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Eyeing off horizons
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Discussion Starter #1
Hi All,

I'm about to attempt my first marine fiberglass repair, and just wanted to check that my plan is solid (so to speak..).

So the problem is that the wooden strut in the rudder assembly at the top of the picture below has come loose from the fibreglass.



This has lead to a small mount of play in the rudder when you hit it hard against the stoppers.

After a bit of research I'm looking at using the 105 Epoxy Resin and 205 (?) Slow Hardener from West Systems. I have no idea what sort of fibre weave to as yet.

My main question is around how well this will bond to the wooden strut. I will sand this back and clean it with acetone before hand, but is there any better resin / hardener products to use to get a good structural bond with the wood, or is Epoxy resin fairly standard for bonding to all materials?

Cheers
Hugh
 

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I would be interested to hear what others say. Injecting epoxy into the crack may fix it. Depending on the size of boat (i.e. the pressure on the part), I would consider bolting the wood in place. I would do this by first reinforcing the fiberglass tabbing (which would mean removing the paint first!), adding a few more layers of more fiberglass, then drilling the reinforced section and bolting the wood solidly in place, and finally injecting epoxy. Overkill? Perhaps.
 

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Eyeing off horizons
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Discussion Starter #3
I was actually planning on taking an angle grinder to the small amount of fiberglass which current covers the wooden strut pedestal.

I'm not sure what is underneath to get a bolt through but I'll check that out as well. Thanks for the idea.
 

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I was actually planning on taking an angle grinder to the small amount of fiberglass which current covers the wooden strut pedestal.

I'm not sure what is underneath to get a bolt through but I'll check that out as well. Thanks for the idea.
Your plan is good - clean the detached glass away, clean everything up with a sander then put new glass down with epoxy. I'd use 17 Oz. uncrimped biaxial fabric, not a woven fabric. I just got done doing a bunch of work with this combo and it's the best I've ever used. Wets out nicely, drapes nicely and squeegees out until it ends up looking like it was vacuum bagged.

Back it up with some stainless through bolts with fender washers and you'll never have to worry again.

By the way, the bolts are only to eliminate any possible shear load induced movement on the wood/glass interface that could eventually break the bond, not to add strength per se.
 

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West 205 is their fast hardener, the slow is 206. I would use the 206 as it gives you more working time before it gels.
 

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I was actually planning on taking an angle grinder to the small amount of fiberglass which current covers the wooden strut pedestal.

I'm not sure what is underneath to get a bolt through but I'll check that out as well. Thanks for the idea.
I'd be very careful with an angle grinder in this case. Even with a medium grit flapper wheel chucked on, it'll remove a lot of material in a heartbeat. The tabbing looks to be only a couple of layers thick, and unless you've got a very steady hand and a light touch you may create some very nasty divots. An R/O sander would probably give you a little more control and pose less of a risk.

If you do go the grinder route, please make sure you use a good respirator or dust mask. The grinder will create an amazing amount of dust in short order. Putting up some plastic sheeting to keep the dust out of other parts of the boat is also a good idea -- you'd be surprised how far that stuff migrates, and will find all the nooks and crannies you've never noticed before.
 

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This place is great - good advice here.

Biaxial cloth is probably a good idea with the curves. Respirator and sheeting off - definitely. Only thing I would add is the importance of acetone, generally before as well as after sanding/cutting, to make sure that you don't drive contaminants into the surface you are preparing.

Also give the wood a light sand and thorough acetone wash (respirator!)

Finally - this will sound odd - the viscosity of epoxy changes dramatically with temperature. I did a project which started in winter, when the epoxy was like molasses, and ended in summer, when it was like water. You want the epoxy to penetrate wood/cracks/cloth, and so may need to *slightly* warm it to reduce viscosity. Clearly this also accelerated hardening, but with a slow hardener you should be fine.

Enjoy! Fixing fiberglass is easy - and fun!
 

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Finally - this will sound odd - the viscosity of epoxy changes dramatically with temperature. I did a project which started in winter, when the epoxy was like molasses, and ended in summer, when it was like water. You want the epoxy to penetrate wood/cracks/cloth, and so may need to *slightly* warm it to reduce viscosity. Clearly this also accelerated hardening, but with a slow hardener you should be fine.

Enjoy! Fixing fiberglass is easy - and fun!
Good point. Another thing I'd add - if it is possible to wet out the fabric PRIOR to putting it in place, do so. A sheet of heavy cardboard set up in an area where it's easy to work will make the wetting out process much easier.

If you can't do that because of cramped access to the work area or something, another way of making it easier is to paint resin on the bonding area before laying the glass in place. If you put a generous coat down and roll the fabric into it, it will hold it in place while you finish wetting it out "from above".

Also, be sure to stipple it with the resin brush and roll it out until all the white spots disappear - then you know it's fully saturated. After that, squeegee any excess resin out with a plastic "Bondo" squeegee and mop it up with the resin brush.
 

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Eyeing off horizons
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Discussion Starter #9
Wow guys. Fantastic feedback. I like the idea of putting down a coat of Resin before laying the glass in place.

Glad to hear that fiberglassing can be classed as fun too. I'm quite looking forward to the project and will post some photos of the finished job.

Btw- Anyone know a cheap supplier of the West Marine epoxy in Sydney, Australia?
 

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Wow guys. Fantastic feedback. I like the idea of putting down a coat of Resin before laying the glass in place.

Glad to hear that fiberglassing can be classed as fun too. I'm quite looking forward to the project and will post some photos of the finished job.

Btw- Anyone know a cheap supplier of the West Marine epoxy in Sydney, Australia?
I assume you mean West System....Google is your friend! It's not that expensive, and you don't need much, so just buy it wherever it is convenient!
 
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