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-   -   Serious Hull Repair - Fiberglass Surgery Questions (http://www.cruisersforum.com/forums/f55/serious-hull-repair-fiberglass-surgery-questions-51776.html)

kta 20-12-2010 21:07

Serious Hull Repair - Fiberglass Surgery Questions
 
This question is purely out of curiosity.

I've seen a couple boat listings lately for 40+ foot boats that have been knocked off their jackstands and the side of the hull has been cracked open. I'm sure this is repairable, but I'm wondering what the process is.

I've done minor fiberglass work to repair small damage, but this is serious damage!

http://www.evanfell.com/screencaps/zqv5pd.png

http://www.evanfell.com/screencaps/5oh7ah.png

Can this be repaired reliably? Is it just a matter of cutting back all the damaged edges to make them smooth, then grind/sand in a taper and start laying new glass? Or will entire sections get cut away and replaced all at once? Some of the cracks run all the way up to the deck joint, so there are serious structural concerns with a repair like this.

I was trying to dig up some threads about a repair like this, but couldn't find other cases that were so dire. It seems that unless you doubled up the thickness of the glass along the whole side of the hull it would never be as strong as it once was.

Anyone fix something like this? I'd love to read about it!

maxingout 20-12-2010 21:35

That is a massive amount of damage from falling over in a boatyard. I would not want to sail offshore in a yacht that can sustain that much damage from a jack stand problem. Even if the yacht could be repaired, I would not have confidence in the hull if that amount of damage occurred from falling over.

My Westsail 32 could fall over without any worry about damage like that seen in the picture. I guess that is why I like heavy displacement monohulls.

The answer is yes. You can fix it.

My answer is that I would not bother to fix it because I would not want to sail such a yacht offshore.

kta 20-12-2010 21:55

Well I can certainly understand that.

The top photo is a Gulfstar 41 that supposedly had an incident with a tornado. Certainly looks like it got blown around a bit. It's not exactly a light displacement boat at 23,000, and I think they have a reasonable rep for having strong hulls. Maybe I'm wrong.

The bottom photo is a Schoechl Sunbeam 40, which I don't know too much about, but is said to have just 'fallen over'.

As for repairing something like this, or any fiberglass job, will the repair ever be as strong as the original glass? What is the preferred technique for doing such a large repair? I'm sure some of the hurricane scrapers are making repairs like this.

beetle 20-12-2010 23:08

Quote:

Originally Posted by kta (Post 582282)
I've seen a couple boat listings lately for 40+ foot boats that have been knocked off their jackstands and the side of the hull has been cracked open. I'm sure this is repairable, but I'm wondering what the process is.

Can this be repaired reliably? Is it just a matter of cutting back all the damaged edges to make them smooth, then grind/sand in a taper and start laying new glass? Or will entire sections get cut away and replaced all at once? Some of the cracks run all the way up to the deck joint, so there are serious structural concerns with a repair like this.

Anyone fix something like this? I'd love to read about it!

I've worked on a few major boat repairs, but not from falling over onto the ground (the repairs I've been involved with are due to point-loading when being hit by another boat).

Short answer is yes, anything can be repaired. Important question: what else is damaged or shifted inside the boat? e.g., bulkheads, liners, deck/hull joints, that sort of thing. Damage like that suggests a lot of other problems will be present in the boat.

Typically what you want to do is work from the inside out if you can, which requires removing everything on the inside of the boat in the damaged area. If the hull shape has been changed from the impact, you'll need to go back outside and re-enforce/support the hull such that shape is what you want (if you're not certain what the shape was before, then you can pull a form from the oppposite side and create a mirror image - which is a long job).

If you can't work from the inside, you still need to get to the inside of the damage to stabilize and support the repair (e.g., remove the furniture). The downside to working from the outside is gravity is not on your side, and the repaint/fairing area on the exterior will be larger than if you worked from the inside. For damage such as in the photo, fairing may be a moot point but working with resin & glass over your head is not (for upside-down glasswork vacuum bagging is a nice thing).

Assuming that the hull shape hasn't been changed by the impact then you support the exterior, grind away inside on a 12:1 bevel (not so much fun), and rebuild the hull from the exterior skin, the core, through to the interior skin. Then you get to fair the exterior, the interior, and colour match...

All of this is a big job; based on the photos, those boats had better be worth of a lot to you for you to take that effort on... it will not be easy, especially if it's your first time at a project of this size as you will be on a fairly steep learning curve.

kta 20-12-2010 23:22

Thanks for the comments beetle.

I have no interest in buying either of these boats, but I saw them both listed as repair projects rather than scrap, so I was just curious the best way to approach the repair.

I hadn't thought about the hull being so misshapen that it might need a mold applied to match it, that would be an incredible amount of work.

If working over your head is problematic, is it possible to lay the boat over on it's other side so you can work in a more normal position? Or would such a stress put too much pressure on the hull and cause the repair to be out of shape? Seems like vacuum bagging such a huge area would be an undertaking in and of itself.

Cheers!

ozskipper 20-12-2010 23:47

As others have said, I wouldnt trust a boat like that. I would always be wondering what problems I had missed. Bulkheads, chainplates etc. I guess if they are solid glass they could be repaired simply for the sake of lake and bay cruising. But if they were laminates a whole new can of worms would be opened as far as the final strength of the repair is concerned.

Cheers
Oz


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