Balsa Core Delamination
- Thread starter Brewkid
- Start date
For those following along, I added 5 new videos.
https://www.youtube.com/channel/UCZXdxU ... l9g/videos
Goodnight!
John
Scallywag
https://www.youtube.com/channel/UCZXdxU ... l9g/videos
Goodnight!
John
Scallywag
Brewkid":1475b4b3 said:
John,
Your videos are pretty interesting. My 22 is the same style as yours regarding the cabinetry and cockpit floor. The PO on my boat had issues with water coming into the cabin from the cockpit. Originally the joint between the cockpit floor panels and the aft bulkhead of that style boat was not sealed. There was a bit of a gap. Apparently the factory expected the bulkhead to floor joint would seal and prevent water entering the cabin.
I would suggest that if you drop a bunch of videos all at once, you might want to number them so viewers can watch them in the proper order. The order is not always obvious from the YouTube snapshot used to display the video.
Thanks.
A
Anonymous
Guest
In the meantime, users can sort the videos on Youtube from oldest to newest. If you've clicked on Scallywag's videos to see all of the thumbnails, there is a "Sort BY" button on the upper right. Click on that and sort by Date added (oldest).
I reviewed the thread and the videos again. Thanks for a comprehensive history of your work!
The question in my mind, is there any other penetration of the inner side of the hull which allowed water to penetrate the inner hull, and get to the Balsa core beyond the water tank? You had the screws holding the water tank down. I don't see any wires so there should be no screws into the core of the hull under the table.
Any water leaking from the water tank would be kept in the compartment where the tank was, with the fiberglass interior having been fully tabbed in as you found by cutting along the tabbing at the bottom of the area where the glass tank was secured. Could it have been water leaking in from around the water fill, or from a loose hose to the fill of the water tank? Still this does not seem like it would have been enough to cause the damage that you have, unless a considerable amount of water stood there for a long time. Looking at the balsa as it is in the Video #4 & #5, it is definitely separated from the hull side of the core--and that suggests to me that both freeze / thaw cycles and boat pounding were involved. Under normal conditions the balsa is firmly adhered to the inner surface of the hull The fiberglass interior gives more stiffness to the hull, than the plywood interior does.
Back to the flat cockpit deck and the aft cabin bulkhead; It looks as if the aft cabin bulkhead is glassed into the inner surface of the hull inside the cabin. I believe it should be well tabbed in on the cockpit side, under the flat deck also. I have seen boats where this was absent, or broken down.
Is there water under the flat deck? Many of the owners who have these flat elevated decks have put inspection plates in to remove water. But you would need holes to allow access--and there should be none there. Also no screws into the inner floor there. It looks as if you have the straps properly screwed into the glassed in cleats and not the core. (maybe outboard into the core?) The unused thru hull fitting aft is a concern--and should be opened up to be checked.
Personally I would go back with Balsa core. I would want the entire hull to be the same material. The balsa is going to be less weight than the Coosa board. (Urethane foam with fiberglass fibers, or the "BlueWater" with woven roving and glad fibers.). If you want you can put glass and epoxy "barriers" between sections of balsa core. I am aware of boats made entirely of balsa (planked), then glassed inside and out and after over 40 years absolutely no core problems. In the 20 boats we cut up (Hurricane Ivan damaged boat) in our studies on delamination and instrumentation, there were many up to 50 years old, with absolutely no core damage, and good adherence of the balsa core. Of course these had no holes in the outer laminate, and had used solid glass or other materials in the way of cleats and other penetrations.
As for cutting in by the door, if you cannot reach its with the Fein type blade, you may be able to use a flexible shaft on a Dremel or Rotozip type of tool, and a rotary blade or cut off wheel. Also air powered die grinders work well getting tight places, especially with a small cut off wheel. The tabbed in glass often separates well, when you have cut most of the other surfaces, and one or two areas remain. The tab bonds are secondary, and not as strong as primarily lay up bonding.
Keep up the great work, along with good videos.
The question in my mind, is there any other penetration of the inner side of the hull which allowed water to penetrate the inner hull, and get to the Balsa core beyond the water tank? You had the screws holding the water tank down. I don't see any wires so there should be no screws into the core of the hull under the table.
