Top Boats 2009

Top Boats 2009

Waterproof Torches: The Best Boat Light

Whether you’re spending time on the water in a boat, raft, canoe or inner-tube it is always a good idea to have a handheld light easily accessible. You can never predict what circumstances may cause your plans to keep you out past dark. In most areas, a working light is mandatory on all vessel, large boats as well as canoes and kayaks. While large ships and boats require strong, spotlights as well as handheld flashlights, a compact, portable waterproof flashlight is perfect for a smaller vessel.

Waterproof Flashlight Must Haves

There are a number of aspects to consider when looking for a good waterproof flashlight to keep on board your vessel.

Size: A waterproof flashlight should be easy to carry and access at any time. Avoid bulky handheld lights you are apt to leave at home rather than take with you on a small boat. If possible, have two lights, one small one that you can attach to your life jacket or fishing vest and a larger one that is tied into the boat.

Directional: Large sailing vessels utilize stationary mounted boat lights to handle their emergency light needs. If you are in a smaller vessel you are going to want a handheld flashlight that can be easily aimed in a direction quickly. Even large vessels should have several torches easily available in addition to mounted lights.

Easy-To-Use: Find a flashlight or waterproof torch that is simple to operate. If it has multiple light beam settings, make sure the transitions can be made easily in an emergency.

Durable: Make sure that the casing and construction of the torch itself can handle the ruggedness of river rafting, boating and any emergency that may occur in that environment.

A well-constructed waterproof flashlight is exactly the kind of light that can provide the reliability you will need. LED (light-emitting diode) waterproof torches can also provide more energy efficiency, longer battery and bulb life than regular incandescent bulb lights. These LED lights are slightly more expensive to buy than a traditional flashlight, but the longer battery and bulb life will save you significant dollars in the long-run.

Extra Flashlight Features

Waterproof flashlights can serve many different purposes, especially if you purchase a light that has multiple colors, brightness variation, and flashing features. Different colored lights can serve several purposes. A red light can be used to signal boats in case of an emergency. A blue light can help you preserve your night vision if alone on the water and a green light can help attract fish during night fishing. A waterproof torch with a flashing light feature can be used as a signal beacon. Other handheld lights have a dimmer or focus switch that allows you to create a wider beam of light to scan an entire lake or a narrow beam to focus out on a distant place downstream. These are all useful features to have at your fingertips while on the water.

Whether you’re boating, rafting, canoeing, or kayaking, you should always carry an emergency light with you that can hold up to the conditions a watery adventure can bring about.

~Richard McNeal, 2009

About the Author

Richard McNeal writes from his home in Portland, OR. Check out
Coast LED product reviews
to better understand the benefits of a
quality handheld waterproof light
in practical situations.

physics problem? need to be solved?

Hi all

Consider the following two-dimensional problem: A 1 kg projectile is launched from the top of a 120 m cliff, with an initial speed of 75 m/s at an angle of 60o as shown in the figure.

http://images.upload2world.com/get-7-2009-upload2world_com_odwes.JPG

or this

At what distance from the base of the cliff should the center of the boat be in order for the projectile to land on the center of the boat?

thanks

If you see my answers, there are many questions similar to this that had been answered. But I’ll give the solution to this anyway.

……………_—-_……..…
………._-‾……….‾-_..…
…… _-‾…………….‾-
Vy…/………………….
‘.↑../…………………….
..|./.60º )………..’……..
..|/—→Vx___________
▓………………………’….
▓…………………………..
▓……………………………
▓…………………………….
▓……………………………..
▓……………………..t = ?…
▓…………………………___☼__
▓≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈▒▒▒▒▒▒▒/ ≈≈≈≈≈≈≈ ..
…|←————–X————-→|

Components of Velocity

Vx = Vcos 60º
Vy = Vsin 60º

The concept of the solution is first to find t
From linear Motion

S = Vit + ½ at ²
………where..S = -Y = -120m
…………………Vi = Vsin 60º
………………….a = -g = -9.8m/sec ²

-Y =(Vsin 60º )t – ½ gt ²
- 120 = 75(.866)t – (4.9)t ²
(4.9)t ² -(65.95)t – 120 = 0 <====quadratic equation

After getting the positive value for t, you can then proceed to the distance from the base of the cliff by usingthe equation

X = Vxt

**************************
Now if you want to avoid the Quadratic equation, you can get the t in two stages. You can use (Vf = Vi + at) then get the Highest point it will reach and solve the time from there.

At the Highest point V= 0

Vf = Vi + at <===where Vf = 0
......................Vi = Vy = Vsin60º
.......................a = -9.8
0 = Vsin60º + (-g) t
gt = (75)(.866)
t = 64.95/ 9.8 = 6.63secs

"h" at this point
2aS = Vf ² - Vi ²
2(-9.8)h = 0 -(75)(.866)
19.6h = 4218.50
h = 215.23m

From this highest point, total distance downwards is 120m + 215.23m = 335.23m and initial velocity will be zero.

S = Vit + ½ at ²....where: Vi = 0
......................S = - 335.23m
......................a = -g

-335.23 = 0 + ½ (-9.8)t ²
- 335.23 = - (4.9) t ²

t ² = 335.23 / 4.9
......= 68.41
......._____
t =²√ 68.41. = 8.27secs

So total time = 6.63 + 8.27 secs. = 14.9 secs

The distance from the base of the cliff

X =Vxt
...= Vcos 60º (14.9)
..= 75(.500)(14.9)
X = 558.75 m

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