Mast Development & Rig Tuning

Technical advice on preventing mast diamonds from slipping out of spreader tips. The solution involves opening the end of the spreader tip with a hammer until the slot is closed sufficiently to keep the wire from coming out, and holding the diamonds in place with marlin or fine copper wire.

Technical notice from mast manufacturer Douglass and McLeod regarding a discovered error in mast lengths on some THISTLE boats. Provides measurement and correction procedures for affected boats.

A technical column explaining how to adjust chainplate positions when the existing holes do not align properly for perfect mast tuning, providing methods for modification using brass protection.

Jim Ness of Fleet 48, Atlanta, provides practical instructions for single-handing the mast-stepping process using the spinnaker halyard and boat tackle, eliminating the need for extra crew members.

The Chief Measurer discusses problems with standard halyard sheaves on the mast that can cause damage and jamming. He proposes that a larger sheave diameter extending properly into the groove would solve these issues while remaining compliant with class rules.

Technical column addressing mast measurement procedures discovered during the Nationals inspection, including findings that many masts exceeded maximum length allowances and recommending stricter measurement protocols.

Technical article discussing wooden mast growth after extended water immersion, citing Bill Nexsen's 1957 Nationals award and describing the engineering problem of mast length changes.

The Chief Measurer clarifies TCA rules regarding adjustable mast steps, ruling that such devices are not permitted on Thistles, as the mast step must remain fixed and not be altered during racing.

The TCA's ruling against aluminum masts has created challenges for the California fleet, particularly for skippers using Shock aluminum masts who want to comply with regulations. Rear Commodore Bill Nexsen expresses concern about the practical impact.

The TCA Measurer George Devlin refused legal sanction for the commercially-developed Schock aluminum mast in December 1959, ruling that its dimensions did not conform to the official wooden mast specifications.

The Schock-manufactured aluminum Thistle mast was refused legal sanction by TCA Measurer George Devlin. A proposal to sanction aluminum spars for the class was rejected pending agreement with the TCA's official specifications.

Continuation of the discussion about the Schock aluminum mast, with measurer George Devlin's technical analysis and the class vote regarding its sanction.

The Schock-manufactured aluminum Thistle mast was rejected for class sanction by TCA Measurer George Devlin after extensive testing. Although the class approved a proposal to use aluminum spars in 1959, Devlin determined this specific mast design did not conform to Thistle specifications and was therefore not permitted.

California boat builder W. D. Schock and TCA President Evans Harrell exchanged letters regarding a Bagpipe article about aluminum masts. While disagreeing on editorial decisions, both affirmed commitment to one-design standards and Harrell disclosed that a die is being made for an official aluminum mast.

Bill Walton provides practical guidance for sailors on how to repair a snapped diamond stay on a mast during a regatta. The method involves using wire cutters and thimbles to create a temporary but serviceable repair.

The Thistle class faces a growing controversy over Schock's aluminum masts, which the TCA maintains are completely illegal for sanctioned events. President Evans Harrell issued a strong open letter denying the legality of aluminum spars, while class members reported problems including poor buoyancy and boats turning over.

President Evans Harrell's comprehensive letter addresses the aluminum mast controversy by providing constitutional and procedural arguments against approving Schock's aluminum spars. He clarifies TCA policy on design changes and explains the required amendment process for any rule modifications.

Notes on equipment and techniques observed at St. Petersburg Midwinter, including details on mast position and rigging equipment used by top competitors.

Technical article explaining how to adjust backlashes and tension on Thistle halyard winches, with specific instructions for both wooden masts and aluminum masts. Includes details on spring mechanisms and winch maintenance.

Technical article on proper adjustment of halyard winches on Thistle aluminum masts. Explains the mechanical adjustments needed for proper tension to allow easy spinning of the winches.

Comprehensive examination of mast material choices for Thistles, comparing wood and aluminum options. Discusses historical development, performance characteristics, costs, and the practical implications of different mast choices for the class.

