Monthly Archives: August 2012

Boating Safety Tips from the U.S. Coast Guard

Prior to the official end of boating season in many parts of the country this weekend, the USCG is providing some extra tips.

Give your Small Boat a Quick Inspection Before Heading Out on the Water

It doesn’t require a 40 ft. cabin cruiser to enjoy the nation’s many lakes, rivers, and coastal waterways, but those operating small boats to engage in water-related activities do need to be aware of their boat’s limitations and behave accordingly. 

Statistically, more than 80 percent of all boating fatalities occur in boats less than 26 feet in length, often the result of capsizing or falls overboard. In many cases, a contributing factor is one or a combination of the Coast Guard’s Big 4: excessive speed, reckless operation, operator inattention/inexperience, and boating under the influence of drugs or alcohol.

But other factors point to hazards particular to smaller craft. In small, open-constructed boats, the wave-size-to-boat ratio is much less than on a larger boat, and a small boat will fill with water more quickly if washed over by a large wave, or even a small one. Transoms and helm station areas are wide open and the boats have smaller and fewer bilge pumps, or none at all. Also, decks are not watertight, and water can enter and damage the control cables, leaving the boat stranded.

Even empty, such boats have little to no freeboard (the distance between the rail or top edge of the boat and the waterline) and even less when fully loaded with occupants, food, and gear. It’s easy to overload these vessels unintentionally, and an overloaded boat is more likely to capsize, even in relatively calm waters.

So keep in mind your boat’s maximum load capacity. On most mono-hull boats up to 20 feet long, this information can be found on the capacity plate, permanently affixed to the hull by the manufacturer. It notes the maximum horsepower rating and maximum load weight at which the boat can safely operate.  If a capacity plate isn’t present, one easy formula for calculating the maximum load for a mono-hull boat is to multiply the boat’s length times its width and divide by 15.  As such, a 6 ft. wide, 18-foot boat can carry up to 7 people safely. 

To make capsizing even less likely, be sure your load is distributed evenly to keep the boat balanced. Standing for any reason in small boats, even changing seating positions, can raise the center of gravity and make the boat less stable. The same is true for sitting on the gunwales or seat backs, or on a pedestal seat while underway. A raised center of gravity means that a wave, wake, or sudden turn can result in a person falling overboard.

For safety’s sake, complete a pre-departure checklist prior to launch to make certain your boat is in good working order and has all the necessary safety equipment on board.  And, big boat or small, be sure to check the weather report and waterway conditions, bearing in mind that conditions considered safe for a 40-foot boat might be unsafe for one half that size.

Small boats are a lot of fun and important to many water-related activities.  Take a moment to do a 15-minute inspection before launch, watch your load, and mind the Big 4.  Make sure that all of your small boat journeys are safe ones.

 The U.S. Coast Guard reminds all boaters to “Boat Responsibly!” For more information and tips on boating safety, visit www.USCGboating.org.

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Weather 101 – Continued

Pressures and Measurements

High-pressure areas are generally cool, clear, calm and stable weather systems. Highs rotate in a clockwise direction circulating out from the center. On the other hand, lows which rotate counter clockwise, circulate in toward the center, and are associated with hot air, clouds, wind, deteriorating weather, and precipitation. The winds in the center of a low are the strongest.

Low-pressure areas are call cyclones and high-pressure areas are called anti-cyclones. A simple way to find the center of a low or a high-pressure area is to use a technique called Buys Ballots’ Law. To find the center of a low, face into the wind and extend your right hand directly out to your side. The center of the low will be slightly behind your right hand.

Using Buys Ballots’ Law, the opposite is true in finding the center of a high-pressure area. Again, face into the wind but this time extend your left hand out to your side. The center of the high will be slightly forward of your left hand.

