17 oz biaxial fiberglass

[Wallman67]

Being that 1708 biaxial fiberglass is used frequently by many people on these forums this is what I decided to use with my restore. I ordered 17 oz biaxial 4 inch tape and 12 yards of 17 oz biaxial fiberglass. I didn't pay much attention when ordering but I received it I noticed the stitching wasn't the same. The 17 oz biaxial tape is +/- 45 deg stitching backed with mat. The 17 oz biaxial is 0, 90 deg stitching backed with mat.

Upon further reading I discovered that the +/- 45 is double bias and the 0,90 is biaxial.
I'm trying to figure a layup procedure for what I now have. I'm using epoxy.

My question...Does this really matter on the stitching ? I know the double bias is stronger being stitched at +/- 45 , but the 0,90 should still be good to use correct ?

I'm going to use the 1708 tape for all joints around hull / transom, how many layers of the 17 oz should I glass over the transom on the inside of the boat ? Fiberglass shop thought 1 layer over all after the tape. 2 layers overkill ? Isn't the strenght from the wood and not so much the fiberglass ?

The stringers...would 2 or 3 layers up and over the stringers be good ? Fiberglass shop thought 1 layer was good. 3 seemed overkill to him.

 

[barbosam]

Re: 17 oz biaxial fiberglass

More details and pictures would help. What type and size of boat is this? Is it inboard or outboard? how much HP? What was the original construction? There are a lot of factors and someone will probably chime in and say this is way to complicated to cover on this forum and you must precisely calculate the laminate schedule and yadaydayada, but for most of the boats restored on this forum we really don't need to get that scientific about it.

Most boats restored here are say 70's era fiberglass boats that were originaly constructed with plywood stringers and transoms. In most cases the wood was left exposed with only the hull as the outer skin and no inner skin to seal the wood. The wood is actually the main structure in these boats, the stringers and transoms were not built useing typical sandwich panel construction that most boatbuilders use today.

If your boat falls in this category then yes one layer of glass over everything will suffice and I wouldn't worry about the orientation of the fibers so much. Really the main purpose of the glass is to seal the wood from moisture. This could be accomplished with just glass mat but the 17 oz biaxial your using will seal and add a little structure at the same time.

More is not always better I've seen boats with nice smooth rides become pounders after some one lays way to many layers of glass over the stringers. Its OK for the boat to have a little flex.

 

[Wallman67]

Re: 17 oz biaxial fiberglass

The boat is a 1976 Glascon tri-hull.

Ok that's what the guy at the fiberglass was trying to say. However researching on the forums on how others have done transom, stringers, etc....that's where the conflict comes. I realize some are using poly resin , so I'm trying to figure everything out using epoxy and the fiberglass that I purchased. The first fiberglass I purchased was 6 oz cloth which the store said would do the job, feeling all I had to do was seal the wood from water and not so much for strength. But after further reading and a few responses to previous posts I decided to use something heavier, and purchased the heaviest he had in stock this 17 oz biaxial.

 

[Yacht Dr.]

Re: 17 oz biaxial fiberglass

Your 0/90 biax or 17 oz woving roving ( both of which ) is fine.

I dont know about that 4" stuff you have..I cant think many uses for it in a rebuild..aside from the first layer of tabbing.

I would do 2 layers of your 17oz on Everything .. Stringers,trans and 3 on tabbs ( Im allways overkilling though ).

The thing that worries me is your choice of epoxy. You may have drainage problems in the glass layups. Not the horizontals but the verticals. I hate to see anyone do that much work and have a quarter of the resin drain out the bottom of the layup.

Show us some picasso's please

YD.

 

[oops!]

Re: 17 oz biaxial fiberglass

dont worry about it bud.........the 1708 is way over kill with what you are doing......plus you are using epoxy.......= no worries.

however......when you lay the stringers and glass them in....lay the glass using the longitudnal weave.....if you go at right angles......the bi ax will fray and be a real pain

 

[Yacht Dr.]

Re: 17 oz biaxial fiberglass

oops.. have you ever had problems with Epoxy draining out of the glass ? If so how did you overcome this ?

I only work with West System epoxy..and its a real PITA when doing layups on verticals..dunno mebbe just me..

YD.

 

[Wallman67]

Re: 17 oz biaxial fiberglass

Ok points noted, thanks guys. I decided to use epoxy in hopes that it's strength will make up for my inexperince in fiberglassing.

I'm going to play with cuts of the 17 oz and try to figure out longitudal weave. I did read this on your thread OOPS's, you had a picture of the 1708 all frayed.


I did notice that on my first repair I did on a hole on the vertical side the epoxy did run down and pool at bottom of hull. Is there away around this ? Maybe slightly thickening the epoxy ? How do others using epoxy stop the resin from draining when doing stringers of transoms ?

