Cored Hull Underwater

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BruceK said:
I`m holding off making an offer, I could go lower than I planned, but the kernel question is, do I want to own it, at all? Which is what this thread will help me resolve.
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Bruce, I've followed your frequent posts for about 7 years (Over 9000) & can't believe you are considering buying a boat that has a completely balsa cored hull! You must be lusting over this vessel to ignore all the wisdom you've displayed over the years. Don't do it! You'll always regret it when it comes time to sell!:blush:
 
Haylands said:
I think if you have to ask on here if you should buy a particular boat because of its construction technique then you have answered your own question....
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That sums up my feelings on the matter. :blush:
 
Codger2 said:
Bruce, I've followed your frequent posts for about 7 years (Over 9000) & can't believe you are considering buying a boat that has a completely balsa cored hull! You must be lusting over this vessel to ignore all the wisdom you've displayed over the years. Don't do it! You'll always regret it when it comes time to sell!:blush:
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Hull design and deck structure

Ocean Alexander has continued to perfect and refine the hull of their yachts to help improve on performance, efficiency and balance. The Ocean Alexander 90 features crash bulkheads and hull stringers which are engineered to offer structural soundness and hydrodynamic stability. The hull is composed of a closed-cell foam core from deck to waterline. The underlying hull below the waterline is an end-grain balsa-cored superstructure. Unidirectional carbon fiber provides extra strength to reinforce the bulkheads and stringers.


seems strange you're so vehemently against coring :eek:
just sayin
 
I guess I have a different take on the value of this boat as I am not too concerned about the balsa coring below the waterline. Looking on Yachtworld, there are 4-5 Swift Trawler 42s listed in the US in ranging from US$200,000 to $275,000. Your boat has two known problems: water leaking around portlights and possibly the ceiling and a poorly designed exhaust system (shared with me by PM).

The former issues may be somewhat expensive to fix, particularly fixing the cosmetic results inside. The exhaust system problems can be managed with extra maintenance.

So put those two issues (the exhaust should be common to all ST42s but few will know it is a problem) against the US boats, figure on 10% less than asking for actual sales prices and add whatever premium that Australian boats command over US boats and see if it is competitively priced.

Then if it is, make an offer at about 10% below what you want to pay to compensate for these risks and see what happens.

David
 
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There is no such thing as "saturated" balsa core, even if infused. Also, even foam cored boats can get wet inside, the scoring that allows the foam to conform provides hundreds of water channels to allow water to run where it wants. Foam will not rot, but some kinds get pretty soft after a decade of being wet.

A cored boat requires attention to detail not usually found in a production builder. Every hull penetration should have the core rebated back and solid glass in its place. There should be no screw penetrations through the outer OR inner skin. It takes a determined custom builder to achieve that.
 
Ka_sea_ta said:
Hull design and deck structure

Ocean Alexander has continued to perfect and refine the hull of their yachts to help improve on performance, efficiency and balance. The Ocean Alexander 90 features crash bulkheads and hull stringers which are engineered to offer structural soundness and hydrodynamic stability. The hull is composed of a closed-cell foam core from deck to waterline. The underlying hull below the waterline is an end-grain balsa-cored superstructure. Unidirectional carbon fiber provides extra strength to reinforce the bulkheads and stringers.


seems strange you're so vehemently against coring :eek:
just sayin
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Comparing a spanking new multi million dollar yacht to a 17 year old Swift Trawler is not easily done, except for argument's sake.

Two very different boats, two different builders, two different build techniques, two different QA/QC protocols and two different eras - a huge difference.
 
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One of our club members had an Offshore 55 footer who got "center punched." By the time he got the boat back into his slip, the balsa coring was saturated. The whole side of the vessel had to be stripped to remove the soggy balsa wood at great cost to the insurer.
 
sunchaser said:
Comparing a spanking new multi million dollar yacht to a 17 year old Swift Trawler is not easily done, except for argument's sake.

Two very different boats, two different builders, two different build techniques, two different QA/QC protocols and two different eras - a huge difference.
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You are exactly right, that's why a blanket statement about in this case. "balsa coring below the waterline" is typically not accurate. As far as the ST goes the salon and galley layout on the ones we on weren't my cup of tea. But I've haven't heard or read anything about water intrusion issues in the hull either.
 
