bite out of rudder

zeehag · Mar 6, 2010

pix??

sailingdog · Mar 6, 2010

It really would help if you said what the rudder is made of. Is it wood? Is it foam-cored fiberglass? Is it wood with a fiberglass skin?

The construction of the rudder will have a lot to do with how you should repair it.

zeehag · Mar 6, 2010

sailingdog said:
It really would help if you said what the rudder is made of. Is it wood? Is it foam-cored fiberglass? Is it wood with a fiberglass skin?

The construction of the rudder will have a lot to do with how you should repair it.

why i asked for pix...same thought process...different method....beneteau should be fiberglass--but what is under it?

zeehag · Mar 6, 2010

gghost said:
It is a 1996 Beneteau 36S7 rudder . I believe they are cored, but where the piece is broken out appears to be solid fiberglass. Sorry no pix at the moment.

make a cardboard piece and use roving to criss cross a fiberglass covering -overlap the good parts by about 4-6 inches....use plenty of resin and squeegie the roving and resin flat into and onto the surface to remove the ding---when it is tacky, use gelcoat repair to make a smooth surface and let dry with wax paper squeegied over--when dry , remove the wax paper and should be just as g ood as the original..with a gorgeous gelcoat --then barrier coat the gelcoat and bottom paint---if you overlap by at least 6 in, should be good. if what i wrote is understandable by humans, then is alll goood--i was taught by hank mckune, of yorktown yachts when he built a boat for me decades ago..lol...was excellent teacher--i am not---

the cardboard is only for filler and shape--the roving is for strength and the gelcoat is for the ego and beauty of the boat--should all be the same depth ads the hole/bite out of the rudder....
ye might wanna practice on a dinghy first.....

sailingdog · Mar 6, 2010

You could also use closed cell foam instead of cardboard. BTW, you should use epoxy resin, not polyester or vinylester. This is for two reasons. First, epoxy has better secondary (adhesive) bonding characteristics. Second, epoxy is less permeable to water than polyester or vinylester resin.

BTW, I wouldn't use roving. It is often too stiff to make the tight bends that the rudder will require. Use cloth instead, as it is more flexible and will drape over the contours of the repair better.

Hermit Scott · Mar 7, 2010

I second the cloth. I bought some 24 ounce roving. LOL It is great on a flat surface. If there is ANY bend at all it will stand right up and out of the epoxy. I still use the 24 oz. but only if it is absolutely flat.
1"X2" is a small repair. It will be easy.

zeehag · Mar 7, 2010

boys, boys boys!!!---roving IS cloth--is woven roving. matt is the other crappy stuff that looks like chopper gun stuff--doesnt bend nor does it have strength LOL...have fun--lay the roving cross wise then the other way so as to add more strength ---donot keep adding the cloth same direction--criss cross..lol

Ross · Mar 7, 2010

24 Ounce roving is used to provide rapid build up of thickness. Four layers of six ounce glass will serve exactly the same purpose and be very flexible.

sailingdog · Mar 7, 2010

No, they're not the same thing. Roving is much heavier and less flexible than cloth. If you look on fiberglasssite.com, you'll see that roving is much heavier at 18oz or 24oz. The cloth is available in weights as light as 1.5 oz...

zeehag said:
boys, boys boys!!!---roving IS cloth--is woven roving. matt is the other crappy stuff that looks like chopper gun stuff--doesnt bend nor does it have strength LOL...have fun--lay the roving cross wise then the other way so as to add more strength ---donot keep adding the cloth same direction--criss cross..lol

Ross · Mar 7, 2010

Dog, Cotton canvas and cotton broad cloth are cloth they are not the same but the same weight of material will have the same strength. 1.5 ounce glass cloth and 24 ounce woven roving are both cloth and 16 layers of 1.5 ounce cloth with build the same thickness as one layer of 24 ounce roving. Mat is more of a felt, it is non woven, non directional in terms of strength and when used with the proper resin is the most conformable of all the glass fabrics. You get a stronger, higher density laminate when you alternate layers of roving and chopped strand mat. As with any hand lay-up skill and experience are more important than the choice of resins. I would use vinylester resin for this repair because it is not as fussy about mixing, and is adequately strong in bond.

