Surveying Fiberglass Power Boats 

2nd Edition

 


Chapter 5

Hull and Its Structures

5. Hull and Its Structures 89

Essentials of Composites 90

Laying Process 90

Solid Laminates 90
Molding Hulls 91
Laying in Cores 93

Structural Properties of Laminates 94

Solid Laminates 95
Cored Laminates 96

Basic Structural Principles 99

Shape Affects Strength 99

Design Elements 100

Decks 101
Stringers 101
Bulkheads 105
Frames 107
Tabbing 107
Internal Structural Materials 108

Examples of Structural Design Defects 110

Stringer Design Error 111
Bulkhead Failure 111

Common Structural Failures 113

Stress Cracking in Superstructures 114
Hull Stress Cracking 116

Structural Weakness 117

Bottom Strakes 118
Bulkheading 120
Stringers 122
Primary Symptoms 125

Cored Hulls 127

Balsa 127
Foam Cores 128
Bulkhead Installation with Foam Cores 133
Water Ingress 133
Other Core Types 136

Coremat 136
Putty or Spray Cores 136

Background 139

Why Design Faults Occur 139
An Embarrassing Example 141
Marketing and Price Pressures 141

Summary 142

Copyright© 2001 - 2005 David H. Pascoe

Excerpt: Chapter 5

This chapter was written from the standpoint of both pre purchase surveys and conducting failure analysis, this because one function inevitably grows out of the other; we find a defect and we are asked, or want to know, what the cause is.

As I pointed out in the Introduction, boat design and materials has changed radically in recent years.

The reader should be cognizant of the fact that it takes time to discover whether new materials, design and methodology prove successful.

The efficacy of the most recent introductions therefore is unknown and cannot be covered herein.

In treating the subject of basic construction and how to conduct a survey, I have broken it down into two sections in three chapters - The Hull and Its Structures, Surveying the Hull, and Using Moisture Meters.

Each of these deals with a separate but interdependent subject which be considered as a whole. Because a hull is a more or less unified structure, all aspects are inter-related.

This presented me with the problem of how to deal with each without resulting in substantial repetition of the discussion.

Ultimately, it turned out that some overlap and repetition was unavoidable since I wanted to organize each chapter so that each would stand on its own.

In order to survey a hull, a surveyor needs to have a basic understanding of the engineering principles involved.

This does not mean that the surveyor himself must be an engineer, for many of the people who design and build boats are not themselves engineers or naval architects.

This chapter will review basic composite boat building and structural principles in considerable detail in order to provide the prospective surveyor with a solid foundation that will assist him in recognizing some of the many structural faults that he will be faced with.

The reader is also reminded that this book attempts to cover a wide range of boats both small and large, old and new, with a wide range of materials, design and techniques. Thus does the surveyor's knowledge have to cover the range of many decades. This, of course, is not easy but will shed light on why I go to such detail in a book on surveying.

Normally, it's not the surveyor's job analyze the structural engineering of vessel upon which he is performing a pre purchase survey. After all, it is a survey that we are doing, not an engineering analysis.

However, as was discussed in Chapter One, it is the surveyor's responsibility to be able to recognize the symptoms of structural faults when they appear.

Copyright© 2004 David H. Pascoe
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Surveying Fiberglass Power Boats
- 2nd Edition

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

Price: $69.50
In Stock

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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.

Biography - Long version


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