Snapped the forestay on H16 in a slight gust

I apologize if there is a thread that addresses this. I searched but did not find one.
I took my 1974 H16, recently acquired and repaired-or so I thought-out to the lake. I left a bit of mast rake, just to experiment. The main wasn't sheeted in too tightly because I was trying to figure a course in a fickle, swirling wind. A bit of a gust from forward port filled the sail, making the popping sound the nylon makes when it snaps into shape. This was instantly followed by the sickening sound of the forestay snapping just a few inches above the bridal.
We self rescued without incident, so all was well. I'm new to sailing in general, but this failure seemed really like a an anomaly. I'll replace all the wires/cables this week, but I still don't know exactly what caused the catastrophic failure. Any thoughts from those of you who are more experienced than I am would be most helpful.
Thank you!

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1974 H16

Normally on an H16, with the jib installed normally, the luff wire in the jib takes all of the forestay load. If it breaks, the regular forestay would be there to take the load.

When you rigged, was your jib halyard tight enough to take the load off the forestay? And was it the forestay that broke, or the jib's luff wire? Did you somehow not have both the luff wire and the forestay in place?

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'00 H16 #104691
'78 H16 #32692 ex-rental [gone]
Old Holsclaw trailer
My Hobie 16 pages

I think you've hit the nail on the head. In order to reduce the complexity of sail management—I am a novice sailor and new to catamarans altogether—a few friends suggested that I rig only the Main. I'm surprised that the forestay would explode in a gust, but if the Jib is structural, then that is exactly my mistake. Thank you so much for the quick response!

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1974 H16

Well, the forestay should have still supported the rig. However, old rigging is a known problem - the strands in the cable start to crack at the crimped ferrules - and replacing it isn't all that expensive.

Be aware that the lengths for these parts have changed over the years as the mast rake has been increased, but some other parts changed to enable that also, so you can't just go to the new spec lengths. The blocks, mast step and base, and jib shape were all changed over the years to allow more rake. So make sure you order lengths that are compatible with the rest of your boat.

In addition to replacing the standing rigging, some people also replace the anchor pins: the rods under the lip of the hull that the shrouds mount to. Overall, you have a great opportunity to inspect everything on your boat.

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'00 H16 #104691
'78 H16 #32692 ex-rental [gone]
Old Holsclaw trailer
My Hobie 16 pages

It's a good idea to check the standing rigging before every sail! Look for corrosion or separation particularly at the ferrules, also check for any kinks or sharp bends in the wires. Those can cause the strands to separate which weakens the wires and any like that should be replaced.

The forestay should be able to support the load either way. If your rigging is original from 1974, then it is LOOOONG overdue for replacement.

You will have a much easier time if you sail with the jib. The boat will tack more easily and the helm will be balanced. You're better off sailing under full sail and just making sure you pick a day with wind speed 10mph or less. With a 1974 boat, you could even reef the mainsail to cut down sail area, but definitely things will be better with a jib.

sm

I do think most—probably all—of the rigging has been replaced, but not for quite some time. Not replacing them as soon as I bought the boat was, at best, cavalier.
Reefing seems like a great compromise, and balancing the helm with the jib is a concept I hadn't considered, so I'm grateful that you pointed it out. It explains why I was pulling the tiller so hard to weather on that same day.
This incident has brought about a great deal of enlightenment. Thanks for the tips and info!

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1974 H16

They also pull the helm HARD to weather when you don't have the rudders locked down into the cams correctly. On older boats, the rubber gets really hard, and they get stuck in the down position. If that looks to be the case, pry them up and lube them good to get them moving again. The handle should snap down into the locked position.

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Steve
1979 Hobie 16 "Orange Crusher"
2017 Hobie 16 "Cayman" sails 114795

That bonus tip really worked, too! My rudder now raises AND lowers very smoothly and locks into place in both positions. My rigging is back in shape, and I solo sailed with the jib raised, and it really tightened up the handling, as you suggested.

Thanks, all!

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1974 H16

Awesome news! The only thing left for you is to post a picture of the new boat!

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Steve
1979 Hobie 16 "Orange Crusher"
2017 Hobie 16 "Cayman" sails 114795