OK.. 3 layers of 1708 to tab the stringer to the hull , then 2 layers of 1708 layed up and over the stinger onto the hull. Correct ? And same with tabbing with transom , covering all with 2 layers.
Missing anything ?

After reading that thread and seeing the troubles OOPS's had going over the top with the 1708 I kinda like the clamp method using cut 2" pvc pipe to hold down the glass til it sets. What method did you decide works best OOPS's to do this ?

I'm taking pics as I go and will post them. Have some already posted on the restore. When I get this done I will add what process I did to it.

 

[Yacht Dr.]

Re: 17 oz biaxial fiberglass

Thats why I love Poly...it Smells bad ( real bad ) but it works with the binders in the glass that you buy.

Epoxy is for woodworking or tinnys ..not lams IMHO .

YD.

 

[erikgreen]

Re: 17 oz biaxial fiberglass

oops.. have you ever had problems with Epoxy draining out of the glass ? If so how did you overcome this ?

I only work with West System epoxy..and its a real PITA when doing layups on verticals..dunno mebbe just me..

YD.

West is formulated to wet out glass easily.. it's just about the lowest viscosity epoxy I know of. I wouldn't use it for vertical lamination at all. Probably it's thin enough to vacuum bag with.

I use the US Composites stuff on vertical lams, and I get minimal run-off from it. It's slightly thicker than the ISO poly I use for molding parts.

Bottom line, if your resin is dripping out of the cloth you're using, either switch resins or lay up in a different position.

By the way, wallman - you don't need the mat on that cloth if you use epoxy. It just soaks up resin without adding a lot of strength. You can buy biaxial glass without the mat, and it'll save you epoxy costs.

Erik

 

[oops!]

Re: 17 oz biaxial fiberglass

oops.. have you ever had problems with Epoxy draining out of the glass ? If so how did you overcome this ?

I only work with West System epoxy..and its a real PITA when doing layups on verticals..dunno mebbe just me..

YD.

dont use the stuff my friend..........i KNOW WHAT EPOXY IS FOR. lol .....and we (building little glass boats) dont need it. its a sales pitch people have fallen for.

glassing on vertials or up side down is allways a pain.....

but..i know where you work, you will be called to use it .......have you tryed milled fibers at a low percentage to thicken the epoxy?

 

[oops!]

Re: 17 oz biaxial fiberglass

Erik

BUDDY.......how the heck are ya !!!!
havent seen ya in a while.......are you still bilding the woodie?....(this is what epoxy is for)

 

[clockwatcher]

Re: 17 oz biaxial fiberglass

Colloidal silica (aka cabosil) mixed to an apple sauce constancy will prevent resin from running. It's also easier to sand than micro fibers.

http://westsystem.com/ss/406-colloidal-silica

 

[Yacht Dr.]

Re: 17 oz biaxial fiberglass

Sanding West System epoxy mixed with Cabosil IS freaking rock hard lol..

oops.. when I said only use WS epoxy..I mean thats the only epoxy I have in the shop..I dont use it anymore for ANY layups .. only for wood working .

I use poly or vinylester for lams

The last time I used Epoxy for a lam I was Forced to by upper management/owners request even though I said NO. So when I started the project I had the upper come and " show me how its done " .. after 1/2 hour he threw down the glass and told me to use whatever I wanted and left LOL I mean.. LMAO !!..

As far as adding a thickener for layups.. I juuust dunno about that...

YD.

Sorry for semi-hijacking this .. but I think its important..

 

[ly_glass]

Re: 17 oz biaxial fiberglass

Being that 1708 biaxial fiberglass is used frequently by many people on these forums this is what I decided to use with my restore. I ordered 17 oz biaxial 4 inch tape and 12 yards of 17 oz biaxial fiberglass. I didn't pay much attention when ordering but I received it I noticed the stitching wasn't the same. The 17 oz biaxial tape is +/- 45 deg stitching backed with mat. The 17 oz biaxial is 0, 90 deg stitching backed with mat.

Upon further reading I discovered that the +/- 45 is double bias and the 0,90 is biaxial.
I'm trying to figure a layup procedure for what I now have. I'm using epoxy.

My question...Does this really matter on the stitching ? I know the double bias is stronger being stitched at +/- 45 , but the 0,90 should still be good to use correct ?

I'm going to use the 1708 tape for all joints around hull / transom, how many layers of the 17 oz should I glass over the transom on the inside of the boat ? Fiberglass shop thought 1 layer over all after the tape. 2 layers overkill ? Isn't the strenght from the wood and not so much the fiberglass ?

The stringers...would 2 or 3 layers up and over the stringers be good ? Fiberglass shop thought 1 layer was good. 3 seemed overkill to him.

The difference between double bias and biaxial is the strength. Double bias has more strength on +/-45 orientation, but Biaxial focuses its strength on 0/90, which works the same as woven roving.