Sorensen's Guide to Powerboats, 2/E: How to Evaluate Design, Construction, and Performance (INTERNATIONAL MARINE-RMP) - Softcover

Sorensen, Eric

Softcover

ISBN 10: 0071489207 ISBN 13: 9780071489201

Publisher: International Marine/Ragged Mountain Press, 2008

Synopsis

The first book ever to reveal what boat builders pay thousands of dollars to learn: the secrets of owner satisfaction

What makes a boat owner happy? Eric Sorensen and J. D. Power & Associates answer that question in detail in this revised edition of Sorensen’s Guide to Powerboats. Now incorporating results from J. D. Powers’ Boat Competitive Information Study, this guide tells you everything you need to know before opening your wallet. From runabouts and pontoons to express cruisers and bassboats, the book covers it all, explaining the implications of different hull designs, construction methods, engine technologies, and more. Includes J. D. Power's "Power Circle" rankings.

About this title

About the Author

McGraw-Hill authors represent the leading experts in their fields and are dedicated to improving the lives, careers, and interests of readers worldwide

Excerpt. © Reprinted by permission. All rights reserved.

Sorensen's GUIDE TO POWERBOATS

How to Evaluate Design, Construction, and PerformanceBy ERIC W. SORENSEN

The McGraw-Hill Companies, Inc.

Copyright © 2008 Eric W. Sorensen
All right reserved.
ISBN: 978-0-07-148920-1

Contents

Chapter One

Introduction

Nothing in life is so exhilarating as to be shot at without result.

—Winston Churchill

Welcome to the wonderful world of boating! You may be getting ready to buy your first boat, or maybe you've owned a series of yachts over the last forty years. But whether you're new to the game or an experienced boater, the more you understand about powerboats and yachts, the better. That's what this book is all about—helping you to better understand powerboat design, construction, and performance; in short, what really makes a boat tick. You'll learn more about the boat you own now—maybe why it porpoises at high speed, whether your hull is likely to blister, or why the bow rises excessively on plane. Or why a semidisplacement hull is really what you've been looking for all along, or the effect of bulwarks on dynamic stability. And of course my hope is that the reader will be a little more discriminating, and have higher expectations, next time around.

Choosing your next powerboat or yacht can be a perplexing process. There are hundreds of models to choose from, and most of the magazine ads say pretty much the same thing: that Brand X is the best, a revolutionary advance over the competition. Talk is cheap, however, and results speak volumes. Two boats, one well-designed and engineered and the other anything but, might look very similar during a quick tour at a boat show. But taking a closer look in the right places, asking the right questions, and insisting on a prepurchase sea trial will reveal the great gulf that may lie between the two boats' quality, performance, reliability, and longevity.

Even the smallest, simplest boats interact with wind and waves in complex ways. And even if it's basically a hull, an outboard, and a 6-gallon gas tank, you'll want your boat to perform well and to last a long time with minimal maintenance. The bigger the boat, the more complicated it gets with all the extra systems that make life afloat more enjoyable.

Whichever boat you end up buying, the more you know about the hull design's capabilities and limitations, the methods and materials used to build it, the propulsion system that makes it go, and the systems that provide fuel, ventilation, electricity, and fresh and salt water, the better off you'll feel about the experience. And feeling good is what owning a boat is all about.

Philosophy

The first half of the book, chapters 1 through 14, discusses the theory and engineering underlying good powerboat design, with plenty of illustrations to flesh them out. Here we explore questions such as what makes a boat seaworthy, and whether a displacement or planing hull is best for you, what propulsion system is most appropriate, and what to look for in topside safety, engine compartment access, helm station design, accommodations, and so on.

In places this book is opinionated. It reflects, among other things, the philosophy about boats I've developed and refined over recent years evaluating boats for consumers, magazines, and boat-builders. And, perhaps more fundamentally, it reflects the twenty years I spent in the coast guard and navy, where safety was always the driving concern in our operations. Chapters 2 and 12 are dedicated to seaworthiness and safety afloat.

