stringer glassing

[wiler55]

i am putting stringers in the hull in front and behind the gas tank my question is.... after i tack the foam in place when glassing the edges first to the hull can i use mat or do i need to use biaxial tape? i was thinking of mat-ing first and then 1808 over the entire stringer with 4 layers is this sufficient or do i need more layers.

p.s. i am sorry to all for all of my questions i just don't want to be on the water in 5 years wishing that i had asked a question when my boat is sinking.

[LilRichard]

First, those are bulkheads.  Stringers run from bow to stern.

Second, 1808 has a layer of 18oz biaxial cloth, and a layer of 3/4 oz mat (hence 18 - 08, 18oz cloth, 0.75oz mat).  When you lay 1808, you normally lay it mat side down- and every layer then has mat between the biaxial cloth.  You don't want to use mat by itself unless it is on a surface you will see- it's only benefit is reducing print through of the heavier cloths.

I would tab the foam down to the hull, meaning using a layer of 1808 tape across the hull - bulkhead joint.  Then cut a few layers of progressively increasing size 1808 to cover the bulkhead - this will give you larger overlap on each layer.  

If you take a detailed look at some of the rebuilds being done you will note that this is how many of them are done.

[love2fish]

First, those are bulkheads.  Stringers run from bow to stern.

Second, 1808 has a layer of 18oz biaxial cloth, and a layer of 3/4 oz mat (hence 18 - 08, 18oz cloth, 0.75oz mat).  When you lay 1808, you normally lay it mat side down- and every layer then has mat between the biaxial cloth.  You don't want to use mat by itself unless it is on a surface you will see- it's only benefit is reducing print through of the heavier cloths.

I would tab the foam down to the hull, meaning using a layer of 1808 tape across the hull - bulkhead joint.  Then cut a few layers of progressively increasing size 1808 to cover the bulkhead - this will give you larger overlap on each layer.  

If you take a detailed look at some of the rebuilds being done you will note that this is how many of them are done.

Richard- I've been putting new layers of 1708 biax along the stringer/hull joint, I have been putting the biax side down with the mat side up. I'm putting several layers (each bigger/overlapping) down and am putting them all down with the mat side "up". There's not a difference really with which side is up/down as long as everything is consistant right?

[Mad Dog]

There's not a difference really with which side is up/down as long as everything is consistant right?

I am not an expert at layign glass but all the advice I received from experts say "mat side down."  Layer upon layer ensures the strength.  I think the biggest issue is the finish.  The biax is easier to fill and fair on an exposed surface.  From what I was told the mat is there to build volume the biax gives it the strength.  If I were tabbing stringers and bulkheads I would use 12 oz biax, laying in 3 layers wet on wet with offsetting overlaps.  Also, I would make sure to put filets in the corners to prevent sharp angles on the cured glass.  The sharp angle creats stress points that may crack over time.

IMHO.

MD  

[slippery73]

I believe the mat helps bonding between layers. Cloth doesn't bond to itself as well as mat so the mat is there to aid in bonding between the layers. At least that is my understanding of it.

[love2fish]

I've been putting a fillet down in the joint first and then putting a 6" strip on that, then a 12" strip (running with the stringers). I'm need to refill some sections of the stringers with new foam and then i wanted to glass from the gunwall/hull joint over everything up and over the stringers.
I havent had any problem applying the resin to the 1708 biax, I've brushed the resin on the area where the glass is going to be layed, then put some on the biax side of the cloth before i layed the glass into place.
I reglassed the top of my console with 1708 as a whhen i got started with all of this and found out the resin would go into the cloth easier with the mat side up.  
My experiences so far....

[LilRichard]

Sorry to give you an answer you don't want to hear - but it is supposed to go mat side down.  As others have stated, the non-directional pattern of mat adhears better to surfaces than the directional pattern of cloth.  

Have you had any problems with air bubbles?  If so, you need to grind off and start over.  Trust me, you are better to waste a few days from rework than worry about your boat after it is all done.

I would highly suggest laying in mat down in the future.

[love2fish]

damn it

[slippery73]

Unless you ground off the existing hull to stringer glass, I wouldn't worry about it. In a perfect world yes you should go mat down for now on. The adhesion differences are probably not huge. The original stringers were just glass on with roving, I dont have any delamination issues in my boat, Im sure you just beefed up what was there. As long as there aren't any air bubbles and everything wetted out and adhered well I'd just leave it.