The Governing Board of the Thistle Class Association met to discuss mast testing procedures and specifications for future racing. The board approved extensive research into mast development, with funding approved for experimental aluminum masts. Discussion focused on standardizing equipment and addressing competitive fairness in the racing classes.

Analysis of mast performance data collected at the 1968 Nationals, examining correlations between mast characteristics (bendiness, weight, deflection) and race results, with recommendations for potential standardization efforts.

A technical analysis of the mast study conducted at the 1968 Nationals, examining the vulnerability of Thistle masts to breakage. The study found that lighter wooden masts (under 28 pounds) and masts bent more than 6.5 inches were more prone to failure, suggesting the need for higher quality standards and dimensional consistency in mast manufacturing.

Minutes of Executive Committee actions covering mast deflection measurements, chief measurer appointment, 1969 Nationals film availability, boat construction specifications, and discussion of regulation compliance and measurement procedures for racing equipment.

Comprehensive memo by Chief Measurer Jim Miller addressing mast specifications, variations in mast performance, and the proposed new mast development program. Covers the Proctor F-section mast study at Sayville, specifications for aluminum and wood masts, and considerations for the new design.

Report on the Heather Bowl regatta at Red Dragon Canoe Club. Jim Miller took the Delaware at the Annual Heather Bowl sailing his Thistle 'Spirit' with the experimental bendy aluminum mast. His sailing technique proved that the new mast is a definite improvement over previous designs.

Chief Measurer Jim Miller discusses mast design, philosophy of class development, measurement concerns, and technical specifications for proposed new aluminum masts for the Thistle Class. Includes detailed technical analysis and personal reflections on the mast study conducted at Sayville.

Detailed technical discussion of a mast development study conducted at Sayville, examining variations in mast weight, bendiness, and construction characteristics among aluminum and wood masts used in Thistle racing, with implications for class fairness and competitive boat development.

Report on the Heather Bowl regatta featuring Jim Miller's experimental mast design, with racing results and commentary on the competition, including performances by various District competitors.

Miller and Wilson discussed the current status of developing a more standardized mast for the Thistle class, noting that investigations should continue along their present course while pursuing a new metal mast design with improved deflection characteristics.

Detailed report on mast performance evaluation tests conducted at St. Pete with experimental designs. The article discusses the Proctor "F" mast, the Helms mast, and proposed new aluminum designs, examining their sailing characteristics and bending behavior under different conditions.

Discussion of different mast options for Thistles based on St. Pete trials, comparing the Proctor 'F', experimental aluminum masts, and wooden masts with recommendations for different sailing conditions.

Chief Measurer discusses an article on aluminum mast development for the Thistle class, noting that while masts proved competitive, the question of whether to adopt an aluminum mast as standard remains open to debate.

Continuation of technical discussion about mast specifications, centerboard standards, and class rules regarding equipment modifications and purchase of sails.

Reader letter from L.C. McCluskey regarding aluminum masts and discussion of design alternatives for the Thistle Class.

Discussion of mast development program and class standardization efforts. Raises questions about potential diamond rig replacements, spreader usage, and rudder improvements for Thistles.

Jim Miller provides an update on the Class's mast development program, discussing testing of different mast extrusions and their structural properties compared to existing models.

Interim report on mast development program. A new 7½' x 3⅜" spar was tested repeatedly with favorable results for sound strength and bending characteristics, making it durable for extended use.

Discussion of the Thistle mast program including aluminum mast development at St. Pete, rigging specifications, and considerations for future mast improvements.

Report on the ongoing Thistle Class mast development program to find the ideal aluminum mast design. Discusses the history of mast studies, prototype testing, and current efforts to develop new mast designs with improved performance characteristics.

As the class prepares for the Mid-Winter program, the Governing Board discussed the new aluminum mast section approved for the 1972 season. The article covers details about mast modifications, including the new 30-foot design specifications, and outlines ongoing initiatives regarding boat weight and measurement standards.