Hermit Scott · Mar 7, 2010

Mat isn't crappy. It is better for certain parts of the repair. Like the part on the outside to avoid any waffle looking areas.

Roving does have the same cross woven pattern as cloth but they are called different things because they are very different. It's just the terminology that is used.

zeehag · Mar 8, 2010

so i guess my yacht builder was wrong??
he told me roving is the woven stuff and matt is the chopper gun effect clothlike substance that is used for filler between layers of roving.....showed me as he laid it into the mold--oh well....he only built yorktowns and champions and olympians etc...for over 40 yrs.....so i still trust his words..oh well......semantics---

sailingdog · Mar 8, 2010

No sh!t sherlock... but have you ever tried draping 24 oz. roving over a tight radius bend???

My point is that roving, which is generally 16 oz or heavier in weight, won't conform to the tight radius curve of a rudder's edge. Using roving for a rudder repair to re-build a missing corner is useless.. it can't conform to the shape of the repair—no matter what you and zeehag say. You need to use a lighter cloth to do that properly.

I wouldn't use vinlyester resin in this repair, since the repair will depend on the secondary (adhesive) bonding characteristics of the resin. Also, epoxy resins are more water impermeable, reducing the chance that water gets into the rudder.

Ross said:
Dog, Cotton canvas and cotton broad cloth are cloth they are not the same but the same weight of material will have the same strength. 1.5 ounce glass cloth and 24 ounce woven roving are both cloth and 16 layers of 1.5 ounce cloth with build the same thickness as one layer of 24 ounce roving. Mat is more of a felt, it is non woven, non directional in terms of strength and when used with the proper resin is the most conformable of all the glass fabrics. You get a stronger, higher density laminate when you alternate layers of roving and chopped strand mat. As with any hand lay-up skill and experience are more important than the choice of resins. I would use vinylester resin for this repair because it is not as fussy about mixing, and is adequately strong in bond.

Ross · Mar 8, 2010

Jeez Dog, I only used two rolls of 24 ounce roving when I rebuilt Bietzpadlin. For tight radii I used 6-10 ounce cloth and csm. Roving will lay to an inside corner pretty well. Use what ever resin system suits you ,they are all very strong.

sailingdog · Mar 8, 2010

LOL... there are no inside corners on a rudder... not any I've seen anyways...lots of outside edges and corners though. Zeehag is trying to say to use roving to build the rudder... won't work cause of the weight of the roving and its inherent inflexibility—which is my main point—roving won't bend or drape to make a decent repair on a rudder.

Ross said:
Jeez Dog, I only used two rolls of 24 ounce roving when I rebuilt Bietzpadlin. For tight radii I used 6-10 ounce cloth and csm. Roving will lay to an inside corner pretty well. Use what ever resin system suits you ,they are all very strong.

Ross · Mar 8, 2010

Finding difinitive iformation concerning secondary bonds in frp systems is like hunting for gold, its out there but you have to search. I found this written for industry and it is the best I have seen so far.
http://www.dual-laminate.org/assets/images/Secondary_BD_strgth_of_FRP.pdf

It has nothing to do with boats but the chemical industry uses more frp than does the boating industry and their safety concerns are much more critical.

Hermit Scott · Mar 8, 2010

zeehag said:
so i guess my yacht builder was wrong??
he told me roving is the woven stuff and matt is the chopper gun effect clothlike substance that is used for filler between layers of roving.....showed me as he laid it into the mold--oh well....he only built yorktowns and champions and olympians etc...for over 40 yrs.....so i still trust his words..oh well......semantics---

Being technically wrong about the terminology of glass doesn't make him a bad boat builder.
When I say chopped strand mat or mat, I am talking about a fabric that looks like what the chooper gun shoots out.

sailingdog · Mar 8, 2010

CSM is definitely weaker than cloth or roving, since it consists of fairly short chopped strands of fiberglass bound together in a mat. That's kind of the definition of the stuff. However, it does have the advantage of being uniformly strong in all directions, unlike cloth or roving. It also doesn't have any "pattern" to it and is often used as a finishing layer to prevent the pattern of the laminate from "printing through" the gelcoat—which can happen as the gelcoat and resin cures.