Not that I confuse a destroyer with a walk-around very often, but there are elements of design that are common to both, and there is much that the builders of pleasure craft can learn from military and commercial vessels. So the book is informed, among other things, by navy and coast guard design practices and assumptions, and ventures to say where they reasonably apply to your boat. Likewise, I will bring in standards applied to commercial vessels issued by regulatory bodies such as the American Bureau of Shipping (ABS) and the Maritime and Coast Guard Agency of Great Britain (MCA).

In a few places I may sound annoyed with boats that are, to put it charitably, unwisely designed—for instance with 18-inch-high bow railings that are placed just right to catch your ankle; with foredecks that slope like ski jumps; with an absence of flotation foam or compartmentation to limit flooding; or with helm stations designed by stylists rather than ergonomics experts. It is frustrating to see how close some models come to being really great boats—if just a little more thought and care had gone into their design. It generally doesn't cost any more to build a boat that's practical and safe as well as good looking. On the other hand, it's the rare boat that doesn't have at least a few positive traits going for it, and most have a lot going for them. Even with a problematic boat, it could be that the judicious investment of a relatively small amount of money could bring it up to snuff.

Perception and perspective are what I hope you will gain from this book. You can skim through the chapters in any order you like, of course. But, if you read it in order, from the Seaworthiness and Other Mysteries chapter (chapter 1) through the Finding Your Next Boat chapter (chapter 14), you'll find that each chapter, to some degree, builds on the last. For instance, it helps to understand the difference between static and dynamic stability (in chapter 2) before brushing up on weight distribution, propeller pocket design, and dynamic instabilities (in chapter 4).

Picking the right type of boat is also key to getting the most enjoyment out of it. Center consoles are great fishing boats, but you wouldn't want to spend a weekend on one. A deep-V is often the way to go offshore, but forget about cruising the Erie Canal in one. An express cruiser eliminates the ladder to the bridge, but you give up a climate- controlled saloon, and so on. As we'll see, it's important to first clearly define your expectations and needs, and then find a boat whose layout, features, and hull form best meet them.

Just like the foundation of a house, the hull of a boat, including its shape, is the entering argument as to its suitability for your purposes. A boat might have the perfect cabin layout, great helm visibility, and a family-safe topsides, but you'd better check out the hull design before making a decision. That 35-footer with the extra cedar-lined locker and bigger berth in the forward stateroom probably gained the extra cabin volume by widening the hull forward, and the result will be a really roomy boat with a rough ride. As you'll see in the planing hull chapter (chapter 4), you can't have the biggest, widest 40-footer in the marina and get a smooth ride. So the choice depends on your requirements and having realistic expectations; do you want to keep up with that Blackfin 33 and run comfortably at 25 knots in a 3-foot chop, or do you want the biggest cabin in your boat's class?

Boat speed depends on many things, but, along with available horsepower, weight, and hull form are at the top of the list. With few exceptions, a lighter boat goes faster than a heavier one of the same shape. To make a boat light is easy and cheap—you just use less fiberglass and smaller structural members. But to make it both light and strong takes time and costs money, as we learn in the chapters on construction. Weight aside, a boat with a flatter bottom goes faster than a deep-V, as we see in chapter 4. But while the 30-foot deep-V will slice through a stiff chop at 25 knots without spilling your coffee, the 50-foot flat-bottom boat will have to slow down to trolling speed to prevent serious injury, let alone discomfort, to its occupants. We'll also look at the relationship between beam and ride quality: given similar hull forms and propulsion packages, a longer, narrower boat will be consistently faster, smoother riding, and more fuel-efficient than one that has the same interior volume but is shorter and wider. Whether at displacement or planing speeds (assuming both have planing hulls), the longer, narrower boat is simply easier to push. The laws of physics and economy tell us that, in spite of those glossy brochures, you can't get something for nothing.

