Fiberglass thickness

[bcc101]

I have been recoring many areas on our Paceship 23.
This has been a process that has taken longer than planned mostly because of outside commitments. Using baltec 1/2" core material I decided to replace the core first, then sand fair and glass over that.
I found with two layers of biaxial (1.5oz matt and 24.5 oz woven) the repair was higher than the deck.
Can I get away with only one layer of this cloth or do I combine it with something else?
Using WEST epoxy.
Thanks
Bruce

[UNCIVILIZED]

You might try lighter skins, though this is a less then attractive choice if you're trying to approximate the strength of the initial layup. So the other option is to use thinner cores in these areas, & if the cores wind up being a tiny bit too thin in order to have the repair thickness match that of the deck, you can add a bit of extra reinforcement, or a bit of thickened resin instead. To bring things up to the same thickness/level as the surrounding deck.

Sometimes if there are a lot of repairs to be done, it makes sense to wait until you've finished doing all of your patching, & then refair the entire area at once. Even if this means that you wind up adding a bit of thickness to the deck in the non-patched areas via fairing compound, in order to make everything even & smooth, prior to painting.

It is a juggling act. And in addition to trying to minimize sanding in general, you don't want to wind up doing a lot of sanding of cured reinforcements. Both because they're more difficult to sand than cores or fairing compound, & that when you sand them you can wind up greatly reducing their strength.

As an example, at times when working with carbon fiber in hulls & decks, particularly in boats not built in molds, sometimes a layer of light weight woven fiberglass is added on top of the carbon fiber to serve as a sacrificial layer when fairing & sanding, so that you don't accidentally wind up directly sanding the carbon fiber itself. Especially as it's so thin. And as such, sanding it will reduce it's strength that much more, proportional to it's thickness, or lack there of.

[Tortuga's Lie]

Are you over-lapping the new laminate over the existing glass? if not, you need to do so for strength. Typically, you would bevel the edges of the existing glass laminate over maybe 3 inches using a disc sander, feathering it out so that the new laminate will overlap those three inches giving it that needed strength. More than 3 inches would be preferable, but on a deck, the top layer will be thin and you don't have the thickness to bevel it out too much.
Here's a good resource:
http://www.westsystem.com/wp-content...anual-2015.pdf

[UNCIVILIZED]

Where's the 3" figure coming from? Scarf ratios I understand, & yes overlaps make sense in some instances. But this is one I'm not familiar with. I should think that if there are specific numbers for overlap, they'd be generated by the specific resin & reinforcements used in a repair (or build). As each one has different properties, & each applicaton calls for different laminate & bond properties as well. Non?

[Tortuga's Lie]

Originally Posted by UNCIVILIZED

Where's the 3" figure coming from? Scarf ratios I understand, & yes overlaps make sense in some instances. But this is one I'm not familiar with. I should think that if there are specific numbers for overlap, they'd be generated by the specific resin & reinforcements used in a repair (or build). As each one has different properties, & each applicaton calls for different laminate & bond properties as well. Non?

The 3" was an estimate, the ratio of the bevel should be 1 to 12 and I was guessing that the top layer of glass was somewhere between 3/16 and 1/4" giving us somewhere near 3"...........of course, the thicker, the wider the bevel.

[Suijin]

Originally Posted by bcc101

I have been recoring many areas on our Paceship 23.
This has been a process that has taken longer than planned mostly because of outside commitments. Using baltec 1/2" core material I decided to replace the core first, then sand fair and glass over that.
I found with two layers of biaxial (1.5oz matt and 24.5 oz woven) the repair was higher than the deck.
Can I get away with only one layer of this cloth or do I combine it with something else?
Using WEST epoxy.
Thanks
Bruce

You need to use something else. The 24.5 oz roving is way too heavy. I would be building it up with something in the 6-10 oz. range.

[bcc101]

Thank you all for the information.
I will try a couple different combinations.
Bruce