glass on schedule

General Discussion
1

Ok. total newbie question. I looked in the archive and didn’t find exactly what I needed.

I’m wondering what the standard schedule is for glass ons? I’m talking thruster (or super thruster 5 fin) shortboards.

I’ve used a 1/4" of rope going about 3/4" past the ends of the fins (sanded back later), then 4 oz about 1-1/2" up the fin and the same amount onto the board. Another 4oz about 3" up and onto the board. And a final 4oz that covers the whole fin or nearly so and goes about 4’ onto the board.

I’m thinking I’m over doing it.

What’s the “industry” standard?

2

That’s a hell of a lot of glass and a hell of a lot of sanding to feather those layers in.

I use seven strands of rovings and one layer of 6oz (lately 4oz s-cloth)up the outside of the whole fin down to an oval shape on the board about 2 1/2".

I have seen in other factories the bare minimum of rovings used with a 4oz patch half way up the fin and the same onto the bottom of the board. Of course these are the ones that I always replace.

3

there are no rules

more glass = more work= more weight = more strength

         the happy spot

less glass = less work = less weight = less strength

you savey???

4

llilibel03,

Ken’s words ring true and with wisdom. Industry standard has been double 6 oz (most of the time

all the way up the fin and staggered footprint on the board) Multiple 4 oz layers will work but

tend to be too “stretchy” compared to 6 oz. We found 3 layers of 4 oz will allow the fin to deflect

more than 2 layers of 6 oz, the result being more cracks along the rope area on the 4 oz installs.

There are a lot of tricks like laying down staggered 6 oz patches (1/2 and 2/3 of the way up the fin,

lots of pro guys like that) then finishing with a large scrap of 4 oz, then once gelled but NOT hardened,

the 4 oz gets slowly and carefully pulled off, leaving a nice smooth surface to hotcoat…

HTH,

George

5

A comment about those “footballs” or oval laps onto the bottom…

Where does the fin crack first? It cracks at the point where the stress (or strain, if you prefer) exceeds the capability of the glass-on job, usually at the forward edge of the fin. Thus, having a “football” glass patch is exactly the opposite of what’s needed. Instead, a wider lap to the bottom near the forward edge of the fin would be more appropriate and yield a stronger overall job.

Football-shaped patches are just easier to sand fair into the bottom. Another instance where final appearance is more important than intended purpose. But for a commercial operation, the intended purpose of any board is to see it leaving the shop under the customer’s arm, after having taken said customer’s green.

But, some may say, what about when there’s a crack running partial or full length down the length of the fin base? Well that’s just an overstressed fillet - too small or not enough glass lapping onto the bottom. I’m with the two-layers-of-six-ounce crew, and I hate to have to do glass on fins, again. It’s a messy, time-consuming, labor-intensive job to get it right, smooth, and fair.

6

Howzit llilibel, Think you should reverse the staggering process. Start with the longer pieces of glass then go shorter. Starting with the shorter then adding the longer can make for sanding through and making for a weaker glass job. Aloha,Kokua

7

Thank for the info guys.

Plus one- does that trick of pulling away the 4 oz work with epoxy too?

8

llilibel03-

that trick only works with poly. There is one kind of epoxy that might do it from Greenroom

Board Co. that kind of gels like poly when it B-stages… …haven’t tried that release trick though.

BTW, when you pull off the 4 oz scrap cover, do not just yank it off quickly, do it carefully

and you will get a smooth clean finish that may not even show any weave after sanding it.

Also, we’ve used Nylon fabric and pulled it off the same way, but NEVER let the whole thing

kick off to completion, or headaches will ensue…

HTH,

George

9

The “Glassing 101” video does a good job with glass on fins. The book “The Ding Repair Scriptures” also covers this subject very well. The “stock” fiberglass fins that I buy for glass ons are very thin and 2 layers of 6 oz cloth on each side gets the fins up to a normal thickness. I do not use football shaped pieces ,I make over sized fin shaped pieces. My biggest problem is getting the bubbles out of the roving/fillet/fin rope. It’s a hobie for me so a little extra sanding time is not a big deal.

I spend a lot of time sanding between the lam and hotcoat to get it all real smooth…I also use UV cure catalyst for poly glass ons. The UV will come out looking a little greener than normal cat…

Ray