Barometers are used to measure pressure. The first barometers measured inches of mercury. These large, easily broken devices (over 30 inches in height) relied on the atmospheric pressure to force a column of mercury up a tube. This mercury-filled tube was inverted into a bowl of mercury.  The changes in pressure made the mercury rise and fall. The differences were read on a scale near the top of the tube. A one-inch square column of air weighed an average of 14.7 pounds. This average weight would hold the mercury in a mercury barometer 29.92 inches up the tube. This average pressure also could be expressed as 1013 millibars.

Modern barometers are the non-liquid, aneroid type. These types are made up of a vacuum chamber, attached to a needle, which indicates barometric pressure on the face of the barometer. Higher than average pressure would push down on the vacuum chamber and result in the needle being pushed to a higher reading on the face. Subsequently, lower than average pressure would allow the chamber to rise resulting in a lower than average reading. The pressure readings may be expressed in inches of mercury or millibars or both. For the most part, modern day weather forecasters will use millibars to indicate barometric pressure. Most weather maps that you see will use millibars to show pressure rather than inches of mercury.

An aneroid barograph is attached to a plotter device that allows you to continually record the pressure changes over time. Barometric pressure is constantly changing and some of this pressure change has nothing to do with weather systems. Diurnal pressure variation for instance, a small naturally occurring pressure change happens twice each day with a high and a low cycle. These variations are normally high at 1000 and 2200 hours and low at 0400 and 1600 hours. These changes are small and often are less than 3 millibars or 0.1 inch of mercury.

Approaching weather systems cause significant barometric pressure changes. The prudent mariner keeps an eye on the barometer in order to help predict impending changes. As mentioned previously, high-pressure systems equate to cool, dry air and good weather while low-pressure systems indicate hot moist air and poor weather. The air in the cool high-pressure system is heavier than warm air in the low-pressure system. This heavier air causes the barometric pressure to rise while the lighter air in a low-pressure system causes the barometric pressure to fall.

In general, a barometric pressure higher than average (29.92 inches) would indicate cool, dry, stable weather approaching while a barometric pressure lower than that would indicate the approach of a possible storm. The key to forecasting is the rate and direction of change over time, especially when predicting the approach of the low. A barometric pressure reading of 28.82 would be considered well below average and may indicate the approach of a severe storm, perhaps even a hurricane. The table below shows a typical scenario that you might observe on your barometer over a three-hour period and what the drop in barometric pressure might indicate. 

Drop in Millibars

Drop in Inches of Mercury

Resulting Weather

3

.1

Approach of a tropical depression

6

.2

Force 6 winds (21-28 knots)

10

.3

Force 8 winds (34-40 knots)

12

.4

Near Hurricane strength

The length of time over which the barometer drops may indicate the length of time the storm will be active. A gradual drop over several hours would indicate a storm which may last for a period of time while a quick drop will indicate a storm that will approach quickly and leave just as quickly.

Lines on a weather map that connect equal points of pressure (much like depth contours on your nautical chart) are called isobars. These lines that connect points of equal pressure will be represented on the weather map at four-millibar intervals.

In high-pressure systems, the center of the high will contain the highest pressure and the pressures represented on the isobars will decrease four degrees for each isobar as you move away from the center.

Isobars that are closely spaced represent a rapid change and steep pressure gradient. Wind speeds will be greater in areas where you see the closely grouped isobars.

In low-pressure systems, the center of the low will contain the lowest pressure and the pressures represented on the isobars will increase four degrees as you move away from the center of the low. 

When forecasting weather, as in navigating, you should not rely on one sole source of information. The barometer is a simple and valuable tool but should be used in conjunction with other forecasting methods such as listening to VHF and SSB weather forecasts, receiving weather fax transmissions, etc.

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Weather 101 – Continued

Since the news has been almost non-stop following Tropical Storm and potential Hurricane Isaac, I thought I would continue the Weather 101 through this week. This may give followers of this Blog some insight into what meteorologists go through as they try to “accurately” predict the weather.

Weather and Weather Advisories

Everyone has heard the old saying, “if you don’t like the weather, wait ten minutes.” Actually, this can be truer than one might think. The weather is constantly changing and it appears in recent years that those changes are getting more drastic and subsequently dangerous. Even with all the most modern equipment, weather forecasting is still a “best guess” based on history, computer models, radar, barometers and other meteorological equipment.

