thoughts on moisture in a balsa core

We just had a boat surveyed and an area showed up with moisture in the hull side apparently from a broken seal around the engine room vent.

I've been told that it can be repaired without any future issues. I've looked around and there really isn't much on this subject on the web except for the wild internet comments like, "run, forest, run'...

Anyone here have any experience with this and what was your results?

thanks

beachbum29 said:

i've looked around and there really isn't much on this subject on the web except for the wild internet comments like, "run, forest, run'...

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imo

BB-of course it can be repaired with no further issues, so can a hole in the hull the size of a refrigerator. How much are you willing to spend to fix it? You need to determine the area (size) of the issue, the extent of the water damage, probably by some form of destructive testing (drilling at the least) and then have a competent yard provide an estimate of the repair. Depending on the above, maybe $1,000 t0 $100,000, who knows?

In general, I tend to agree with the Run idea.

THD said:

BB-of course it can be repaired with no further issues, so can a hole in the hull the size of a refrigerator. How much are you willing to spend to fix it? You need to determine the area (size) of the issue, the extent of the water damage, probably by some form of destructive testing (drilling at the least) and then have a competent yard provide an estimate of the repair. Depending on the above, maybe $1,000 t0 $100,000, who knows?

In general, I tend to agree with the Run idea.

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I'm waiting for an estimate. The sale price of the boat is being adjusted for the repair costs.

In deference to my red arrow smart ass reply, I offer the following.

When buying a boat, new or used, there are plenty of problems large & small that pop up unexpectedly. Why saddle yourself with a known problem (possible extensive migration of water through a balsa core) from day one?
Yes, anything can be fixed (or attempted to be fixed) given you have enough money, but in this economy, why even expose yourself to this potential liability at the outset? There are a ton of great boats out there if you open your mind to just not looking locally. An $8-10K transport bill covers a hell of a lot of miles. Not to mention that when the time comes for you to sell the boat, you have a moral obligation to disclose the history of the boat. (Including the wet balsa problem.)

I was thinking of these things when I posted the RED ARROW.

What says your surveyor:

• What is the water ingress reality and potential for the entire vessel or is this the only spot he found "wet".
• Were ER vents epoxy bedded to begin with or caulked into the hole cutout in the coring.
• Solid FRP hull bottom or core
• Engine and drive train mechanical condition

What is model, age and overall appearance?

BB-what kind of boat? I would make sure that the full scope of the repair is determined as accurately as possible. As noted above, water will migrate through balsa, sometimes not easy to determine how far.

It appears the sealer around the port aft engine vent either failed or was never properly sealed from new.

Moisture is showing up in an area above the water line about 10-12 in length.

I've been told using a vacuum method until dry then injecting some type of polymer or something similar is the accepted method used by manufactures for warranty work.

The boat is a 35' cruisers flybridge.

I have had a great deal of experience repairing wet balsa core on my '72 Bruno-Stillman lobster boat (not the Willard shown here). Two small hull issues but a dozen or more foredeck, transom deck, trunk cabin top, & cabin top areas.
All the areas could be accessed from inside so I have never had to get out the Skilsaw. I think I have all the areas and problems that caused them handled now (I have owned the boat since '74).
My routine has been to sound the boat with a mallet each fall b/4 storing for the winter. This is important in a cold climate because a wet area that freezes causes it to enlarge. If a wet area is found, I mark it out inside, drill 3/16" holes 1.5" apart throughout the area passing through the inner skin and balsa. Sometimes some water (brown juice) actually runs out. then I set up a heater and/or dehumidifier tenting the area with plastic as needed.
After a couple weeks, I load up my disposable grease gun w/ pointed tip or syringe or empty caulking cartridge, with epoxy and glass micro-baloons and working from one edge of the area across to the other, squeeze in the mixture till it comes out the next hole, apply a sheet metal screw to the first hole, start injecting in the second and so on. After the epoxy cures, remove all the screws, fill the holes w/ epoxy paste and paint or not.
Really not difficult. I repaired a friends sailboat years ago, Gulfstar I think, the surveyor told him to burn it, 12 years later it is still going strong and he says better than new. This really doesn't add much weight because the microbaloons are mostly air.

If it is a boat you want, and a good deal, I would not let the core delam stop you.

Thanks

sunchaser said:

What says your surveyor:

[*]What is the water ingress reality and potential for the entire vessel or is this the only spot he found "wet".
[*]Were ER vents epoxy bedded to begin with or caulked into the hole cutout in the coring.
[*]Solid FRP hull bottom or core
[*]Engine and drive train mechanical condition
What is model, age and overall appearance?

