Mast Cracks near Masthead Sheave Box

Here's something I thought I'd share with the group.

Original mast in a 1981 382. I found a very small crack in the masthead sheave box while inspecting the rig for our recent transatlantic. Though possible, it was very difficult to see the crack with the naked eye. In fact, I only noticed it while reviewing the photos we took during the inspection (we performed the inspection via bosun's seat). This crack was located in the lower aft corner of the masthead sheave box, port side. The starboard side was fine, as was the forward side of the mast.

Due to the very small size of the crack, I thought it was pretty inconsequential. However, due to the ramifications of losing a mast 1,000 miles offshore in the North Atlantic, I figured that I should consult with a professional. I hired Brion Toss to take a look, and he was adamant that this was anything but inconsequential. He said that he has seen numerous examples of mastheads being, essentially, ripped from the top of masts. Given the location of the cap shrouds (a few feet below the top of the masthead) and the cut/welds in the corners of the sheave box, he said that this is a built-in design weakness to this type of rig. Not uncommon. He also suggested that once the cracks form, they can progress VERY rapidly. Given this route's reputation of turning into a heavy weather passage, he strongly advised NOT attempting a west-to-east crossing of the Atlantic without addressing the problem - he gave the mast 50:50 odds of surviving the trip if I did nothing to address the issue.

The ultimate fix would be to cut the top of the mast off and replace it with a new masthead - sleeved to the old. That wasn't an option for me given my location (Antigua) and timeline to get moving - we were bumping up against the end of May (hurricane season starts June 1 in the Caribbean). We needed to get moving one way or another - out of the hurricane box. The next best solution would be to drill stop the crack and install a "band-aid" patch in the form a 1/8" stainless steel plate (as large as would fit) riveted transversely across the repair. This is how I addressed the problem.

What you're seeing in the photos is a 1/4" hole drilled at the point of the crack. Brion suggested that it's almost impossible to remove too much material with this method and suggested using this size drill bit. The larger the hole the better - the crack should ideally "see" an infinite radius to minimize the risk of the crack jumping across the drill hole and continuing on the other side.The drill hole is the primary repair - the stainless steel patch is just extra insurance. It was very difficult to get a 1/8" stainless steel plate bent to the proper compound angle/curve to perfectly conform to the mast. Especially given it's location at the top of the mast - sitting in a bosun's seat.

While I have no way of knowing whether or not the mast would have failed without the repair, I'm glad we went through the work to address it. Our passage turned out to be rather challenging. We had wind forward of the beam for 16 of the 18 days it took to get to the Azores, and we had winds in excess of 30 knots or greater for nearly all of the last 7 days (including a total of 25 hours hove-to with wind gust to 48 knots) at sea. We had a 3rd reef in the main for about 1/3 of the entire 2300 mile trip (St. Martin/Azores).

As I mentioned in another thread, this boat is such a joy to sail offshore. She handles rough weather great. She does great in light winds (even loaded down for cruising as we were). Easy to single hand. I estimate that I've put about 15,000 nautical miles (offshore/ocean sailing) on her in the last 4 years of cruising, and she just gets better and better the more I learn about her.

Ken, thanks much for sharing this. I am pulling the rig this winter and will look very carefully now. I probably would have missed something so small. Do you and Toss now consider this a permanent fix, or are you going to cut the top of the mast now you are in Europe? Are you in the Med? By the way, I have never heaved to in my Morgan, although I should have practiced. What sails did you use and how did you adjust them to successfully heave to? It seems to me it might be hard to get the boat to drift back and create the slick, given the fin keel design.

terry_thatcher said:

Ken, thanks much for sharing this. I am pulling the rig this winter and will look very carefully now. I probably would have missed something so small. Do you and Toss now consider this a permanent fix, or are you going to cut the top of the mast now you are in Europe? Are you in the Med? By the way, I have never heaved to in my Morgan, although I should have practiced. What sails did you use and how did you adjust them to successfully heave to? It seems to me it might be hard to get the boat to drift back and create the slick, given the fin keel design.

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I forgot to mention that we inspected the mast in the Azores to see how the repair handled the trip. Everything was fine; I saw no signs that the crack jumped the drill stop hole. The trip from the Azores to Portugal was much more benign than the first leg. The boat is on the hard right now while we are land travelling Europe. We'll return to the US for the winter and start our Med cruise next year. I need to replace the wiring for my anemometer, so I'll likely pull the stick before starting the cruise - I can do a 2nd more thorough inspection at that time. Assuming that the crack hasn't grown, I will most likely consider the repair permanent. I can't imagine the downwind trip back across the Atlantic to be more strenuous on the rig than the upwind slog its already endured. Obviously continue to monitor the issue while I own the boat. Make sure you look closely at the shroud compression posts (uppers and lowers) while you have the mast down. I found cracks in 2 out of the 4 welds back when I replaced the rigging in 2014. Also a common problem on many rigs, and easily repaired with doubler plates.

Heaving to: We used only the 3rd reef in the main, sheeted hard (traveler slightly to windward) - no headsail at all. We added the 3rd reef while in Antigua, and, unfortunately, it's a bit too shallow - the optimum placement was blocked by a batten. As a result, we did find it difficult to completely halt all forward progress, and we forereached at about 1 knot. This was perfectly acceptable given the sea state (no breaking waves), and the boat settled down very well. We were able to get some sleep and enjoy some relative peace. I think with a deeper reef, we could have easily stopped all forward progress. If things got worse, we would have tried to a Delta drogue to stop the forereaching. And we were prepared to deploy our Jordan Series Drogue if the waves started to break.

Our next mainsail will be built with 3 reefs - we used it A LOT on this passage (and not just to heave to). Our 1st and 2nd reef will both be deeper than they currently are. In 2 seasons of Caribbean sailing, we were nearly ALWAYS double-reefed. Even when deeply reefed, we're nearly always sailing at or near hull speed.

I used my triple reef regularly even when reaching and running on our Polynesia trip, often with a full or nearly full genoa. Morgan 382s are jib driven boats and, in my view, a little squirrely down wind. We found the main reefs were essential to allow the Monitor to steer the boat well.

terry_thatcher said:

I used my triple reef regularly even when reaching and running on our Polynesia trip, often with a full or nearly full genoa. Morgan 382s are jib driven boats and, in my view, a little squirrely down wind. We found the main reefs were essential to allow the Monitor to steer the boat well.

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I can't say enough good things about our Monitor. If we're sailing, it's steering. It steers well through just about everything. Obviously we have to balance the sail plan and try to maintain reasonable amounts of weather helm... but, aside from that, it rocks! With that said, the only "issues" we had on the entire crossing had to do with the windvane. Line chafe was an issue, but that was because I used a few undersized blocks (not at all the fault of the windvane). We also hit something with the pendulum one night and it bent the safety tube - I have no idea what. That was a bit of a pain in the butt to repair. We had about 25 knots of wind and decent seas. We hove to and hung over the back of the boat to remove the pendulum and repair. It took about an hour start to finish (including emptying the cockpit locker to retrieve the spare). Not too bad, but I'd rather not have to do it again.

We don't have any trouble with the boat when sailing off the wind until the seas get big... then the boat tends to "carve" a bit. It's not terrible, but I often wonder if the larger rudder on the later models would make a difference. I mean, how well does any boat track when racing down the front of wave?