brucephenry

Rudder Repair - Cascade 29

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Okay, got the rudder out (hat tip to @longy for advice on removing the head) and on the bench to ponder my options. I have a few questions.

First off, the rudder was submerged in freshwater for about a week after the “event”. When removed, I can best describe it as being “buoyant as hell”, the rudder shot to the top of the lake with me in tow. How long should I let it dry out for before glassing in a repair?

Speaking of glass, what weight/type cloth would y’all recommend for this type of repair?

85952A6E-263D-4ADD-94C1-3373C6A4C96C.thumb.jpeg.1f75f85d8558bab85a1091e67d10d21d.jpeg

7BEA83E8-01AE-44B0-8D31-15C97B22C561.thumb.jpeg.3c0e87a514dfecc40dc967f639317907.jpeg

I’m also halfway considering cutting away enough of the section that’s damaged to clear the prop. Although I’m seriously doubting the kid is gonna try the reverse the tiller experiment again. 

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That rudder is just a bit of glasswork. What kind of shape is the prop in?

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If you have the time, give it a week in well heated area. I suggest the living room. But seriously after 2-3 days in a warm spot, you're into much diminishing returns with the amount of water left in the foam.

Glass - just equal in thickness to the original skins. But if you use stitched fabrics (biaxial/triaxials) it will be stronger than the original which is probably WR/mat/maybe a finish layer of cloth.

100 gm/m2 = 0.1mm thickness

9 oz = 0.3mm thickness

(both are approximation assuming no mat, good firmly squeegeed hand lamination or vac bagged.

 

Uh is there plywood there ? Kinda a hint in bottom photo?

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11 hours ago, Zonker said:

Uh is there plywood there ? Kinda a hint in bottom photo?

Yeah, there's some plywood in there. I think there's a plywood "skin" around the foam.

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Ugh.  Then a minimum of a week drying time. With a fan blowing at the exposed area.

And a dehumidifier in the room where it is. Buy a cheap one on craigslist and then sell it when you are done with it.

You want that water that has wicked in to the plywood all gone before even thinking about closing it up.

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Okay, I was wrong. A few fiberglass strands bashed into the wood colored foam fooled me. I've got no wood!

I beveled things at about 3:1 (figuring the trailing edge of a rudder is pretty low load) and sanded back ~2" from the start of the bevel. My plan is to just start laying up layers and build up the whole repair out of glass. is this a crazy plan? Is there something simpler that I'm missing?

Here's what things look like with the grinding complete...

rudder1.jpg.b436cc5039eb19ae97099d67713bf95a.jpgrudder3.jpg.c9f3500fd7186c1c30a469e4190b6b0b.jpgrudder2.jpg.8080e9ff1826bbe3b3cdaf799795cd43.jpg

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Oh, and I've got West System 105 + 205 and 1.5oz mat + 6oz cloth on hand that I figure should be perfectly adequate and not require a trip to the store.

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I would first rebuild the core shape with some thickened epoxy, then glass over that. West 207 filler is easy to shape and strong enough as a core replacement.

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^ This - building that thickness out of 1.5 mat and 6 Oz. cloth is going to take a jillion layers

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^^ Both of theses, plus you really want the bevel in the fiberglass skin to be closer to a 12:1 bevel.

Read the west system manual On fiberglass boat repair.  Avail online and really quite good.

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24 minutes ago, Crash said:

^^ Both of theses, plus you really want the bevel in the fiberglass skin to be closer to a 12:1 bevel.

Read the west system manual On fiberglass boat repair.  Avail online and really quite good.

Oh god, more grinding? Well, I guess I don’t have anything better to do while I wait for core to dry. :mellow: On the plus side, that can be accomplished with a beer or two on my bench. 

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On 10/19/2020 at 10:31 AM, brucephenry said:

Okay, got the rudder out (hat tip to @longy for advice on removing the head) and on the bench to ponder my options. I have a few questions.

First off, the rudder was submerged in freshwater for about a week after the “event”. When removed, I can best describe it as being “buoyant as hell”, the rudder shot to the top of the lake with me in tow. How long should I let it dry out for before glassing in a repair?

Speaking of glass, what weight/type cloth would y’all recommend for this type of repair?

85952A6E-263D-4ADD-94C1-3373C6A4C96C.thumb.jpeg.1f75f85d8558bab85a1091e67d10d21d.jpeg

7BEA83E8-01AE-44B0-8D31-15C97B22C561.thumb.jpeg.3c0e87a514dfecc40dc967f639317907.jpeg

I’m also halfway considering cutting away enough of the section that’s damaged to clear the prop. Although I’m seriously doubting the kid is gonna try the reverse the tiller experiment again. 

Nice ruler. I really like the Shinwa Japanese brand of machinist tools. Nice bevel gauges & unique squares. Switch to metric and your rudder will be more accurate.

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8 hours ago, CaptainAhab said:

Nice ruler. I really like the Shinwa Japanese brand of machinist tools. Nice bevel gauges & unique squares. Switch to metric and your rudder will be more accurate.