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I just spoke to my surveyor and he feels the issue can be handled by the right person.

Considering the concessions by the seller, how much we like the boat and the condition of the rest of the vessel there should be no lingering problems from this issue.

We'll see where the estimates come in at...

Since this is a totally non structure area drying and resealing would be just fine.

No need for the chainsaw or the pick axe, jusr repair it so no more moisture can enter.

If you wish to research Balsa hull failures Pro Boat Builder has great past tech articles that can be purchased.

Many of the lighter built (they have to be to keep weight down) boats like the Cruisers suffer "fatigue" from window and other larger through hulls developing into leaks. It is caused by hull flexing under load at 20+ knots. ER vents for this reason are normally very well bedded with stouter FRP around them. For future repair I'd request some mat/glass added for additional strength. How old is the Cruisers and any chance you could store it under cover?

I made the engine room intake vent repair to Scout. There had been some water intrusion around the vent into the balsa core.
Also built a 'dorade box' type fixture to prevent water from coming through the vent. Picture below and finished product.

I'm thinking that I should use the guys with the vacuum setup to try and completely dry all of the moisture before injecting.

Anode said:

I made the engine room intake vent repair to Scout. There had been some water intrusion around the vent into the balsa core.
Also built a 'dorade box' type fixture to prevent water from coming through the vent. Picture below and finished product.

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I don't think this is as complicated as many are saying it is.

beachbum29 said:

I don't think this is as complicated as many are saying it is.

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You are right, no bid deal, just part of owning a cored boat. However, if you can't get at the areas from the inside, due to liner whatever, then things get more complicated.

Brooksie said:

.... just part of owning a cored boat. However, if you can't get at the areas from the inside, due to liner whatever, then things get more complicated.

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So why even expose yourself to this possibility before even buying the boat? I've always believed when buying a boat, mitigate the potential maintenance problems as much as possible before signing on the dotted line! It's obvious that the OP loves this boat and is willing to ignore some potentially serious warts!

Unlike many who fall in the "run, forest, run" camp I don't think what you're describing would make me run from that boat.

When I bought Beachcomber there were two areas of the boat that showed elevated moisture content. The first, on the port side above the shear line, was caused by what appeared to be the boat hitting a piling while docking. There was an 8" long area of the plastic that holds the rub rail that had been chipped and a piece on the underside was missing. This was near the stern and allowed moisture to get into the coring, likely from waves. The area with the high moisture was about 10" tall by 8' long and extended from the break in the plastic toward the stern.

The surveyor, knowing I was bringing the boat to a desert climate, said not to worry about the elevated moisture there. He suggested I repair the plastic area that was broken, then let the dry climate wick the moisture out through the gelcoat.

The second area was the swim platform. The PO had mounted a dinghy crane on the swim platform and failed to properly seal the holes in the platform. The entire platform was wet, wet, wet. We removed the crane, cut out the entire swim platform area and made a new swim platform to fit in there.

The first repair only cost a few bucks. The second one cost a couple thou but we ended up with a much larger swim platform. Here's a shot looking down at the stern after the old swim platform had been cut away. The red stripe near the stbd side of the swim platform is the channel where the new platform was fitted into.



Here's the boat yard crew working on sanding the platform prior to applying the first coats of paint.


Here's the crew mounting the platform onto the stern.


This isn't the best shot in the world, but it shows what it looks like....

SeaHorse II said:

So why even expose yourself to this possibility before even buying the boat? I've always believed when buying a boat, mitigate the potential maintenance problems as much as possible before signing on the dotted line! It's obvious that the OP loves this boat and is willing to ignore some potentially serious warts!

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I don't disagree with this at all. In my case, I sought out a cored Bruno because of their light weight, and low powering requirements compared with the solid model (both were available at the time). If it were a fancy, lined boat, where the inside of the hull, deck, overhead were inaccessable then I would have had to cut up a lot of this boat over the years to get at the areas I have repaired. So my needs were fulfilled but someone else might have went crazy with this boat.

GFC said:

Unlike many who fall in the "run, forest, run" camp I don't think what you're describing would make me run from that boat.

When I bought Beachcomber there were two areas of the boat that showed elevated moisture content. The first, on the port side above the shear line, was caused by what appeared to be the boat hitting a piling while docking. There was an 8" long area of the plastic that holds the rub rail that had been chipped and a piece on the underside was missing. This was near the stern and allowed moisture to get into the coring, likely from waves. The area with the high moisture was about 10" tall by 8' long and extended from the break in the plastic toward the stern.