Reality

The second half of the book is a market survey in the form of boat reviews, where we take all the theory we have learned and apply it to actual boats. In addition, new data from the J.D. Power and Associates boat competitive information studies has been included. We will look at all the major powerboat types—from center consoles to pilothouse motor yachts—to see what each type does well (and not so well) and what to look for in each. You will find in-depth evaluations of representative boats, both new and old, to use as a starting point to assess design, construction, performance, comfort, and safety. All reflect my own independent analysis, judgment, and opinions. Some include performance data, and one may just be of the boat you're looking for. The inclusion of a boat means that I have a generally favorable impression of it, even though I am sometimes critical. Supplementing these full-length evaluations, you will find briefer "snapshot" reviews that cover related models.

A great many boatbuilders, kindly and without reservation, provided photos for use in this section of the book.

So what's the difference, really, between a name-brand and a no-name? It depends. The fact is, between large, premium-brand builders and their small, relatively unknown counterparts, modern manufacturing techniques and materials have tended to level the playing field to a large degree. Using advances like vinylester resins, core bonding putties, simplified vacuum-bagging techniques, and computer-aided design, the little guys can, and often do, turn out excellent products. (Construction techniques are discussed in chapters 6 and 7.) Some little-known boats—especially small boats powered by outboards and stern drives—are better than some of the pricier marquee names. So while that premium-brand cruiser may give an owner bragging rights with their dockmates, the shopper who takes the time to peer through the hype and haze can maybe buy a better boat for less money or a bigger boat for the same expenditure.

There is often a direct correlation between price and quality. Some well-known builders produce wonderful, long-lasting boats, and their prices reflect it. But their sticker prices also reflect the ego appeal and prestige of the brand, as well as the boat. A name-brand boat will tend to hold its value better over time, which is an important factor. Top-end boatbuilders may also have higher standards for their dealers than others and keep close tabs on buyers' selling and service experience through customer satisfaction surveys.

You should also factor the dealership into the equation. I'd rather have a decent boat backed by a good dealer than a better boat sold by one who's incompetent or indifferent. You'll feel the same when your starboard cooling pump breaks on a Friday morning just as all your relatives are arriving in town for a long weekend.

I'd even be prepared to pay more for a boat if it's sold by a good, reputable dealer. Dealers need to make a profit, without which they wouldn't be able to afford the people and facilities needed to get your boat back up and running by Friday afternoon. The same goes for working with a broker—find one with a good reputation, and he or she will stay with you and watch out for your interests as you trade up, or down, over the years. We cover boat shopping in chapter 14.

Finally, boatbuilders aren't just competing against each other for your discretionary income—they're also up against golf and ski resorts, travel agents, campgrounds, and motor home manufacturers. And whoever delivers the most satisfaction for harried, hurried, hard-working families gets the nod. The recreational boating industry is in the business of luring people to the boating world, so it's not surprising that marketing and styling sometimes take on an inflated importance.

In the best boats, however, form and function blend seamlessly to make them safe, reliable, durable, attractive, and ergonomically engineered for the user's pleasure. Building safe and user-friendly pleasure boats isn't rocket science. It's a matter of applying common sense and care in their design and construction.

There are many terrific boats out there. Let's find out what makes them tick.

Chapter Two

Seaworthiness and Other Mysteries

Falling in love is not at all the most stupid thing that people do—but gravitation cannot be held responsible for it.

—Albert Einstein

Alot has been written about the subject of what makes a vessel "seaworthy," or literally "worthy of the sea." One legal definition says that a vessel is seaworthy if she can carry out the mission for which she was intended. Usually, the operative phrase is "fit for her intended purpose." Therefore, a coastal cruiser can be very seaworthy for coastal cruising, but not necessarily offshore voyaging. Yet she is still considered seaworthy for the use for which she is intended; it all depends on which "sea" we're talking about.

For our purposes, though, we apply a more stringent definition. The bottom line? Seaworthiness refers to a vessel's survivability, including its ability to resist capsize, and to its behavior, including its controllability and predictability, in rough water. When any vessel puts to sea, it must be able to provide its occupants a high degree of safety and security en route to its destination, and be able to take severe conditions of wind and sea in stride. The farther offshore a vessel travels, and the slower its speed, the higher the expectations for its seaworthiness, since safe haven may well be unreachable in time to avoid heavy seas and high winds. An adjunct to seaworthiness is the matter of seakindliness, as we discuss below, which acknowledges the importance of crew comfort to maintaining a vessel in a seaworthy condition.

