Leak connection transom - Hull

[florealdrie]

I have an oceanis 390. I have a leak in the joint hull - transom.
The joint between them boat is not reinforced and consists just out of polyester smeared on both of them without the use of fibreglass matting. Now this joint is cracked and water is coming in depending on wave and weather conditions. Also when there is a lot of rain some water leaks in through this joint.

I assume this joint is not meant to take a lot of stress since the materials used to jo join both are not very strong. I think the polyester joint is cracked due to stresses and movement in the hul and deck? I redid the jo exactly the same way (with polyester no matting). +But after a short time the joint is coming lose again. Has anybody an idea how to fix this or what the reason of this is?

 

[savageseadog]

[ QUOTE ]
I assume this joint is not meant to take a lot of stress since the materials used to jo join both are not very strong. I

[/ QUOTE ]No it's not supposed to take a lot of stress it's the bit that holds the boat together

 

[florealdrie]

I don't think that's true, the deck and transom are one part and are joint by the toe rail. The force from the backstays is taken by polyester matting which goes directly to the hull.

The transom is not rivetted to the hull like the deck. Just the polyester joins it.

 

[Lakesailor]

Best if you can get some pictures posted.

 

[florealdrie]

i have no pic from the inside but i have a picture from the transom of a similar boat to sho you what i mean. but how do i add a picture?

 

[Guest]

It might not be polyester. The last boat I saw being stuck together used an epoxy based white material that was premixed with all the correct microfibres and thixotropic agents already added. Did the material fracture or did the joint between the hull and the material come apart?

 

[florealdrie]

It was the joint between the transom and the material which parted. The joint between hull and material was ok. I cut evrything away with a hammer and a chissel which was very easy. Then i redid the job with a micture polyester and fibres. (but no matting). But this parted also.

 

[VicS]

[ QUOTE ]
how do i add a picture?

[/ QUOTE ]

Look at these two

HERE

AND HERE

The first is the better of the two IMHO and very comprehensive but the second is simpler to follow (but I don't think it covers resizing the image or any advice on the file type to use)

You will find it quite easy once you have worked it out.

 

[Blueboatman]

I think you have almost answered your own question-The joint is (for whatever reason) now failing. Maybe excessive backstay tension,bumped into a quayside,whatever...

I assume you are repairing from the inside of the boat.So...

My advice is to get the chisel and hammer out again-and a Dremel type tool is useful too-and chip,sand and grind back an area at least 50mm either side of the failed joint. Finally wipe it with acetone to help give a bit of a chemical as well as a mechanical ''Key''.

Now redo the joint using epoxy,not polyester and at least 3 strips of woven matting 95mm wide(much stronger than chopped strand matting).
If access is difficult-and it probably is-you can lay all 3 strips of cloth on a smooth surface and epoxy them together,'wet on wet'and whilst still wet,press them along the (also epoxy wetted) keyed surface of the joint..Use a stiff paintbrush to make sure the two are pushed together,and/or a small wallpaper roller tool (from decorators shop or B n' Q). You should now have a sound bond between transom and hull.
This advice is given without benefit of piccies of course. I am sure a real boatbuilder can 'refine'it too!
Good luck

 

[oldsaltoz]

G'day Floreal, and welcome to the YBW forums.

When repairing normal GRP with standard resins the bonding is only mechanical, so you need a very clean area with a good key. However if you use an epoxy resin the bonding is both mechanical and chemical so will be stronger.

Avagoodweekend......

 

[yogi]

I assume this is one of those modern so called sugar scoop transoms. In that case any repairs on the outside would stand proud of the gell coat and would be difficult to finish to a good standard.
The proper way would be to repair from the inside remembering if you use epoxy not to use mat. the outside could be cleaned out and filled with 3M 5200 or the like.
By the way what's woven matt.

 

[oldsaltoz]

G'day Yogi,
-----------------------------------
By the way what's woven matt.
-----------------------------------

Woven mat, or roving's is a fibreglass cloth woven at 90 degrees and can be used to top off a lay-up of fibreglass using standard or epoxy resins, it's used to give a smoother finish and ensure no raw end strands are exposed.

Chopped Strand mat (CSM) should never be used with an epoxy because the voids will hold too much rein and actually weaken the finished work. Almost all epoxy resins use a woven mat, referred to as a cloth, flat strands are woven together and stitched in some cases, all have very small voids. The weave can be a simple one or very complex, crows foot is a common and very strong but light lay-up cloth.

I hope this helps.

Avagoodweekend......

 

[oldsaltoz]

G'day Floreal,

As Tim (Blueboatman) has advised, it sounds like it should be glassed with an epoxy resin.

However you make it a bit stronger and easier if you first add a fillet of micro fibres and epoxy rein, I use the back of a plastic spoon to form the shape and scrape away the excess each side when still wet, let this start to cure and when firm add the woven epoxy cloth, it's important that you do not leave too much resin in the cloth so roll it out with a small thread roller available at any fibreglass outlet.

When cured, give it a light sanding and paint it protect it from UV, as it will deteriorate if left exposed to light.

Avagoodweekend......

 

[yogi]

It must be a different terminology used in Australia. Here when you refer to mat it is CSM while roving is thick very open bundles of glass in an open weave. Between these is Cloth which is fine bunbles of glass in a tighter weave. Here if you order mat you get CSM which is not compatable with epoxy resin because the binder is made of polyester and will not dissolve in epoxy resin