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Old 04-06-2020, 09:12   #1
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Question Leaking transom / core repair?

Hey,

Pretty much DIY all jobs on the boat which I've had for about a year.

The boat takes on a bit of sea water when on a port tack and it's taken me a little while to find the source as wasn't coming from anywhere obvious.

I've now realised this was coming from the transom area, there is a seal that goes around the lip of the transom to deck level. There is also some sealant (I believe as it's quite soft in places) underneath which is partly broken and exposing the core (balsa?) which is a bit rotten in a few places.

I've attached a few pictures and looking for advice on how best to repair it while keeping costs down. Can I simply attempt to remove the bad wood and fill it with epoxy or something and then replace the seal?
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Old 05-06-2020, 03:36   #2
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Re: Leaking transom / core repair?

Sorry but I can't help you with balsa core problems (mine is Airex and Divinycell) But you are no Robinson Crusoe as other have similar problems too with balsa.

Have you had a look at the video clips?






https://www.google.com/search?source...sclient=psy-ab
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Old 05-06-2020, 03:50   #3
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Re: Leaking transom / core repair?

There is no balsa in these pictures. The grain is running the wrong way for that to be balsa.

What junk it is, I can’t begin to imagine.

Are you sure it’s wood at all and not just the end of the fiberglass? Looks kind of like dry fiberglass and the grain is in the correct orientation to be glass.
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Old 05-06-2020, 03:54   #4
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Re: Leaking transom / core repair?

Looks like it may also be some kind of wading they stuffed between the hull skin and the transom skin. Then sealed over. It’s fibrous. But fibers running the wrong way to be balsa. Maybe it’s bent plywood or laminated timber?

Crazy to use this at/below waterline. Really low quality.
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Old 05-06-2020, 04:00   #5
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Re: Leaking transom / core repair?

To fix: take a router and route out all that wood down a centimeter or so. Fill the resulting gap with thickened epoxy. Better than new.
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Old 05-06-2020, 05:06   #6
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Re: Leaking transom / core repair?

Thanks for the replies.

No idea what it is, definitely feels like some form of wood. A google on the boat (Beneteau 2004 473) shows they used a balsa core but quite surprised to see it here.

I'll route out as you suggest and fill
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Old 05-06-2020, 05:22   #7
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Re: Leaking transom / core repair?

Quote:
Originally Posted by Chotu View Post
To fix: take a router and route out all that wood down a centimeter or so. Fill the resulting gap with thickened epoxy. Better than new.
Agree for a quick fix, but you may need to go deeper to see remove rotted core/inspect the amount of damage and let it to dry out a bit. If you saw water elsewhere coming out of the inside skin at a different place (further forward), then you most likely have a decent amount of sea water in there. While sealing it in w/thickened epoxy will be a cheap/quick fix, leaving a soaked core will eventually destroy it if it's wood of any type (balsa, ply, etc.).
It may take more time, but drying out the core may save you a bigger headache down the road. Would inspect the hull w/a mallet and moisture meter to determine the extent of the water intrusion before sealing the transom up w/epoxy.
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Old 05-06-2020, 06:07   #8
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Re: Leaking transom / core repair?

Does it look something like this?
It might be worth a couple more 'googles' or a Bene owners' group query before routing and replacing. If you are removing wood that used to be the primary joint transom to hull then it might warrant something other than just filling in.
Actually I am not that pre-thinking of a person. I would have stuck a screwdriver through the bad spot and see if I could see it on the inside the boat. Then I start 'googling'...
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Old 05-06-2020, 06:10   #9
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Re: Leaking transom / core repair?

Quote:
Originally Posted by Bill O View Post
Agree for a quick fix, but you may need to go deeper to see remove rotted core/inspect the amount of damage and let it to dry out a bit. If you saw water elsewhere coming out of the inside skin at a different place (further forward), then you most likely have a decent amount of sea water in there. While sealing it in w/thickened epoxy will be a cheap/quick fix, leaving a soaked core will eventually destroy it if it's wood of any type (balsa, ply, etc.).
It may take more time, but drying out the core may save you a bigger headache down the road. Would inspect the hull w/a mallet and moisture meter to determine the extent of the water intrusion before sealing the transom up w/epoxy.
Thanks for the reply, the boat has been out of the water the last 7 months. As water found a way to the inside of the boat beneath the swim platform, I'll run a dehumidifier on the inside for a while and take out as much of the moisture as possible.
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Old 05-06-2020, 06:32   #10
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Re: Leaking transom / core repair?

Quote:
Originally Posted by retep007 View Post
Thanks for the reply, the boat has been out of the water the last 7 months. As water found a way to the inside of the boat beneath the swim platform, I'll run a dehumidifier on the inside for a while and take out as much of the moisture as possible.

Not sure if the dehumidifier is going to do it. Would remove any rotted core out of the the stern then keep the stern covered to keep rain, out. Again would check w/ a moisture meter (read previously linked article from Boat Poker) to check the extent of the water intrusion. If not too bad, could apply some heat to the underside of the hull (w/the end open) to help drive out the moisture. If more water than you thought, could drill some small drain holes in the outer skin under the transom to get a majority of the water out.
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Old 05-06-2020, 10:17   #11
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Re: Leaking transom / core repair?

Pick out rotten wood no mater how far you have to dig. Then dry out what is left. You can accelerate the drying process by saturating the wet wood with denatured alcohol. As the alcohol evaporates it takes the water with it. Seal the remaining wood with epoxy and then you can fill the void with the filler of your choice.
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Old 05-06-2020, 22:39   #12
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Re: Leaking transom / core repair?