Every vessel is the end result of a series of competing interests that must be compromised to achieve the desired mix of qualities. To create enough interior volume to make a yacht attractive to some buyers, a designer may opt for a large deckhouse and full, blunt bow sections, both of which tend to make a vessel less seaworthy. In this and many other cases, a design objective may pull against the interests of seaworthiness. You can't have everything in a boat, no matter what the advertisers say.

Few vessels are designed with just one or two priorities, such as high speed or shallow draft. Most boats can accomplish several missions quite well but are utterly unsuited to some other purposes. By analogy, consider a sports car. A Ferrari can go 180 mph, but it would not be your choice to carry a load of plywood home from the lumberyard. Its utility is limited—and it costs a lot. You buy a Ferrari for speed, not for its climate-control system.

The SUV, on the other hand, represents a host of compromises and is much more useful. It can carry a load of passengers, it goes about half the speed of the Ferrari, it costs far less to buy and maintain, and it even pulls a trailer. But, it also guzzles gas and is far more susceptible to rollover than the Ferrari. Most pleasure vessels are more like the versatile SUV, representing a chain of compromises that produce a marketable product.

Ultimately, it is important that you understand and fully appreciate a boat's capabilities and limitations, and where compromises have been made that affect seaworthiness. In this chapter we look at the essential elements of seaworthiness and the effect on seaworthiness of the many competing design interests. We also point out a few important details to look for when choosing your next boat.

When heading offshore, and especially when your intended track takes you more than a few hours from the nearest safe refuge, safety considerations ought to be at the top of the priority list. For our purposes, offshore capability doesn't necessarily imply transoceanic range, simply the capability to operate with a high degree of security in the open ocean, many hours from shelter. For the run from Ft. Lauderdale to the Bahamas, for example, I for one would want offshore capability.

Range alone doesn't convey seaworthiness. Plenty of boats carry fuel enough to cruise hundreds of miles, but I personally wouldn't want to go offshore in them. When you're shopping for seaworthiness, range is important, but only one aspect. Hull design and construction quality are just two of the many other elements impacting seaworthiness.

Now let's consider how stability, roll damping, flooding resistance, steering, and speed, among other things, affect a vessel's seaworthiness. You'll see that naval architects have a language all their own, but the concepts are clear enough, so hang in there as we discuss a few of them.

Stability

For a vessel to be seaworthy, it must first of all resist capsizing under the most severe conditions that it can reasonably be expected to encounter. The term stability refers to the tendency of a hull to return to an even keel, or equilibrium, after an upsetting force is applied; stability is the result of the opposing forces of buoyancy and gravity working together. A boat lists when one side is more heavily loaded (by gear, equipment, fuel, or even green water on deck) than the other, and it heels when a dynamic movement, like a sharp turn or a wave or wind is introduced.

Seaworthy vessels have both initial stability, determined largely by the shape of the hull, and ultimate stability, governed more by weight distribution vertically within the boat. A boat derives stability from the righting arm (RA) created by the opposing forces of buoyancy and gravity. The longer the righting arm, and the greater the vessel's displacement, the more stable it will be.

If this is as clear as mud, don't worry: we'll return to it in a moment. First, however, let's have a look at a few key terms you'll need to understand to know what's going on when your boat rolls and pitches, and keeps coming back to an even keel.

(Continues...)

Excerpted from Sorensen's GUIDE TO POWERBOATSby ERIC W. SORENSEN Copyright © 2008 by Eric W. Sorensen. Excerpted by permission of The McGraw-Hill Companies, Inc.. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Edition details

• Publisher: International Marine/Ragged Mountain Press
• Publication date: 2008
• Language: English
• ISBN 10: 0071489207
• ISBN 13: 9780071489201
• Binding: Paperback
• Edition number: 2
• Number of pages: 496