Weather Principles

What causes weather? The basic weather principles are fairly straightforward. If you understand the following principles and how they interact with each other you will have a basic understanding of weather.

  1. The earth is tilted on its axis by 23.5 degrees.
  2. The earth rotates one full rotation every 24 hours.
  3. The earth’s surface is composed of land and water that heat and cool unevenly.
  4. Hot air rises.
  5. Air over land and water absorb moisture at different rates.

 How do these five principles interact to cause weather?

First let’s take the fact that the earth is tilted on its axis by 23.5 degrees. This tilt actually causes the seasons because parts of the earth’s surface are exposed to more sunlight than others. Those areas closest to the sun and exposed to the most direct sunlight are in summer season and those furthest from the sun and have the least sunlight are in winter season. As the sun’s relative position moves from 23.5 degrees north of the equator to 23.5 degrees south of the equator the seasons are created.

We know that the earth rotates 360 degrees in 24 hours that causes day and night. During the day the earth’s surface is warmed and this warmth is transferred to the air above the surface. At night the earth cools rapidly and subsequently the air above it is cooled as well.

How fast is the earth actually rotating? Since 360 degrees in 24 hours equates to 15 degrees per hour, and at the equator each degree equals 60 nautical miles, some simple math concludes that the earth is rotating at 900 miles per hour at the equator (15 x 60 = 900). North and south of the equator the distance around the earth is less than at the equator so the speed of rotation at points north and south of the equator would be less that at the equator. This situation causes Coriolis effect or horizontal deflection. The Coriolis effect causes winds to be deflected from the direction that they are attempting to move. It is the combination of the rising and falling of air and the Coriolis effect that makes weather systems in the United States generally move from west to east.

The uneven heating and cooling rates of the different surfaces of the earth (e.g. land and water) cause pressure systems and ties into the hot air rises principle. As one surface heats up rapidly and transfers that heat to the air surrounding it, that air rises causing a low-pressure area. As this air rises into the cooler atmosphere where, at some point, it becomes cool enough that now it falls back to earth creating a high-pressure area. When a low-pressure area was created, the cooler air from the high-pressure area moves in to fill the partial vacuum. Does the word circulation start to come to mind?

Warm air is able to hold more moisture than cool air. This difference in the ability to absorb water at different rates produces certain weather phenomenon. As moisture content builds in an air mass, clouds form and eventually rain and/or fog may follow.

To be continued…

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Weather 101 – What Clouds Tell Recreational Boaters

With all the current potential hurricane activity threatening the US, here is a reminder on how to “read” the weather to avoid finding yourself in a difficult situation.

You should not leave the dock without first checking the local weather forecast. You can get weather information from TV, radio, your VHF radio and on the Internet. While on the water, your VHF radio is the best source for weather warnings. Even so, at certain times of the year weather can change rapidly and you should continually keep a “weather eye” out, especially to the west, in order to foresee changes which might be impending.

Clouds are a tool you can use to predict or forecast weather. The type of cloud and direction of movement can warn you of weather changes that are imminent. Clouds are categorized by the altitude at which they appear and the shape that they take.

This is not an in-depth study of clouds, but an attempt to simplify the subject for use by recreational boaters.

Cloud Group Cloud Height Cloud Types
High Clouds = Cirrus Above 18,000 feet Cirrus
Cirrostratus
Cirrocumulus
Middle Clouds = Alto 6,500 feet to 18,000 feet Altostratus
Altocumulus
Low Clouds = Stratus Up to 6,500 feet Stratus
Stratocumulus
Nimbostratus
Clouds with vertical growth   Cumulus
Cumulonimbus

It is helpful to remember the following definitions of cloud shapes:

cumulus5.jpg (2658 bytes) Cumulus meaning “heap, a pile, an accumulation”
stratus5.jpg (3159 bytes) Stratus meaning “spread out, flatten, cover with a layer”
stormcloud2.jpg (2474 bytes) Nimbus meaning “rainy cloud”

Variations of cloud types are created by combining the cloud’s shape/description with the altitudinal names as a prefix or suffix.

