Balsa Core question

G

gands111

New member
I'm considering purchase the of C-dory and have a question. It looks like the construction includes balsa between two layer of glass. Has there been any problem with the balsa absorbing water?? I'm a long term owner of a boston whaler that has absorbed water in the foam and believe me I don't want to deal with that again.

Comments would be appreciated.


Thanks
 
That was one of my concerns also having dealt with a saggy floor in and old Owens runabout and a 22 foot Cobia. I've only been a C-Dory owner for a couple years first a 16 and a 22 but I've been and avid reader on this site for about 4 years. In that time I've seen very few incidents of water causing significant damage and mostly those were related to abuse or improperly sealed hardware. One owner had a problem with apparent delamination of a 2002 boat and the factory gave him a brand new 2008 boat. Just a few days ago someone posted about removing a sensor from his transom that had been there since 1983 and the screw holes were dry as a bone. While many don't like the new molded interiors in the 22's one plus is they are glassed in place rather than held in place with L-brackets screwed to the deck. I don't know enough about it to say but C-Dory claims that if you do have water get into the core it's slow to migrate because of the honey cone design of the core. I don't know if it's correct but I read that the 26 Venture has a foam core.
 
I have a little drill saw core of the sandwiched 1/4 "balsa from the top of my v-berth. While not exactly the same, I sank it in a glass of water today with a weight on it and will report back in a week or so, whatever obvious I can tell, if anything.

Not really very scientific but.................... at least it hasn't been bubbling yet! That be my scientific 1 hour observation.

chris
 
The balsa core on C-Dories is sandwiched "on end grain", i.e. the grain is perpendicular to the surface. This orientation tends to isolate water damage and make it slower to migrate. Plywood grain is parallel to the surface, which makes it easy for a leak to travel far and cause great damage before detected.

However, even with the perpendicularly oriented balsa grain, long term exposure to moisture can cause serious damage. As such, all holes into the balsa cored area should be drilled oversize, filled with epoxy compound, and redrilled for the fasteners in such a manner that no part of the fastener touches the balsa core itself.

Most C-Dory and other Balsa cored craft owners try to avoid drilling and fastening into the cored areas.

If one does end up with extensive damage from long term water exposure to the balsa core, in most cases it is easier to cut the surface glass off, recore and rebond the glass surface back than it would be to repair such damage in the old foam core techniques.

Dr. Bob of Thataway has extensive experience in avoiding, detecting, and repairing water damage areas in cored hulls, so you might search the topic and his posts for detailed accurate info.

The vast majority of C-Dory owners experience little or no core damage problems. Most of those that have had the problem found it around hatches and attachments frequently exposed to water and with pretty limited horizontal migration. Dr. Bob did find a CD25 hull which had left a large crack unrepaired for a long time which suffered extensive cockpit floor damage which he repaired.

You have to observe and evaluate the condition of any boat and no boat should be left out in the rain with cracks and holes open to the core for long periods without repair.


John
 
It's to bad they can't come up with a core product that absolutley won't absorb water, or delam. Maybe I better stick with aluminum boats. I do however really like the lines and design of the c-dory. Tough decision.
 
There are cored products (such as the Nada core I used in the cockpit floor repair of the 25). Some boats are made of this product, but there are some qualities of balsa which make it a better core material. If properly build and cared for it is a fine material. Dr. John has pretty much summed it up.

I have no problem buying balsa cored boats, but do modify the fasteners to avoid water penetration. There are several boats, mostly in the 2002 on era which have had core problems. So far the factory has stood behind these boats; mostly repairing the area damaged.
 
My 2003 CD 25 with in excess of 9000 miles on it developed pretty extensive core damage in the cockpit floor due to inadequately sealed floor hatch openings. The repair is turning out to be much bigger and more expensive than I had anticipated, and although I have had many problems communicating with C Dory over the warranty, it looks like they will step up to the plate. We cover much of the cockpit floor with a mat which tended to mask any floor softness, and by the time we noticed real squishiness around the hatches the damage had already migrated to more than half the floor. I would advise all CD owners to double check the sealing of all floor hatch openings as a matter of course.
 
gands111

I owned a CD 22 cruiser for 16 years with no core problems.

On any screw that penetrates into the core, I would at least remove the screw and replace it using a sealer like 4200.

