Cored Hull Underwater

CptnPete 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.

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As I mentioned earlier, boat yards, particularly those in northern climes that store boats in heated winter storage buildings are acquiring hydraulic trailers so that they can quickly move boats to/from the haul out basin and then cram then into storage buildings as tightly as possible. Some of the trailers are keel lift with the side pads only providing stabilization. Some lift the entire weight of the boat via hydraulically actuated pads (with no keel support whatever). I would not go near a cored boat that had ever been on one of the latter, and I'd have serious reservations about a solid glass hull that had been on one. I refuse to allow our storage yard to put our boat on their (pad lift) trailer, which forces them to use the travel lift all the way to the building....which they dislike immensely. I am convinced there are a growing number of cored hull boats with squashed coring and stress cracked outer skins lurking in the inventory. And there is no cost effective way to make the determination, as it's hidden under bottom paint. Ultrasound or some other sophisticated non-destructive testing technology is probably the only way to make a finding. Certainly not a tap hammer..... No cored hulls for me. Do you know where your boat has been?

BandB said:

..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. .

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Australia has a lack of twin engine trawler type boats. This is one,it has good features and accommodations, but there is that hull.
I`m not looking to be dissuaded,I`m not even persuaded yet,and I greatly appreciate the thought which has gone into the posts and PMs. If it had a solid f/g hull we would not be having the discussion and I`d be happier.
The boat has signs generally of generally good maintenance,and good equipment maintenance. For example, 5 Lifeline AGMs, and 2 massive Century AGMs. The engine linkages are all nicely greased at moving points. Little things, but indications.I`m not citing the positives,so it looks like I`m just being critical. Which I suppose I am, in terms of this discussion.

Comodave said:

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...

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I think that's it. No reason to have coring in a stout displacement-ish hull. But weight savings matters in a boat like the ST. Coring allows the construction of a stiff light boat at moderate cost, and that leads to the performance and/or economy that helps make the ST such an attractive package.

I've owned a few sailboats with coring, and for me it was always something to be aware of and be careful with, but a reasonable trade-off for the performance gains. But it was also easier to buy my 40 year old Mainship knowing the hull is not cored.

djmarchand said:

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

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How reliable are these?

I have also heard the operators can provide false positives if they don't have the proper experience/training.

One comment above was that the only advantage to coring was speed. Properly done, coring can also add strength especially by allowing a careful planning for flexing versus no flexing at all. Using a combination of materials provides a lot of potential. Now, note I said properly done.

Then there's the question of Balsa vs. Foam and I have a fan of foam coring over Balsa. I just don't like wood.

Fletcher500 said:

How reliable are these?

I have also heard the operators can provide false positives if they don't have the proper experience/training.

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Some reading here...
Moisture Meter Mythology and Flir thermal imager

smitty477 said:

Some reading here...
Moisture Meter Mythology and Flir thermal imager

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Good article. One persons opinion but he has the experience and has done his due diligence. Take aways regarding these meters: Use with caution, and there are ALOT of variables than can impact the readings. The moisture debate continues.

BandB said:

.... Properly done, coring can also add strength especially by allowing a careful planning for flexing versus no flexing at all. Using a combination of materials provides a lot of potential..
Then there's the question of Balsa vs. Foam and I have a fan of foam coring over Balsa. I just don't like wood.

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Boatpoker says above that resin adheres better to wood than to foam. I agree,non absorbent foam is good, a foam deck sandwich saved $$ in my deck redo.
It`s puzzling that although we have ST42/44 owners on TF,no one commented on this issue. It would be useful to know how the thru hull openings were protected during construction to prevent water ingress reaching the core.

Said I trust cored boats and I do. Don't want to leave this without reinforcing that idea.

Lifeboats designed to drop from platforms over the ocean while loaded with dozens of people probably best demonstrate this.

https://www.dailymail.co.uk/news/ar...tower-brace-nose-dives-water-safety-test.html

https://www.dailymail.co.uk/news/ar...signed-oil-rigs-launch-sea-great-heights.html

I`ve decided not to make an offer for the subject boat. The only temptation would be a low offer from the broker when/if he calls back,though that would raise concerns of itself.
Thank you to members who so posted generously on the issue, along with my own research you greatly added to my knowledge.
It`s surprising such a major manufacturer builds hulls in this configuration in 2019. These are not cheap boats. New,the cost was $800K AUD. Balsa cored above the waterline,solid below, maybe. Foam cored above and below,maybe. But balsa above and below is I think,a step too far.

The laminate schedule is key many older hull layups with cored BWL were robust enough to not need coring for support. So coring imo moot from functional perspective. Cored topsides with less robust schedule if wet balsa delam likely may oil can so to speak ....have seem few times water works in from deck level thru unbedded stanchions etc into core. If layup topsides frp is thin it could be big problem.

BruceK said:

I`ve decided not to make an offer for the subject boat. ........But balsa above and below is I think,a step too far.

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You won't regret this decision, Bruce.

Codger2 said:

You won't regret this decision, Bruce.

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Thanks, I felt a bit sad after making it, but I knew I had to walk due to the risks. To be fair, B makes lots of sailboats and I found no reports of wet hulls online. Strangely there was no comment either way from TF B owners.
I certainly took into account your frank observations, thanks for the input.