Cirros (high) or Cirro can be used with cumulus (heap) to indicate a cirrocumulus or high, lumpy cloud. Cirrocumulus clouds, sometime called “mackerel skies”, can indicate the approach of a hurricane in the tropics. It can also be used with stratus (flat, layered)as in cirrostratus to indicate a high, flat or layered cloud.

Alto can also be used with cumulus and stratus to indicate altocumulus and altostratus which are middle altitude lumpy clouds and middle altitude layered clouds respectively.

Nimbo or nimbus might be used with cumulus or stratus to indicate a cloud formation that is producing precipitation. These clouds could be either cumulonimbus which would be a lumpy, vertically-rising rain cloud or nimbostratus which would be a sheet or flat-looking rain cloud.

High clouds exist above 18,000 feet and are cirrus clouds.

cirrus.jpg (2106 bytes) Cirrus clouds are the most common of the high clouds. They are composed of ice and consist of long, thin, wispy streamers. Cirrus clouds are usually white and predict fair weather. Sometimes called mares tails, they stream with the wind. By watching the movement of cirrus clouds you can tell from which direction weather is approaching. The appearance of cirrus clouds usually indicates that a change in weather will occur within 24 hours.
cirrostratus.jpg (2244 bytes) Cirrostratus are sheetlike, thin clouds that usually cover the entire sky. The sun or moon can shine through Cirrostratus clouds. Cirrostratus clouds usually come 12-24 hours before a rain or snow storm.
cirrocumulous.jpg (1969 bytes) Cirrocumulus are small, rounded puffs that usually appear in long rows. They are usually white, but sometimes appear gray. Cirrocumulus are usually seen in the winter and indicate fair, but cold, weather. In the tropics, they may indicate an approaching hurricane.

Medium high clouds occupy altitudes of 6,500 feet to 18,000 feet. These clouds are called alto clouds. Alto clouds are used to predict weather changes in 6 to 12 hours.

altostratus9.jpg (2660 bytes) An Altostratus cloud usually covers the whole sky. The cloud looks gray or blue-gray. The sun or moon may shine through an Altostratus cloud, but will appear hazy. An altostratus cloud usually forms ahead of storms with continuous rain or snow.
altocumulus.jpg (2601 bytes) Altocumulus clouds are grayish-white with one part of the cloud darker than the other. Altocumulus clouds usually form in groups. If you see Altocumulus clouds on a warm, sticky morning, be prepared for thunderstorms by late afternoon.

Low clouds, called stratus clouds, are at altitudes up to 6,500 feet. These clouds form a solid sheet or layer of cloud mass.

stratus2.jpg (3278 bytes) Stratus clouds are uniform gray in color and almost cover the entire sky. Light mist or drizzle is sometimes associated with Stratus clouds.
stratocumulus.jpg (3331 bytes) Stratocumulus clouds are low, lumpy and gray. Most form in rows with blue sky visible in between. Precipitation rarely occurs with Stratocumulus clouds, however, in frontal weather they may turn to Nimbostratus.
nimbostratus.jpg (3293 bytes) Nimbostratus clouds are dark gray with a ragged base. Rain or snow is associated with Nimbostratus clouds.

Clouds with vertical growth

cumulus2.jpg (3420 bytes) Vertically developing clouds are the Cumulus type. These small, lumpy clouds are low “fair weather” clouds. However, as they develop vertically (by rising hot air) they may go from small, fair weather clouds to large, boiling, vertically-growing monsters called cumulonimbus.
cumulonimbus.jpg (3273 bytes) Cumulonimbus are generally known as thunderstorm clouds. High winds will flatten the top of the cloud into an anvil-like shape. Cumulonimbus are associated with heavy rain, snow, hail, lightning, and tornadoes. The anvil usually points in the direction the storm is moving.