The worst core problems have been in the decks of CD 25's. CD 22's don't have that kind of deck.

CD's are not built like Boston Whalers, and don't have the same problems.
 
In the name of "utterly useless and inane science" i have now removed my little sandwiched balsa core sample from it's water glass a couple of times over 3 days and there is no obvious penetration, it still floats about the same, there is no sponginess, no squishiness and no delamination. I can't even pry up the glass at the edges with fingernails.

I wish I had a micro scale that I could use to see if there were any signs of logging over time.

My plan is to give it a week, dry the top as thoroughly as I can with a paper towel, and cut off a glass side with a razor to see if there are any signs of obvious migration. For now i am impressed, but as many have said, this is not at all the same as having the glass separate from your transom and having all of the end grains subjected to water for extended periods of time. But maybe a little screw hole would not be such a problem except for an extremely long time?

Chris
 
Days, weeks or even months are not enough to show problems with balsa core penetration. It takes months and years for problems. Compounding the water intrusion is the growth of molds and fungi in the core structure. Also flexing of the water soaked material, allows breakdown of the end of the short celled balsa wood. Look at some of the photos of the various materials growing in my album--and the "Fungus Amoung us" thread on the deck of the CD 25.

The boats earlier than 2002 very rarely had problems. Although I don't know the exact laminate schedule, I suspect that the cockpit floor of the 2002-2005 CD 25's were a bit light on the amount of glass applied. Glass is still important as a structural element to give rigidity thru time.

Also look at David Pascoe's articles on delamination by pounding which has occured in Sea Ray cored bottoms. This was without water intrusion--but inadequate amount of glass and bonding.

Paradoxically, Balsa is a "hardwood" as classified by cell structure. The cells are short and thus if the cell membrane remains intact, the water does not penatrate well.

Some may remember the Kon Tiki raft which became water logged thru its voyage. Any wood will adsorbs water with time--because balsa is light in weight and has short cells, it adsorbs slower than many other woods.
 
The simplest thing a C-Dory owner can do to reduce the probablility and extent of water intrusion is to cover the boat when it is not in use.

Keep it under a covered slip, hang a cockpit cover on the aft half, or use a full cover.

All the C-Dorys I have seen tend to accumulate and hold water in the cockpit/transom area. If there is any tiny imperfection in the glass surface or hatch/fitting seal, this exposes it to water intrusion pressure on a constant basis.

So, I think that habitually keeping the boat dry between uses is even more important that the sealant technique/material choice. Of course this mainly applies to areas where water tends to accumulate.

John
 
As summarized by the experts above, the key is sealing anything that goes into the core. As you have experienced, this holds true for Whalers with foam core or wood cored boats.

The advantage to cored boats is weight reduction, engine requirements, and thus fuel consumption.
 
Sounds like water intrusion is a real problem with the c-dory line of boats unless a significant amount of effort isn't performed to insure this dosen't happen. Why wouldn't the manufacture address this??

Second question: I was specifically considering a new 2007 25 cruiser however it sounds like that particular model has specific issues including water in the balsa. Has the manufacture addressed these issues specific to the 25 in the later years or are things still status quote.

Comments are appreciated.

Thanks

Dan
 
Due to the many thousands of PM’s I’ve, no doubt, received on my balsa core test, from nail biting C-Brats and others, I’ve decided to end the test a few hours earlier than originally planned. DRUM ROLL PLEASE……..OK, many have stated that the results of this test mean just about nothing. I tend to agree, but I feel compelled to report the outcome anyway.

Restating, at the start of this thread, I had about a 2” circular hole saw cut of the balsa core from my 87 v-birth with fiberglass on both faces and about a 1/8” hole in the center. I sunk it in a glass of water for a week (actually 6.5 days). The idea was to see if I could, after removing the facing, determine the extent of any water migration in the wood or delaminating of the fiberglass.

Scientist that I am[In my 4 control glasses I placed a common sponge, a Brawny paper towel, a piece of Chamois and a box of Jello 'cellulose'gelatin] 3 control samples failed the water migration test miserably. I can’t report on the Jello as it disappeared the same day my granddaughter visited.

Core Balsa Result. There was no delaminating and the “scientific” removal of the fiberglass skin took the form of a serrated knife and a hammer. I could not skin it with a razor. There was absolutely no perceptible water penetration of even a fraction of a mm over this short time frame by naked eye observation. SEE LAST PHOTO IN ALBUM.

