Matrix (Bilge Liner) Detachment and Repair

[byroncoughlin]

Hi everyone,

I've reached out to many friends and surveyors, (and have visited every website I could find on the subject), but no one seems very knowledgeable about the repair we need to make -our surveyor even insisted that we did not have a matrix/bilge liner.

We found two locations on our boat (on either side of the sump box -see photos) where the "bilge liner"/matrix is separated from the hull. We did have water freeze in our bilge over the winter, but I cannot be sure if it was already separated when we acquired the boat last fall or if the freezing water caused it. I have ground away the detatched part of the matrix on the starboard side of the sump box and have just started on the port side.

Questions: 

What was used to bond the matrix to the hull originally? and is west system epoxy and fiberglass (cloth and chopped strand mat) adequate for the repairs/patches to the matrix?

Do we want the hull and liner to be one solid piece when we rebuild the detatched sections -should we be worried about creating a hard spot

We plan to grind down through the matrix/liner in different locations around the bilge in order to check for other detatched areas, then refill with fiberglass glass and epoxy. Does anyone know of a better way to find detatched sections of the Matrix?

Photos:

1 - Looking into the starboard side of our sump box in our bilge - the initial crack we noticed is right where the bilge liner ends in the sump.

2 - I have removed the support for the table and have started grinding away at the matrix/liner exposing the separation between the matrix and hull

3 - I have continued grinding away at the separation until the separation is gone on the starboard side (hull and liner are bonded again in all directions) - I have also started grinding at the port side exposing the separation on this side

[Mohammad Bayegan]

I would contact Todd or Ward at Beneteau US to get their advise.

Marengo B 49

Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------

From: byroncoughlin <byronc...@gmail.com>

Date: 5/8/17 9:24 PM (GMT-06:00)

To: Beneteau Owners <benetea...@googlegroups.com>

Subject: {Beneteau Owners} Re: Matrix (Bilge Liner) Detachment and Repair

Sorry, the pictures didn't go through! Here they are:

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[Mohammad Bayegan]

I would call Todd or Ward at Beneteau US to get their advice. 

Marengo B49

[Btbogdan46]

First, I agree with Marratu to contact Beneteau in Marion, SC. Second, what year and Model is your Beneteau? Third, I went to the Ben factory and saw my  Oceanis 45 being built and believe the liner and hull  were epoxied together under heat and pressure. Your repair seems the way to go with me. Not sure how many layers of glass you would need and finally paint the finish with bilge paint.

[byroncoughlin]

Thank you Btbogdan and Marratu!

I sent an email to Todd yesterday - he has been most helpful to me in the past.

The boat is a 1985 First 42. We plan to layer and layer and layer fiberglass until it matches the surrounding matrix, then coat with bilge paint

Next question: I believe a recommended way to perform this repair would be to unstep the mast, drop the keel, and carefully support the boat on stands. If the repair was instead performed in the water (we are hoping the hull will maintain a natural shape in the water) can anyone see a downside?

Byron

[Johnny Ross]

Byron,

Just completed extensive repairs to our 1996 Oceanis 351 where the matrix to hull was separated due to a hard grounding in 3' seas.  Not good!  You are wise to want the repairs done correctly as a poor job can lead to delamination of the hull and losing the keel.  Todd and Ward at Beneteau have always been very responsive in helping me with other problems, but because of the liability potentials with this, were very tight mouth.  They would not even discuss the repairs with one of their dealers.

 

There is a tremendous amount of info on the internet about matrix to hull separation and it is critical to get it repaired correctly.  Attached is a Sailboatowners.com thread on repairs to a 351 in Canada and the final report on the sinking of the  Cheeki Rafiki by the UK Marine Accident Investigation Branch.  All four crew members were lost when the Cheeki Rafiki went down due to the keel falling off due to faulty repairs to the hull to matrix joint.

  

The repairs to our 351 were accomplished by cutting the bottoms out of all the matrixes and and re-attaching the stringers and laterals to the hull with six layers of polyester resin and woven mat.  The matrix was originally attached with polyester putty (per Todd at Beneteau) beads on the underside of the matrix bottoms.  What concerned me the most was that only about 30% of the matrix bottoms were ever attached to the hull prior to the grounding.  With the beads of putty varying from 1/8" to 1.0", it was easy to see where the new separation was and where the putty had never been in contact with the hull.  The good news is that our 351 is stronger now than when it left the factory 21 years ago and the noises down below that Beneteaus are known for, are gone.

It sounds like you are approaching your repairs correctly.  Rather than grinding the bottoms out of the matrixes, it was easier and less dust to cut the bottoms out with an oscillating multi-tool with a fiberglass cutting blade.  Even where the bottoms were attached, they popped out with a small pry bar.  

Good luck and will be glad to answer any questions. 

Johnny Ross

sai...@mchsi.com

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[byroncoughlin]

Hi Johnny,

Thanks so much for the response! I've been reflecting on what you've written.

Questions for you if you have a moment: 

Is there a reason you chose polyester resin instead of epoxy? We were leaning toward the epoxy route.

Was your bilge liner the same thickness throughout - I worry about using a cutting tool in case we cut too far through the bilge liner.

I'm very happy to hear your rebuild went well!

