Scamp LUNA was dismasted yesterday!

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pocketyacht
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Re: Scamp LUNA was dismasted yesterday!

Post by pocketyacht »

Hey Dale.

Once again, glad the important bit happened, everyone was safe and now you are a more experienced/better sailor. Good on Ya!

I have noted your description of the mast break and looked at the photos. I have also noted Simeon's input regarding how the masts were built. I pen the view point below with respect to all, just observations because breaking spars is a really big deal.

Given that I have not seen your mast I make the following observations.

1. There are now two masts that have failed in the same manner both built together in the same group build hence my initial question if you had built the mast or was it part of a group build. I actually sailed the other mast on several occasions and know it very well as I helped Brice purchase his boat, which I delivered across country for him.
Two failures out of eight spars warrants a look because losing a mast, while inconvenient and costly is in my book potentially very dangerous if not potentially disastrous. Think of your spar blowing up as you are passing a dangerous lee shore, in ship traffic, etc.

2. You noted that the mast breaks were only in the wood not the glue joints. However, unless I misinterpreted your photos it appears the breaks are also across glue joints as well as within the wood. I believe spar breaks come in may forms one of which is one tiny flaw or small start to a break, such as a wood flaw (I don't see that here) and a non fully adhered glue joint.

3. Cyclic loading. Unstayed masts undergo tremendous cyclical loading. Your boat with the rig under tension, add sailing through seas, puffs of wind, etc all movement causes loading and spring back, potentially fatiguing any glue joint.

4. To achieve proper glue joint adhesion (raw wood to raw wood) both surfaces need to be wet out with raw epoxy before glue is applied. It is a requirement, not an option to wet out the birds mouth cut outs before applying thickened epoxy and clamping. My method evolved from wetting out just the birds mouth to the inner face of the stave as well bit I moved on from this method. Now I wet out the entire stave, all sides. The reason being is that Scamps are dinghies and dinghies sometimes capsize and spars go Unser water. Some are capsize tested and so having a raw wood inner spar is in my view not optimal.

It appears to me from your photo that the glue joints look a little glue starved and the the inner spar is raw wood and now we know the staves were not wet out during glue up. Another piece of this is could be how thick the glue was mixed. If it was too thick (stiff) it will likely not penetrate effectively into the un-wet out raw wood. This is why wet out is critical. The wet out penetrates into the two wood faces and the thickened epoxy (glue) then chemically bonds through and within the wood building a bond unit of woodgluewood.

Dale this take away by you is so spot on, I had to quote it here. Open minds make good sailors!!!

You wrote:
"Obviously I should’ve reefed right away, as soon as I saw that squall coming. Barring that, when I tore off downwind and found it too much, I should’ve let the sheet run, flagging the sail forward. That’s the beauty of an unstayed cat rig, but I’ve never done it before… too many years of sailing boats that the main pins against the stays… and that cost me a mast (and way too much excitement, and scaring the hell out of my wife, risking a marriage from lack of practicing a simple skill). Or, just round up to starboard and not sheet in, until the boat comes abeam of the wind, and drop the sail. It didn’t matter if the reefing lines and cleats were on the wrong side of the boom, once you’ve got the sail down you can just deal with the inconvenience. Sheesh. Live and Learn."
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Spike A
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Re: Scamp LUNA was dismasted yesterday!

Post by Spike A »

Sorry to hear of your troubles. It was a nice read. My Luna in Florida sends regards.
Mike
Luna Gig Harbor Scamp #462
Selway Fisher 50/50 Sailing Canoe
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dsimonson
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Re: Scamp LUNA was dismasted yesterday!

Post by dsimonson »

Thanks Howard!! Great input! I have to run to catch the tide, but a quick response to point 4:
pocketyacht wrote:
Mon Jun 14, 2021 4:21 am
4. To achieve proper glue joint adhesion (raw wood to raw wood) both surfaces need to be wet out with raw epoxy before glue is applied. It is a requirement, not an option to wet out the birds mouth cut outs before applying thickened epoxy and clamping.
To the best of my recollection, our assembly that day included wetting out before adding glue, but only to the gluing surfaces. Point taken that the insides of the staves would benefit from a coating.

Perhaps too much clamping pressure? We used hose clamps, and got good squeeze out... maybe they're too effective?