What can be said? I think it is safe to say that the side grains of properly bonded waterproof end grain balsa are far less conducive to water migration than the common sponge or chamois (I think). And further that the Brawny paper towels would make really lousey transom stiffeners.

One need only look at the pictures of failed transoms and floors on this and other sites to see that they do fail over prolonged time and with the long-time aid of microorganisms.

But, kidding aside, for anyone who removed a fuel tank screw last week and forgot to repair it for a week, I don’t think I’d lose too much sleep. But fix it this week or your sleeping days are numbered!

Or, better yet, sell that puppy cheap (to me) and go aluminum!

Chris

Ps: how do you check if you’ve gotten ANY PM’s?

Dan, I don't know what to say, obviously my boat has been pretty good and serviceable for 21 years, although there have been transom crack issues. But I will clearly state this.
I would never buy a $50,000+ + boat from a Company that does not EVER respond to any inquiries to it's own customer service e-mail site.
 
gands111":2a7slljs said:
Sounds like water intrusion is a real problem with the c-dory line of boats unless a significant amount of effort isn't performed to insure this dosen't happen. Why wouldn't the manufacture address this??

Second question: I was specifically considering a new 2007 25 cruiser however it sounds like that particular model has specific issues including water in the balsa. Has the manufacture addressed these issues specific to the 25 in the later years or are things still status quote.

Comments are appreciated.

Thanks

Dan
Click to expand...

Water intrusion is a problem on all cored boats made at any price level, I have not yet found one that properly seals anything drilled into the core. 4200 squirted on the outside of a washer is not proper sealing but this is what they all do. With any cored boat you buy, you will need to make sure the things they installed are sealed and seal properly as necessary. The manufacturers don't address this QC problem likely due to cost/time.

I can't comment on the C-25 other than from what I have read here.

Good luck with your search.
 
Dan,

I don't think the gist of the thread so far warrants your feeling that the owner of a CD 25 has to go to great lengths to prevent significant damage to the hull/core area.

Incidents of serious damage reported on this site are rare, and most have involved ignoring common sense of sealing up visually evident, open cracks in areas where water tends to accumulate in open storage. Smaller areas of core wetting have come from unsealed hardware, bolts and screws, but are mostly limited in area, size and severity to the point that simple hand tools can be used to clean out and repair them.

Whatever boat you buy, there are things the owner must oversee and tend to in regular maintenance. Even aluminum hulls can suffer problems with improperly installed fittings, electrical, pumps, and accessories. There are things the owner needs to watch out for in maintaining and modifying ANY hull.

Most owners install a lot of equipment at the outset of ownership and only occasionally after that, so there is not a great deal of work for the owner or the installers to do - they simply need to know the proper way to install in cored hulls and do it.

I think the most basic guidelines for boat storage include providing cover from the elements when the boat is not being used. This saves a great deal of damage, and resultant maintenance/repair from sun, wind, dirt, and water damage. I don't know of any protected hull that has suffered serious damage, other than maybe Fishtails, which the factory replaced.

So there is no big "consumer warning" about owning a cored hull.

You just need to find a craft whose basic reputation, performance and layout coincide with your needs and, working thru a reliable dealer, take the dive and enjoy!

John
 
Dr. John,

I couldn't have said it better. Nice explanation.

Dr. John":33ytwap5 said:
Incidents of serious damage reported on this site are rare, and most have involved ignoring common sense of sealing up visually evident, open cracks in areas where water tends to accumulate in open storage.
Click to expand...

Dan, don't be scared off by the balsa core. When we took delivery of our 2005 22' Cruiser, we immediately dunked her into the water and have enjoyed her immensely ever since. We didn't go over every screw in the boat before using her. However, due to others experiences on this site, I am fully aware to continuously monitor the boat for any signs of problems. Bottom line, these are great little boats, very seaworthy and economical, and if you take care of them properly and pay attention to potential problem areas, you'll enjoy one of these boats for a long time.

Peter
 
I imagine you guys think I'm paranoid, however keep in mind I've dealt with serious water absorbtion issues in my Whaler and I NEVER want to do that again.

I'm only trying to obtain as much information as possible about the real possibility (risk) of this happening in the c-dory.

I really do appreciate your comments.

Dan
 
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