Byron

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[Johnny Ross]

Byron,

My initial thoughts were to use epoxy, but changed my mind after looking at the data and talking to a local shop that had some problems with epoxy.  Some of the fiberglass mat has a coating that epoxy will not bond to.  This is primarily with the non woven mat, but there has been some of the woven mat that also has the coating.  The bonding strength and cured strength with polyester is not that far off of epoxy and an extra layer of polyester and mat should make up any difference. The big advantage I saw with epoxy was the moisture penetration compared to polyester and I did not see that as a problem in this application.

The matrix thickness was very uniform and when you start cutting, it was easy to tell when you went through the matrix. The least space I saw between the matrix and hull was around 0.25" and as much as 0.75".  There were a couple of places where the saw blade touched the hull, but it was minor and easily covered with the resin and glass.  Bottom line, quality control on the matrix appeared to be much better and consistent than on the hull and when you try to mate a precise surface (the matrix) with a less precise (the hull) there will be variations.

  

The good new is that it can be corrected and when you finish, it will be stronger than before.  Have you heard anything from Beneteau?  Hope this helps.

Johnny 

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[DAVID Fletcher]

My understanding is the vinyl Ester resin is the most waterproof product.

Fletch

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[byroncoughlin]

Hi John,

Thank you for all of the info!

Would you happen to have any before and after or progress pictures?

Byron

[Johnny Ross]

Byron,

Attached are the pictures of the repairs before a new layer of gelcoat was applied.  I will try to find the before pictures, but am not sure where they are.

Johnny

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[byroncoughlin]

Johnny,

Wow!

That looks awesome. Thank you so much for the pictures and if you do find the before (or even afters too) we would be forever grateful. I bet it sure feels nice to have a completely reattached/stronger-than-ever matrix!

Three more questions if you're down:

Are your white floor/stringers/laterals hollow inside like ours are?

Did your boat have limber holes? If so, they are covered over with fiberglass in these pictures?

Did you re-cut new limber holes? -I think you'd have to, right? I don't like the idea of water ending up inside of the hollow floors/stringers/laterals, but maybe I just need to accept that there will be water and the limber holes act as drains..

Again, thank you so much for the info!

Byron

[Johnny Ross]

Byron,

The stringers and laterals of the matrix are hollow and route water to the bilge.  The holes have not been drilled in the photos I sent.  Waited till after the gelcoat was replaced to drill new holes.  On the 351, the "pans" drain into the stringers and laterals to the bilge.  That was the other reason we used six layers of resin and glass to make sure the bottom of the "pans" were higher than the hull under the stringer/laterals.

You are correct about the comfort factor knowing how strong 'Bout Time is now.  It did burst my opinion bubble of Beneteau, though.  

Johnny

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[BillM]

"Next question: I believe a recommended way to perform this repair would be to unstep the mast, drop the keel, and carefully support the boat on stands. If the repair was instead performed in the water (we are hoping the hull will maintain a natural shape in the water) can anyone see a downside? " IS ANYONE AWARE OF AN ANSWER TO THIS QUESTUION? I am exploring work on the after section of the keel stringers.

[William Arbaugh]

You might want to check out this youtube team: https://www.expeditionevans.com/

They're doing exactly the same thing on a newer beneteau 49. The last few episodes show how they did the fiberglass work.

On Mon, May 8, 2017 at 10:22 PM byroncoughlin <byronc...@gmail.com> wrote:

Sorry, the pictures didn't go through! Here they are:

--

[byroncoughlin]

We ended up doing ours out of the water.

We hauled out, unstepped  mast, dropped the keel, cut out the old liner and relayed all the fiberglass in the sections. We also ran the fiberglass up the sides of the top hat stringers.

This Instagram account has some good pictures of how another person did his (also out of the water)

https://instagram.com/svbreakaway

Removing the keel was crucial to our rebuild (so we could fiberglass below the keel backing plates and bolts). It was also nice to get the entire area completely dry before fiberglassing -which may be difficult if attempted in the water).

Good luck!

[Rick T]

I've enjoyed watching Expedition Evans on youtube, and look forward to their next episodes.  Makes me aim to always have plenty of water beneath my keel.  A 20-ton boat traveling at 6 knots at impact has a kinetic energy of over 86,000 Joules, equivalent to a 3,000 pound car (make that a fiberglass Corvette) impacting at little over 25 MPH.

[DAVID FLETCHER]

20 tons or 10 tons

Seems to me a 423 does not weigh in that heavy. 

Sent from my iPhone

On Dec 1, 2020, at 5:46 PM, Rick T <rnbth...@gmail.com> wrote:

I've enjoyed watching Expedition Evans on youtube, and look forward to their next episodes.  Makes me aim to always have plenty of water beneath my keel.  A 20-ton boat traveling at 6 knots at impact has a kinetic energy of over 86,000 Joules, equivalent to a 3,000 pound car (make that a fiberglass Corvette) impacting at little over 25 MPH.

To view this discussion on the web visit https://groups.google.com/d/msgid/beneteau-owners/24d6f56e-d4e2-4677-a68b-f4edae8342bbn%40googlegroups.com.

[Mark J Wilme]

Probably 10,000kg loaded  (22,000 lb)

To view this discussion on the web visit https://groups.google.com/d/msgid/beneteau-owners/6B78AD81-D465-4AA2-A040-A0988AE82703%40rogers.com.