I have a metric one, but I didn't want to confuse the "old salts" on SA. :lol:

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10 hours ago, Crash said:

^^ Both of theses, plus you really want the bevel in the fiberglass skin to be closer to a 12:1 bevel.

Read the west system manual On fiberglass boat repair.  Avail online and really quite good.

Yes, as a general rule, but it doesn't look like a structural repair to me. 12:1 may make an unecessarily big project out of what appears to be a cosmetic repair. Plus, consider what the costs and dangers are if the repair somehow fails in the future?

As for cloth, use what you see inside there, and look at this:

https://www.westsystem.com/the-105-system/reinforcing-materials/determining-laminate-thickness/

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14 hours ago, brucephenry said:

Oh, and I've got West System 105 + 205 and 1.5oz mat + 6oz cloth on hand that I figure should be perfectly adequate and not require a trip to the store.

If you're using epoxy, it's not a good idea to use mat - unless it is stitch mat like  1708.  Regular mat will not smooth out as intended using epoxy.

With 6 oz cloth, you will need about 10 lams to build 1/8"  (0.125) thickness. 3 lams of 1708 will get you about 0.15"

For a rudder, I would consider triax.  If you can't source it locally, Fiberglass Supply in Burlington WA, has 19 and 22 oz versions at pretty decent prices.  I've bought quite a bit of fiberglass from them.  Excellent supplier IMO.  Quick order fulfilment IMO: http://www.fiberglasssupply.com/Product_Catalog/Reinforcements/Knitted_Fabrics/knitted_fabrics.html

Triax can be a bitch to cut straight using scissors.  Highly recommend investing in one of those "pizza wheel" rotary fabric cutters with a cutting board.  I picked up one with an 18" board from Michaels for something like $25 and it has been one of my more useful tools.  Leaves a very clean edge.

Fiskar.jpg

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+1 to the rolling rotary cutter (with a carbide edge). I actually wore out one disc and had to buy another but that was after cutting 100's of meters of glass

Agree on the thickened epoxy as a core repair.

Agree don't use regular mat with epoxy. It will wet out eventually - but poorly and slowly. The binder needs styrene to properly dissolve. I've done it but it's not good practice.

The final skin thickness is hard to tell but more than 1/8" is likely overkill. So a 1/8" x 12 = 12/8 = 1.5" lap. You're fine with 3" taper in the existing glasswork. 

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You can buy mat that uses a binder that will work with epoxy but you have to specify it.

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OMG! That rotary cutter is the BOMB! I don’t know how I survived without one. Seriously, this thing SO far exceeded my expectations. Great, GREAT suggestion!

Okay, back to getting everything in the garage sticky. 

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Okay, to start out this repair I have ground back a compromise 8:1ish bevel. Being that the whole thing needs to end up roughly in line with the trailing edge I needed something to hold that up. So I laminated a thin sheet of 2 layers of 6oz woven with epoxy and cut it to roughly the right shaper to be the center layer of the laminate on one side. I made it thin enough to be translucent so I could easily trace the area I wanted to cut it to.

IMG_0816.jpg.adaea50d2914fbee00a6368005042311.jpgIMG_0822.jpg.e1115223190701b3827ac85eb9a42033.jpgIMG_0823.jpg.7c7eccee7ade57abe28cba1de714d8ae.jpg

Then I mixed up a batch of epoxy thickened with silica and glued it in place after coating both surfaces with unthickened epoxy.IMG_0824.jpg.2d76e90b12d37cce29507ea2ffd417aa.jpg

Then flipping the rudder over, I faired in with thickened epoxy to replace the foam I had ground away and stuck the whole thing under a hot lamp to kick. Tomorrow I'll wash the amine off and sand to prep for laying up the 22oz glass that is supposed to be arriving today or tomorrow.IMG_0825.jpg.1457a6ac5228f0eb0e2c33d0b131a3c3.jpgIMG_0826.jpg.2169f090f860bdd220e42fa4fccedd3f.jpgIMG_0828.jpg.d54b98d421f30fcf8cf1b19e02d4378a.jpgIMG_0829.jpg.417a1ffc22753ac25bf69957662b962f.jpg

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22 Oz. glass?

Why so heavy?

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21 minutes ago, SloopJonB said:

22 Oz. glass?

Why so heavy?

That seemed to be the consensus above for building up a 1/8" skin without having half-a-bajillion layers. Previously I was thinking 6oz + mat, but folks pointed out that to build 0.125" I could do it in 3 layers of heavier cloth.

[edit] - I just got the box delivered and in fact I ordered 1708. So yeah, 22oz would have been overkill. 

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To build a 1/8" thick skin - 3 lams of 22 oz is about right.

Now whether 1/8" is too thick is another question altogether.  I don't have an answer for that - but I assume the OP resolved that that is how thick the original laminate was.

