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J/30 Spreader Brackets

A Safety-Oriented Upgrade

by Al Schreitmueller, Jaguar

Last update: January 7, 1997  (Copied from Old J/30 Class Website)

The J/30 provides owners and crew many hours of enjoyment, both on the race course and while cruising. As with any boat, there are features which can be improved upon – given the benefit of years of use and 20/20 hindsight. Some enhancements are performance-oriented and will benefit the PHRF sailor only; some are simply safety-oriented and benefit both the one-design and PHRF sailor. An example of the latter is an upgrade to the J/30 spreader brackets.

Potential Weakness

In the past few years, there have been several dismastings reported of J/30’s. By review of the causes, a possible weakness in the design of the spreader bracket has been identified, and fairly simple methods of reinforcement developed. This does not mean your unmodified spreader brackets are a ticking time bomb, but a careful inspection may yield some surprises.

The problem usually occurs in boats that have been raced hard, and where the rig has been subject to a fair amount of pumping. In the July 1980 issue of Practical Sailor, the author recommends running backstays for off-shore work to minimize pumping. Boats sailed “in-shore” over a long period can develop the same associated problems. “Pumping” is accentuated by the swept-back spreaders when the backstay is very tight when sailed in heavy air with a significant wave chop. The middle of the mast will pump forward as the boat meets the resistance of a wave, and then back in the trough.

This action works mostly at the rivets which hold the forward edge of the spreader bracket to the mast, and the easing motion works at the aft rivets. An initial symptom is the appearance of stretch in the forward rivets; this initial play then accelerates the failure process. The aft rivets may finally fail, or the pressure is transferred to the aft section of the brackets (and mast), crimping the aft part of the mast section under severe pressures. Either cause will take out the windward speader and crumple the mast at that point. I have been told that the J/24 suffers from the same weakness.

Possible Solutions

Several Annapolis firms have worked on J/30 spreader brackets. According to Tom Wohlgemuth at Chesapeake Rigging/Annapolis Spars, there are a variety of ways to attack the problem. These include a retrofit of existing brackets, thru-bar mounted brackets (a la J/24), and new fabrications which replace the older ones. In most cases, a new fabrication (external to the mast) will be the least expensive, primarily because of labor to install. Wohlgemuth recommends a fitting similar to the original, except a stainless band is welded from the front of one bracket, goes around the front of the mast, and attaches to the front of the other bracket. That reinforces the front rivets. A compression tube is also run through the mast to keep the aft part of the mast from compressing.

Bob Muller of Muller Marine feels the front collar is the key. If the front rivets are secure, the back rivets should be fine, he emphasizes. He offers the compression tube, too, if the owner desires it.

The typical boat has gone 10 years without the modification, and the front collar provides most of the strength of the upgrade. Both Wohlgemuth and Muller recommend the procedure be done with the mast out of the boat. Typical costs might be $150 – $200 for removal/restepping the mast, and $100 – $160 for the spreader kit. Both firms are planning to make available a kit which could be shipped to owners outside the Annapolis area.

Wohlgemuth advises that it is important to use the existing rivet holes in the mast, and to carefully drill holes for the new fitting that line up with them. This reduces the holes in the mast that absorbs a lot of stress.

The downside of this retrofit is that a little weight is added aloft. However, a DNF when the stick comes down is very slow, and the safety and well being of your team is well worth any nanoseconds lost!

Editor’s note: Annapolis Rigging Company’s Jay Herman has also designed a modification to our spreader brackets and installed it on a short section of an old mast. Terry Rapp has inspected it and approved it for use on our boats.

For more details, contact:
Chesapeake Rigging/Annapolis Spars (410) 268-0956
Muller Marine (410) 626-1238
Annapolis Rigging Company (410) 269-8035