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Drogue Information

Investigation of The Use of Drogues To Improve The Safety of Sailing Yachts

by U.S. Coast Guard, Groton, CT

Report No. CG-D-20-87
U.S. Coast Guard Research and Development Center
Avery Point, Groton, Connecticut 06340-6096
and
Donald Jordan
Consulting Engineer
FINAL REPORT
MAY 1987
DISTRIBUTION STATEMENT A
Approved for public release
Distribution Unlimited
This document is available to the U.S. public through the
National Technical Information Service. Springfield, Virginia 22161
Prepared for:
U.S. Department of Transportation
United States Coast Guard
Office of Engineering and Development Washington, DC 20593

N O T I C E
 This document is disseminated under the sponsorship of the Department of Transportation in the Interest of Information exchange. The United States Government assumes no liability for its contents or use thereof.
The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this report.
The contents of this report reflect the views of the Coast Guard Research and Development Center, which is responsible for the facts and accuracy of data presented. This report does not constitute a standard, specification, or regulation.
 
SAMUEL F. POWEL, III
Technical Director
U.S. Coast Guard Research and Development Center
Avery Point, Groton, Connecticut 06340-6096

 


Table of Contents

1.0 Introduction

1.1

The Capsize Problem

1.2

Breaking Waves

1.3

Drogues
2.0 Scaling Considerations
2.1 Model Scaling
2.2 Wave Scaling
3.0 Model Tests
3.1 Early Work
3.2 Model Tests in Simulated Breaking Waves
3.2.1     Introduction
3.2.2     Test Equipment
3.2.3     Test Procedure
3.2.4     Discussion of Results
3.2.5    Computer Simulation
3.2.6    Conclusions

3.3

Circulating Water Channel Tests
3.3.1    Introduction
3.3.2    Test Equipment
3.3.3    Test Results
3.3.4    Conclusions

3.4

Hull Drag
3.4.1    Introduction
3.4.2    Test Equipment and Procedure
3.4.3    Test Results
3.4.4    Conclusions
4.0 Full-Scale Testing

4.1

Drag Tests of a Series Drogue
4.1.1    Introduction
4.1.2    Test Procedure
4.1.3    Test Results
4.1.4    Conclusions

4.2

Fatigue Tests of a Series Drogue
4.2.1    Introduction
4.2.2    Test Procedure
4.2.3    Test Results
4.2.4    Conclusions

4.3

Deployment & Retrieval Test of a Series Drogue

4.4

Test in Simulated Storm Seas
5.0 Mathematical Model

5.1

Introduction

5.2

Boat and Drogue in Regular Waves

5.3

Breaking Wave Strike
6.0 Recommended Design Requirements for Drogue Systems
6.1 Drogue Size
6.2 Design Loads
6.3 Towline and Attachments
6.4 Boat Design
6.5 Types of Drogues
6.6 Sea Anchor Deployed from the Bow
7.0 Conclusions
Appendix A-- Computer Program--Boat in Regular Waves
Appendix B-- Computer Program--Boat in Breaking Waves
Appendix C-- Estimating Drogue Size for Large Yachts

List of Illustrations

Figure 1

Sailboat Models
Figure 2 Breaking Wave Simulator
Figure 3 Sailing Yacht Model Characteristics
Figure 4 Standfast Model
Figure 5 Diagram of Test Run
Figure 6 Drogue Loads
Figure 7 Test Set-up in Circulating Water Channel
Figure 8 Drogue Models
Figure 9 Comparisons of Measured & Computed Drogue Loads
Figure 10 Forces During Wave Strike
Figure 11 Model Characteristics
Figure 12 Model Hull Drag
Figure 13 Model Hull Drag
Figure 14 Model in Flow Channel
Figure 15 Full-Scale Hull Drag
Figure 16 Series Drogue
Figure 17 Series Drogue Construction
Figure 18 Splicing Methods
Figure 19 Drag of a Series Drogue
Figure 20 Fatigue Test Set-up
Figure 21 Forces on Boat/Drogue System
Figure 22 Computer Simulation / 20 foot Waves
Figure 23 Computer Simulation / 80 foot Waves
Figure 24 Drogue Design Data
Figure 25 Recommended Drogue Size
Figure 26 Towline Design Data