If you still can’t remember all of the cloud names and formations, you can always watch the clouds for two specific weather situations that indicate a high probability of a storm:

    1. A “lowering ceiling”: This means that the height of cloud formations continues to get lower and lower, usually caused by a warm front. As the ceiling lowers you will see clouds in the following order:
  • Cirrus
  • Cirrostratus
  • Altostratus
  • Stratus
  • Nimbostratus – storm clouds!
    2. On the other hand, watch for cumulus (puffy) clouds that start to rapidly develop vertically to become cumulonimbus thunderstorm clouds. On hot and humid days, these storms occur over water as the radiant heat from the land absorbs moisture from nearby water and rises to produce thunderheads. These storms can also indicate a cold front and may be preceded by squall lines, a row of black storm clouds. Wind shifts unpredictably and accelerates dramatically. Lightning can occur for miles in front of a storm and after the storm appears to have passed.

Other things to look for that indicate an approaching weather change:

  • Weather changes generally come from the west so scan the sky with your weather eye, especially to the west.
  • A sudden drop in temperature and change in the wind (increasing winds and/or seas) often means that a storm is near.
  • If you have a barometer on your boat check it every two to three hours. A rapid drop in pressure means a storm is approaching.

IF A STORM IS NEAR…

  • Reduce speed and proceed with caution
  • Put on PFDs.
  • Close all hatches and ports.
  • Head for the nearest shore that is safe to approach and duck into the lee of land.
  • Put the bow into the wind and take waves at about a 40-45 degree angle.
  • Watch for other boats and floating debris.
  • Pump out bilges and keep dry.
  • Change to a full fuel tank.
  • If there is lightning, unplug electrical equipment and keep away from ungrounded metal objects.
  • Secure loose items which could be tossed about.
  • Keep everyone low in the boat and near the centerline.

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Properly Loading Your Boat

The Coast Guard requires all single-hulled boats of less than 20 feet in length to have a capacity plate, installed where it is visible from the operator’s station. Since most boats in the U. S. are less than 20 feet in length, boaters need to know what it says and why.

Capacity plate showing maximum horsepower and poundsThe capacity plate tells you the maximum number of people or carrying weight in pounds, and the maximum horsepower recommended for the boat. Overloading your boat, either in weight or in power, can be fatal.

 

Do not exceed the maximum capacity as shown on the boat’s capacity plate.

A motor larger than recommended will make the stern too heavy and can cause the boat to flip. The transom will ride too low in the water and you could be swamped by your own wake or a passing boat’s wake. Your boat will not sit properly in the water and will be difficult to handle.

If there is no such label or plate on your boat, use the formula “number of people= (length of boat)times (width of boat)divided by 15”.

When you’re loading your small boat at the dock, have someone stand in the center part of the boat while you hand things into the boat to them. Don’t step or jump into a small boat loaded down with the ice chest, soda, and snacks.

Too many people (and/or gear) will also cause the boat to become unstable. Always balance the load so that your boat maintains proper trim. Too much weight to one side or the other will cause the boat to list and increase the chance of taking on water. Too much weight in the bow causes the boat to plow through the water, and too much weight in the stern will create a large wake. All of these situations make the boat difficult to handle and susceptible to swamping.

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Naval Vessel Protection Zone

As I strolled the docks recently I noticed how close some of the curious recreational boaters were getting a Navy vessel berthed there. Apparently a lot of recreational boaters are not aware of the security laws that could cost them a lot of money. Even some of the commercial tour boats which require USCG licensed captains were coming extremely close.

In light of new security measures brought about by the events of September 11, 2001, it is critical that all boaters be aware of and comply with new homeland security measures set forth by federal, state and local governments. These should include, but are not limited to:

  • keeping a safe prescribed distance from military and commercial ships
  • avoiding commercial port operations areas,
  • observing all security zones,
  • following guidelines for appropriate conduct such as not stopping or anchoring beneath bridges or in a channel, and observing and reporting suspicious activity to proper authorities.

