Lake Tahoe is a large freshwater lake in the Sierra Nevada of the United States. At a surface elevation of 6,225 ft (1,897 m), it straddles the border between California and Nevada, west of Carson City. Lake Tahoe is the largest alpine lake in North America. Its depth is 1,645 ft (501 m), making it the second deepest in the United States after Crater Lake (1,945 ft (593 m)). Additionally, Lake Tahoe is the sixth largest lake by volume in the United States at 122,160,280 acre·ft (150,682,490 dam3), behind the five Great Lakes.
The lake was formed about 2 million years ago and is a part of the Lake Tahoe Basin with the modern lake being shaped during the ice ages. It is known for the clarity of its water and the panorama of surrounding mountains on all sides. The area surrounding the lake is also referred to as Lake Tahoe, or simply Tahoe. More than 75% of the lake’s watershed is national forest land, comprising the Lake Tahoe Basin Management Unit of the United States Forest Service.
Lake Tahoe is a major tourist attraction in both Nevada and California. It is home to a number of ski resorts, summer outdoor recreation, and tourist attractions. Snow and skiing are a significant part of the area’s economy and reputation. Mountain and lake scenery are attractions throughout the year. The Nevada side also includes large casinos. Highways provide year-round access to the area.
Artificial lake: A lake created by flooding land behind a dam, called an impoundment or reservoir, by deliberate human excavation, or by the flooding of an excavation incident to a mineral extraction operation such as an open pit mine or quarry. Some of the world’s largest lakes are reservoirs like Hirakud Dam in India.
Endorheic lake, terminal or closed: A lake which has no significant outflow, either through rivers or underground diffusion. Any water within an endorheic basin leaves the system only through evaporation or seepage. These lakes, such as Lake Eyre in central Australia, the Aral Sea in central Asia, or the Great Salt Lake in the Western United States, are most common in deserts.
Meromictic lake: A lake which has layers of water which do not intermix. The deepest layer of water in such a lake does not contain any dissolved oxygen. The layers of sediment at the bottom of a meromictic lake remain relatively undisturbed because there are no living aerobic organisms.
Fjord lake: A lake in a glacially eroded valley that has been eroded below sea level.
Oxbow lake: A lake which is formed when a wide meander from a stream or a river is cut off to form a lake. They are called “oxbow” lakes due to the distinctive curved shape that results from this process.
Rift lake or sag pond: A lake which forms as a result of subsidence along a geological fault in the Earth’s tectonic plates. Examples include the Rift Valley lakes of eastern Africa and Lake Baikal in Siberia.
Underground lake: A lake which is formed under the surface of the Earth’s crust. Such a lake may be associated with caves, aquifers or springs.
Crater lake: A lake which forms in a volcanic caldera or crater after the volcano has been inactive for some time. Water in this type of lake may be fresh or highly acidic and may contain various dissolved minerals. Some also have geothermal activity, especially if the volcano is merely dormant rather than extinct.
Lava lake: A pool of molten lava contained in a volcanic crater or other depression. Lava lakes that have partly or completely solidified are also referred to as lava lakes.
Former: A lake which is no longer in existence. Such lakes include prehistoric lakes and lakes which have permanently dried up through evaporation or human intervention. Owens Lake in California, USA, is an example of a former lake. Former lakes are a common feature of the Basin and Range area of southwestern North America.
Buoy Installation Lake Tahoe California
Unlike ordinary anchoring, a permanent mooring system is designed for leaving your boat unattended for long intervals. A mooring, in many cases, is the safest and most cost effective way to leave a boat in the water, whether riding out a storm or leaving it til next weekend. The following is a guide to building your own mooring; it provides an outline of common practices, including recommendations from maritime authorities such as Chapmans and various harbormasters. Whenever installing a mooring, it is absolutely necessary to first check with local harbormaster. Before purchasing gear, find out the ground tackle requirements in your harbor.
Anchor – think heavy Buoy Installation Lake Tahoe California
Mooring anchor Buoy Installation Lake Tahoe California
The anchor weight and type are crucial to holding strength on any mooring. The more exposed a mooring site, the rougher it will be during storms. For exposed moorings go supersize. Exposure to open sea or fetch allows wave and wind strength to build enough force to drag gear around. On the other hand, protected inlets require less hefty ground tackle. In general, permanent moorings are designed with less scope than traditional anchors, thus forming a tighter swing radius. The compromise, shortened scope means a more effective anchor is required. Therefore, a permanent mooring anchor must be significantly heavier than your everyday use anchor. Mooring scope from anchor to the end of pennant should be at minimum 3 times the depth of water at highest tides. Your local harbormasters will specify type and weight of approved mooring anchors in the harbor.
