cracking on hull around the skeg

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mikenfi

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We have a sabre 27 and have decided to strip the hull back to the epoxy layer. We have noticed since removing the 20 layers of antifoul that there is a crack where the rudder/skeg join. This crack appears to continue in an oval type shape around the skeg.

Can anyone off any advise on fixing this. Im thinking epoxy epoxy epoxy.

What are your thoughts?

Thanks
 
Thanks for your speedy reply.

The skeg is a separate moulding that is bolted into a recess in the hull with a ring of 1/4" machine screws, all are then glassed over,the skeg is bedded on polyester filler then filled with foam afterward
 
Grind the cracked out and fill it. From the way you describe it the structural strength is in the fastenings and the filler cosmetic.
 
That must be the case. Any slight movement will have caused the cracking, but not be a significant concern. GRP mouldings are flexible to a surprising extent.
 
Tranona said:
Grind the cracked out and fill it. From the way you describe it the structural strength is in the fastenings and the filler cosmetic.
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Filling it won't solve the problem as it will crack again.Either leave it alone or grind a shallow V along the crack and laminate over with a few layers of roving and epoxy.
 
Cracks are a result of stress, filling will be cosmetic only and could make things worse because filler little support on a good day and you have a section perhaps about to fail, filling wont help at all.

You need to grind that out completely, to the point that no cracked section is visible, then a bit more to provide a good base for the application of an epoxy resin cloth designed for use with an epoxy.

You could use a high power flood light to maintain a good curing temperature when applying and overnight to ensure a good strong cure.

I have found that adding a small amount of Micro-fibres to the mixed resin before applying the cloth gives a little more strength to lay up.
Though the test sample was only subjected to a load from side only, till it broke well after the identical lay up on the other end of the sample, around 9.5% stronger. Good for spot repairs of this type. Interestingly, doing the same test on a sheet of foam made little or no difference. the ratio was 5% fibres to volume of mixed resin.

The lay was done under a flood lamp to ensure the resin was warmed up when applied to increase the viscosity and thus avoid air entrapment.

Good luck and fair winds. :)
 
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oldsaltoz said:
I have found that adding a small amount to the mixed resin before applying the cloth gives a little more strength to lay up.
Though the test sample was only subjected to a load from side only, till it broke well after the identical lay up on the other end of the sample, around 9.5% stronger. Good for spot repairs of this type. Interestingly, doing the same test on a sheet of foam made little or no difference. the ratio was 5% fibres to volume of mixed resin.
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+1
The "small amount" oldsaltz mentions is presumably the microfibre mix he refers to later. As said, for some reason 'painting' the cloth with such a mix inhibits air entrapment, which can be a problem, especially if the glass cloth is closely woven. Pre-wetting is also a help in application when working upside-down, as I presume will be the case: lay the cloth on with a roller (a bit like wallpapering a ceiling).
 
Thanks Mac,
I have reworded my original post to avoid any confusion.

I would also add that it's very important to get as muck resin rolled out as possible, this also ensures no air is trapped.
For some reason seen to use Epoxy resind like standard poly resin when it comes to quantity applied.
The end result of adding too muck resin is a weaker and far more brittle repair.

Good luck and fair winds. :)
Foot Note:
Lifted the Cat out Last Sunday week, all 11 + tons of her.
Planning to do some modifications to the keels so she will take the beach and drying out without ant wear and tear problems.
Nothing like a couple of lengths of Stainless steel to avoid minor repairs later.
 
30boat said:
Filling it won't solve the problem as it will crack again.Either leave it alone or grind a shallow V along the crack and laminate over with a few layers of roving and epoxy.
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Rather OTT. The boat is 40 years old and the join is not structural. The filler is cosmetic and no reason why grinding out a refilling should not last another 40 years.
 
Tranona said:
Rather OTT. The boat is 40 years old and the join is not structural. The filler is cosmetic and no reason why grinding out a refilling should not last another 40 years.
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I'm not disputing that,my reply was not about the structural integrity,only about how to make the crack not return.
 
Have you checked the condition of the screws since they have now been subjected to water ingress?
If you just fill the crack, you will be sealing in dampness for ever.
 
I have not checked the screws as i think that would require me to grind further into the gel coat / glass. Whisch as a novice at this sort of thing, i am hessitant to do.

I cannot seem to get ahead with this boat. I rebuild the engine, i also have to change the cutlass bearing. I strip back the hull. I find these cracks. I'm now waiting for the next thing to go wrong.

Thanks guys ill perhaps look at the screws.
 
Ok guys here another pic of my screw. Its 40 years old looking good? I think so!
There appears to be no moisture damage!
So... next moves?
 
mikenfi said:
I have not checked the screws as i think that would require me to grind further into the gel coat / glass. Whisch as a novice at this sort of thing, i am hessitant to do.

I cannot seem to get ahead with this boat. I rebuild the engine, i also have to change the cutlass bearing. I strip back the hull. I find these cracks. I'm now waiting for the next thing to go wrong.

Thanks guys ill perhaps look at the screws.
Click to expand...

Looking at your photos, would perhaps use some glass cloth and epoxy to build up the deeper areas and then fill and fair the whole area with epoxy filler. Suggest you get the epoxy in normal unfilled form which you can use for laminating the glass (use the proper glass cloth) and mix you own filler with fairing filler. You might find the information on using epoxy for repairs on www.wessex-resins.com useful.

Doubt you will have problems with any damp in there. Looks like you have cut back to sound GRP and the epoxy repair will be better than the original!

Edit. Just seen your screw picture. Confirms my suspicion. Nothing to worry about. Fill the head hole and laminate over as suggested.

BTW great boat the Sabre. Learned to sail in when - when they were new! However hope yours does not have the horrible little Brit engine that one had.
 
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Yes Finally something is going right for me! I will be get on this first thing tomorrow, when i have good weather! I will be setting sail the end of next week with any luck. But I have probably just jinxed it saying that but hey hoe! I'm feeling on top of the world right now!
 
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