Unfortunately there is no way to fix that 'simply'.

From your pictures the 'delamination' of the deck from the hull appears to extend from the sheer to as far down as has been exposed; at least to the center of the hull, judging by the crack between the skin of the deck and whatever the core lining the hull is.

That it is only leaking a small amount is probably a testament to whatever bonding material they used when assembling the boat.

That is, if what we're seeing is not a repair.

If it's not a repair, and Beneteau used wood in that application, shame on them.

If a repair was done using wood there, shame on the 'boatwright' making it.

And it certainly looks like some kind of wood, or at least some kind of organic material. Seems like something is growing in there, as can be seen by the tiny green filament in the lower left corner of the image below.

Wonder if your boat is rigged with a split backstay?


Anyway, as previously noted, digging out the exposed rotten wood and filling what you can with 'X' should be looked at as only a stop-gap repair.

From what we can see in the picture, if the crack extends along the whole starboard side, it would be safe to assume that the whole joint, gunwale to gunwale, is suspect.

Perhaps the most 'proper' fix would be to remove all core in the joint, clean/sand the faying surfaces to solid raw glass, reglue the joint with epoxy and structural filler, and then grind, fillet and laminate a minimum of three staggered layers of glass cloth (or stitched-reinforcement equivalent) on the inside.

To gain access for such a repair will likely be difficult, and could be impossible, but to guarantee the best chance of an effective, longlasting and a durable-in-extreme-conditions repair the inclusion of as much interior reinforcemnt as possible is important.
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Old 06-06-2020, 01:47   #13
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Re: Leaking transom / core repair?

Quote:
Originally Posted by Bill O View Post
Agree for a quick fix, but you may need to go deeper to see remove rotted core/inspect the amount of damage and let it to dry out a bit. If you saw water elsewhere coming out of the inside skin at a different place (further forward), then you most likely have a decent amount of sea water in there. While sealing it in w/thickened epoxy will be a cheap/quick fix, leaving a soaked core will eventually destroy it if it's wood of any type (balsa, ply, etc.).
It may take more time, but drying out the core may save you a bigger headache down the road. Would inspect the hull w/a mallet and moisture meter to determine the extent of the water intrusion before sealing the transom up w/epoxy.
This is excellent advice, Bill O.
Think on't retep007!

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Old 06-06-2020, 01:53   #14
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Re: Leaking transom / core repair?

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Originally Posted by jimbunyard View Post
Unfortunately there is no way to fix that 'simply'.

From your pictures the 'delamination' of the deck from the hull appears to extend from the sheer to as far down as has been exposed; at least to the center of the hull, judging by the crack between the skin of the deck and whatever the core lining the hull is.

That it is only leaking a small amount is probably a testament to whatever bonding material they used when assembling the boat.

That is, if what we're seeing is not a repair.

If it's not a repair, and Beneteau used wood in that application, shame on them.

If a repair was done using wood there, shame on the 'boatwright' making it.

And it certainly looks like some kind of wood, or at least some kind of organic material. Seems like something is growing in there, as can be seen by the tiny green filament in the lower left corner of the image below.

Wonder if your boat is rigged with a split backstay?


Anyway, as previously noted, digging out the exposed rotten wood and filling what you can with 'X' should be looked at as only a stop-gap repair.

From what we can see in the picture, if the crack extends along the whole starboard side, it would be safe to assume that the whole joint, gunwale to gunwale, is suspect.

Perhaps the most 'proper' fix would be to remove all core in the joint, clean/sand the faying surfaces to solid raw glass, reglue the joint with epoxy and structural filler, and then grind, fillet and laminate a minimum of three staggered layers of glass cloth (or stitched-reinforcement equivalent) on the inside.

To gain access for such a repair will likely be difficult, and could be impossible, but to guarantee the best chance of an effective, longlasting and a durable-in-extreme-conditions repair the inclusion of as much interior reinforcemnt as possible is important.
Even MORE excellent advice, bunyard!

Geez, you guys are on fire today!

Good on ya,
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Old 06-06-2020, 02:42   #15
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Re: Leaking transom / core repair?

Am I to understand that people think this is just the end of a hull panel left wide open and this is some kind of core material we’re looking at?

I know Beneteaus aren’t known to be the best boats, but no way they just left the core open and put some pretty trim over it. No way.

If they did, absolutely no one should buy a Beneteau ever.

What I see is a closed off core both on the hull side and the transom side making a flange on the hull and a flange on the deck. Both flanges are solid glass. Then both flanges brought close to each other in a sort of hull/transom joint with some wood or other type of filler between the flanges, held together by the adhesive.

If they just didn’t close out the core and left it wide open here, beneteaus should have a value of about $50 each.

The thing is, that wood or whatever we’re looking at isn’t any normal core material used in boat building. Nor does it have the required grain direction to be a balsa core, or any core for that matter other than plywood. All cores with grain have end grain orientation to resist compression.

It’s just a filler in a joint held together by adhesive. So, getting rid of it and bonding the flanges together with thickened epoxy is better than the original as the original adhesive failed. Probably failed at the point where the wood rotted.

At least from what can be seen in these pics.

You could go through all the trouble of glassing the joint but why? It was put together with an adhesive to begin with and epoxy is the strongest adhesive out there. The hull or transom would break before the thickened epoxy bond would.
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