Any water leaking from the water tank would be kept in the compartment where the tank was, with the fiberglass interior having been fully tabbed in as you found by cutting along the tabbing at the bottom of the area where the glass tank was secured. Could it have been water leaking in from around the water fill, or from a loose hose to the fill of the water tank? Still this does not seem like it would have been enough to cause the damage that you have, unless a considerable amount of water stood there for a long time. Looking at the balsa as it is in the Video #4 & #5, it is definitely separated from the hull side of the core--and that suggests to me that both freeze / thaw cycles and boat pounding were involved. Under normal conditions the balsa is firmly adhered to the inner surface of the hull The fiberglass interior gives more stiffness to the hull, than the plywood interior does.
Back to the flat cockpit deck and the aft cabin bulkhead; It looks as if the aft cabin bulkhead is glassed into the inner surface of the hull inside the cabin. I believe it should be well tabbed in on the cockpit side, under the flat deck also. I have seen boats where this was absent, or broken down.
Is there water under the flat deck? Many of the owners who have these flat elevated decks have put inspection plates in to remove water. But you would need holes to allow access--and there should be none there. Also no screws into the inner floor there. It looks as if you have the straps properly screwed into the glassed in cleats and not the core. (maybe outboard into the core?) The unused thru hull fitting aft is a concern--and should be opened up to be checked.
Personally I would go back with Balsa core. I would want the entire hull to be the same material. The balsa is going to be less weight than the Coosa board. (Urethane foam with fiberglass fibers, or the "BlueWater" with woven roving and glad fibers.). If you want you can put glass and epoxy "barriers" between sections of balsa core. I am aware of boats made entirely of balsa (planked), then glassed inside and out and after over 40 years absolutely no core problems. In the 20 boats we cut up (Hurricane Ivan damaged boat) in our studies on delamination and instrumentation, there were many up to 50 years old, with absolutely no core damage, and good adherence of the balsa core. Of course these had no holes in the outer laminate, and had used solid glass or other materials in the way of cleats and other penetrations.
As for cutting in by the door, if you cannot reach its with the Fein type blade, you may be able to use a flexible shaft on a Dremel or Rotozip type of tool, and a rotary blade or cut off wheel. Also air powered die grinders work well getting tight places, especially with a small cut off wheel. The tabbed in glass often separates well, when you have cut most of the other surfaces, and one or two areas remain. The tab bonds are secondary, and not as strong as primarily lay up bonding.
Keep up the great work, along with good videos.
You mentioned vacuum bagging and I assume resin infusion. Do we know for certain that vacuum baggings was done for the layup of the 2008 boats? Certainly there is no primary bond between the mat adhered to the Balsa and the outer hull. Almost as if the first layers (mat and roving?? of solid glass had cured, and then the balsa core put in to a contaminated surface. Lets say that the laminating resin had wax in it by mistake. I don't know the lamination schedule of that specific boat.. I suspect it will no longer be available.
Some boats which are vacuum bagged there is a two step process. Also if not done properly resin can not flow to all areas. Just a little kink in a tube can resin starve a significant area.
You are doing a great job--and it must be very disheartening to find more wet core.
I have the same "General" moisture meter and I have found the relative moistures are quite accurate in fiberglass.
A sub set of all of this may be the suggestion that all marine surveyors do a moisture meter on the inner hull in the cabin. (unless there is obvious water sitting there or has been there in the last few hours.)
Some boats which are vacuum bagged there is a two step process. Also if not done properly resin can not flow to all areas. Just a little kink in a tube can resin starve a significant area.
You are doing a great job--and it must be very disheartening to find more wet core.
I have the same "General" moisture meter and I have found the relative moistures are quite accurate in fiberglass.
A sub set of all of this may be the suggestion that all marine surveyors do a moisture meter on the inner hull in the cabin. (unless there is obvious water sitting there or has been there in the last few hours.)
The things of nightmares...
Has anyone considered dipping their boat in a giant vat of Flex Seal?
Kind of a joke, kind of not. Having the older model cruiser where water collects forward in the cockpit at the bulkhead, I'm wondering if there's anything I can do to add extra protection in that area. So far, I haven't seen any evidence of delamination... but there are some super fine stress cracks down there right at the "joint" of the bulkhead - too fine and seemingly different materials involved so the usual gel coat repair that I'm used to probably wouldn't apply down there.
