Mast safety check

[Jackdaw]

Last night we had a race in 15-20 knots, with VERY lumpy seastate at the starting area and lower 1/2 of the course. Just after their start a Capri 25 lost its mast. No one was hurt. Back at the dock, I asked a crew member what happened. Seems that the small wire that is used to hold the shroud to the spreader tip broke or simply fell off under the rubber boot. While pounding upwind, the shroud jumped out of the small groove at the tip. First the crew noticed the cap fall off, then the shroud was out. A few seconds later, the mast was down.

If you have a boat of this type/generation, I'd really suggest taking a look under that rubber boot and check the state of that little wire. It was an iffy way too hold the shroud on, but is OK if the wire holds. But it if fails you're going to have issues. Newer boats have better spreader tip design to solve this problem.

99% of mast failures are maintenance/inspection issues. They don't just fall down.

 

[Jackdaw]

If you have these

It's supposed to look like this under there.

But ignore them, and the wire could break, or even worse.

 

[Apex]

Good PSA JD!
I blew the head of my jib last weekend, and am going up tonight to retrieve the swivel block jammed under my forestay. A chance to wipe spider webs of the chicken, check for what may have caused the webbing to chafe, general inspection of the masthead, move the radar reflector further up the backstay, and NOW check the seizing wire under the spreader boots.

 

[Gunni]

My rigger hates spreader boots, now I know why, he even confiscated my shroud turnbuckle covers! But that bailing wire shroud attachment is just rinky dink, dissimilar metals too. Needs a proper shroud clamp.

 

[Jackdaw]

My rigger hates spreader boots, now I know why, he even confiscated my shroud turnbuckle covers! But that bailing wire shroud attachment is just rinky dink, dissimilar metals too. Needs a proper shroud clamp.

yea, there's a reason modern spreader tips look like this. All SS at the contact point. Holds the shroud super securely. Smooth shape with low windage, nothing to snag and does not need a boot.

 

[JRT]

Is it possible to retro fit? I'm planning to haul out the O'Day 25 this winter for removing all below waterline holes and I'm considering dropping the mast for VHF antennae fix, remove broken FM/AM antennae and in general inspect for any issues. My boots are long gone, so I was planning to replace them anyway.

 

[jviss]

Wow, great post JD, thank you. My C65 has aluminum spreaders with cast aluminum tips, and the shrouds are seized with monel wire. I confess I haven't inspected them every year. The Tartan has something similar, though they have sewn-on leather spreader tip covers. I will inspect and/or renew those in the Fall.

Was the C25's mast or anything else expensive ruined?

I also suspect their rig wasn't tight enough. A rig should be tensioned so that you don't have shock loads on the shrouds. If it could loosen enough in pounding seas to jump the spreader tip groove, I guess it wasn't tight enough. Your thoughts?

 

[IDtrucks]

Thanks jack. That’s what mine look like and I wondered at first if it was a hack job repair but I guess it’s supposed to look like that. Luckily my mast is off and on the ground right now so it’s the perfect time to do a good inspection and replace/reinforce that wire!

 

[Jackdaw]

Wow, great post JD, thank you. My C65 has aluminum spreaders with cast aluminum tips, and the shrouds are seized with monel wire. I confess I haven't inspected them every year. The Tartan has something similar, though they have sewn-on leather spreader tip covers. I will inspect and/or renew those in the Fall.

Was the C25's mast or anything else expensive ruined?

I also suspect their rig wasn't tight enough. A rig should be tensioned so that you don't have shock loads on the shrouds. If it could loosen enough in pounding seas to jump the spreader tip groove, I guess it wasn't tight enough. Your thoughts?

Its not uncommon for leeward shrouds to go slack in bigger breeze. The bumpy seas don't help, as the Capri25 is a bit of a noodle. Most boats at WYC tune their rig tension to expected conditions. I don't know this boat that well so not sure what they do. We had our rig tuned in our '3' setting (1-4).

The mast broke in two at the spreaders, and they punched a nice hole in their laminated mainsail right aft of the boltrope. That should be an easy repair. The WYC Capri fleet actually maintains a stock of C25 masts. They lose 1-2 on average every year. AFAICT no other damage.

 

[Jackdaw]

Here's an aft-facing vid of the PHRF 1 start, showing the conditions. A bit choppy but not too bad. We're in sequence, so the Capri's have just started, and the mast must just be falling. Behind us there is thunder and lighting in the near-distance, so the RC abandons the race. You can hear the radio call then the 3 guns.

 

[jviss]

Wow, scary.

Its not uncommon for leeward shrouds to go slack in bigger breeze.

Yes, I agree, but from my research, they shouldn't; the rig should be tensioned such that the shrouds never go slack, else they are subject to impact loads that are well above what they will see otherwise. It may be that the boat can't stand this amount of tension, i.e., the hull is too soft.

I realize this is a controversial topic.

 

[pateco]

I probably need to check this out on my boat.

