UWSH Ch.2 Flashcards
Why are keel mounted anchors fitted to the bottoms of some ships with bow mounted sonar domes?
Allows the ship to anchor without danger of the anchor chain dragging across the sonar dome.
What is the transmitting and receiving head for underwater signals?
Transducers.
What is a rodmeter?
A part of a pitometer log that projects through the ship’s hull to measure speed. Also known as a pitsword.
A masker system consists of ______ of perforated plates that run vertically along the hull at the forward bulkhead of machinery spaces.
Belts
How do fin stabilizers work?
Counters the ships roll by manipulating the water flow around the fins.
When fin stabilizers are not in use, they are secured in neutral position with a ________
Locking pin.
What are the 2 types of bilge keel?
Flat plate and v-shaped.
What type of thrust does a bow thruster provide?
Transversal thrust.
What provides the shape of a hull and forms a watertight barrier between the interior and the sea?
Shell plating.
Full cleaning on ships shall not be accomplished on intervals less than how many months?
6 months
What 3 things indicate a need for a hull cleaning and inspection?
A reduction in speed of 1 knot or greater, An excess increase of 5% fuel consumption, increase shaft rpm in excess of 5% to maintain speed.
Prop fouling can account for as much as what percent of increased energy demand associated with a light to moderately fouled hull?
50%
Thresholds for ships outfitted with ICS (Impressed Current System) cathodic protection is what percent bare metal observed on the underwater hull?
10%
Thresholds for ships with sacrificial anode systems are what percentage bare metal or an observation or any inactive anodes?
5%
What is gathered after locating a crack on a ship?
The depth, length, and width.
What percent of fuel saving comes from cleaning props and shafts?
50%
What is the primary corrosion protection system for the underwater hull plating and appendages?
Anti-corrosion coating system.
What is the primary protection against biological fouling of underwater hull plating and appendages?
Anti-fouling coating system.
What is the threshold for ships with a sacrificial anodes?
5%
What are the 3 types of fouling?
Soft, Hard, Composite.
Fouling rating 40 (FR40)
Hard “calcareous” fouling, tubeworms less than ¼”
Hard growth is present in what fouling ratings?
FR 40-90
Describe fouling rating 20 (FR20)
Slime, dark green, yellow, or brown colors.
Describe FR 30?
Grass up to 3” projection up to ¼ inch, soft non-calcerous fouling. Fouling can not be easily wiped by hand.