Detailed article discussing the development and testing of a new aluminum mast design for the Thistle, including the engineering challenges and resolution with the mast builders.

Technical article on the new aluminum mast now in production for Thistles, with detailed specifications, test results, and information about availability through ARO Spar Company.

Expert commentary from Chuck Steigerwald, Bob White, and Doug Laber on the new aluminum mast, discussing its performance characteristics compared to wood and discussing advantages for high-performance sailing.

Jim Miller provides detailed technical instructions on the history and rigging specifications of Thistle masts, including information about mast construction materials, spreader sizing, spinnaker pole attachment, and step casting specifications for proper rigging.

Continuation of mast rigging instructions covering halyards, sequence of assembly, spreaders, diamonds, and other technical specifications for proper mast installation and tuning.

Measurer's report on mast failures and centerboard issues discovered during the 1976 St. Petersburg Mid-Winters. Details problems with spreader strength and annealed tubing affecting boat performance.

Reports on recent mast failures in Thistle racing, particularly from the southeastern part of the country. Analyzes the technical aspects of mast failures and discusses recommendations for avoiding similar problems in future races.

Technical discussion on mast placement and fairlead positioning, with detailed explanation of placement ratios and engineering considerations for optimal sail performance and structural integrity.

A detailed technical article examining mast failures in Thistle sailboats. Scharenberg discusses the design, specifications, fabrication methods, and various failure modes of aluminum masts, providing insights into causes and contributing factors based on investigation of broken masts.

A detailed technical analysis of failures in Thistle mast design and construction, examining the evolution from aluminum to new materials, design specifications, and the structural factors that contribute to both catastrophic and stress-related failures.

Technical analysis of Thistle mast design and rigging loads by Phil Bucher. The article examines the various forces acting on the mast and supporting rigging, provides tables of estimated loads on different components, and discusses the critical stress areas. Recommendations are made for maximum sizes on shrouds, halyards, and the forestay to ensure safe operation.

A comprehensive technical analysis of Thistle mast design, rigging loads, and structural forces, examining the various components and their interactions during sailing.

The Chief Measurer provides updates on recent measurement requests and policies. He announces a new mast builder, Bryant Spars of Buffalo, and notes the introduction of ARO mast caps. He discusses approval for wooden Thistle construction using the West epoxy system and addresses requests about building rules.

An overview of the history of mast material development in the Thistle Class by Larry Haupt. The article traces the evolution from wooden masts to aluminum, describing the class's consideration of different materials and the eventual adoption of aluminum masts.

A continuation of the aluminum masts discussion from page 17, addressing the ongoing challenge of maintaining fairness in mast selection and the evolution of mast technology in the Thistle Class.

Technical memo from the Chief Measurer discussing mast construction problems found at the 1981 Nationals, with specific measurements of oversized masts and recommendations for checking and correcting mast tolerance issues.

The Chief Measurer discusses findings from the 1981 Nationals regarding mast measurements and tolerances. Various masts were found to exceed specifications, and the report documents systematic problems with mast supplier quality control and manufacturing processes, leading to recommendations for stricter oversight.

A comprehensive table of 42 masts measured at the St. Pete 1982 event, showing boat numbers, manufacturers, and specific dimensions including maximum and minimum lengths and weight specifications.

A comprehensive Q&A article with Buzz Ballenger of ARO Boatbuilding providing practical advice on mast maintenance, repair, and upkeep. Covers guidelines for shroud replacement, solid wire care, fitting inspection, corrosion prevention, and specifications for various mast components.

Klotz discusses his experience racing Thistles in high winds at the Mallory quarter-finals, analyzing what causes mast failures and offering practical advice for preventing damage. He addresses tradeoffs in mast design and emphasizes the importance of proper vang tension and careful jibing technique.

