Desirable and undesirable characteristics of offshore yachts by unknow

Author:unknow
Language: eng
Format: epub
Tags: Yachts
Publisher: New York : W.W. Norton
Published: 1987-01-14T16:00:00+00:00

VENTILATION

you can improve the atmosphere below by hanging your smelly clothes in the sun when the chance arises.

Since screens reduce ventilation by about 50 percent, anybody cruising in a hot, buggy area will have to make a sacrihce. Many people can get by with sprays and lotions and a screen located in the companionway only (it may help to spray the screen with bug repellent). Other people, however, need screens everywhere. For some reason, bugs do not seem to want to swarm down a vent cowl; perhaps that’s because there’s no light in the vent to attract them.

Safety

So far, we have been talking primarily about how good ventilation improves the crew’s on-board comfort. Now we will address safety concerns. U.S. Coast Guard-regulations concerning ventilation are provided in detail in the American Boat and Yacht Council (ABYC) manual Safety Standards for Small Craft, Sections H2, H24, and H32.

The ventilation of the engine compartment is necessary to remove flammable gases and heat. For this reason, I strongly recommend the use of diesel engines and fuel. Gasoline is particularly hazardous and extreme precautions are necessary to be certain that all gasoline fumes are removed before starting the engine. Because of this danger, the Coast Guard has certain specihc regulations about the ventilation of boats with gasoline engines and enclosed gasoline fuel tanks. These rules, and regulations concerning ventilation of diesels, are listed in Coast Guard publications and are summarized in Piloting, Seamanship, & Small Boat Handling (“Chapman’s”) and The Annapolis Book of Seamanship. If you have any doubts about the legality or safety of your engine ventilation system, request a courtesy inspection by your local Coast Guard Auxiliary.

When running, engines act as their own exhaust fans by taking in air from the engine compartment and blowing it out through the engine exhaust system. Still, while requirements for ventilation for diesel engines are much less stringent than those for gasoline engines, it’s a good idea to have a system that includes a blower and two large natural-draft vents leading from the deck to the engine compartment through clam-shell vents and large-diameter vent tubing. One vent will serve as intake, the other will serve as exhaust.

Cabin Heaters

It is not safe to use open-flame cabin heaters whose combustion discharges into the cabin. There are several reasons for this recommendation. First, the time when they are used—cold weather—is also the time when ventilation is reduced by shutting the companionway and hatches. Second, their flames produce increased humidity, undesirable levels of carbon dioxide, and possibly carbon monoxide. Alcohol heaters, like alcohol stoves, also turn out smelly, tear-forming acetaldehyde. Cabin heaters, then, should exhaust through their own independent flues or chimneys.

But even chimneys may be dangerous. A chimney works only if the hot gas inside is sufficiently lighter than the surrounding air to provide suction, which creates an upward draft. However, this will not happen if the surrounding air in

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