Repairing hull damage on a Hanse.

[vpbarkley]

In both "Sailing Aurora" and "Expedition Evans" the owners choose a very labor intensive solution to reattach the grid to the hull using fiberglass.

It is true that a fiberglass connection is stronger than the adhesive used during original assembly. So it follows that the boat as modified is stronger than it was originally.

But is this the correct conclusion? One also assumes that the manufacturers chose an inferior method of construction to reduce cost.

In each instance the boat endured a hard grounding. In each case the keel remained attached and the boat did not sink.

Instead the adhesive failed. When the adhesive failed it increased the flexibility of the structure to absorb the grounding. The adhesive acted as a fuse.

If the hull and grid were strongly attached there is a possibility that the failure could have been more severe. The effect would be increased rigidity, not necessarily positive.

If you believe that boats that are assembled with adhesive are demonstrably durable in normal use, then a repair using original materials is completely reasonable.

Removing the old adhesive and replacing it with new would have been enormously less involved. And, the boat would have been restored to original.

Happy Valentine's Day and smooth sailing.

[Greg K]

10 mil hull glass thickness at the bottom. Seriously?

Can anyone still claim with a straight face that such modern production hulls are stronger, more seaworthy, better built etc..etc.. than classic plastic from 60's 70's and 80's?

[C-Wolf]

Hanse...thickness of the hull where keel bolts are located is 10mm or 3/8”....bonded grid to a paper thin hull...well folks that’s telling you all...

[boatpoker]

Take a look at the comments on the "bottom" of this Hanse I surveyed.
Two years old and a never grounded dock queen.

[guyrj33]

Originally Posted by Emmalina

Mmm epoxy doesn,t bond to polyester ...

You couldn’t be more wrong!

[motion30]

[QUOTE=Emmalina;3342167]Mmm epoxy doe would not have beensn,t bond to polyester

I would agree the polyester certainly would have not been my choice. Epoxy has a much much better secondary bond strength. Perhaps a cost cutting measure but a poor place to try and save money

[Cheechako]

Bonded liners have always worried me a bit. Yet, I have tested some of the modern CA? bonding adhesives and I'll tell you, it was pretty surprising how strong they were.
We were building aluminum boats and a salesman was trying to get us to stop welding some parts of the boats for less labor (and so he could sell bonding agents!). So we installed a ~2 x 2 angle on a big aluminum plate and let it cure. We then had one of our large guys try to break it off with a big sledge hammer. It took maybe 10 minutes of hard labor to finally get it off after breaking one end a bit loose. Impressive, especially since flat, fairly smooth, aluminum is not a surface which as good "teeth" to bond too.

How well a liner fits may be the biggest issue. Molding all that and trying to get it to fit intimately inside the hull must be a challenge for sure. Not only do things vary, but there's shrinkage also.

I've also had experience with a 42 ft boat hitting a rock hard. There was a lot of damage to interior cabinetry coming loose from the hull as well as the engine bed coming loose. Some of it was fiberglass tabbing that failed. Some was liner. Either way, the modern glue or the tabbed fiberglass.... both are brittle.

[boatpoker]

a big issue with bonded liners for me is that the liner is fit blind.
One has no idea if it actually bonded or not.
Liner Bonding Failure

[NevilleCat]

I assumed that insurance is paying for the repairs, and that the repairers have agreed to give him access.
I don't think it's logical to assume that a hand built boat would have fared any better in the same grounding.
That sure is a messy job though.

[RSB333]

I'm very interested as I'll be doing a similar repair (DIY) later this spring. Not as extensive, but I now want to look for additional cracks or damage. Fortunately, our boat is a 1984 Pearson, and damage looked minor - ok for a DIY repair.

[Snore]

Originally Posted by boatpoker

Take a look at the comments on the "bottom" of this Hanse I surveyed.

Two years old and a never grounded dock queen.

I have read a fair number of surveys for the boats I have delivered.