Chris Klotz reports on the Midwinters East Regatta, noting technical issues with masts and equipment. He discusses broken masts, forestay failures, and other problems encountered, along with recommendations for maintenance and repair including vang adjustments, boom positioning, and proper centerboard handling.

Technical column discussing measurement restrictions for Thistle masts, particularly addressing issues with oversized masts and the need for consistency in measurement enforcement.

Technical article on how to straighten bent aluminum Thistle masts using hydraulic jacks and proper support techniques.

News report about the development of a new two-piece folding mast for Thistle sailboats by local sailsmith Bent Brentman and Thistle sailor Eli Philanderer. Describes the initial testing and experimental process using Uniradial Geodesic Spinmakers in a marina parking lot.

Technical article describing a practical method for straightening bent aluminum Thistle masts, including specific techniques for determining the bend location and applying controlled force using a portable workbench as a fulcrum.

Dunn provides a detailed technical explanation of mast bend in Thistle dinghies, covering both lateral and fore/aft mast bend. He explains how diamonds, shrouds, and the mast step affect sail shape, and provides practical tuning advice for sailors.

Chief Measurer Pollak addresses the six mast breakages at Midwinters East, explaining that the Measurement Committee will investigate systematically rather than speculate. He also confirms that measurement issues regarding tack slugs and rudder compliance are under review but not in crisis mode.

A retrospective on the development of Thistle aluminum masts from the 1960s onward. Glover discusses how the original wooden masts were replaced with aluminum designs, the engineering challenges faced, and how design changes over time have affected mast strength and durability.

Chris Pollak explains the technical aspects and history of mast shims in Thistle racing, including the rules that govern their use. He traces the practice back to the late 1970s when North Sails began experimenting with mast bend control, and outlines the specific limits and restrictions under which shims can be used. Key points include that shims cannot exceed 3/16" total thickness and cannot be changed during racing.

A comprehensive technical guide to Thistle mast setup and tuning. Turney walks through straightening the mast, tuning diamonds with consistent tension gauges, measuring head stay tension and mast rake, and controlling prebend through shims. The article explains how to adjust for different wind and water conditions and provides visual indicators for proper mast bend using wrinkle patterns.

A comprehensive technical guide to Thistle mast setup and tuning, covering straightening the mast, diamond wire tension, prebend adjustment using shims, and controlling mast bend. The article includes detailed photographs showing proper techniques and explains how mast bend affects mainsail shape.

Comprehensive guide covering mast maintenance and tuning for Thistle sailors, including inspection of halyards and sheaves, achieving mast straightness, diamond tension adjustments, and procedures for stepping and raking the mast.

Pollak provides a precise method for determining mast straightness using a string stretched between the halyard sheave and gooseneck, allowing detection of mast curves as small as 1/2-turn of a spreader bolt.

Doug Laber provides a technical analysis of mast breakage in Thistle sailboats, focusing on heavy-air off-wind conditions. He explains the physics of column loading, sail forces, and mast deformations, then discusses three types of breakage mechanisms and strategies for prevention.

Announcement of an online survey to gather data on Thistle mast failures. The survey asks respondents about conditions, actions, and setup details surrounding mast failure events to help the class understand what causes mast failures and make informed decisions.

A technical article with photos explaining mast inversion in Thistles during gusty conditions. The piece features advice from Mike Ingham on how to minimize inversion by maintaining mainsail tension, easing the spinnaker sheet, and bearing off to keep mainsheet tension rather than dumping the vang completely.

The Chief Measurer discusses the Measurement Committee's efforts to simplify mast bend control systems in Thistles. Current methods using shims and diamond wires are complicated; the committee is exploring alternative designs and seeks input from engineers and machinists who might help develop improvements.

Technical analysis of mast assembly components and methods for adjusting lower mast bend, including recommendations for easier adjustment procedures using bolts instead of shims to maintain competitive boat parity.