Ka_sea_ta said:
You are exactly right, that's why a blanket statement about in this case. "balsa coring below the waterline" is typically not accurate. As far as the ST goes the salon and galley layout on the ones we on weren't my cup of tea. But I've haven't heard or read anything about water intrusion issues in the hull either.
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You miss one critical element in your argument. Beneteau and other builders of small recreational vessels do not always put the time, money, effort and research into building the best composite hulls. I know what Westport has done for 20 years, building excellent composite hulls. Hopefully the big OAs are even better.

All sorts of planing composite hulls on the market, especially in the size and weight range where lifting them out of the water is common. This is a great application, normally.

If you're buying or building a smaller "glass" in the water all the time yacht, stick with the herd in avoiding any chance of hull saturation - go solid FRP and do it well - makes sense to me.
 
bogranjac1 said:
.

Hi Bruce,
I have read your numerous posts over this boat,starting from the hull blisters noticed around the transom to yesterdays post.
You seem very wary and ill at ease over this boat !!
Walk away from this boat or you will never feel relaxed and always be thinking of some negative. Your spending huge money here. Go find another fish from the ocean.
Regards to you both.
Brett
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Thanks Brett but there are 2 boats, a Pacific 40 in Cairns, and this Beneteau in Sydney. So far the Beneteau hasn`t revealed any osmosis, if it did I wonder how that would be complicated by coring? Badly, I suspect. I have a tendency to chase rabbits down burrows, more so when I see a boat which fits the bill but turns out to have issues I`d like to solve, but recognize I may not.
 
Because the boat fits most of our needs(except I can`t find space for solar panels),I have persisted with it, perhaps to perseverative error, but I have my eyes open. We`ve spent 3.5 hours going all through the boat. As David says, the riser raw water injection/turbos problem may be manageable, and certainly can be dealt with at survey, by tear down if necessary, as Sunchaser wisely suggested.
The hull construction is different, it`s permanent. A simple error with a thru hull can bring on a wet rotting core. And what if it developed osmosis? Against this, there doesn`t seem to be history of Beneteau hull failures, and as the video shows they are built to a program, not cobbled together in unpredictable conditions.
I`ve raised the 2 main issues, there are others which would not deter me. We both like it as a boat,but I`m having trouble pulling the trigger. In real estate(my short post retirement fun "career") a colleague would sometimes ask "Is there a price at which you would buy it"? That`s the question,sometimes the answer is "no",I`m very close to that. I may have a chat with the broker and see if he volunteers another price. He`s entitled to the courtesy of a " thank you but no thanks".
The boat has been for sale a while, hull may be why, though trawlers don`t sell so well in Sydney. Price is not far off a Riv 40 of similar age, they`re not giving it away. I`ve a feeling they`ve lost buyers before due to the hull construction,and they may well lose another.
 
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Ka_sea_ta said:
.. As far as the ST goes the salon and galley layout on the ones we on weren't my cup of tea. But I've haven't heard or read anything about water intrusion issues in the hull either.
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Beneteau should have followed the Clipper 40/Mariner 40 layout. The worst design aspect imo is 2 tiny adjacent bathrooms,one large one would be better. But in general, the design suited us. We figured to use one bathroom as head, the other as shower. Our IG separates the two completely.
 
If you're buying or building a smaller "glass" in the water all the time yacht said:
I think you would be surprised at the number of in water boats that are cored below the waterline. Among them Viking, Cabo, Bayliner, Carver and Lindells just to name a few. The real problem with coring is two fold improper installation of thru hulls and failed bedding of penetrations above the waterline. Even our Defever suffered from delamination around the Windlass where the sealing to the hull failed. That is the reason to always have a boat surveyed
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Benneteau isn’t following the 1970s era techniques. In fact one of the advantages of a large producer like this is they can optimize and use modern techniques and technology.
My understanding of their process:
- they are using vacuum bagged infusion
- the balsa is perforated to support resin take up.
- the balsa is pre-infused with a resin designed for this process
- the balsa appears to be saturated before its ever placed in the mold or under the vacuum bag
- I can’t imagine they don’t leave extra space around thru hull locations and probably use carbon fiber or Kevlar reinforcement when needed.

Boat tech does advance more slowly than some other areas but composite technology has been continuously evolving for over a century.

All general rules of thumb based on construction techniques should be specific to a time period when the problem happened, and we shouldn’t assume that manufacturers never update their technology.

Horror stories about 20+ year old boats seem inappropriate.
 
Reformed-sailor said:
- the balsa is perforated to support resin take up.