An approved professional mooring installer can set the whole rig for you for a fee. Most towns have a list of approved installers in the area. Professionals installers can also offer more than just the traditional anchors. Helical screws driven into sand bottom seabed with a hydraulic tool have superior holding power. Pioneered by oil rigs decades ago, sand screws leave only an exposed eye to connect tackle. Along with better holding power, sand screws are less likely to foul, but they’re also easy to lose should the gear part. Newer Hazelett Elastic Mooring Systems also offer amazing forgiveness in extreme weather with their elastic technology, but the gear can be a significant investment. Other areas may require several anchor points connected in a bridle system. Whenever setting up a mooring for the first time, ask around to find what works best in your harbor of choice.
Anchors Buoy Installation Lake Tahoe California
Several types are in common use, and we’ll review them in order of their holding power, from the wimpiest to the most tenacious:
Concrete Blocks: Many boats use 50-gallon drums filled with cement, concrete blocks, auto engine blocks and other types of dead weight. This type provides the least holding power, working on the principle of sheer weight, but is reliable if pulled out of the bottom. If they drag, they will resist motion with a constant amount of force. Note that concrete loses over half of its weight when submerged in water, so a mooring designed to withstand a 500lb. the pull will need 1,000lb. of concrete.
Mushroom Anchor: the most common type of mooring anchor is the mushroom, which, under ideal conditions, with the right kind of bottom, can dig in, create suction and develop good holding power. Mushroom anchors work best in a silt or mud bottom and are not as effective in rocks or coarse sand. If a mushroom gets pulled out of the bottom, it is less likely to reset itself completely, and will merely skip along across the bottom. A weight of 5-10 times boat length is a good rule of thumb, as a bare minimum. The heavier the better, as long as you don’t have to move it.
Pyramid Anchor: The cast-iron Dor-Mor pyramid anchor is a superior alternative to the mushroom. Its smaller size, concentrated weight and pyramid shape allows it to embed itself more rapidly, and its holding power (at a scope of 3:1) is up to about ten times its weight. Recommended by Practical Sailor/Powerboat Reports in 2009.
Helical Screw: while the above types rely for holding power on sheer weight or a combination of weight and embedding themselves in the bottom, the helical anchor is screwed into the seabed, usually by a barge-mounted hydraulic device. Helical screws have long, high-tensile steel shafts (8′ length is common) with large screw threads (10″ to 14″ diameter) on the bottom and an attachment eye at the top. These professionally-installed anchors, originating in the offshore oil industry, have gained popularity with recreational boaters since the 1990s, and have the most extreme holding power in relation to their weight.
The table below provides a comparison of the holding power of the different anchor styles:
Mooring chain Buoy Installation Lake Tahoe California
Chapman’s recommends two sections of galvanized chain: a heavier, primary chain and a lighter, secondary chain. The primary (ground) chain lies on the bottom. Its length should be 1 1/2 times maximum water depth. The secondary (riding) chain, is connected to the ground chain with a galvanized shackle or swivel. It’s usually half the size of the ground chain and equal in length to maximum water depth. The heavier chain is not used for the entire run so that the mooring buoy does not have to support an excessive amount of weight.
Mooring buoy Buoy Installation Lake Tahoe California
The sole purpose of the mooring buoy is to support the mooring chain. The two preferred designs for mooring buoys are a traditional buoy with hardware or a buoy with a tube through the center. Both offer reliable flotation and will last for several seasons, depending upon the salinity of the water. Obviously, freshwater applications will extend the useful life of any mooring system.
The buoy must have about twice as much flotation as the suspended chain has weight in order for it to ride high enough in the water to be visible. The Taylor Sur-Moor™ T3C™ buoys allow you to pass the chain through the center of the buoy, and attach the pendant on top. Secure the mooring chain at the top using a 4″ galvanized O-ring, such as Model 201105, and add the T3C™ Mooring Collar to protect the buoy from wear by the anchor chain and extend its lifespan.
Mooring pendant Buoy Installation Lake Tahoe California
The pendant (pronounced “pennant”) attaches the chain to the boat. Large-diameter three-strand nylon line is used because its inherent elasticity (stretching about 10 percent under a load equaling 20 percent of its tensile strength) allows it to act as a shock absorber. Polyester line, Dyneema line or stainless steel wire is preferred by some for better chafe resistance. Length should be about 2 1/2 times freeboard. Diameter should be as large as is practical—it must be able to fit through bow chocks and around a bow cleat.
Effective chafe protection is recommended for the point where the pendant passes through a chock. This is critical, as a failure caused by chafe at this location is one of the main reasons why boats end up on the beach. A light pick-up buoy at the boat end makes it easy to grab the pendant.
Moorings Buoy Installation Lake Tahoe California
Replacement: Taylor’s Storm Surge Anchor System allows three anchors on a swivel. For real holding power, we would use real anchors instead of the concrete blocks in Taylor’s diagram!
