Blood-Alcohol Levels

Blood-Alcohol Levels

The following chart allows a calculation of when it becomes dangerous to drive after drinking alcohol.  The chart was developed by the Toronto Police Department for car drivers, but it also applies to persons operating vessels.

The Criminal Code of Canada reports the legal limit for alcohol as 80 milligrams of ethyl alcohol per 100 millilitres of blood (80 mg%). This is also often expressed as 0.08 grams of ethyl alcohol per 100 millilitres of blood.

Instructions:

• Find the column that corresponds to the number of drinks consumed
• Locate the number matching the weight of the person
• The number entered in the box where 1 and 2 meet shows the blood-alcohol concentrations (BAC) in grams of alcohol per 100 millilitres of blood

Weight (lbs)	1 drink	2 drinks	3 drinks	4 drinks	5 drinks	6 drinks
100	0.043	0.087	0.130	0.174	0.217	0.267
125	0.034	0.069	0.103	0.139	0.173	0.209
150	0.029	0.058	0.087	0.116	0.145	0.174
175	0.025	0.050	0.075	0.100	0.125	0.150
200	0.022	0.043	0.065	0.087	0.108	0.130
225	0.019	0.039	0.058	0.078	0.097	0.117

Note: One drink = 1.5 oz of liquor (40% alcohol) = 5 oz. of table wine (10-14% alcohol)  = 12 oz of regular beer (5% alcohol).

Attention: The time elapsed since drinking and other factors can affect the data in the chart.   For women, blood/alcohol concentrations are higher than specified in the chart.

The Effects of Alcohol

Alcohol has the same effect on a boat operator as a car driver.  However, boating involves certain specific factors. Here are a few examples:

Balance

Most people who die in a boating accident fall out of a vessel and not necessarily because it capsizes.

Balance is one of the first faculties impaired by the very first drink of alcohol or the first beer.   It affects the body quickly, and obviously, a fishing boat roughly 3.5 meters in length is much less stable than solid ground.

Coordination

As the blood-alcohol level rises, people are less and less capable of coordinating their movements and reflexes.  An intoxicated person will find it very difficult to swim or grab onto a lifebouy, regardless of their ability when sober.  Moreover, alcohol also affects vision.

Judgment and Sense of Risk

Most people lose their normal reasoning ability after just a few drinks.  Under the influence of alcohol, the people may be inclined to take risks.

Hypothermia

Contrary to popular belief, two or three “stiff drinks” do not warm up a cold person.  On the contrary, alcohol causes the blood to rise to the surface of the skin, giving the impression of warmth, although body heat quickly dissipates into the air or water.  Cold water is dangerous enough without alcohol  reducing  survival time even more.

Body Heat Regulation

The term “human body heat regulation” pertains to the mechanism that maintains an even body temperature.  Physical activity, on land or in the water, increases the body’s glucose level (blood sugar). Glucose, which carries energy to the muscles, is needed to produce heat when we exercise.  But alcohol interferes with the liver’s ability to produce glucose.  Drinking alcohol and engaging in strenuous exercise at the same time can reduce glucose levels (hypoglycemia) and make a person confused and weak, and interferes with the body’s heat regulation.  Shivering, a reflex by which the muscles produce heat, is impeded by alcohol.  Alcohol causes the blood vessels in the skin to dilate (expand), thus increasing the amount of heat that leaves the blood and enters the air.  Cold water is also more effective than cold air in removing body heat.  For these reasons, high levels of alcohol in the blood diminish the body’s ability to produce heat as quickly as it is lost in cold water, and the body temperature can therefore fall.

A pleasure craft operator should always check weather forecast information before heading out to avoid putting the craft and persons on board at risk.