dismasted freedom 39 ph

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gamayun
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Re: dismasted freedom 39 ph

Post by gamayun »

This is the first I'd heard masts were originally laid up in multiple pieces. I have heard; however, about sleeving a mast to repair a a break. Certainly Eric Sponberg would know this history of the original masts (but maybe not the 39s...?).
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moy
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Re: dismasted freedom 39 ph

Post by moy »

So is this a Tillotson Pearson mast?

I don't know about your F39, but I know the TP carbon fibre masts on the F35 / F33 have known issues with circumferential cracking, for which Eric Sponberg devised a remedy.

Had yours ever shown sign of that circumferential cracking? Has it been through Eric's remedial process...?

In a way, the fact that a carbon fibre mast with known issues should break might not be that surprising, if those issues were never treated.

What would be far more interesting,though, is if it had failed despite having been through the remedial process.....

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GeoffSchultz
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Re: dismasted freedom 39 ph

Post by GeoffSchultz »

I'm also curious as to why you've had the mast "inspected prior to every departure"? Was there something that you were concerned about? What experience did the person have with carbon fiber masts that was doing the inspections? Given that this occurred in light conditions, just after departure, I would ask for my money back!
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adam
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Re: dismasted freedom 39 ph

Post by adam »

the black ring has been there for 20 years is not a crack , has been inspeceted in detail before every passage and is where the white paint got rubbed off by the spare halyards [ mast was originally black and subsequently painted white] mast was made in two pieces at factory and then joined together As per eric schonberg . mast failed 1 foot below the factory splice, hope this clears it up Adam

adam
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Re: dismasted freedom 39 ph

Post by adam »

Freedom 39 ph masts were constructed in 2 pieces and then joined together at the factory ( as per eric Schonberg) you may confirm this with him if you like, dont know about the other boats , the splice consists of an approx 1/8 inch x 3 foot internal sleeve, the wall thickness of the sleeve is supposed 1/8 inch and the wall thickness of the mast at this point was specked at a 1/4 inch and has been confirmed by carbon fiber expert prior to repair , the black rings that you see are not cracks but are rubbed off paint by haylards and other gear (masts were originally black and subsequently painted white ) the mast failed at approximately 1 to 2 feet below the factory splice anyway , The carbon fiber guy could not find any defects in the layup, hope this clears it up a little Adam

adam
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Re: dismasted freedom 39 ph

Post by adam »

Freedom 39 ph masts were constructed in 2 pieces and then joined together at the factory ( as per eric Schonberg) you may confirm this with him if you like, dont know about the other boats , the splice consists of an approx 1/8 inch x 3 foot internal sleeve, the wall thickness of the sleeve is supposed 1/8 inch and the wall thickness of the mast at this point was specked at a 1/4 inch and has been confirmed by carbon fiber expert prior to repair , the black rings that you see are not cracks but are rubbed off paint by haylards and other gear (masts were originally black and subsequently painted white ) the mast failed at approximately 1 to 2 feet below the factory splice anyway , The carbon fiber guy could not find any defects in the layup, hope this clears it up a little Adam

moy
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Re: dismasted freedom 39 ph

Post by moy »

adam wrote:
Sat Dec 03, 2022 1:00 am
Freedom 39 ph masts were constructed in 2 pieces and then joined together at the factory ( as per eric Schonberg) you may confirm this with him if you like, dont know about the other boats , the splice consists of an approx 1/8 inch x 3 foot internal sleeve, the wall thickness of the sleeve is supposed 1/8 inch and the wall thickness of the mast at this point was specked at a 1/4 inch and has been confirmed by carbon fiber expert prior to repair , the black rings that you see are not cracks but are rubbed off paint by haylards and other gear (masts were originally black and subsequently painted white ) the mast failed at approximately 1 to 2 feet below the factory splice anyway , The carbon fiber guy could not find any defects in the layup, hope this clears it up a little Adam
So the sleeve is 3 ft long, & the mast failed 1 - 2 ft below the splice. Can't quite visualise what the mechanism would be, but that does sort of seem like it could be relevant, does it not? That maybe the failure occurred right around the bottom end of the sleeve...? Which would presumably be 1.5ft from the splice, no..?

Have you been able to take a close look at the 2 sides of the failure? Is that the case that you have sleeved section above the break, & unsleeved mast below? Or was the sleeve itself broken?

Could it be that the stiffness of the sleeved section prevents the spar from flexing uniformly along that section of its length, thereby somehow transferring heavier point loading around the ends of the sleeve..?

Just thinking out loud. Probably gibberish....

adam
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Re: dismasted freedom 39 ph

Post by adam »

i am not composite engineer but, it seems reasonable that however well made the splice was made and because of the xtra thickness there that then would be somewhat of a hard spot and transfer more flexing/ load directly under the splice Adam

adam
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Re: dismasted freedom 39 ph

Post by adam »

when you look inside the mast with a flashlight you can clearly see the splice and the break was well lower than that by about 3 feet

adam
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Re: dismasted freedom 39 ph

Post by adam »

boat was purchased from original owner about 12 years ago masts were in original condition and no circumferential cracking was observed at that time, we then painted the masts white in situ with a laytex elastomeric paint specifically to prevent further uv exposure. adam

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