- the balsa is pre-infused with a resin designed for this process

- the balsa appears to be saturated before its ever placed in the mold or under the vacuum bag

- I can’t imagine they don’t leave extra space around thru hull locations and probably use carbon fiber or Kevlar reinforcement when needed.
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1. The balsa is not perforated, it is kerfed.The purpose of the kerfs is that the sheets of balsa on scrim are flexible for forming in the mold. Even vacuum processes do not ensure all kerfs are filled. If all kerfs were filled as many mfg's have claimed, there would be no migration of moisture to adjacent kerfed blocks and we all know that happens frequently.

2.The balsa cannot be saturated. This would require evacuating the lignin which is about 40% of the balsa by weight and also filling all the cells which is not possible with any of the several current vacuum systems. Even if possible this would defeat the benefits of balsa altogether i.e. light weight and strength. Resin barely penetrates the end grain of balsa but does bond exceptionally well even better than it bonds to foam cores.

I've never seen a Beneteau with carbon fibre or Kevlar (which is added for abrasion resistence not strength as it is tough but too flexible).

I'm not a fan of balsa below the waterline but still like to keep the facts straight.
 
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The video mentions they use other materials, besides fiberglass and balsa for strengthening. It’s not a kerf they showed, and elsewhere it has been claimed they are perforated.

Given that plastic foam is relatively inexpensive there must be some reason for choosing balsa instead. I don’t believe it is a cost saving measure these days.
 
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Reformed-sailor said:
The video mentions they use other materials, besides fiberglass and balsa for strengthening. It’s not a kerf they showed, and elsewhere it has been claimed they are perforated.

Given that plastic foam is relatively inexpensive there must be some reason for choosing balsa instead. I don’t believe it is a cost saving measure these days.
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They use balsa because resin bonds to it better than foam and it is stronger (when dry) than most available foam cores.

I just realized what you mean by perforated. There is a balsa core available with a one or two small holes punched through each square of kerfed balsa (a marginal bonding improvement).
 
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Intentional Oversimplification

Balsa cored boats are wood boats with some fiberglass on the outside. Been trying to change that view and can't. The thread about wood rot porn is not going away. You peel the fiberglass off one to do structural work and take the paint off the other.

Someone posted a link to a yacht survey website. Those cored boat articles on that site are eye-openers too.
 
Boat said:
Balsa cored boats are wood boats with some fiberglass on the outside. Been trying to change that view and can't. The thread about wood rot porn is not going away. You peel the fiberglass off one to do structural work and take the paint off the other.

Someone posted a link to a yacht survey website. Those cored boat articles on that site are eye-openers too.
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I couldn't disagree more with that viewpoint. Wood boats are structurally sound with or without paint or outside coatings. Balsa cored fiberglass is an engineered composite structure where each component interacts with the other to provide its structural strength. A balsa cored hull would fall apart without the fiberglass on the sides.


I don't know any work that requires you to "peel off the fiberglass to do structural work" on balsa cored hulls. You do have to recreate the three layers if the structure is compromised, usually by tapering back the fiberglass layers, laying in new core and glassing back the outside layers.


David
 

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In my opinion it's not coring or not, it's the quality of coring. There are some of the finest boats on the market that have cored for decades with Airex and never had an issue. There are balsa cored boats with no problems. Coring or not would not by itself make my decision for me. I'd look at the builder's reputation and experience and all the other factors of the boat. All the issues I've heard of regarding Swift Trawlers and none of them have been regarding the coring. I'd definitely have a moisture check in survey and I'd be concerned about other things you've mentioned.

Now, as to you and this boat. Sounds to me like you posted thinking we'd discourage you from a purchase you're not comfortable with. I have one piece of advice, "When in doubt, don't." I can't discourage you because the coring doesn't bother me, but seems like enough other things have you concerned.

As to Pascoe, I dismiss him on this like I do on 90% of his reviews and comments. He had a mindset from decades before he was even born and no objectivity as far as boats that didn't fit it or new ideas of anything else.
 
Ka_sea_ta said:
I think you would be surprised at the number of in water boats that are cored below the waterline. Among them Viking, Cabo, Bayliner, Carver and Lindells just to name a few. The real problem with coring is two fold improper installation of thru hulls and failed bedding of penetrations above the waterline. Even our Defever suffered from delamination around the Windlass where the sealing to the hull failed. That is the reason to always have a boat surveyed
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You paint with too broad a brush, just like Pascoe.

Not all boats by those or any makers were built the same. many , many changes happened over the years including complete takeover of the company. My Carver for example had a solid bottom.
 