The surveyor, knowing I was bringing the boat to a desert climate, said not to worry about the elevated moisture there. He suggested I repair the plastic area that was broken, then let the dry climate wick the moisture out through the gelcoat.

The second area was the swim platform. The PO had mounted a dinghy crane on the swim platform and failed to properly seal the holes in the platform. The entire platform was wet, wet, wet. We removed the crane, cut out the entire swim platform area and made a new swim platform to fit in there.

The first repair only cost a few bucks. The second one cost a couple thou but we ended up with a much larger swim platform. Here's a shot looking down at the stern after the old swim platform had been cut away. The red stripe near the stbd side of the swim platform is the channel where the new platform was fitted into.

Here's the boat yard crew working on sanding the platform prior to applying the first coats of paint.

Here's the crew mounting the platform onto the stern.

This isn't the best shot in the world, but it shows what it looks like....

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The two boats look very similar.

The fiberglass guy is taking core samples Monday to determine if this is a fixable situation. According to him if the water has been present for years then his repair wont work.

Good luck with your surveyor's assessment.

If the job turns out to be a much larger one than anticipated it might be time to go back to the seller with the information. He's going to have to get it fixed before he sells the boat so maybe it's time for him to seriously rethink the selling price...if you're still interested in it.

GFC said:

Good luck with your surveyor's assessment.

If the job turns out to be a much larger one than anticipated it might be time to go back to the seller with the information. He's going to have to get it fixed before he sells the boat so maybe it's time for him to seriously rethink the selling price...if you're still interested in it.

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Drastic reductions have already been made. Now it's time whether I want it or not.

The surveyor, knowing I was bringing the boat to a desert climate, said not to worry about the elevated moisture there. He suggested I repair the plastic area that was broken,C


The surveyor has it exactially backwards , go to a dry climate a few months THEN fix the sealing method.

"then let the dry climate wick the moisture out through the gelcoat."

While some moisture will travel theu GRP , it is a very very slow process , takes years!

Many repair folks do not believe balsa just being wet is very harmful to the hull strength , rotten is a different matter .

FF said:

The surveyor has it exactially backwards ...

"then let the dry climate wick the moisture out through the gelcoat."

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Good catch FF. typical toy boat surveyor. I wonder if the guy believes that there is some kind of hydro diode built into hull material that permits moisture to move in one direction only?

RickB said:

Good catch FF. typical toy boat surveyor. I wonder if the guy believes that there is some kind of hydro diode built into hull material that permits moisture to move in one direction only?

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The moisture has to be removed or it will continue to rot the balsa and move through the hull causing even more damage.

beachbum29 said:

The moisture has to be removed or it will continue to rot the balsa and move through the hull causing even more damage.

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Correct. The existing moisture must be removed and source of ingress must be sealed.

Visualize the moisture advancing through the core the same way a drop of water spreads out on a piece of cloth. At a certain point behind the line of advance the moisture content is ideal for the growth of cellulose eating bacteria. If more moisture can enter, that line of advance continues to spread rapidly. If the source of moisture is sealed and no more can enter, the advance will slow but the moisture that entered will always be there, it just gets recycled by the growth, death, and birth of the bacteria in essentially a closed system. Until the finite amount of moisture in a sealed space is spread around a large enough volume of edible core that it becomes a virtual desert the rot process will continue. Munch munch.

As others have mentioned, repairing wet balsa core in modest amounts isn't a big deal if the area is easily accessible from the inside. Had 2 areas in my '73 Bruno & Stillman that needed to be repaired. The through transom exhaust pipe and a depth transducer hole were improperly sealed. Both areas were cut open from the inside. Wet balsa was removed till we came to dry clean core. The good core was sealed with West System. Then the coreless area was rebuilt with layers of epoxy and cloth. Finally the top layer was woven roven which over lapped onto the undisturbed adjoining areas. The removed core area was maybe a little over a 1' square. In each case, the fiberglass below the core was never disturbed. The added weight of making those areas solid as opposed to cored is insignificant.

Ted

beachbum29 said:

{The moisture has to be removed or it will continue to rot the balsa and move through the hull causing even more damage.}

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Now, it's starting to sink in!.

SeaHorse II said:

Now, it's starting to sink in!.

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The moisture or into my head???