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The Terminology of Boat Technology

When it comes to boat terminology, constantly changing methods and materials can contribute to increased confusion.
Boating Safety


CATHODIC PROTECTION: A means of preserving certain metals against erosion from electrolysis by attaching sacrificial metals more susceptible to electrolysis.

PROPELLER CAVITATION: Extreme diversity between pressure on the front and back sides of a propeller blade causes the water to actually vaporize (boil), which can cause loss of ­efficiency and damage the propeller.

PROPELLER CUP: The curved lip on the trailing edge of a propeller blade that reduces slippage and ventilation, and improves hole shots.

PROPELLER DIAMETER: The distance from the center of the hub to the extreme tip of the blade times two. On a list of prop specifications, this is always the first number.

PROPELLER PITCH: This theoretical number is a movable feast. It refers to how far forward the propeller should move in a single revolution. Pitch is inexact, however, because slippage is always present in varying degrees. Pitch is always the second number listed in propeller specifications.

PROPELLER RAKE: The angle at which propeller blades slant forward or ­backward compared to the hub.

PROPELLER SLIPPAGE: Slippage is where the real world meets theory. This number represents the difference between theoretical pitch and how far the propeller actually moves through the water in a single revolution. Experts agree that the right propeller for a given vessel should move through the water at approximately 80 percent to 90 percent of the pitch.

PROPELLER VENTILATION: Often confused with cavitation, ventilation occurs when air or exhaust surround the propeller blades in a turn or when the vessel is incorrectly trimmed. Ventilation causes over-revving and loss of boat speed and efficiency.

ZERO-EMISSION GENERATOR: A ­gasoline generator that emits 99 percent less carbon monoxide.

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The U.S. Coast Guard is asking all boat owners and operators to help reduce fatalities, injuries, property damage, and associated healthcare costs related to recreational boating accidents by taking personal responsibility for their own safety and the safety of their passengers. Essential steps include: wearing a life jacket at all times and  requiring passengers to do the same; never boating under the influence (BUI); successfully completing a boating safety course; and getting a Vessel Safety Check (VSC) annually from local U.S. Coast Guard Auxiliary, United States Power Squadrons(r), or your state boating agency's Vessel Examiners. The U.S. Coast Guard reminds all boaters to "Boat Responsibly!" For more tips on boating safety, visit

Mar 3, 2012

I thought it was Length Over All, and LoW was Length Over Water.

Mar 3, 2012

fishing is a fun magical time for the young and old

"Tean Lucky" (not verified)
Jan 1, 2012

LOA...This is a common misconception of many people! Most of the manufactures and boat dealers call the LOA, "Length on Axis", in order to confuse the buyer into thinking the boat is larger than it actually is.
This is why you should always ask what the real length is! Many people would buy say a Model 1900 of XYZ brand only to find out later that the real length of the boat is say 18'1" not adding in the bow pulpit or the transom platform. It's a tricky little deal to get more boat for your money!
Measure any boat from the bottom of the transom V to the point of the bow to get your real length!
This started back when dealers would add a optional "bolt" on transom platform and add the length into the boat . Not illegal by any means, just sales trick.

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