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HOME > Surveying Fiberglass Power Boats (2E) > Chapter 16


Chapter 16

Plumbing Systems

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Small boats, as well as large yachts, can have extensive plumbing systems that need thorough inspection.

As referred to here, plumbing means all of the piping, hoses, valves, strainers, filters, tanks, scupper, drain and pumps that conduct water in all its various forms.

The examination of plumbing can constitute a major part of the survey since the various components are likely to be scattered all throughout the hull.

Regardless of the fact that much of it may be hidden or obscured, making the survey process and servicing of systems more difficult, every aspect of the plumbing needs to be inspected.

When it comes to plumbing, there is just no end to the kind of faults surveyors find daily.

Everyone from boat builders to owners and repairmen seem to have a major disconnect from the fact that any plumbing system connected to the outside of the boat becomes part of the vessel's hull and therefore must be treated with respect.

But people do lose sight of this fact, and so the surveyor is frequently presented with substandard materials, faulty designs and dangerous conditions.

The purpose of this chapter is to highlight some of the more common problems so that the beginning surveyor will be aware of just how pervasive these problems can be.

System Types

Plumbing systems are usually categorized into four types, freshwater, sea water, gray water and blackwater. Fresh and sea water systems are self-explanatory; gray water refers to waste water from sinks and showers while black water refers to sewage systems.

Smaller boats usually have three of these systems but large yachts will often separate the gray water from the black water, either diverting it overboard or into a separate tankage system so as not to overtax the blackwater system. Long range cruisers will often utilize a reverse osmosis system and recycle the gray water.

A sea water system is any system that brings sea water from outside the hull into the vessel, usually for purposes of cooling machinery, but can include other uses such as reverse osmosis water conversion, bait wells, airconditioning and sea water deck wash downs.

The survey of sea water systems gets the highest priority by surveyors for two reasons.

First, sea water is highly corrosive to most all metals and, second, because sea water brings outside water inside, any breach in the system runs the risk of either sinking the vessel or causing damage from the leakage of sea water onto other components. For these reasons, sea water systems need to be carefully designed, utilize high quality materials, and be equipped with sea cocks and strainers to prevent foreign materials such as seaweed, plastic bags and the like, from entering and fouling the system.

Black water systems, of course, interest no one but are capable of causing great discomfort when something goes wrong. Sewage systems can also pose serious dangers to both the vessel and passengers for a variety of reasons. One of those is that some, if not most, black water systems mix sea water with waste.

The combination of decomposing fecal matter and sea water can make for a brew of corrosives and acids that is lethal to most metals. Most system materials today utilize plastics wherever possible to minimize the metals corrosion problems.

Of all the affordable metals, only high quality bronze for pumps will stand up even reasonably well to the highly corrosive environment found in black water systems, which accounts for the trend to the use of vacuum or diaphragm pumps since these systems eliminate the need for metal housing pump orifices. These pumps expose only the low cost, easily replaced synthetic diaphragms to the corrosive fluids.

Copyright© 2004 David H. Pascoe
(Additional spaces are added for easy screen reading.)

Table of Contents: Chapter 16

16. Plumbing Systems 351

System Types 351
Health Hazards 352

System Materials 353

PVC Piping 354
Copper Pipe 356
Brass 356
Bronze 357
Stainless Steel 358
Aluminum 358
Iron and Steel 359
Marine Hose 359
Hose Failures 360

Marine Sanitation Systems(MSD’s) 362

Legal Requirements 362
Macerator Pump Systems 364
Reverse Siphoning 365
System installation 366
Valving 367

Sea Water Systems 367

Design 367
Check Valves 368
Strainers 369
Valves 370
Plastic Valves 371
Plastic Through Hulls 371
Air conditioning 372
Bait Wells 373
Plastic Transducers 373
Plastic Pipe Fittings 374
Fresh Water Systems 374
Aluminum Tanks 375

Bilge Pumping 376

DC Pumping 377
Number of Pumps 378
Primary Service Pump 379
Stern Pump 379
Forward Pumps 379
Backup Pumps 379
Float Switches 380
Idiot Lights 380
High Water Alarms 380
Capacity ratings 381
Riser Loops 381
Emergency Pumps 382
Why Bilge Pumps Fail 383
Open Boats 384
Freezing Climates 385

surveying Fiberglass Power Boats Surveying Fiberglass Power Boats
- 2nd Edition

Soft Cover
480 pages
Publisher: D. H. Pascoe & Co., Inc.
Published: 2005
Language: English
ISBN-10: 0965649601
ISBN-13: 9780965649605

Price: $34.50
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David Pascoe - Biography

David Pascoe is a second generation marine surveyor in his family who began his surveying career at age 16 as an apprentice in 1965 as the era of wooden boats was drawing to a close.

Certified by the National Association of Marine Surveyors in 1972, he has conducted over 5,000 pre purchase surveys in addition to having conducted hundreds of boating accident investigations, including fires, sinkings, hull failures and machinery failure analysis.

Over forty years of knowledge and experience are brought to bear in following books. David Pascoe is the author of:

In addition to readers in the United States, boaters and boat industry professionals worldwide from over 70 countries have purchased David Pascoe's books, since introduction of his first book in 2001.

In 2012, David Pascoe has retired from marine surveying business at age 65.

On November 23rd, 2018, David Pascoe has passed away at age 71.

Biography - Long version

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