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Old 10-22-2019, 03:40 AM   #1
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To Duflex or not to Duflex

I was wondering if anyone has experience with Duflex balsa cored fibreglass laminated materials used to construction a hull or deck of a boat. We are currently looking at a 2007 power tri constructed from this product and have heard varying opinions on longevity and potential big repair cost due to water ingress and delamination or rotting of the balsa cores. The hull and deck are made from this material. Not sure if below the waterline or just above. I understand that if holes are drilled into the material they need to be sealed / epoxied correctly to prevent potential water ingress. That's ok. Would it turn anyone off from buying this type of constructed boat?
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Old 10-22-2019, 06:19 AM   #2
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If you do a search for terms like cored hulls you will discover a lot of discussion on this.

My hull is solid 'glass, but decks were balsa cored. I had my foredeck re-cored as the balsa had lots of wet & rotten areas. It took something like 20 years for the problem to develop, despite the foredeck having 960 screw hole in it. The PO kept the caulking in reasonably good condition which enabled it to last such a long time. The area was about 92 sq ft and with me doing some of the work the cost was $17k to re-core etc. I see that as a fairly modest cost as the issue was known to buyers and PO alike and influenced asking & selling price.

But, while I would not be overly perturbed by balsa decks (identified and negotiated) I would personally be very nervous about balsa cored hulls in regard to potential costs. Modern coring, with closed cell foam would be OK provided there was no core/skin de-lamination.
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Old 10-22-2019, 03:11 PM   #3
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Thanks Brian. I'm still trying to find out how much of the hull is balsa. It's just my luck that I thought I had found the perfect boat and then inadvertently find out that the hull is made from a balsa cored product. Everything else on the boat is absolutely perfect. ��
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Old 10-22-2019, 03:17 PM   #4
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If the deck core gets wet it can be repaired but it is a lot of work. My concern would be below the waterline if it is cored. Compass Marine has several excellent articles on DIY repair including one on bedding deck hardware that is certainly worth a read.
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Old 10-22-2019, 05:21 PM   #5
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I have used Duflex in a couple of builds I have worked on.

Duflex is totally different to production balsa cored boats .
Duflex uses epoxy, which is an actual adhesive for timber - polyester resin is not.
The Duflex panels are made under pressure, so no voids - unlike polyester production boats using contour balsa (small squares on scrim with voids between squares)
The knitted fabrics used are lighter but offer superior strength to weight - unlike polyester production boats.

I would rather foam over duflex and at that price point I am surprised people use it (someone drank the ATL composites/west system koolaid)

Saying that a well build boat, which if she's the boat I have in mind is ("Liberator") then you should have no problems.
The only issues I know of in any duflex boat is where clueless owners have drilled holes or done cutouts and didn't pick or route out the core and backfill with reinforced glue therfore allowing water to get into the core.
Even then, due to the end grain nature of the core and no voids, damage had been very localised and easily repaired.
In production builds using contour balsa, as mentioned above, the water and air can and does travel far and wide causing large scale damage.
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Old 10-22-2019, 07:53 PM   #6
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I rejected a known factory produced "trawler" due to it having imo(someone else disagrees) a balsa cored hull. Decks may be different,my 1981 boat has foam cored decks which are still good. Simi knows his stuff, but it sounds like you still have to take precautions and care, over and above a solid f/g hull. I wonder about the affect of impact damage penetrating the outer skin. Your appetite for risk may be a factor, in context of a boat you like.
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Old 10-22-2019, 11:11 PM   #7
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Quote:
Originally Posted by BruceK View Post
I rejected a known factory produced "trawler" due to it having imo(someone else disagrees) a balsa cored hull. Decks may be different,my 1981 boat has foam cored decks which are still good. Simi knows his stuff, but it sounds like you still have to take precautions and care, over and above a solid f/g hull. I wonder about the affect of impact damage penetrating the outer skin. Your appetite for risk may be a factor, in context of a boat you like.
For a vessel like the op is talking about , this one

https://www.boatsales.com.au/boats/d...AG-AD-17610503

solid glass is not an option, the design calls for light.

