Four Mast Failures

BOAT REPAIRS & MODIFICATIONS

Four Mast Failures--Nobody knows the damage I see!

In the last few years, SYDI has received a fair number of consulting calls on various sailing yacht mast failures. The following is a review of four of those cases. Three masts were made of carbon fiber, one was made of aluminum. Two of the masts could be saved, two could not. One of the carbon masts was struck by lightning but survived practically unscathed. The other three were not very well built, in my opinion, and in the following I explain why. I offer these stories here so that you can see some of the stuff that I am faced with in my day-to-day work.

Gitana VIII--Mast collapse at the dock.

Gitana VIII is a custom-designed and built aluminum racing yacht, built in Italy in 1984. In about 1996, the second owner had a carbon fiber mast built for it in France, and in 2000, he sold the yacht to its current owner. At this point of sale, the carbon fiber mast was replaced because a shroud had pulled out through the mast wall. The new mast was built by the same mast builder. The current owner refurbished the yacht in 2003/4, including some new standing rigging. Gitana VIII was always known to have a "soft rig", meaning that it was a little too bendy in the fore/aft direction, and it had to be sailed with some care and attention.

Fig. 1. Gitana VIII, in St.Barts, without her broken mast.

In January 2006, Gitana VIII went through a complete marine survey. The surveyor found cracks in the carbon fiber spreaders and boom and recommended a complete rig overhaul. In April, a technician from the mast builder arrived for some of those rig repairs and noted some cracks right the way through the mast wall on the aft side at various locations up high. The technician repaired these areas by fashioning and gluing in place some carbon fiber doublers on the outside, bridging over the cracks. In May, Gitana VIII's captain was preparing to depart St. Barts for a short trip up the islands, and he tensioned the rig by powering up the hydraulic mast step. The mast suddenly collapsed on itself right in way of the deck partners in an area hidden by the mast boot. Soon, I received a call from the insurance adjuster, Doug Wager of Wager & Associates in Pensacola, FL: "Eric, can you tell us why this mast broke?"

I had the broken section of mast cut free and sent to me in St. Augustine, and it soon became obvious that this was a very poorly made mast. See the next photos taken from my forensic report.

Figs. 2 & 3. (Left) The break showing eroded edges (red regions) and frayed fibers (blue regions with white arrows). (Right) This is the other end of the same sample. Note the area of extreme thinness (white arrows) and air pockets in the laminate (red ovals).

This mast was defectively built. The wall thickness varied too much--too much fiber on the sides, not enough in the corners or leading edge. It is probably not intended to be this way, it looks to be a fault in the production process--vacuum bagging over a male form. This mast has very poor fore/aft moment of inertia, and that is why it was always so bendy--"soft"--in that direction. The cracks that had been reported and repaired were in the aft corners where the laminate was thinnest and therefore under the highest stress, marked by the right white arrows in the right photo above. The crack that actually failed all the way through, in the left photo, showed that it had existed for some time (polished and worn faces of the mating surfaces of the crack--red areas) and that some of the fibers were totally dry of resin (seen elsewhere in the samples.) There were large air pockets in the laminate (red oval areas in right photo). Since the mast was defective, the insurance company was not obligated to pay out for coverage due to latent defects, which of course no one knew about until this failure occurred. So, the owner was not happy, but he bought a new mast from a more reputable and talented mast builder, and as far as I know, Gitana VIII has been sailing well ever since.

MITseaAH--Severe grounding, not the best mast lamination, plus a lightning strike.

Fig. 1. MITseaAH is a well-known 156' aluminum/composite sailing yacht with huge twin engines and a telescoping carbon fiber stayed mast.

The sailing yacht MITseaAH is notable for a few reasons: First, the bottom of her hull is aluminum, but the topsides are composite. She has a huge swinging keel that sits between two 3,500 horsepower MAN diesel engines, 7,000 HP total, which gives her a top speed under power of about 25 knots. Her carbon fiber mast is massive, and the top 30' of it telescopes out of the top of the lower main section.