Has anyone considered dipping their boat in a giant vat of Flex Seal?
Kind of a joke, kind of not. Having the older model cruiser where water collects forward in the cockpit at the bulkhead, I'm wondering if there's anything I can do to add extra protection in that area. So far, I haven't seen any evidence of delamination... but there are some super fine stress cracks down there right at the "joint" of the bulkhead - too fine and seemingly different materials involved so the usual gel coat repair that I'm used to probably wouldn't apply down there.
Bob,
Honestly I have no idea. I'm just making assumptions on my very little fiberglass knowledge and would think your hypothesis correct. I just skimmed off a section of the bubbled area (you'll soon see in my video) and was surprised to find a sunflower seed husk underneath. Who knows the state of the company in 2008. It could have just been one disgruntled employee that day that was lacking attention...
Disheartening, yes. I'm trying very hard to keep a positive attitude but if you ask me at this moment if I'd buy another cored boat my answer wouldn't be positive....
All,
I do want to be clear, that although there seams to be lay up issues, I'm not pinning the water damage on that. I've cleared out enough balsa from under the back bulkhead and the void under the back deck may have been the culprit. The rear bulkhead appears to be glassed off from the floor, and I cannot feel or see a seam from the underside so I'm not sure what the sealant seals off where the deck and bulkhead meat....
As far as upkeep of the boat. She's always been covered, never spent more than a week strait in the water and other than fished hard, she's been babied. Aside from pulling every screw and re-bedding them, I'm not sure what else I could have done. The water could have found its way in before I purchased it.
I'm also uploading my survey for anyone interested in what one looks like.
Edit, after looking at the build albums. Pictures look pretty close to my year.
http://www.c-brats.com/modules.php?set_ ... php&page=1
http://www.c-brats.com/modules.php?set_ ... _photo.php
R/
John
Scallywag.
Honestly I have no idea. I'm just making assumptions on my very little fiberglass knowledge and would think your hypothesis correct. I just skimmed off a section of the bubbled area (you'll soon see in my video) and was surprised to find a sunflower seed husk underneath. Who knows the state of the company in 2008. It could have just been one disgruntled employee that day that was lacking attention...
Disheartening, yes. I'm trying very hard to keep a positive attitude but if you ask me at this moment if I'd buy another cored boat my answer wouldn't be positive....
All,
I do want to be clear, that although there seams to be lay up issues, I'm not pinning the water damage on that. I've cleared out enough balsa from under the back bulkhead and the void under the back deck may have been the culprit. The rear bulkhead appears to be glassed off from the floor, and I cannot feel or see a seam from the underside so I'm not sure what the sealant seals off where the deck and bulkhead meat....
As far as upkeep of the boat. She's always been covered, never spent more than a week strait in the water and other than fished hard, she's been babied. Aside from pulling every screw and re-bedding them, I'm not sure what else I could have done. The water could have found its way in before I purchased it.
I'm also uploading my survey for anyone interested in what one looks like.
Edit, after looking at the build albums. Pictures look pretty close to my year.
http://www.c-brats.com/modules.php?set_ ... php&page=1
http://www.c-brats.com/modules.php?set_ ... _photo.php
R/
John
Scallywag.
The photos do show vacuum bagging for the core. No resin infusion. Just having vacuum bagging, does not have any bearing on the adherence of the core to the outer shell. If you found sunflower seed shells there, there was very poor "sanitary control". Also fiberglass work is difficult, and "dirty". The shop pictured in the series you linked to, was what I would call "dirty". I see photos of current builds and I have spent time in factories where boats were being laminated on a mass production basis (Specifically Columbia/Coronado and Cal yachts). All a lot "cleaner". Any dust, material particle (even husks) can be a nidus where there is no lamination. Also if the underlying glass has set up fully, there will be less of a bond than if it is still tacky.
A lot of water got in that core--from some place. I also suspect some freeze thaw cycles??
You are doing great work, with fantastic documentation! Thanks.
A lot of water got in that core--from some place. I also suspect some freeze thaw cycles??
You are doing great work, with fantastic documentation! Thanks.
PaulNBriannaLynn
New member
This is a great technical thread, thank you for sharing all this. Its a little scary for me with a 2007 with the same cabinet and cockpit floor.
