How much Fiberglass to use on my Stringers?

[MR nova @#25]

I'm replacing the stringers on a 1976 Wellcraft Nova. The old stringers were 5/8 pine covered with one layer of woven roving. I'm using Biaxial Fiberglass and West System 105 Epoxy resin. My question: How many layers of Biaxial do I need to use on the stringers?


Thanks in advance.

 

[tpenfield]

Re: How much Fiberglass to use on my Stringers?

If your new stringers are similar to your old stringers, you can use a similar amount of encapsulation. While comparing biaxial to WR is not an exact science, your tabbing will be in multiple layers, but you can go with 1 layer of the biaxial in the upper portion of the stringer. 2 layers would be extra strong, if you have the additional material.

 

[Scott Danforth]

Re: How much Fiberglass to use on my Stringers?

I found that you take the best guides out there for amount of resin and cloth. then double that and you will be close.

 

[Woodonglass]

Re: How much Fiberglass to use on my Stringers?

What Weight of Biaxial Fabric are you using. If it's 1700 or 1800 then since you're using epoxy, 1-2 layers would be plenty.

 

[MR nova @#25]

Re: How much Fiberglass to use on my Stringers?

Thanks for the replies: I was actually second guessing myself, before I put the floor in. This is how I did my Stringers and bulkheads, Cabinet grade 3/4 plywood, with 2 application of Smiths Clear Penetrating Epoxy Sealer. The stringers were seated with Smiths layup & laminating epoxy. The edges were tabbed with a 2in strip than a 4in strip of Biaxial, then covered with two layers of biaxial. I think I might me good??

 

[bakerjw]

Re: How much Fiberglass to use on my Stringers?

You're good. How tall are your stringers?

I tabbed my stringers in with an 8" strip of 10 ounce cloth and then used 1708 6" out from the bottom and up to the top of the stringers where it was capped with more 1708. With all of the bulkheads in my boat, it is solid as can be.

 

[Woodonglass]

Re: How much Fiberglass to use on my Stringers?

Cabinet Grade is not a good choice for stringers. The laminates are not glued with water proof glue and the wood used is not that great either. Since you used epoxy that is beneficial. a 2" tabbing is not that great either unless the stringer is only 4" tall. Tabs should be a minimum of 1/2 the height of the stringer and then the next full height. Epoxy has a lot of strength so it will help some. You still haven't said what weight the biax was.

 

[MR nova @#25]

Re: How much Fiberglass to use on my Stringers?

Sorry, I type faster than I Read 12in &14in Tab on a 16in stringer. The Glass is 17oz Biaxial with 3/4oz backing

 

[Woodonglass]

Re: How much Fiberglass to use on my Stringers?

With epoxy you don't need the 3/4 oz backing just 17 oz biax 1708 is typically used with Polyester resin. You can use it with Epoxy but basically the extra CSM stitched to the back will just soak up extra epoxy resin and add nothing to the layup.