Damage like any vessel needs to be addressed in a timely manner but duflex is pretty good.
I did repairs on a cat once that had below water damage several weeks prior to coming out.
Inner skin was fine but outer skin had been punctured. Water hadnt really travelled anywhere due to being end grain and no voids.
Repair was simple, zip out balsa a few inches past the damage and it was dry and as I didn't have balsa on hand, I replaced with divinicell foam and reglassed.
To easy.
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Old 10-23-2019, 01:35 AM   #8
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If the price is right...
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Old 10-23-2019, 05:40 AM   #9
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The key with balsa is the workmanship when installing anything, especially below the WL.

I would hope the owner would allow an invasive survey.

Pay to have a qualified individual take down a sea cock and thru hull to inspect the hole for proper sealing and correct procedures to insure the core remains dry.

If the work is correct , sounds good to me.
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Old 10-26-2019, 06:37 PM   #10
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I have contacted the boat builder who said that he now works for the company that manufacturers the Duflex balsa cored panels and mentioned that they have gone away from using balsa cores for the hulls of boats. Then I contacted a few Shipwrights who advised to keep away from balsa cored hull boats and I also spoke to a couple of boat surveyors who advised the same.
Sooo, I think I'll leave this particular boat. Very frustrating as I really did like this boat, apart from the balsa cored hull.
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Old 10-26-2019, 08:00 PM   #11
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Originally Posted by Ralsy View Post
I have contacted the boat builder who said that he now works for the company that manufacturers the Duflex balsa cored panels and mentioned that they have gone away from using balsa cores for the hulls of boats.
So he is not a boat-builder anymore, he is a rep for a company and has a vested interest in pushing the product that has the most fat in it for him/them.

Interesting how ATL still sell it https://atlcomposites.com.au/categor...mposite-Panels
for hull construction and the actual boatbuilders/designers are still ok with it and actively push it for their designs


Quote:
Then I contacted a few Shipwrights who advised to keep away from balsa cored hull boats and I also spoke to a couple of boat surveyors who advised the same.
Im guessing these shipwrights and surveyors are not active in the multihull or performance vessel industry.
If they were, they would not be saying that.
They, like many who comment are still back in the stoneage , their only experience with cored hulls, especially balsa, being poorly executed, contour core, polyester resin, full of voids variants that were prone to problems.
Duflex is not that.

Quote:
Sooo, I think I'll leave this particular boat. Very frustrating as I really did like this boat, apart from the balsa cored hull.
Your call of course but if you really like it Id be speaking to the owners and designers of actual duflex vessels.
I can assure you, their opinions and decades of real life usage should sway you.

Perhaps give Bob Oram , the designer of that vessel and Jeff Schionning a call and ask them what their decades of usage has revealed?


https://www.boboramdesign.com/

http://www.schionningdesigns.com.au/material-choices
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Old 10-27-2019, 01:09 AM   #12
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Hey Simi 60,
The builder is still building boats, but for ATI. Mate, you sound like you have shares in the company or a vested interest in either the brokerage or you know the owner.
Noooo, only joking. Some one else said "if the price is right" maybe I should take note. Just worried about resale potential as we are newbies into boating and as live aboard. It may be that my missus says after 6 or 12 months that it's not for her and we have to sell. I don't like others have a bottomless wallet.
Cheers mate.
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Old 10-27-2019, 02:16 AM   #13
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Quote:
Hey Simi 60,
The builder is still building boats, but for ATI. Mate, you sound like you have shares in the company or a vested interest in either the brokerage or you know the owner.

Don't know the broker or owner, have met Bob Oram the designer a few times way back in the day and had no idea ATL were in the boat building game, news to me and I reckon a lot in the industry.

All I know is that there are dozens of strong, light, fast duflex boats getting around with zero issues.



Quote:

Noooo, only joking. Some one else said "if the price is right" maybe I should take note. Just worried about resale potential as we are newbies into boating and as live aboard. It may be that my missus says after 6 or 12 months that it's not for her and we have to sell. I don't like others have a bottomless wallet.
Cheers mate.
And that's a fair point and a different issue again and I wholeheartedly agree.

I'd be more concerned about the powered trimaran thing not being the same as everything else and only ticking a few peoples box.
A relatively lightweight powered trimaran is a strange beasty thats too far outside the box for the masses and only appeals to the select few.
Most won't even understand the concept or reasoning why.
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