I believe Scott hit the nail on the head earlier. The raised cockpit floor holds water, we've all determined that. When I got our boat, there was water under there. If the trailer wasn't tilted with the tongue up, or while it sits level in the water... water would creep through the bulkhead somehow and find its way into the cabinet with the water tank and puddle on the floor between the dinette and the sink cabinet. I've found standing water in that cabinet before and who knows how long its sat there. At one point I resealed the cockpit floor and that was the end of that, but now I'm going to have to check those water tank screws and bed them properly and pray I don't find anything like this while I'm doing the work. Agreed with the freeze/thaw cycles compounding the problem over time. The water is not supposed to creep that far in theory.
I'll be following along with the videos.
I believe Scott hit the nail on the head earlier. The raised cockpit floor holds water, we've all determined that. When I got our boat, there was water under there. If the trailer wasn't tilted with the tongue up, or while it sits level in the water... water would creep through the bulkhead somehow and find its way into the cabinet with the water tank and puddle on the floor between the dinette and the sink cabinet. I've found standing water in that cabinet before and who knows how long its sat there. At one point I resealed the cockpit floor and that was the end of that, but now I'm going to have to check those water tank screws and bed them properly and pray I don't find anything like this while I'm doing the work. Agreed with the freeze/thaw cycles compounding the problem over time. The water is not supposed to creep that far in theory.
I'll be following along with the videos.
I don't know exactly how these 22's were built.--but the usual way, was to tab the aft cabin bulkhead to the inner bottom of the boat all along its bottom and up the sides. I have seen several boats, including several 22's and at least 3 C Dory25's where this tabbing had either broken down or was never complete. This can also lead to water intrusion into the lower part of the aft bulkhead (which is also balsa cored). In light of this it would be prudent for any buying of these specific boats to do moisture testing on the inner cabin floor. Normally this floor should have no more moisture than the solid glass on the sides.
Persons who own these boats currently should use one of the in-expensive moisture meters to determine if there is any excess moisture trapped in the core.
In our discussion of locations of bilge pumps in different years of the boats, there are many variations of location. Some have a 'step' just inside of the cabin aft bulkhead. These also have a hole thru that bulkhead,--and often a sump there, to collect water which might pool in this area. For example my 2006 C Dory 22 had the step and sump just inside of the cabin door. It had the removable floor. Thus no water was "trapped" under it. It flowed to the sump.
I might be tempted if I owned one of the affected boats with the built in level floor in the 22, to consider putting a hole in the aft bulkhead and placing a bilge pump under a step, and "dam" of fiberglass to contain any water in a sump area.
Persons who own these boats currently should use one of the in-expensive moisture meters to determine if there is any excess moisture trapped in the core.
In our discussion of locations of bilge pumps in different years of the boats, there are many variations of location. Some have a 'step' just inside of the cabin aft bulkhead. These also have a hole thru that bulkhead,--and often a sump there, to collect water which might pool in this area. For example my 2006 C Dory 22 had the step and sump just inside of the cabin door. It had the removable floor. Thus no water was "trapped" under it. It flowed to the sump.
I might be tempted if I owned one of the affected boats with the built in level floor in the 22, to consider putting a hole in the aft bulkhead and placing a bilge pump under a step, and "dam" of fiberglass to contain any water in a sump area.
colbysmith
Active member
Hi Bob. Can you recommend or link to the kind of moisture meter you like to use or refer to? Thanks. Colby
colbysmith":2dlcdfgw said:
I have two moisture meters which I bought for comparison. The General MMD7NP
The Gneral MMD7NP about $45.
And the Ryobi CW1302
Both are pinless and have have 4 settings Wall, Masonry, Soft Wood and Hard Wood. The two meters agree within about 10%; 90% of the time.
A must read on moisture meters, balsa and cored hulls by David Pascoe.
Here is another good read on moisture meters, brass hammers and balsa.. They recommend the Ryobi. (which I believe is out of production, and I have not used the latest one, which hooks up to the I phone.)