Cyclone Mooring Pendants, a new product line made from STS-12 Dyneema line, was developed by Nantucket Moorings in conjunction with MIT. Traditional pendants are made from three-strand nylon, to absorb shocks by their elastic nature. This stretch, while allowing your boat a comfortable, cushioned ride, allows the line to move across the bow chocks, creating friction and causing chafe.
Cyclone Pendants are attached (using a lunch pail hitch, also called a “cow hitch”) to your standard nylon pendant with its floating pickup buoy, and allow the the use of a low-stretch upper section. Their high tensile strength allows smaller lines to be used, so they fit more easily on boats with smaller cleats and chocks. Very low elongation result in a dramatic reduction in friction, heat, and chafing. Also, because the top and bottom sections are just looped together through spliced eyes, you can replace a damaged section without replacing the entire pendant.
Surviving a storm Buoy Installation Lake Tahoe California
Hurricanes making landfall in locations along the Eastern Seaboard have wrecked hundreds of boats over the past twenty years, many of which were driven ashore with their complete and intact mooring systems still attached. Weather forecasters predict that we’re now in a period where we can expect more storms of greater destructive force. Just how large does a mooring system need to be, in case you’re caught by extreme weather with the boat swinging on its mooring? The following chart gives an estimate of the wind loads (based on the windage of the vessel) and the required size of a pyramid anchor.
Aids to navigation Buoy Installation Lake Tahoe California
Aids to navigation are special structures like lighthouses, lightships, beacons, buoys, etc that are used to enhance safety by providing more opportunities to obtain LOPs.
These lights and marks are prescribed across the world by the International Association of Lighthouse Authorities (IALA). In 1977 this IALA endorsed two maritime buoyage systems putting an end to the 30 odd systems existing at that time. Region A – IALA A covers all of Europe and most of the rest of the world, whereas region B – IALA B covers only the Americas, Japan, the Philippines and Korea. Fortunately, the differences between these two systems are few. The most striking difference is the direction of buoyage.
All marks within the IALA system are distinguished by:
Shape
Colour
Topmark
Light
Light identification
During daytime, the identification of aids to navigation is accomplished by observing: location, shape, color scheme, auxiliary features (sound signals, RACON, RC, etc) or markings (name, number, etc).
During the night, we use the features of the aid to navigation’s light to both identify it and ascertain its purpose. There are three features to describe the light:
Colour: Either white, red, green or yellow. If no color is stated in the chart, the default is white.
Period: The time in seconds needed for one complete cycle of changes. period of light The arrow indicates the 10 second period of this flashing light “Fl(3) 10s”.
Phase characteristic: The particular pattern of changes within one complete cycle (hence, within one period). Below are the most common types:
Fixed F
Fixed This light shines with an unblinking and steady intensity and is always on. In this example, a yellow fixed light is shown.
Flashing Fl:
Flashing The duration of the light is always less than the duration of the darkness. The frequency does not exceed 30 times per minute.
Quick Flashing Q:
Quick Flashing Again, the duration of the quick flash is less than the darkness. The frequency is at least 60 times per minute.
Very Quick Flashing VQ:
Very Quick Flashing Also here, the duration of the very quick flash is less than the darkness. The frequency is at least 100 times per minute.
Interrupted Quick Flashing IQ:
Interrupted Quick Flashing Like Quick Flashing with one moment of darkness in one period.
Isophase Iso:
Isophase or Equal Interval (E int). This Light has an equal duration between light and darkness. A period consists of both a light and a dark interval. Also called Equal Interval (E Int).
Group Flashing Gp Fl(x+x):
Group flash (2+3) This is actually a combination of two patterns in one period. In this example, the first 2 flashes followed by the pattern of 3 flashes result in Gp Fl(2+3).
Occulting Occ:
Occulting is the opposite of flashing, the light is more on then off.
Alternating AL:
Alternating White Green An alternating light changes color. This special purpose light is typically used for special applications requiring the exercise of great caution. In this example ALT.WG is shown, alternating between green and white.
Morse U-Mo (U):
Morse code: U This light shows two flashes and a long flash, which is equivalent to the letter “U” in Morse code.
Long-Flashing LFl:
Long Flash This light has one long flash in a period. A long flash is at least 2 seconds long.
Let’s look at some examples using color, period and phase characteristics.
Six types of navigation buoys:
Lateral
Cardinal
Isolated danger
Safe water
New wreck
Special
Lateral buoys and marks
The location of lateral buoys defines the borders of channels and indicates the direction. Under IALA A red buoys mark the port side of the channel when returning from sea, whereas under IALA B green buoys mark the port side of the channel when sailing towards land. Red buoys have even numbers and red lights; green buoys have odd numbers and green lights. Lateral lights can have any calm phase characteristic except FL (2+1).
