
performance on large motors.
Stainless-Steel Reputation
Stainless steel is the material of choice for most seasoned boaters. It’s extremely tough
and rustproof, and the high strength allows it to be cast into very thin blades that slice
through the water more efficiently than the thicker blades required in aluminum castings.
Steel also holds its shape at extreme speed and load, while aluminums tend to flex, slightly
but enough to lose efficiency at maximum rpms on big motors.