Cheers,
Dale
"storing a Gartside, and sailing Luna" #162!
dalesimonson.ca | photos on Flickr
pocketyacht
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Re: Scamp LUNA was dismasted yesterday!

Post by pocketyacht »

Hi Dale
I noted Simeon's response and may have misinterpreted his words and meaning the birds mouth cuts were not wet out, perhaps he meant the interior coating of the mast. Sim?

If it was just interior coating that was not done then I doubt this factor had much bearing on the failure.

Hose clamps should be used judiciously given that they can be over tightened forcing too much glue out of the joints. I would have expected to see more squeeze out on the interior of the spar.

It seems odd to me that two spars from that group build of eight have failed.
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Editors
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Re: Scamp LUNA was dismasted yesterday!

Post by Editors »

Thanks for the report, Dale! So glad it all worked out reasonably well. Hopefully we can learn more about why your mast failed. Old #1's mast has been thoroughly abused, as you know and somehow held up.

I trust Chris has filed the divorce papers finally? ;-)

Josh
The smaller the boat the bigger the adventure.
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Re: Scamp LUNA was dismasted yesterday!

Post by Bcbimmer »

Dale, so glad everyone is ok. Kind of scary how similar that fracture looks to the one that Brice posted. Making that mast thicker overall would make it a fair bit heavier to raise and lower. I assume from your discussion about the addition of internal blocking that the fish tail design at the upper end somehow dissipates the stress otherwise it seems to me that you are just recreating the issue higher up the mast. Is there a link to a discussion on how to add that type of stiffener somewhere? If you and Chris call it a day who gets Luna? Probably safe as my wife always says not worth the bother of trying to train a new husband.
Stay safe
Dan
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dsimonson
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Re: Scamp LUNA was dismasted yesterday!

Post by dsimonson »

Timo wrote:
Mon Jun 14, 2021 12:59 am
Yes, please, share with us John's analysis if he comments on the issue.
Thanks, Timo,
Here's John Welsford's quick response:

"... on my own masts I generally build in a solid blocking about 300mm above and below the top partner, as you say "fishtailed" to prevent there being a stress riser at the ends of it."

Cheers,
Dale
"storing a Gartside, and sailing Luna" #162!
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Re: Scamp LUNA was dismasted yesterday!

Post by dsimonson »

Spike A wrote:
Mon Jun 14, 2021 5:42 am
Sorry to hear of your troubles. It was a nice read. My Luna in Florida sends regards.
Thanks Mike, great to hear your Luna is so congenial! Exactly 300 sail numbers and what, 3000 miles?, separating the two, but of one accord: "keeping their crew safe", coast to coast!

All the best,
Dale
"storing a Gartside, and sailing Luna" #162!
dalesimonson.ca | photos on Flickr
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Re: Scamp LUNA was dismasted yesterday!

Post by lhav »

This is particularly interesting to me, as we are anticipating our own mast construction. What exactly does "fishtailed" blocking entail? Is the blocking itself tapered inside the mast so there is no edge directly against the mast interior?
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Re: Scamp LUNA was dismasted yesterday!

Post by dsimonson »

pocketyacht wrote:
Mon Jun 14, 2021 7:52 am
It seems odd to me that two spars from that group build of eight have failed.
Editors wrote:
Mon Jun 14, 2021 9:38 am
Hopefully we can learn more about why your mast failed. Old #1's mast has been thoroughly abused, as you know and somehow held up.
Yup, it's very disconcerting... I'll have to review the notes about Brice's mast failure, but I seem to recall it was not in particularly adverse conditions. I looked up the nearest weather station data, at that time Pam Rocks reported 26kts, with gusts at 32kts, way too much for the stunt I tried to pull with a full sail up, so perhaps there's not much correlation. However, #1's mast has likely put up with some similar stunts!

I'll take some more close-up photos, in case that would help with forensics.
Editors wrote:
Mon Jun 14, 2021 9:38 am
Thanks for the report, Dale! So glad it all worked out reasonably well.
...
I trust Chris has filed the divorce papers finally? ;-)
Haha, thanks Josh, no sheriff at the door, so far! But I did leave the screaming parts out of the tale... do you think flowers would work?

Cheers,
Dale
"storing a Gartside, and sailing Luna" #162!
dalesimonson.ca | photos on Flickr
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