A few years ago, the captain was cruising at high speed, with the keel down unfortunately, and he smashed right into a submerged ledge off the coast of Rhode Island. No real damage was done, surprisingly, or so the crew thought until two years later. While preparing MITseaAH for a charter and then eventual sale to new owners, the crew noticed that the mast wall in way of the spreader bases was moving, or bubbling. They took the mast down, and I got the call from the rigger, Colin Kiley, at Global RSI (superyacht rigging specialists) who said, "Please come, we need help."

Fig. 2. MITseaAH's mast as I found it at Rybovich's yard in West Palm Beach, FL.

MITseaAH's mast is huge--I could crawl up inside it. The main problem was from the grounding. When the yacht hit the ledge, the boat itself stopped, but the mast kept going. It appeared that the spreaders, normally swept aft, had all rotated forward, and their forward-side mounting feet punched down into the mast laminate causing the mast wall to delaminate. Similar damage occured at the deck partners. This was not discovered until the later inspection. Once the mast was substantially disassembled, we also noted that the tops of the holes in the mast, through which the mast lifting beam passed in the fore/aft direction, were badly crushed. Hydraulic rams under the ends of the lifting beam raise the beam and the mast upward to tension all the rigging. Also, the top of the mast had been struck by lightning, and there was burn damage from a side flash at the lightning arrestor mounting. Finally, we found that the mast was so massive that it had to be laid up in stage laminations with cure cycles for each stage. The quality of the laminate was not good, and there seemed to be lots of voids and delaminations in the very thick laminate.

What also surprised me was that the captain at this time (obviously, the previous captain had been fired!) showed me, on his computer, a complete copy of my investigation and repair report for Gitana VIII (the story above). This report, apparently, had gone around the world and so was quite well known. And that's why they called me--I would know what to do. For MITseaAH, I wrote a master report detailing the areas and kinds of repairs to make. The crew then contacted Formula Spars in England, who had taken over some of the assets of Hood Yacht Systems who had built the mast but who had gone out of business shortly after this mast was complete. Formula Spars provided some new carbon fiber splice pieces. The crew also contacted High Modulus of New Zealand for additional repair specifications. I made a second trip to the yacht to review the repairs at about mid-stage.

Figs. 3 & 4. (L) The mast laminate under the S-1 spreader bases was so badly damaged that the mast wall had to be completely ground away--square holes--and new internal splice pieces added, outlined by the blue tape. New outside laminations were added back. (R) A close-up of the lifting bar hole shows how badly the very thick mast was crushed. These areas were completely rebuilt.

It was during this job that I met Marty Ford, a journeyman boatbuilder and repairer with extensive experience in repairing carbon fiber composites. Marty is a New Zealander, but he lives in South Carolina. Marty did all the repair to MITseaAH's mast. We consulted back an forth on ideas to make sure the repairs were complete and sound. Marty did a great job, and he and I have been able to work on a number of boat repairs ever since.

Figs. 5 & 6. (L) You can see how thick the mast wall is, about 1.5" (38 mm) where I am sticking my pocket knife into the end laminate of the telescoping top mast in a void between stage laminations. (R) This shows the side flash in the laminate from the lightning that struck the lightning arrestor. This is superficial damage--the arrestor and lightning ground did their job by keeping the lightning in the conductor and down the mast, not allowing it into the mast laminate itself.

All the repairs were carried out to everyone's satisfaction and MITseaAH was on its way back to Europe to re-enter charter service and secure a new owner. Despite the obvious delaminations and voids in the laminate, the mast appeared to be so overbuilt that there was enough wall thickness and solidity to compensate. Except for the grounding, this mast had survived well for some years. Building a new mast as complicated as this, and which still did work, was out of the question.

Unfortunately, MITseaAH got as far as the Azores when she got slammed by some bad weather that came roaring into the harbor where she was moored, and she was banged up against a big jetty for about 6 hours. She finally made it out to sea in 60-70 mph winds. The hull got pretty badly beat up, but the mast held up beautifully. As far as I know, MITseaAH was successfully repaired.

Dragon Fly Plus--Another lightning strike on a carbon fiber mast.

