hull cracks around strut and stern tube

[ferrailleur]

Worried about some cracking around the strut and stern tube on my 1985 Catalina 27 which is on the hard.

We knew before the haul out that the prop shaft was low on the stern tube and we needed an engine alignment.
The cracks developed after a few weeks on the hard. The alignment has not been done. The plan is to do it on the hard and recheck it when in the water.

Could the cracks have been caused by me running the engine (Universal M 18) a few minutes at 1,200 rpm on the hard (with the correct liquid intake of course) while circulating Barnacle Buster and winterizing?
Could the engine vibration had caused the cracking while running with the boat on the hard?
The cracking is just outside the hull. No trace inside.
I plan to grind down the cracks and fill up with epoxy.

What do you think? Thanks.

[JimsCAL]

I agree, that doesn't look good. I really doubt that running the engine on the hard caused the cracks. Much more likely is the misalignment of the engine you mention. Are the cracks just in the paint? Or just in the gelcoat? Or deeper into the laminate?

[coopec43]

"Feb 17, 2012 Basically, the shaft log is cracking and developed a slight leak. ... I had a similar issue with the shaft log on my 1985 C36. ... It appears by your picture that the leaking stern tube on your boat may also be the result of the prop ..."

https://www.catalina36.org/forum/tec...shaft-log-tube


Dec 27, 2006 - My Catalina 30 is also a 1985 model. ... I would add a cracked stern-tube rto the list. Rare, but happened to me with my C27. Check to see if ..

https://forums.sailboatowners.com/index.php?threads/wet-bilge.83677/

Clive

[ferrailleur]

Originally Posted by JimsCAL

I agree, that doesn't look good. I really doubt that running the engine on the hard caused the cracks. Much more likely is the misalignment of the engine you mention. Are the cracks just in the paint? Or just in the gelcoat? Or deeper into the laminate?

Thanks, the paint is gone (soda blasting). The newly discovered cracks (see pics) are deep enough to be felt with nail and finger. My plan is to grind them down (up, I should say!!) as deep as they go and refill with epoxy.
As I said nothing visible inside.
Good plan?

[coopec43]

Originally Posted by ferrailleur

Thanks, the paint is gone (soda blasting). The newly discovered cracks (see pics) are deep enough to be felt with nail and finger. My plan is to grind them down (up, I should say!!) as deep as they go and refill with epoxy.
As I said nothing visible inside.
Good plan?

Can you lay some epoxy/glass on the inside to stiffen it all up?


Clive

[boatpoker]

Those two areas are heavily faired with fairing compound right from the factory. If it was a brittle resin used in the fairing it may, just may be a cosmetic issue only.

Chisel away at the fairing compound til' you get to the laminate. If there are no fractures in the laminate you are good to re-fair.

[ferrailleur]

Originally Posted by coopec43

Can you lay some epoxy/glass on the inside to stiffen it all up?


Clive

yes I could.... but more difficult access and work.... and wouldn't that be an overkill??

[ferrailleur]

Originally Posted by boatpoker

Those two areas are heavily faired with fairing compound right from the factory. If it was a brittle resin used in the fairing it may, just may be a cosmetic issue only.

Chisel away at the fairing compound til' you get to the laminate. If there are no fractures in the laminate you are good to re-fair.

thanks... tha't my plan: grinding instead of chiseling....
what do you recomment for re-fairing?

[JimsCAL]

Originally Posted by ferrailleur

thanks... tha't my plan: grinding instead of chiseling....
what do you recomment for re-fairing?

Use epoxy mixed with fairing filler. DO NOT use autobody filler (BONDO).

[boatpoker]

Originally Posted by JimsCAL

Use epoxy mixed with fairing filler. DO NOT use autobody filler (BONDO).

I agree with Jim. You can mix your own but if not familiar with cabosil and microballoons it may be better to buy a tub of pre-mix epoxy fairing compound.

[coopec43]

Originally Posted by ferrailleur

yes I could.... but more difficult access and work.... and wouldn't that be an overkill??

Maybe? But maybe not......

I reckon this guy has done a beautiful job and I think he had the same problem as you (not sure).

I think it is worth a look at what he has done anyway.

https://www.sailnet.com/forums/gear-...be-repair.html

Clive

[GeoBay]

Is it possible the cracks are the result from haulouts especially if the straps were directly under the prop shaft and strut area?

[ferrailleur]

Originally Posted by GeoBay

Is it possible the cracks are the result from haulouts especially if the straps were directly under the prop shaft and strut area?

Thanks.... no chance. The straps were property positioned. I was there with a schematic of the lifting position as recommended by Catalina.

[ferrailleur]

Originally Posted by coopec43

Maybe? But maybe not......

I reckon this guy has done a beautiful job and I think he had the same problem as you (not sure).

I think it is worth a look at what he has done anyway.

https://www.sailnet.com/forums/gear-...be-repair.html

Clive

Thanks for the link.... very instructive. I hope the damage on my boat is not that bad!!

[Suijin]

The key issue in repairing this is to grind out the cracked material entirely. There is a good chance that the cracks go deeper than just fairing compound and gelcoat, into the first schedule of laminate. As you grind, occasionally wipe down with acetone which will reveal any remaining cracking.

If you find yourself grinding down into cracked laminate you’re going to want to repair/replace with biax cloth. After all you want the fix to be stronger that the (inadequate) original. I would even add an extra schedule of biax on the outside and fair it in.