Fiberglass Supply has an on-line calculator for number of lams of varying cloths to obtain a desired thickness: http://www.fiberglasssupply.com/Product_Catalog/Reinforcements/Knitted_Fabrics/Knit_Laminate_Calculators/knit_laminate_calculators.html

image.thumb.png.840769b787e3e6592359120e3fbb6f91.png

Above is a screen shot for 1/8" of 1708.

If you're not using a stitch mat then you may want to up the lams a bit to 4 rather than 3 because the mat layer adds a fair amount of bulk.  For 18 oz I think it comes up with 5 lams for a 1/8" thickness. 

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The calculator is all in.... inches and pounds etc.  Shudder.

For non-mat stitched glass layups in metric world:

100 gm/m2 = 0.1mm thickness (well squeeged or vacuum bagged). A little thinner for vac. bagged, a little thicker for hand layup.

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9 minutes ago, Zonker said:

The calculator is all in.... inches and pounds etc.  Shudder.

For non-mat stitched glass layups in metric world:

100 gm/m2 = 0.1mm thickness (well squeeged or vacuum bagged). A little thinner for vac. bagged, a little thicker for hand layup.

Yeah, but I'm old school (very old school) - I still visualize everything in imperial units.  Never feel comfortable in metric - at least from an engineering pespective.  So I love this type of calculator.

You must remember exams where everyone is twisting their right hand with thumb in the air

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1 hour ago, 12 metre said:

Yeah, but I'm old school (very old school) - I still visualize everything in imperial units.  Never feel comfortable in metric - at least from an engineering pespective.  So I love this type of calculator.

You must remember exams where everyone is twisting their right hand with thumb in the air

Unless the charge was negative. :lol:

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Okay, here's what my layups look like. 3 layers of 1708 wet out with West Systems 105 + slow hardener (because I've got heat and a willingness to take my sweet time).

Starboard side
IMG_0834.jpg.b45ac96358f87e62305d500d8670ba74.jpg

Port side
IMG_0837.jpg.8ef6e9dd866b7517050c96dfab302695.jpg

I probably could have squeegeed some more of the epoxy out of the fabric, but it's not like it's a structural hull repair.

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Alright! Almost there...

Sanded the rudder fair having made sure the buildup was proud of the faired surface.

IMG_0847.jpg.58370ceb92583b56b71d42df518b3f1c.jpgIMG_0842.jpg.87da123745e176cd231cc114bba10a70.jpg

I'm going to scuff up the bottom paint on the rest of the rudder and repaint.

Question:
Should I prime that glass repair before bottom painting?

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What’s on the rest of the rudder? Your repair is all out of epoxy so no need for barrier coat, unless you sanded through any barrier coat on the rest of the (likely) polyester rudder while fairing. Looks like no barrier coat on the rudder to me

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7 hours ago, Will1073 said:

What’s on the rest of the rudder? Your repair is all out of epoxy so no need for barrier coat, unless you sanded through any barrier coat on the rest of the (likely) polyester rudder while fairing. Looks like no barrier coat on the rudder to me

I don’t see any barrier coat, unless it was black like the bottom paint. Is there an easy way to tell cured epoxy from polyester?

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48 minutes ago, brucephenry said:

... Is there an easy way to tell cured epoxy from polyester?

Epoxy/glass tends to have a milky colour often with a greenish tint.  

Poly/glass tends to be amber to red/brown.

You have great examples on your rudder - i.e. the original poly and the epoxy repair.

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On 11/3/2020 at 2:20 PM, brucephenry said:

Alright! Almost there...

Sanded the rudder fair having made sure the buildup was proud of the faired surface.

IMG_0847.jpg.58370ceb92583b56b71d42df518b3f1c.jpgIMG_0842.jpg.87da123745e176cd231cc114bba10a70.jpg

I'm going to scuff up the bottom paint on the rest of the rudder and repaint.

Question:
Should I prime that glass repair before bottom painting?

Looks like a nice job.

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On 11/3/2020 at 2:20 PM, brucephenry said:

Question:
Should I prime that glass repair before bottom painting?

No need - epoxy alone is a great primer. Just make sure it's been thoroughly washed (to remove amine blush), and sanded. From those photos it looks like you're ready to paint.

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Pray for me. Tomorrow’s the day to put on my wetsuit and try and coerce this back into the boat. I’ve remanufactured the Teflon bushing at the rudder-hull joint. 
Any advice on grease for the shaft? Stainless shaft in fiberglass tube.31D83BE7-6F7C-4A9A-B93B-F15442045249.jpeg.9fdf5233af0b59a15c68969c24c5ac7e.jpeg

C66899A8-FAEB-4421-BE08-124266FD8E1D.jpeg.dad8a68fe96ceb1ca071588091938e54.jpeg

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Water pump grease?

Very good looking work.

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Does rudder float? If so tie lead dive weights to bottom of blade. If it sinks, tie flat foam to top of blade. You want neutral buoyancy, you'll have enuff problems with the shaft always trying to point straight down. Can you tie a line to the top of the post? This is best way, get rudder to slight negative buoyancy, have top side person pulling up on line while diver works on angular alignment.

Pray for glassy sea conditions/no current

Good luck

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