Having said all of this, "moisture meters" do not measure moisture. They measure capacitance. Many things can give false readings; both false negative and false positive. We took apart a number of laminates, from hurricane wrecked boats, and a couple of bow thruster cutouts of boats with known blister and wet core problems. A friend of mine had designed an ultrasonic technique gauge which could read thru laminated core of various materials. Surveyors would not spend the several thousand dollars to buy and then take the time to wse the equipment, so it never went to market. I acquired the 2 moisture meters I have, and we also used a Tramex Moisture Meter for comparison to measure moisture under experimental conditions and in real boat scenarios
I do think that if you have a badly saturated core, as in this example, a moisture meter should show the areas. Keeping in mind that any metal nearby will increase the reading that voids will give false negatives. The the moisture is only relative, and if you have suspicions, then holes can be drilled and the core sampled. I do not recommend drilling a bunch of holes in the inner surface of the hull unless. you have some very strong reason to suspect an issue.
colbysmith
Active member
Thanks. But it looks like both your links go to the same meter. I'll see if I can google to find the Ryobi. Colby
Sorry about that Colby.
Here is the proper link. It may not be in production?
The only real positive about it was it seemed a little easier to read than the General.
Here is the proper link. It may not be in production?
The only real positive about it was it seemed a little easier to read than the General.
clayhubler
Member
Is anybody else getting the 404 page not found when clicking the link to the videos?
Oops, just realized the links work on my phone but not on the pc. Not sure why.
John, I'm going to have to get caught up on your videos. Looks like you are literally in the same boat as me. I too have a very expensive boat that I cannot use.
I am looking at cutting out the entire floor in the cockpit and probably the cabin on my 2003.
I just yesterday took the boat off the trailer and blocked it up with support under the chines because I was worried about the hull flexing with all the balsa removed.
Initially I was optimistic about completing this repair quickly, but I now know that will not be the case.
Oops, just realized the links work on my phone but not on the pc. Not sure why.
John, I'm going to have to get caught up on your videos. Looks like you are literally in the same boat as me. I too have a very expensive boat that I cannot use.
I am looking at cutting out the entire floor in the cockpit and probably the cabin on my 2003.
I just yesterday took the boat off the trailer and blocked it up with support under the chines because I was worried about the hull flexing with all the balsa removed.
Initially I was optimistic about completing this repair quickly, but I now know that will not be the case.
John-
I just finished watching video #16. It's discouraging to find isolated pockets of core rot in areas beyond the line where it the balsa appears to be solid. The more you look.... the more you find. As painful as it is, I guess you just keep going.
I'm wondering if you have tested the accuracy of using a phonic hammer and the moisture meter to predict the core rot problem areas. Maybe you could map areas using those those methods on the floor before you lift the top fiberglass layer to see how those methods relate to what you find underneath?
As you are running out of floor area to work from, you might want to use some lumber (i.e. 2 X 8's) that span the over the work area to avoid putting your weight directly on the bottom hull layer.
Jim
I just finished watching video #16. It's discouraging to find isolated pockets of core rot in areas beyond the line where it the balsa appears to be solid. The more you look.... the more you find. As painful as it is, I guess you just keep going.
I'm wondering if you have tested the accuracy of using a phonic hammer and the moisture meter to predict the core rot problem areas. Maybe you could map areas using those those methods on the floor before you lift the top fiberglass layer to see how those methods relate to what you find underneath?
As you are running out of floor area to work from, you might want to use some lumber (i.e. 2 X 8's) that span the over the work area to avoid putting your weight directly on the bottom hull layer.
Jim
Jim,
Thanks for following along. I haven't used a phonic hammer. The moisture readings however were just too all over the place unfortunately... I would have a hole here and a hole there and at the end of the day it looks like the most of it will just have to come out anyway...
If you noticed, I'm sitting on the outboard/thick section while I'm working and stay off the weaker middle section, but if need be I'll scaffold it up for sure! When I pull the back deck that'll be the real challenge I think. I may even need to cut it out in two sections midship.. We'll see...
R/
John
Scallywag
Thanks for following along. I haven't used a phonic hammer. The moisture readings however were just too all over the place unfortunately... I would have a hole here and a hole there and at the end of the day it looks like the most of it will just have to come out anyway...
If you noticed, I'm sitting on the outboard/thick section while I'm working and stay off the weaker middle section, but if need be I'll scaffold it up for sure! When I pull the back deck that'll be the real challenge I think. I may even need to cut it out in two sections midship.. We'll see...
R/
John
Scallywag