Bad News - Wet Balsa Core

[Terra Nova]

Originally Posted by ramblinrod

Seriously, there are very few cored boats over 20 years old that don't have some moisture ingress.

Where do you suppose wet core comes from?

[ramblinrod]

Originally Posted by Terra Nova

Where do you suppose wet core comes from?

Failed bedding materials.

The life expectancy of most bedding materials is 20 years at best.

If the boat is over 20 years old, and the deck fittings have never been rebed (prolly 95% of all 20+ year old boats fall in this category) there will be elevated core moisture somewhere.

If that moisture has not created a structural integrity loss (delamination or rot) the core does not have to be removed.

If there is no rot or delamination, remove the fittings, rebed, and good to go for another 20 years.

If one wishes to remove damp core for piece of mind, or to avoid it showing up on a survey, they of course are free to do so (but it won't be free by any stretch of the imagination).

If a surveyor of a 20+ year old boat detects elevated core readings, they should sound it. If it sounds out solid, they should note this on the survey and their recommendation should be to seal the offending fittings. They may suggest core replacement as an option, but it shouldn't be a requirement.

If the prospective purchaser will not accept a survey with core moisture reported, well, they should only consider boats 10 years old or less (and even then likely 20% of boats will not pass muster for this reason alone), or be prepared to pass on a lot of excellent boats that could be fixed just fine with a $10 tube of SikaFlex.

(That being said, I always recommend mounting holes be resin potted before rebedding fittings, and I won't make a core penetration without resin potting it, because I know there is only a 1% chance the fitting will be rebed before it starts leaking again in oh, say 20 years or so).

[smj]

Originally Posted by ramblinrod

Failed bedding materials.



The life expectancy of most bedding materials is 20 years at best.



If the boat is over 20 years old, and the deck fittings have never been rebed (prolly 95% of all 20+ year old boats fall in this category) there will be elevated core moisture somewhere.



If that moisture has not created a structural integrity loss (delamination or rot) the core does not have to be removed.



If there is no rot or delamination, remove the fittings, rebed, and good to go for another 20 years.



If one wishes to remove damp core for piece of mind, or to avoid it showing up on a survey, they of course are free to do so (but it won't be free by any stretch of the imagination).



If a surveyor of a 20+ year old boat detects elevated core readings, they should sound it. If it sounds out solid, they should note this on the survey and their recommendation should be to seal the offending fittings. They may suggest core replacement as an option, but it shouldn't be a requirement.



If the prospective purchaser will not accept a survey with core moisture reported, well, they should only consider boats 10 years old or less (and even then likely 20% of boats will not pass muster for this reason alone), or be prepared to pass on a lot of excellent boats that could be fixed just fine with a $10 tube of SikaFlex.

And what do you think causes the balsa core to rot?


Sent from my iPhone using Cruisers Sailing Forum

[smj]

Originally Posted by ramblinrod

Failed bedding materials.



The life expectancy of most bedding materials is 20 years at best.



If the boat is over 20 years old, and the deck fittings have never been rebed (prolly 95% of all 20+ year old boats fall in this category) there will be elevated core moisture somewhere.



If that moisture has not created a structural integrity loss (delamination or rot) the core does not have to be removed.



If there is no rot or delamination, remove the fittings, rebed, and good to go for another 20 years.



If one wishes to remove damp core for piece of mind, or to avoid it showing up on a survey, they of course are free to do so (but it won't be free by any stretch of the imagination).



If a surveyor of a 20+ year old boat detects elevated core readings, they should sound it. If it sounds out solid, they should note this on the survey and their recommendation should be to seal the offending fittings. They may suggest core replacement as an option, but it shouldn't be a requirement.



If the prospective purchaser will not accept a survey with core moisture reported, well, they should only consider boats 10 years old or less (and even then likely 20% of boats will not pass muster for this reason alone), or be prepared to pass on a lot of excellent boats that could be fixed just fine with a $10 tube of SikaFlex.

And what do you think causes the balsa core to rot?


Sent from my iPhone using Cruisers Sailing Forum

[AJ_n_Audrey]

Thanks to all for the input. Lots to think about. And this is only one of about seven projects I need to tackle.

[Suijin]

Originally Posted by ramblinrod

Seriously, there are very few cored boats over 20 years old that don't have some moisture ingress.