THAT shows a level of detail missing in many surveys! Well done sir.

[Eder]

I rammed a rock at 6.5 knots...bow rode right up on it and scraped more as I waited for tide to let me off.. Cost me $580 from Blackline Marine to fix the damage...didn't tell the insurance company. (not a Hanse)

[David B]

Well for what it's worth, I found the video interesting. Sure there are some things he doesn't understand, but we have eyes to see for ourselves thanks to his efforts to document the repair process.

And yes, it would be nice to have a modern production boat built with extra lay-up, and better bonding of bulkheads and grid, but are we prepared or able to pay for it? If so, then there are a number of options out there.

[jimbunyard]

Please.

It's hard to believe we're all watching the same video.

Which is a train wreck of a cluster fxxx of a fubar attempt at the construction of a boat.

As for the video being informative --- mostly not, unless one wants to know what years of watching TV produces; (the emulation of) shallow, opinion-based, low-information-content visual fluff featuring a narcissitic narrator who obviously thinks 'we're' more interested in his pretty face than the subject he's supposedly educating us about.

Sadly, for a large percentage of people, he's probably right.


But to the point.

From what little can be gleaned from the video despite it's 'production values', it is quite obvious that Hanse is both liable and culpable for the failure.

Starting at 2:53 and again at 3:09, there are a couple brief shots showing hardened methyl acrylate bonding agent at least 1/2" thick between the grid structure and the hull, which means that the grid was neither fitted correctly to the hull before installation nor adequately 'clamped' to the hull after it was installed.

The adhesion of MA 'glues' is ferocious, but, as noted in the video, it is brittle, a characteristic that is magnified when used in 'thick' applications.

As related in Cheechako's post above, the grip of MA adhesives on properly bonded parts is tenacious. I wonder if the parts in his example were cleaned and then clamped or just 'stuck together', and also about the thickness of the 'glue line' in that example. Could be illustrative.

Anyway, regarding Hanse's liability, it lies with either quality control (most likely) or design. And if bonding an entire critical structural member with a layer of MA varying between 1/2" to 3/4" thick is a design parameter, to use a homely homily, I'll eat my hat.

For a properly resilient structure in that application, whatever the design actually specifies, the grid and the hull should be fitted together so that the minimum adhesive thickness, set by a structural analysis, is maintained between the grid and hull, thus allowing the stresses to be transfered thoughout the structure instead of being concentrated in the comparatively rigid failure points introduced by the variable thick layers of MA adhesive.

Given the construction shown in the video of that particular (new) vessel, I'd guess that with enough normal heavy usage that sooner or later there would have been delamination issues even without a 'heavy' grounding.

At 13:40 a keel bolt hole is (kinda) shown that verifys that the hull thickness there seems to be around half an inch. This is a 41+', what-looks-like-semi-planing boat with a probably 4-5 ton (it's not specified) cast iron keel with the keel/hull interface being of a low transverse cross section dimension bolted directly to that 1/2" skin. With such a thin skin, the integrity of the hull is reliant entirely on all of the elements of the system comprising the hull working together as designed.

Failure to ensure that an element as important to that integrity, as the grid/skin bonding absolutely is, was successfully executed is negligence (at minimum) of the highest degree.


But hey, caveat emptor --- Maybe 'Darwinian (actually Spencerian, Darwin doesn't appear to be much afflicted with the philosphical arrogance disease) attrition' isn't such a bad thing. Ha ha ha.....

[Joli]

Friends of ours took a hard grounding on their production boat. They broke the liner free from the hull. When lifted out the keel was swinging loosely although no damage was apparent from the outside. The removed all interior furniture and glassed the liner to the hull. They said the plexus wasn't bonded to the hull and would pop off if pried lightly with a screwdriver. The boat is now repaired and sailing but the builder and insurance company wanted to scrap it. I don't know how you check the integrity of a liner/hull bond without taking the boat apart.