The Ship's Carpenter New Jersey

Basic Boat Terms and Concepts

Welcome to TheShipsCarpenterNJ.com! The following article will give new boaters a good starting point in understanding boat and boat part terms. The Internet is a great tool for understanding a subject or finding schematics and diagrams. Even though the Internet is vast in content and user friendly, your searches will only be as good as the key words you use in your search. To increase your chances of finding what you are looking for you should have a good working knowledge of the subject of your search.  The following is a basic lesson on select boat topics that are broad in scope.

 

Boat Types

Sailboats use wind power for movement. They typically have a small inboard or outboard motor for docking and navigation purposes. Hull designs include a keel that is either fixed or is capable of being raised for shallow water navigation.

Power boats use mechanical propulsion for movement. Engine arrangements are Inboard, Inboard/outboard, or outboard.

Inboard engines are similar to Automotive engines. An internal combustion engine block is located in the hull of the boat and is connected to a transmission. The transmission allows for forward and backward (astern) propulsion. Driveshafts pass through the hull (via a stuffing box) and into the water where they turn a propeller. Steering is provided by rudder(s) behind the propeller(s). These engines typically have cooled exhaust systems.

Inboard/outboard (I/O, stern-drive) engines have an internal combustion engine block located at the back of the boat (Stern). The engine is connected to an out-drive unit which serves as the transmission and steering system. The propeller turns at a predetermined ratio. Steering is provided by turning the out-drive These engines typically have cooled exhaust systems.

Outboard engines are essentially self contained propulsion systems. An engine and an out-drive type are combined into a single unit which is located on the transom (the stern or back) of the boat. Outboard engines have become very powerful and advanced in recent decades. Outboard engines have a compact footprint in that they do not take up bilge or deck space.

Hulls are considered to be either planing or displacement type. Planing hulls are designed to cut through the water by rising up out of the water at a given speed. When up on plane a smaller amount of hull is in the water and draft is decreased. The resulting reduced drag in the water enables the boat to achieve higher speeds than displacement hulls. The characteristics of the bow (typically a Vee design) such as the angle and flaring, affect the performance in differing sea conditions.

Displacement hulls do not rise out of the water rather they push water out of the way. These hull types have the same draft while underway as they do while at the dock. These hull types are slow when underway and generally are trawler type boats in the recreational boat world however, there are some larger cruisers that are displacement hybrid designs. These can feature deep Vee hulls for a more stable ride in rough seas yet are not designed to plane.

 

Parts:

Two basic categories of parts are engine parts or boat parts. Engine parts are those that are required for the normal operation of the engine(s). Boat parts are those that contribute to the operation of the boat. As with everything in life the choice is rarely a binary one. The waters are often muddied by interdependence of parts in these two categories. For example, the role of gauges serve both the boat and the engine to some extent. An engine temperature sender is located in the engine but sends information to the gauges. Are the gauges an extension of the engine located in the boat or are the gauges part of the boat powered by the engines? A better understanding is critical to figuring out what the part in question is and should do. On some occasions a part should be replaced with an equivalent OEM type. On other occasions a part must be replaced by a part that is compatible with another replacement part. The temperature sender must cooperate with the gauge, so if a temperature gauge has been replaced with an aftermarket gauge then an OEM type may not work or may work but provide inaccurate readings.

Keep in mind that when working on your boat a previous owner or mechanic may have installed an aftermarket part that replaces an original part. An excellent example would be replacing a “points” style ignition system with an electronic type. By installing the newer electronic type a number changes was made to the original design. The original ignition coil may not be compatible, the formerly required Resistor would be removed, and setting the dwell is no longer required. All of these things would appear in the original service manual but would no longer apply. The only way to realize that the “points” type system is no longer in use would be to remove the distributor cap and recognize the new electronic module.

A good start for most problems is to understand the problem, not just the symptom.  If an oily sheen appears in your exhaust where there was not one before, the first step is to think about what could cause the issue.  There could be un-burned fuel, engine oil, or transmission oil in the exhaust water .  Do the easy things first, check to see if the choke is open, if carbureted.  If it is closed then try manually opening it and check for sheen.  Next, check the plugs and see if they are fouled.  Perhaps a plug is not firing properly. If you find a fouled plug check the wire and the contacts in the distributor.  If all are in good shape then move on to the oil coolers.  If a cooler has a pinhole then oil is getting into the cooling water before the exhaust enters the equation. Coolers are heat exchangers and as such are not easy to diagnose.  The best way is to pressurize the passage thought to leak and then observe to see if the pressure holds.  This leak down test will only tell you if the exchanger is not holding pressure. It does not tell you why or if it can be fixed.   

These are just simple examples of how to think about and diagnose problems that will arise. Identify the start of the process and the end of the process and then try to determine when the problem may be occurring in that process.  See the following pages  for more information on what to look for and how to diagnose problems.

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