It is odd, the lack of B owners flagging it as an issue given the discussion here. Maybe its like steel tanks, it takes a few decades for the problem to manifest, at which point it becomes A Big Deal. Knowing what I do now, I would likely have the same response as you.

So then there was just one. How was the inspection of it?

Insequent said:

It is odd, the lack of B owners flagging it as an issue given the discussion here...
So then there was just one. How was the inspection of it?

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We spent nearly 4 hours crawling all over it, I have pages of notes. Generally good, well thought out, good creature comforts. Two bathrooms when one would be better, some wasted space in the saloon.Plumbing festoon under floor.
There are others for sale, but same hull except post 2005 they are injection moulded. Back to searching. Trawler,40ft,twins.Would that Riv still built trawlers.

I've written about this before. I don't think my KK42 could have been built any better for doing what I am doing.
here is the blog I wrote a couple of years ago, Why I Am Not Afraid:

https://dauntlessatsea.com/2016/05/21/why-i-am-not-afraid/

IMO the original construction would probably not fail. It is things that happen or are done to the boat later that cause problems

bayview said:

IMO the original construction would probably not fail. It is things that happen or are done to the boat later that cause problems

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Yup - things like travel lifts, blocking for work or storage, work performed on the hull , underwater strikes and groundings.

I`d have thought the weak point was the thru hull openings. I never discovered how they were resolved to eliminate the risk of core wetting. Best practice would be glassing around predetermined factory openings, but for all I know it could have relied on Sikaflex or other sealant applied during installs.
That subject boat had obvious leaks at the well above waterline portlights in the bow cabin,with corrosion on the inner half of the frame,did not suggest good sealing of hull openings. For all I know the core could have been wet around those portlights, it would have been a survey focus had I proceeded further.

The David Pascoe web page reported on two cored hull 63 foot Bertrams that suffered catastrophic hull failure. It's worth a read.

djmarchand said:

Well, they sure don't know how to design and install an exhaust system, so I would be suspicious.
David

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These are the same people that install brass NPS throughuls with brass NPT ball valves. Suspicion is warranted.

Boat said:

Said I trust cored boats and I do. Don't want to leave this without reinforcing that idea.

Lifeboats designed to drop from platforms over the ocean while loaded with dozens of people probably best demonstrate this.

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I've launched in one of these as part of my Marine Emergecy Duties training,
Not a pleasant experience. Don't forget they only have to survive one voyage.

Both of these were brand new boats on their delivery trip. The bow of one fell apart and she went to the bottom with massive core separation. The other, well you can see from the pictures was very close to the same fate. Both boats suffered this catastrophic damage in calm (2' if I remember) seas.

The confused story at the end of the article as to the name and model year of the surviving boat suggests an attempt to cover it's history.

A little more on the Bertram 63 that sank. The photos and a video provided by the plaintiff can be viewed on yachtforums.com

A few photo teasers .....

djmarchand said:

...Beneteau is a good boat builder, but I would be careful. Witness the bad injection elbow installation in the boat you are considering that you sent me pics of in a PM...
David

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David, one other peculiarity for me was the raw water supply. The seacock was at the aft end of the ER,the hose ran the length of the ER fwd to a strainer mounted on the fuel tank,and back 3/4 of the way, to the engine.To me,the longer the hose, the more connections, the greater the risk of something going wrong. Why would they do that?

ancora said:

The David Pascoe web page reported on two cored hull 63 foot Bertrams that suffered catastrophic hull failure. It's worth a read.

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Pretty easy to find stories of cored and uncored boats that sank. And steel, aluminum, wood, etc. Bad use of a material doesn't make the material bad. In the sailing world, high performance boats are almost exclusively built with cored construction, many of them are subjected to worse conditions than any Bertram will ever see.

DDW said:

Pretty easy to find stories of cored and uncored boats that sank....

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Despite the many Beneteaus built with balsa cored hulls below the waterline, I could not find reports of waterlogged hulls, let alone boats that sank due to coring. Do you have references or links to the cored hull sinkings?

BruceK said:

Despite the many Beneteaus built with balsa cored hulls below the waterline, I could not find reports of waterlogged hulls, let alone boats that sank due to coring. Do you have references or links to the cored hull sinkings?

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See post #84

DDW said:

high performance boats are almost exclusively built with cored construction, many of them are subjected to worse conditions than any Bertram will ever see.

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This is true however, very high performance boats such as Spirit of Canada with Nomex honeycomb core (I worked on this one) are painstakingly built to extreme standards. Not so production boats built by low skill itinerant labourers overseen by one or two guys who know what they are doing with an order to get that thing out of the mold real quick.

Photo is of Spirit of Canada an "Open 60" during self righting tests in Toronto Harbour.

boatpoker said:

See post #84

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That`s one, it`s not a Beneteau. DDW says they are easily found and implicitly, quite common.
I rejected the boat under consideration because of the hull construction,but remain puzzled at the lack of reports of Beneteaus with hull core saturation,whether from TFers or otherwise. DDW says they are easily found,and implicitly common. So,references or links please.
Despite my decision based on caution, I don`t want to see a boat brand criticized for failings unless they really occurred.