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.
Interim cleaning WILL be conducted when the running gear has a Fouling Rating of _____ or greater.
FR-30
Composite growth is FR____?
100
Docking blocks are usually FR____?
70
Describe FR 60?
Combination of tube worms and barnacles less than ¼”.
Describe FR 70?
Combination of tubeworms and barnacles greater than ¼”
Describe PDR 50?
Harder blister, anticorrosive/steel interface.
Shafts are cleaned when what Fouling Rating or greater is observed?
FR 40
Describe FR 50
Hard fouling. Calcareous fouling barnacles less than ¼”
FR ______ for ablative self polishing paints.
FR40+ over 20% a full hull cleaning shall be accomplished. Excludes docking blocks/appendages.
FR______ for non-ablative antifouling paints.
50+ over 10% a full hull cleaning shall be accomplished.
Describe FR 80?
Tube worms are closely packed. Barnacles growing on top of one another 1/4 inch or less in height. Calcarous shell appear clean or white in color.
Full cleaning shall be accomplished when what fouling rating is present over 20% for ablative paint?
FR 40
Describe FR 90?
Dense growth tube worms with barnacles, ¼” or greater in height. Calcareous shells are brown in color.
That rating of PDR-40 is significant in it indicates either excessive cleaning actions or ______ due to internal failure of the paint system.
Blistering
What are the longitudinal member in the bottom called?
Longitudinals
What are the members under the deck called?
Deck girders.←Look this one up.
Where are the specific types and chemical compositions of the Ship’s hull coating in particular areas found?
The ships painting schedule or NSTM ch.631
Describe PDR 40?
Failure at the anti-corrosive/antifouling interface, resulting in a soft blister.
What fouling ratings contain soft growth?
FR 0-30? Maybe just 10-30, challenge that if it shows up.
What is the “A” strake, or Garboard strake?
Strake on the bottom nearest the center line.
Fouling release coating systems in no case should be cleaned without specific written approval by whom?
NAVSEA
Masker belts shall be cleaned when what percentage of blockage is observed on any belt section?
15%
When time or other resources are limited, the priorities for underwater cleaning are what 3 things?
First priority: Props. Then: Forward ⅓ of the hull, then AFT ⅔ of the hull.
Cleaning properly prepared and newly painted hull surfaces should be unnecessary during what interval of time after undocking?
12 to 18 months.