This time the mast survived quite well--the lightning ground wire behaved exactly as it should have. Dragon Fly Plus is a customized Swan 53 that is campaigned actively in the most popular races and has a pretty good winning record. Dragon Fly Plus has been hit twice by lightning, unfortunately, and the first time the result was not so pretty. No sooner had she been repaired, with a new mast, and put back in the water, than she was hit by lightning a second time. But this time she fared much better. There was little damage to the mast and the boat, and only some electronics needed to be replaced. I don't have a picture of the boat itself, but below is the mast as I saw it in the shop at All Points Boats, Inc. in Ft. Lauderdale, FL.

Fig. 1. Dragon Fly Plus' mast out of the boat. Note the lightning arrestor in the foreground, with a rounded end, which is the current best design. A heavy wire from the base of this arrestor passes down the mast and out the bottom to of the boat via an attachment to a keel bolt and the lead ballast keel.

The lightning arrestor is a composite tubular wand with a stainless steel rounded end, inside of which is attached the grounding wire. The photos below show close-up views.

Figs. 2 & 3. Close-ups of the ends of the lightning arrestor (L: top; R: mounting base) show where the heat and energy of the lightning strike caused some delamination. These were just superficial wounds. The wand was replaced and the cosmetic damage in the mast wall repaired.

Current designs of lightning arrestors have these rounded tops, like a thumb radius, which gives the best protection to the boat. The lightning traveled down the lightning ground wire which passed through a hole in the mast side wall near the base and onto a connection to a keel bolt. I saw evidence of bubbling in the paint on the bottom of the keel where the lightning probably travelled on its way to ground.

Figs. 4 & 5. (L) The lightning ground wire coming out the lifting bar opening. (R) The base of the mast that sat on the metal mast step. There were no evidences of lightning leaving telltale white stains or burn damage where it could have exited the mast. Therefore, the lightning stayed within the grounding wire.

When lightning travels through a carbon fiber laminate, it sometimes leaves evidence of a white stain in the laminate where it exits the laminate. In Dragon Fly Plus' mast, there was no other evidence of white stain anywhere in the mast or on its base. There were no other side flash burns. Therefore, we think that the grounding wire performed exactly as it was supposed to, protecting the rest of the mast and the boat against damage. Since the electronics grounding wire was also attached to the keel, some of the charge did go back up to some electronics and electrical equipment and blew those out. Those pieces of equipment had to be replaced. The cost of all of this was covered by insurance. For comparison, the photo below shows the top of Dragon Fly Plus' first mast, which was also there at the yard. Obvious burn and explosive entrance damage are apparent.

Fig. 6. Dragon Fly Plus' original mast where it had been struck by lightning, obviously more catastrophic.

The necessary repairs were made to Dragon Fly Plus, and her mast was put back up. To date she seems to be continuing her successful racing program.

HULA GIRL--A sudden dismasting with absolutely no warning.

Although I specialize in the design, care, and feeding of carbon fiber masts, I also get asked from time to time to consult on common aluminum stayed masts. This is another case from the insurance adjusters, Doug Wager and Associates. Hula Girl is an Admiral 40 fiberglass catamaran built in South Africa. She came to the US across the Atlantic Ocean on her own bottom and immediately went into bareboat charter service in Ft. Lauderdale. After about 6 or 7 charters, she went out on yet another charter, and that first day just offshore on a port tack broad reach under reefed main with the wind at 20 mph, gusting 30 mph, the mast suddenly and inexplicably fell over to the port side without prior warning or noise. The mast tube had obviously broken about 12' above the deck between the mast step and the only set of spreaders, rigged with double nesting diamond wires. All the rigging was accounted for except the jumper stay. There was considerable consequential damage to the deck and lifelines, but no one was hurt. No one could figure out why the mast would suddenly keel over all by itself, so Doug Wager called and said they needed some investigative help.

Fig. 1. Hula Girl at the dock without her mast.

Fortunately, all the broken pieces were there, save for the jumper stay, and spread between the charter dock and the rigger's shop. Speculation as to cause at first centered around the missing jumper stay, and maybe a weak deck or hull which maybe could have deflected enough to loosen the rigging. But on inspection these were quickly ruled out. The jumper would not have been under appreciable load on that particular point of sail, and the hull and deck structures were substantially built, strong and stiff. So investigation quickly went to the mast itself.