I have owned boats with Balsa core although not below the water line.
I have owned boats with closed cell foam core as well.

The 3 boats with balsa coring (not below water line) all had some spots which eventually were compromised with water. The balsa in those area turns to something the consistency of "oatmeal' ….it has no strength,, the affected area expands quickly , it is harder tp repair correctly.
With the foam core problems I have seen (which are rare) there is a much smaller affected area, strength is not as easily compromised and they are more easily repaired correctly.
My experience only - I cannot say what I have not seen.
 
bayview said:
You paint with too broad a brush, just like Pascoe.

Not all boats by those or any makers were built the same. many , many changes happened over the years including complete takeover of the company. My Carver for example had a solid bottom.
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Sorry I didn't mean to get anyone's knickers in a knot. What I should have said is these builders have built certain models of boats using coring as a construction method.... My apologies to those that may have found fault with my generalized statement. And please don't compare me to Pascoe, he was much more knowledgeable about boats then I ever will be:)
 
I would assume that Beneteau would know how to properly lay up a cored hull. My concern would be who has done what with the hull since new and has there been any damage to the hull inside or out and how was it repaired? If there is one place for water to get in it may run a long way and then you have balsa mush.
 
Comodave said:
I would assume that Beneteau would know how to properly lay up a cored hull. My concern would be who has done what with the hull since new and has there been any damage to the hull inside or out and how was it repaired? If there is one place for water to get in it may run a long way and then you have balsa mush.
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Well, they sure don't know how to design and install an exhaust system, so I would be suspicious. But I think that you can see if there is solid fiberglass around the thru hull penetrations- it is thinner than the surrounding cored hull. If I could check all thru hull penetrations and see solid glass I would be confident it was built right.


But you are also correct that any non factory installations would be suspect. Those wouldn't be easy to check as any core dug out around penetrations and filled with thickened epoxy would be impossible to see without removing the thru hull.


A moisture meter reading around those new penetrations might give you a good clue though.



David
 
Boat said:
Balsa cored boats are wood boats with some fiberglass on the outside. Been trying to change that view and can't. The thread about wood rot porn is not going away. You peel the fiberglass off one to do structural work and take the paint off the other.

Someone posted a link to a yacht survey website. Those cored boat articles on that site are eye-openers too.
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I said this is an intentional oversimplification.

For the same reasons people fear wood boats they should also fear cored boats.

The initial designs and quality control are important and equally important are any modifications and maintenance.

I'll venture a step further out on this limb. Foam cored boats should feared for voids created by economy of materials. If there is room for water to take up space in a hull, it will. Problems ensue. Stuff they use to fill the voids is sometimes just stuffing. All it does is take up space, until it doesn't.

Foam tears. Strap me down to piece of foam and I'm not feeling very secure.

All this being said I have trusted boats and aircraft with foam cores, wood, metal. It's all good with reservations. I think a generation of Corvettes had a foam core floor. (it's wood, I checked)

Anything humans build, nature can dismantle. "History shows again and again how nature points out the folly of man."
 
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Well, in looking at the question in general, what are the benefits of a cored hull? The main benefit as I see it is weight savings. I have a “trawler”. I really don’t care that much about weight. But I do care about whether my hull comes apart. So put me in the camp of rather having a solid core, unless a boat I just really really have to have comes along, then I might roll the dice...
 
I had a sailboat i bought new that had balsa coring below the water line. It was made by a reputable builder known for their glass building technology, but not necessarily their cored glass technology.

For 25 years I had the boat hauled and transported by truck 50 miles for winter storage on stands and blocks in my yard. Most of the weight was on the keel.

It had solid glass for all factory thru hulls, but the dealer installed electronics through the cored part of the hull.

When i sold it the only moisture noted by the surveyor was where the dealer put the thru hull.

That said, i always wondered/worried about damage from transport and storage, although never noticed any.

And it was not a boat i would have ever wanted to leave in year round.

I followed that with a sailboat with foam coring above the water line. It felt more robust and rock solid.

Give me thick solid glass and i think i sleep better.
 
CptnPete said:
Give me thick solid glass and i think i sleep better.
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I would too.

I’m glad you mentioned sleep quality, because that’s what this is really all about. It’s psychological. There are so many variables, not just in production practices but in the experience the boat has had.

The fact water damage can be hidden in fiberglass emphasizes the psychological factor here.

The only solution is to switch to all aluminum hulls. This way we can watch the zincs and know for sure. Plus it’s lighter and stronger.
 
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