Lateral red buoy.Lateral green buoy.
Preferred channel to starboard: keep buoy to port (IALA A). Generally, when two channels meet, one will be designated the preferred channel (i.e. most important channel). The buoy depicted on the right indicates the preferred channel to starboard under IALA A. The light phase characteristic is R-FL (2+1): Red buoy indicating a preferred channel to port (in USA, Japan.
Preferred channel to port: keep buoy to starboard (IALA A).The buoy depicted on the left indicates the preferred channel to port under IALA A. These buoys are marked with the names and numbers of both channels. The light phase characteristic is G FL (2+1):
Green buoy indicating a preferred channel to starboard (in USA, Japan).
For an example of lateral buoys used to mark a (preferred) channel, see the direction of buoyage below.
Cardinal buoys Installation Lake Tahoe California
The four cardinal buoys indicate the safe side of a danger with an approximate bearing. For example, the West cardinal buoy has safe water to its West and the danger on its East side. Notice the “clockwise” resemblance of the light phase characteristics. The top marks consist of two black triangles placed in accordance with the black/yellow scheme of the buoy. When a new obstacle (not yet shown on charts) needs to be marked, two cardinal buoys – for instance a South buoy and an East buoy – will be used to indicate this “uncharted” danger. The cardinal system is identical in both the IALA A and IALA B buoyage systems.
Cardinal buoys around a selection of dangers.
Marks indicating isolated dangers Buoy Installation Lake Tahoe California
Marks indicating isolated dangers.This type of buoy indicates the position of an isolated danger, contrary to cardinal buoys which indicate a direction away from the danger. Body: black with red horizontal band(s); Topmark: 2 black spheres. The light (when present) consists of a white flash: Fl(2).
Marking of isolated dangers Buoy Installation Lake Tahoe California
Marks indicating safe water. Notice that whereas most horizontal striping spells “danger”, this safe water buoy is vertically striped. These marks are for example seaward of all other buoys (lateral and cardinal) and can be used to make landfall. Body: red and white vertical stripes; Topmark (if any): single red sphere. Lights are typically calm and white: Morse A, Iso, Occ or LFl 10s.
Marks for new wrecks Buoy Installation Lake Tahoe California
After the sinking of the “Tricolor” in the Pas de Calais (Dover Straits) in 2002, several other vessels hit the wreck despite standard radio warnings, three guard ships, and a lighted buoy. This incident spawned a new type of buoy, the emergency wreck marking buoy, which is placed as close as possible to a new dangerous wreck.
Emergency wreck marking buoy for new wrecks
The emergency wreck marking buoy will remain in position until a) the wreck is well known and has been promulgated in nautical publications; b) the wreck has been fully surveyed and exact details such as position and least depth above the wreck are known, and c) a permanent form of marking of the wreck has been carried out.
The buoy has the following characteristics:
A pillar or spar buoy, with size dependent on location.
Coloured in equal number and dimensions of blue and yellow vertical stripes (minimum of 4 stripes and a maximum of 8 stripes).
Fitted with an alternating blue and yellow flashing light with a nominal range of 4 nautical miles where the blue and yellow 1-second flashes are alternated with an interval of 0.5 seconds.
B1.0s + 0.5s + Y1.0s + 0.5s = 3.0s New wreck light character.
If multiple buoys are deployed then the lights will be synchronized.
A racoon Morse Code “D” and/or AIS transponder can be used.
The top mark, if fitted, is a standing/upright yellow cross.
It is important to realize – especially for the colour-blind – that this new buoy breaches the useful and crucial convention: vertical stripes equal safety, horizontal stripes equal danger.
Special buoys and marks Buoy Installation Lake Tahoe California
Marks used for special indication.
I have saved these buoys for last since they lack an actual navigational goal. Most of the time these yellow buoys indicate pipelines or areas used for special purposes.
I have drawn the five official IALA shapes, from left to right: conical, spar, cylindrical, pillar and spherical.
Buoy Installation Lake Tahoe California.
Chart symbols Buoy Installation Lake Tahoe California
The seafaring nations of the world – members of the International Hydrographic Organization – agreed in 1982 on a universal set of chart symbols, abbreviations, colors, etc to be used in the nautical chart, in order to obtain uniformity.
On regular charts, a white, red, yellow or green lights will be indicated by Standard chart light color, and on GPS displays and modern multi-coloured charts in specific colors: Lights in the multicoloured nautical chart, with the yellow colored lobe indicating a white light.
The precise position of a chart symbol is its center, or is indicated with a line and circle Position of chart symbol, the “position circle”.
Buoy Installation Lake Tahoe California.