The heart is made of a unique muscle type known as cardiac and it never tires. But the body also has many other paired muscles, some voluntary that are attached to the skeleton and help the body move, some involuntary that work the internal organs and cannot be controlled.hey are attached to the skeleton and can be controlled. Voluntary muscles have fast twitch and slow twitch fibres. Fast twitch fibres contract quickly, but do not use oxygen well and tire quickly. Slow twitch fibres contract slowly, but use oxygen well and keep going for a long time.
While all boats in the United States must meet minimum standards established by the. U. S. Coast Guard (USCG), the NMMA ensures manufacturers participating in its voluntary certification program adhere to standards set by the American Boat and Yacht Council (ABYC), as well as those of the USCG.
To understand in detail what ABYC does it is important to differentiate what they do not do as well. Perhaps the most fundamental distinction is that ABYC does not test or certify any components that are used aboard boats. They do specify what type of components need to be installed, in what situations and how they need to be installed. In some cases ABYC also will specify a standard such as those from UL that a component must conform to or a type of functionality that a component must have.