Cracked deck at bow

[glenn1489]

Uh-oh! My top deck cracked right at the bow. While under sail, I heard a crack then saw the deck lifted up. Here are a couple of pix. I've got someone coming over to do some fiberglass repair and reinforce with bolts. Has anyone had this issue on a PC? I suspect it's from the tension at the forestay. Maybe I had it too tight? Any thoughts or suggestions are appreciated.

[bruce]

Yeah, that's not right. I haven't seen this failure before. The only upward force routinely experienced there is the headstay, but you might have hung up on a dock or collided with something before this.

Normally, the headstay is readily hand tightened by the Highfield lever, no undo force is in play. It may have been adjusted too tight. I'd check the mast step for compression as well.

The deck layup is 1/4"+ thick here. Properly restored, that should be strong enough. Com-Pac doesn't do backing plates, only standard washers at the bow roller. A real backing plate to distribute the load wouldn't be a bad idea. It does look like the deck flange wasn't deep enough to be captured by the rub rail screws, but this type of failure isn't common.

You might run it by Com-Pac, they may have some input.

[Jon898]

Yeah, the deck flange looks to have been a bit skimpy.  I assume that's just an anchor roller and you're not one of those people who tries to convert a cat rig to have a foresail and then flies a honking great genoa?

Jon

[glenn1489]

It took a while to fully resolve this (2 recent bouts of Covid didn't help!), but I'm back on the water and the foredeck is stronger than ever. Gerry at Com-Pac was amazingly helpful, and they fabricated two backing plates for me: a v-shaped one for under the hull flange, and a "house-shaped" pentagon for under the bow roller (which I was able to place by reaching through the deck pipe hole). Both were 3/8" aluminum and I fastened everything with truss-head machine screws through the top of the foredeck and hex bolts through the bow roller plate. I took her for a trial sail yesterday and saw no signs of stress or movement of the foredeck. My confidence is high that the issue was permanently resolved and thrilled to be back on the water!

[bruce]

I'm glad Com-Pac helped. I posted you're problem on the Picnic Cat Group on groups.io, and no one had a similar experience, and the archives back to 2000 yielded a similar result. Some pointed out that the bow roller backed with only a washers by the factory was always suspect. I note your failure showed that the bow roller pealed back from the deck flange first, the forward bolt appears to have pulled through the deck. The washer may have been inadequate, or the nut may have backed off and the washer lost.

Another offered that several PCs have hit overhead obstructions with the mast raised at the ramp causing extensive damage to the mast, but the deck hadn't been damaged.

Glad you found a solution!

[glenn1489]

Thanks Bruce. I wasn't aware of the groups.io group, but just read the posts and applied for membership. Seems like lots of good stuff in there!

[glenn1489]

I should have added about forestay tension... is it adjustable? I don't see any turnbuckles or other means of adjustment on mine.

[bruce]

No, there is no ready adjustment in the headstay, but the masthead tang is just attached with a through bolt (through the shroud tangs as well). It would be easy to add new holes here. You could also shorten/remount the tang enough to install a turnbuckle for tensioning.

My headstay is taught when rigged, but not overly tight. The lever firmly snaps in place with moderate force. The shrouds are adjustable, and, if tightened, would cant the mast aft and make the headstay tighter. I've never heard of anyone canting the mast on a PC on purpose. At rest, the shrouds are also minimally taught. Underway, the leeward shroud is very loose, but the windward shroud is under tension and the mast should be roughly perpendicular side to side. Many get carried away and crank down on the shrouds to remove the slop to leeward, repeat the process on the other side, and over tension the rig. Over time, the stay and shrouds can stretch of course, but Com-Pac cautions against making the shrouds too tight.

Your headstay has presumably experienced excessive loading during the damage to the deck, so it might be stretched more than normal. I just measured mine, pin to pin, new in 2010 and never overly stressed in my memory, and get 128" even.

If your headstay and shrouds snap in place with some moderate tension, and the mast looks perpendicular fore and aft and side to side at rest and underway, I think you'll be OK. If your headstay is significantly more than 128" then I'd probably replace it before messing with the tang. Part # MR00R0117, $58.35
https://www.dropbox.com/sh/xtfxq40jvl9esw9/AADHttjwMACdw5Voo2NYBoLVa?oref=e&preview=PICNIC+CAT+2021.pdf

[KObek]

Being that it happened while under sail, was it a particularly heavy air day? Were you close hauled or tacking when the failure happened? 

Also, we must remember that forestay tension 'at rest' is much less than when sailing. It is interesting that the crack is between the hawse pipe and the edge.

[bruce]

We've all been caught out in heavy weather, unreefed when we know we should have been. No one that I have heard of has reported this failure, fortunately.

My guess would be that the rig was severely over tensioned, or that had been previous damage that hadn't been noticed.

[fried fish]

Based on your profile photo, I am assuming you moor your boat. Is it possible a larger boat creamed your rig?

[glenn1489]

Well, no one left me a note ;-) but that's a real possibility! Right, I keep the boat moored and there are about 10 other boats (mostly power) nearby. Even a slight hit in the right place (at the anchor roller) could have caused the damage, which I might not have noticed until I headed into the wind. Meanwhile, two seasons later and the repair is holding well, even if it's not the prettiest fix.