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.
What are the 2 types of hard fouling?
Barnacles (usually acorn) and Tubeworms (serpulidae)
Formation of ______ is the first step in the fouling process.
Slime
Full hull cleaning shall be accomplished when a fouling rating of _____ or higher, over what percentage of the hull for NON-ABLATIVE paints?
Fouling rating of 50 or higher, over 10%.
Full hull cleaning SHALL be accomplished when a fouling rating of ____ over what percentage of the hull for ablative and self-polishing paints. (Excludes docking blocks.)
40+ over 20%
Sacrificial anodes, usually placed along the bilge keel and near the stern, waste away as a result of what?
Galvanic corrosion.
Underwater tasks that can be performed on Auxiliary Propulsion Units include inspecting and changing what 3 things?
The motor, electrical cables, and faring plate.
What is the difference between the tail shaft and the line shaft?
The line shaft is between the prop and the hull, the tail shaft is the piece upon with the prop is mounted.
Where are the main strut and the intermediate/secondary struts located?
Main strut is just forward of the Prop, and aft of the intermediate strut. The intermediate strut is located between the main strut and the stern tube.
Fairwaters are usually made up in two pieces, how are they connected to the bearing housing?
Welded or bolted on.
Rudders on large ships are either _____ or filled with a _______.
hollow/empty or filled with a preservative.
What PDR is indicative of advanced deterioration or the entire anticorrosive/antifouling paint system?
PDR 60 to PDR 100.
________, which have survived cleaning, indicates a probable failure at the anti-corrosive/steel interface.
Relatively hard bisters.
What PDR is associated with normal physical wear due to underwater cleaning action or hydrodynamic effects?
PDR 10-30
What NSTM chapter illustrates paint deterioration conditions?
Ch. 081.
When a PDR of 40 or higher is found over a substantial portion of the hull, what must you consult before planning any future hull cleaning?
NSTM ch. 081 p.2.1.8 and 2.1.8.1
_______ fouling, including both hard and soft growth, is extremely detrimental to the ships performance, coating, and machinery systems.
Composite fouling
_______ fouling may become detrimental to the performance of the ship and the coating systems.
Hard
_______ fouling such as algae, slime, and grass, have minimum effect on the coating system and performance of the ship.
Soft
Types of fouling are separated into what 3 categories?
Soft, Hard, Composite.
What are the dominant organisms in the soft fouling stage?
Slime and grass.
What lifeforms make up slime?
Bacteria, fungi, protozoa, and algae
A clean, foul free surface; red and/or black anti fouling paint or a bare metal surface indicated what FR?
Soft-0
Light shades of red and green (slime), bare metal or painted surface is visible, indicates what FR?
Soft-10
Tubeworms, closely packed together and growing upright away from surface. Barnacles growing ONE ON TOP OF ANOTHER, ¼” or less in height. Calcareous shells appear clean or white in color indicated what type of FR?
Hard-80
A combination of tubeworms and barnacles, greater than ¼” in diameter or height, indicated what type of fouling?
Hard-70
A combination of tubeworms and barnacles LESS THAN ¼” in diameter or height indicates what fouling rating?
Hard-60
Calcarous fouling in the form of barnacles less than ¼” in diameter or height indicates what level of fouling rating?
Hard-50
Calcareous fouling in the form of tubeworms less than ¼” in diameter or height indicates what level of fouling rating?
Hard-40
Grass up to 3” in length, projections up to ¼” in height; or a flat network of filaments, green yellow or brown in color, or a soft non-calcareous fouling such as sea cucumbers, grapes, or squirts projecting up to ¼” in height. The fouling CAN NOT be easily wiped off by hand. What fouling rating does this indicate?
Soft-30
Slime as dark green patches with yellow or brown areas (usually referred to as advanced slime.) Bare metal or painted surfaces may be obscured by fouling. What fouling rating is this indicative of?
Soft-20
Dense growth of tubeworms with barnacles, ¼” or greater in height; calcareous shells are brown in color (Oysters or mussels) or have a slime/grass overlay. What fouling rating is this?
Hard-90
All forms of fouling are present. Soft and hard. Particularly soft sedentary animals without calcareous covering (tunicates) growing over various forms of hard growth indicates what level of fouling?
Composite-100
What is the dominant form of fouling on propulsors?
Hard fouling such as barnacles and tubeworms.
The presence of even immature barnacles or tubeworms causes a ______ loss in propulsor efficiency.
Severe
Propulsor surface roughness can be determined using a _________.
Rupert comparator scale.
For ships with sacrificial anodes, what should be conducted whenever either of the minimum thresholds are observed of bare metal under the ship’s hull.
A hull potential survey.
A Fouling rating of Hard-40 is generally observed where?
Over covers and around the perimeter of sea-chest grating.
Fouling on the interior surfaces of gratings and sea-chests, inaccessible to rotary brushes, must be cleaned by what other means?
Hand brushes or sea-jets
What is the interval for cleaning ships?
Since effects of fouling vary between ships classes, no specific interval can be stated. It’s imperative that ships be scheduled for pre-cleaning inspections regularly to determine if cleaning is necessary.
Delaying full hull cleaning to the point where a significant amount of hard fouling has formed can result in damage to the paint system. What FR is that limit in Ablative/Self-polishing and Non-ablative anti-fouling paint.