Figs. 2 & 3. (L) The lower section of Hula Girl's mast at the charter dock. (R) The upper section at the riggers.

Looking at the ends of the broken mast section, a possible cause of the failure became apparent. The break was a compression collapse on the port side. The mast wall was severely bent inward at a compression break that was located at the top of a halyard exit opening. The mating faces of the break were slightly peaned, but not badly, indicating some prior wear, although not much. The other side of the break was a typical tension tear failure. My opinion was that the port side wall collapsed first, causing the mast to start falling over to the port side, then the starboard side of the mast wall tore and broke as the mast continued to fall.

Figs. 4 & 5. (L) Close-up of the break on the upper section of Hula Girl's mast which indicates compression failure where the mast wall is severely buckled in (left side in photo), and tension failure on the opposite side. (R) A side view of the same part, note the black arrow which points to the top of the halyard exit opening through which the break was located. This halyard exit opening was in a typically high-stressed portion of the mast.

We also had the mast material analyzed by a nearby metalurgical laboratory, and they determined that the break was a single event failure, not a fatigue failure, and that the alloy of the mast was not 6061-T6 as was stated by the mast manufacturer, although it was later determined it could be a close relative alloy. I also learned that the mast had never been inspected since new other than to attend to a small repair on the mast at the sheave for the spinnaker halyard at the top of the mast shortly after the boat arrived in the US. After the transatlantic crossing, one would normally inspect absolutely everything on a sailing yacht for unusual wear and tear, but, in fact, this was not done. No inspection of the rig was ever carried out, even during the subsequent 6 to 7 charters.

This mast could not be saved, and so a new mast was ordered, although I don't know the disposition of the insurance and whether that paid for it. The broken sections were sent back to the mast builder in South Africa for their further analysis.

If you have a yacht with damage and need some extra help in determining what went awry or how to repair it, give us a call and we may be able to help. Here are some other recent examples of repair projects we have had in the last few years:

Hull Damage:

MY Christael, Carver 56: Stove-in front windshield. Determined that the deck structure was not strongly enough built for on-coming green seas. Inspected boat and wrote repair spec. for Thunderbolt Marine, Savannah, GA.

MY Grand Finale, Sunseeker 56: Damaged bottom while on trailer transport from Florida to the Great Lakes. A large built-in fuel tank prevented repairs from both inside and out, so it had to rebuild the hull from one side only. From photos only, wrote a repair spec. for Catawba Island Marina in Port Clinton, OH.

SY Sabbatical^2, Lagoon 41 catamaran: This poor boat was just visiting a local restaurant in Savannah, GA, when it got caught between a dock and a passing tug and barge--talk about squished between a rock and a hard place! Lots of crushing damage on both sides. Inspected the boat and wrote a repair spec. for Thunderbolt Marine and Marty Ford.

MY Phoenix, Hood 52 catamaran: Bad fire in the engine room which burned out a lot of fiberglass and core on the inside of the hull and deck, and some on the hull outside. Inspected the boat and wrote a repair spec. for Thunderbolt Marine and Marty Ford.

Rudder Damage:

SY Cabochon, Custom Fontaine/Hood 92: Improperly built rudder when new in Taiwan. Inspected the boat in Florida after it was temporarily repaired in Trinidad. Wrote rebuild spec. which included removing the spade rudder, rebuilding that and the hull, rebuilding the rudder gudgeon mounting, and realigning the bearings, for Rybovich Marina in West Palm Beach, FL.

SY Swept Away, Bennett 48: The boat was going to be sold but the rudder was sticking badly. Found out on inspection that the rudder was so badly misaligned that it had to be removed and the neck bearing completely rebuilt. Visited boat and wrote a repair spec. for Hinckley Marine in Stuart, FL.

SY Zambesi, Oyster 62: Zambesi was coming up the Savannah River when the current carried her onto the rock-hard sand shoal. The impact broke the skeg completely in two and jammed the rudder up into the hull. Inspected the boat and wrote a repair spec. for Thunderbolt Marine and Marty Ford.

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