100-Yard-Approach WARNING!

Do not approach within 100 yards of any U.S. naval vessel. If you need to pass within 100 yards of a U.S. naval vessel in order to ensure a safe passage in accordance with the Navigation Rules, you must contact the U.S. naval vessel or the Coast Guard escort vessel on VHF-FM channel 16.

You must operate at minimum speed within 500 yards of any U.S. naval vessel and proceed as directed by the Commanding Officer or the official patrol.

Violations of the Naval Vessel Protection Zone are a felony offense, punishable by up to 6 years in prison and/or up to $250,000 in fines.

Boaters Can Help Keep Our Waterways Safe and Secure…

Navy Ship approaching dockKeep your distance from all military, cruise line, or commercial shipping! Do not approach within 100 yards, and slow to minimum speed within 500 yards of any U.S. naval vessel. Violators of the Naval Vessel Protection Zone face 6 years in prison and a $250,000 fine, not to mention a quick and severe response. Approaching certain other commercial vessels may result in an immediate boarding.

A port with container cranesObserve and avoid all security zones. Avoid commercial port operation areas, especially those that involve military, cruise line or petroleum facilities. Observe and avoid other restricted areas near dams, power plants, etc. Violators will be perceived as a threat, and will face a quick, determined and severe response.

Ben Franklin Bridge

Do not stop or anchor beneath bridges or in the channel. If you do, expect to be boarded by law enforcement officials.

Young girl looking through binoculars

Keep a sharp eye out for anything that looks peculiar or out of the ordinary. Report all activities that seem suspicious to the local authorities, the Coast Guard and the port or marina security. Do not approach or challenge those acting in a suspicious manner.

Safer boaters help reduce public demands by permitting Marine Patrols to focus their limited resources on Homeland Security.

For more information on security zones and how you can help, call the Coast Guard at 800-368-5647 or go to the USCG website at http://www.uscgboating.org/

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How Old Are Your Charts?

In an effort to inform boaters about the importance of up-to-date navigational information, several boating industry leaders have announced that they have joined forces to form the Alliance for Safe Navigation. Sponsored by NOAA, the Alliance consists of BoatU.S., Jeppesen Marine, the United States Power Squadrons (USPS), OceanGrafix and the Sea Tow Foundation for Boating Safety and Education.

Is your chart current?

The purpose of the Alliance is to raise boater awareness about the importance of having and using the most current navigation information to avoid potential groundings and other accidents. The Alliance has identified a widespread lack of awareness among boaters regarding the accuracy of their charts, whether electronic or paper. The truth is that inaccurate chart information can turn a safe and enjoyable cruise into a dangerous situation.

Unlike commercial mariners, who are required by law to carry up-to-date charts, recreational boaters are not held to the same regulation. In fact, recreational boaters aren’t required to have any charts onboard. Nautical charts, whether paper or electronic, can become quickly outdated as storms and currents alter waterway topography or aids to navigation change with little warning.

Boaters can go to http://www.allianceforsafenavigation.org/ and enter the numbers of their most commonly used charts and instantly see a list of all the changes for that chart since the last print date. Some boaters and anglers will be surprised at the number of updates posted for their local waters.

Many boaters don’t realize that even though they have a GPS and a chartplotter, the electronic charts in their receiver may be just as out-of-date as their paper charts. Fortunately, updating is easier than ever with print-on-demand charts and free NOAA downloads available. Manufacturers of chart products also have update subscriptions to alert their customers when a new edition is released.

Keeping electronic and paper charts up-to-date is inexpensive and easy. The Alliance’s goal is to educate the boating community about how quickly their charts can become outdated and how easy it is to keep them current. In addition, the Alliance wants to encourage boaters to be aware of the significant and frequent changes that are occurring in their local boating area.

For more information or to be surprised as to how many changes have been made to your charts, go to http://www.allianceforsafenavigation.org/.

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