FR 50 for non ablative, FR 40 for ablative/self polishing.
Are the calcareous deposits that form on the dielectric shield to be removed or preserved?
Preserved
Devices shall be placed in the vicinity of ICS, dielectric shield to guard against damage during cleaning. Shield size is approx how large? ←Look this one up. Ch. 081-3.3.2
16 ft wide and 13 feet high with the anode located in the geometric center.
The Skeg is a deep, fin like projection on the aft part of a ship near the stern that may do what 4 things?
Support the lower edge of the rudder, support the prop shaft on a single screw ship, improve the steering in multiple-screw ship/barges, help support the ship in dry dock. UWSH 2-2.2.20
Fouling on the surfaces of ICS current cathodic protection system anode shall be cleaned with what?
By hand, using either wooden or plastic scrapers and white or green abrasive hand pads.
Fouling on sacrificial anodes shall be removed with what?
Wire hand brush, or a wooden, plastic, or metal hand scraper.
Can you use multibrush units on any propulsor surface?
No.
For effective cleaning of bare nickel, aluminum, or bronze surfaces of a propulsor with a fouling rating of FR Hard-50 and up, are best removed using what?
A scraper, water jet gun, or rotary brush which severs it from the basal plate. UWSH 081 3.3.3.2.1
When using abrasive discs, cleaning trailing edges with a knuckle, the discs and back-up pad or holder shall be _____ to prevent the disc from rounding the distinct edge.
Rigid. UWSH 081 3.3.3.2.2
For effective cleaning of bare nickel aluminum bronze surfaces of a propulsor with a FR hard 40 or less, it’s a one step process using a ________ or ____ ___ ___ ___.
Abrasive brush, disc, or abrasive hand held pad. UWSH 3.3.3.2.1
When using abrasive discs, cleaning CONVEX surfaces such as leading edges with no distinct knuckle or break. THe discs and back-up pad shall be _____ to allow the disc to conform around the curvature.
Flexible UWSH 081 3.3.3.2.2
When using abrasive discs cleaning flat surfaces, the disc shall be ______?
Kept flat.
When cleaning painted propulsor surfaces use hand scrapers, and _____ with nylon, ______ polyester bristle may be used to remove fouling.
Rotary brushes with nylon, polypropylene and polyester bristle may be used to remove fouling. UWSH 081 3.3.3.2.3
What does a partial cleaning dictate?
Refers to any cleaning where only discrete sections of the hull (⅓ or forward ⅔) appendages, and systems are cleaned. Is intended to provide the ultimate pay-off when time or resources are limited.
For use on trailing edges, all metallic scrapers SHALL comply with NAVSEA Drawing- _______?
245-7605783 Virginia Class Propulsor Scrapers
For use on trailing edges, metallic scrapers are not permitted for use within ______ of edges and adjacent surfaces.
3 inches Propulsor cleaning Table 081 3-2
What are the 3 ship’s performance indicators to conduct an early underwater hull inspection?
A reduction of 1 knot in speed with shaft RPM set for standard speed.
Increase excess of 5% fuel required to maintain a specific shaft rpm.
Increase in shaft RPM in excess of 5% to maintain given speed.
Interim cleaning is required when what FR is present on propeller surfaces?
FR Soft-30
Ablative and self-polishing anti-fouling paints are _______ than non-ablative vinyl antifouling paints. They are designed to wear away in ________ quantities while the ship is underway.
Softer, Smaller. UWSH 081 2.1.4
Fouling release coating systems are designed with a ____ ____ ____ to reduce marine fouling ability to permanently adhere to the coating while the ship is underway.
Low surface energy. 081 2.1.5
On fouling release coating systems, if during a hull inspection/interim cleaning, what level of fouling requires further guidance from NAVSEA for cleaning advice.
FR Hard 50 or greater over 10% of the hull.
WHere can guidance be found for cleaning a ship coated with Fouling Release Coating systems on a case by case basis?
NAVSEA Code 00C
All requests should be submitted by fleet activities in the form of Naval messages utilizing the subject line ______?
Waterborne Underwater Hull Cleaning. 081 2.1.5
The message to request hull cleaning should include date of _____, ____ ____, ____ ____ ___.
Date of last underway period, max ship speed and duration within last underway period.
What PDR does advanced deterioration begin?
60
What is the dominant fouling found on props?
Hard fouling, such as barnacles and tube worms.
What type of fouling is expected on a sonar dome?
FR-10-30. If Antifouling paint failure should occur FR-50 and above with form.’
For painted surfaces, the use of water jets is restricted to ____, ____ and ____.
Sea Chests
Painted mask emitters
Painted portions of propulsors.
What is the most common damage resulting from the premature deterioration of concrete?
Cracking and loss of material
What is a surface indication?
Any inconsistency of the surface that looks like a scratch or hairline crack but cannot be felt or buffed out.
What is the form number for underwater hull inspection?
4730/3
What are deadlights?
Cooling water ports in the stern tube.
What are 3 ways localization can be determined on a ship?
Lines descending from known locations/frames.
Hammering on a valve/hull at location.
Push air from a fitting.
At no time should high pressure water jets being used on bare propulsore surfaces be allowed to operate above _____psi.
10,000
At no time should a water jet being used on PAINTED propulsor surfaces be allowed to operate at pressures over _____psi.
2000psi