That's just a corollary for saying there are fewer and fewer well maintained cored boats over 20 years old. My boat has a cored deck and had only one small leak from a single screw and it's 31 years old. Actually it was not well maintained before I bought it, but everything was bedded with 5200, which for all the grief it gets is one amazing bedding compound.

[JPA Cate]

Originally Posted by minaret

If you go from the top, consider laying out your cut about 2" inside the non skid line. Then triple tape the smooth with preservation tape. Make your cut, remove core, decore the margins, grind for prep, recore the margins, recore the center, reglass top skin, rough fair and apply nonskid. No finish work required. Done it many many times. Yes to Coosa for core.

This, because it will be strongest, and easiest. ^^^^^^

Ann

[ramblinrod]

Originally Posted by smj

And what do you think causes the balsa core to rot? Sent from my iPhone using Cruisers Sailing Forum

Fungus.

[smj]

Originally Posted by ramblinrod

Fungus.

Yes and fungus only grows in moist wood.

[ramblinrod]

Originally Posted by Suijin

That's just a corollary for saying there are fewer and fewer well maintained cored boats over 20 years old. My boat has a cored deck and had only one small leak from a single screw and it's 31 years old. Actually it was not well maintained before I bought it, but everything was bedded with 5200, which for all the grief it gets is one amazing bedding compound.

Price of tea in China?

The Valiant 40 is a lovely boat (almost every boat is in my eyes) but many have succumbed to deck rot.

The reality is, a damp core is not the end-of-the-world many believe it is.

If a core is damp, and there is no rot or delamination, core replacement is not necessary. The composite is still structurally sound.

Seal it up to keep the rot out and prevent the wood from becoming saturated, and all is well.

If there's a little rot, dig it out, seal the good wood, fill the void, and all is well.

[ramblinrod]

Originally Posted by smj

Yes and fungus only grows in moist wood.

Incorrect. Fungus only grows in saturated wood fibre.

Depending on definitions, moist is not enough, and just damp is not nearly enough to support rot.

But even with 100% saturation, if it is sealed before rot gets into it, it can stay that way indefinitely, and still be structurally sound. (Usually what happens though is after being sealed, the moisture disperses and the area becomes less prone to rot.

Therefore, when inspecting a boat deck, the presence of elevated moisture is not the end of the world, and cause for immediate core replacement, only reason to inspect more closely to determine how wet, and if there is any delamination or rot. Those need to be repaired.

[smj]

Originally Posted by ramblinrod

Incorrect. Fungus only grows in saturated wood fibre.



Depending on definitions, moist is not enough, and just damp is not nearly enough to support rot.



But even with 100% saturation, if it is sealed before rot gets into it, it can stay that way indefinitely, and still be structurally sound. (Usually what happens though is after being sealed, the moisture disperses and the area becomes less prone to rot.



Therefore, when inspecting a boat deck, the presence of elevated moisture is not the end of the world, and cause for immediate core replacement, only reason to inspect more closely to determine how wet, and if there is any delamination or rot. Those need to be repaired.

It takes over 20% moisture for fungi to grow in wood. When you find moisture in a balsa cored deck do you have a method to determine whether the moisture level is below 20%? Do you guarantee a job where you cover up wet core? I may take a chance on my own boat knowing at a later date the moisture will probably degrade the structural integrity of the deck, but as a professional do you advise your customers that this may happen?

[smj]

Another thought Ramblinrod, considering your business is located close to Toronto aren't you worried about water in the core freezing and causing delamination?

[minaret]

Originally Posted by Suijin

Well it's a question of whether he's going to try and repair and match the existing gelcoat (if he has gelcoat and not paint), which would be a huge job with that much of a patch. If paint is in the future, I would do the whole job in epoxy, probably using biax along the edge of the cut skin for the repair. Honestly would probably be easier (and a better quality repair) to put new glass down on top of the new core. Getting the old skin back down without voids would be a chore.

It's one of those jobs where the demo and basic reconstruction takes 30% of the time and 60% goes into making it look good.

I did explain how to do this job from the top with no color matching, blending, finish fairing, spray painting, gelcoat application, etc. just a few posts before yours. Was it just too technical/obtuse a post? I often wonder, as it seems few understand what I'm trying to say and post things which make it clear they didn't read my post or didn't get it shortly thereafter. Often.

[AJ_n_Audrey]

Fyi, I'm getting moisture readings way over 20 all over the soul - like 35.