PS. Is it OK for the leeward shrouds to be a little loose in a decent breeze, or should I be scheduling a rig re-tuning? Rig has not be re-tuned since the mast was stepped 3.5 years ago. I check for corrosion regularly, with no issues found, and all of the cotter pins locking in the turnbuckles are still fixed.

I would do it myself, but I don't own a loos gauge.

 

[jviss]

From Loos, the rigging tension gauge guys:

"Contrary to popular thought, a slack rig is more punishing on a hull than a properly adjusted, tight rig. Insufficient tension will not reduce the loads transmitted in the hull. Slack rigging will punish the spar and rigging needlessly by allowing excessive movement, chafe and shock loading. Modern fiberglass hulls should not be damaged by a properly adjusted, tight rig."

"If the shrouds are not set up with enough tension, the leeward shrouds will go slack when the boat is sailing to windward. This can result in fore and aft pumping of the mast in a head sea. This mast movement will change the shape of the mainsail and can cause performance loss as well as possible structural damage."
​

https://loosnaples.com/how-tos/tension-gauges?tmpl=component&p=

 

[Jackdaw]

Wow, scary.

Yes, I agree, but from my research, they shouldn't; the rig should be tensioned such that the shrouds never go slack, else they are subject to impact loads that are well above what they will see otherwise. It may be that the boat can't stand this amount of tension, i.e., the hull is too soft.

I realize this is a controversial topic.

Good points. I personally would not say never. But they should stay taut to about 15 knots of breeze powered up. Is is a balance. Too tight adversely effects sail shape, as does too loose. This it true for both masthead and fractional boats, but more so for fractional. Most 'default' tuning guides are on the high end, to be safer for cruisers and those who do not adjust their rig tune every day. But its slower.

 

[Jackdaw]

From Loos, the rigging tension gauge guys:

"Contrary to popular thought, a slack rig is more punishing on a hull than a properly adjusted, tight rig. Insufficient tension will not reduce the loads transmitted in the hull. Slack rigging will punish the spar and rigging needlessly by allowing excessive movement, chafe and shock loading. Modern fiberglass hulls should not be damaged by a properly adjusted, tight rig."

"If the shrouds are not set up with enough tension, the leeward shrouds will go slack when the boat is sailing to windward. This can result in fore and aft pumping of the mast in a head sea. This mast movement will change the shape of the mainsail and can cause performance loss as well as possible structural damage."
​

https://loosnaples.com/how-tos/tension-gauges?tmpl=component&p=

Those are good words and great advice for the average cruiser. A lot of that advice is based on the fact that most people without a Loos gauge set their rig too LOOSE, as they don't have a good feel for what proper tension is like, and are afraid of making it too tight!

 

[jmce1587]

Chip. I would schedule a re-tune or use the funds to get a Loos gage and good article on trimming a swept B&R rig and go after it. I think I have a tuning guide for this rig that I can scan and send to you My shrouds on the Leward side were lose in high winds/ rough sea state and in my opinion I believe this contributed to my rig failure and the chain plate rod breaking.

 

[IDtrucks]

From Loos, the rigging tension gauge guys:

"Contrary to popular thought, a slack rig is more punishing on a hull than a properly adjusted, tight rig. Insufficient tension will not reduce the loads transmitted in the hull. Slack rigging will punish the spar and rigging needlessly by allowing excessive movement, chafe and shock loading. Modern fiberglass hulls should not be damaged by a properly adjusted, tight rig."

"If the shrouds are not set up with enough tension, the leeward shrouds will go slack when the boat is sailing to windward. This can result in fore and aft pumping of the mast in a head sea. This mast movement will change the shape of the mainsail and can cause performance loss as well as possible structural damage."
​

https://loosnaples.com/how-tos/tension-gauges?tmpl=component&p=

Thanks for the tip. I think stepping my mast every time I sail, the leeward side moves more than it should. Knowing this is the preferred tightness of rigging, ill be sure to check for shroud tension and tighten accordingly with a few practice tacks at the start of each day

 

[BigEasy]

most people without a Loos gauge set their rig too LOOSE, as they don't have a good feel for what proper tension is like, and are afraid of making it too tight!

Trying to tune without the Loos gauges is a “crap shoot” at best. It’s impossible to hand shake the rig to get a feel as to what the tension should be on a given wire, not to mention trying to balance the tension on the rig. I set the tension to only 10% of breaking strength on my rig, which is on the loose side, but it’s tight enough to prevent slack leeward shrouds. Even at 10% the wires “feel tight”. Unfortunately, the manner in which Loos gauges are configured, you will need two gauges to accommodate all the wire sizes on boats over 30 feet.

 

[Slick]

If I could ask a newbie question. How do you check tension on the forestay with a roller furler installed? I have Loos tension gauges. Do you have to completely remove the furling setup to get a measurement on the stay?

 

[Gunni]

You get the mast plumbed and check that the furler foil has no bend. Shorten the forestay to achieve that outcome, adjust mast position with your backstay(s).