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Old 08-12-2008, 15:50   #16
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You want to use at least 40 oz. biaxial which is pretty thick. I doubt you will get even thickened epoxy to not sag and settle to the bottom of everything. Build it up as the original was done. If it is all layers of glass than that is what you should do.
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Old 08-12-2008, 16:49   #17
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Before you cause yourself a lot of trouble, have you thought of vacuum bagging? It isn’t hard to do and will give you the best results – no voids—

If you have a couple inches around the cut out that you can tape a bag to gravity will not be a problem. However in any case laying-up more than inch at a time is not something I would recommend (too much heat generation, cures too fast = weak (er)).

You can generate plenty of vacuum with a shop vac no need to buy a vacuum pump although my current one was only about $150 and generates a lot of vacuum.

I would recommend using 17oz biaxial cloth (DBM1708 by Knitex) as it is light enough to wet out easily. (3 layers = 1/8 inch. / 12=1/2 inch) When You start the job wet out the cloth on a separate board (horizontal) and then transfer the cloth to the job after you squeegee out the excess resin, too much resin = weak end result. Add peal ply, bleeder material and tape the bag /turn on the pump… working at a decent pace you should be able to do the whole thing in a day or two.
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Old 08-12-2008, 16:57   #18
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Thanks for all of the tips / info!

Chuck - I should correct one thing - I said that it was solid glass encasing several inches around the rudder post, and the welds to the internal framework, etc. It does NOT seem to be layers of glass / cloth, but rather as soid block of glass (or maybe some substance like lightweight / porous foam, that was completey wetted with resin. What I was trying to point out was the fact that I could not just open it up, and look at the welds / framework, as they were encased in glass, and not just dry or (worse water-soaked foam).

I will likely take some pics next weekend, or over Xmas, so I can show it a bit more clearly!!
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Old 08-12-2008, 19:04   #19
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Northeaster,

I work mostly metric, I have used vector ply quad axial cloth and bi-axial Vectorply the quad that I used most recently for my repair spec out at about 1.5 mm per lamination at about a 55/45 resin to glass ratio the complete lamination was about 14-16 mm or 9/16"-5/8" as this was part of the hull repair it is very strong with no voids. In your case you could us a thicker cloth say it 3mm or 1/8" if you can lay 12 layers in a day that will give you 36mm or 1.4" half your required thickness. At the end of the day use peel ply, the next morning pull of the peel ply start your next lamination schedule again you will get a chemical bond as you are within the 24 hour window. The peel ply will handle the amine blush that occurs with epoxy. I suspect that you are going to have to faze your lamination into the existing and this may be better done using various lamination materials. You may find that by the end of the day as the heat builds up into part that the 60 minute time window will shorten the resin will harden faster. A 3" lamination is too thick it will cock off and you will end up grinding it out and starting over or your repair will be suspect. The beauty of laying up in stages is that you can control the heat in the part. I use one of those laser thermometer to keep control of my work. The best way is to plan your laminations by creating a schedule of cloths prior to starting work. The other method is to use a vacuum bag however you still have to control the thickness because of the heat.
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Old 09-12-2008, 15:15   #20
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As I do have a cheap IR temp gun, can you give some average temps that you would expect to encounter during the curing process. As I have a wood furnace in the garage, temps would be average 15-20 degrees celcius, when working.

Thanks again to you guys, for all of the information. As mentioned, I will try to take some pics of the opened-up rudder, before proceding. No rush, as I am 5+ months from spring launch!!
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Old 09-12-2008, 17:45   #21
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Nor-easter,

I was very distressed to read your recent posts, and the follow-up, and discover we (or at least I) gave you a bum steer (sic). In fact, I have had to rebuild 3-rudders--on a 1963 Rhodes Reliant; a 1976 Cal 2-29; and, most recently, a 1986 Beneteau First 42--and all were constructed, and the rebuilds all completed, in the manner described to you in my earlier, unhelpful, post.

From your description it sounds as if your blade was built with a core filled with resin thickened with micro-balloons (and maybe a little chopped mat for adheasion) but that is a totally different approach from anything I've ever seen.

I could offer some suggestions but as it seems you have no shortage of contributors already, for my part: "Here Homer nods".

The one thing that doesn't make sense to me given your revelations is your earlier report of the blade moving independantly of the post!?!

N'any case, please accept my apologies for the mis-information.

Sincerely,

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Old 09-12-2008, 19:17   #22
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HyLyte - Don't worry in the least. In fact, I would not say that I was given "the bum steer" at all. I really did not know what the condition was like inside, and from reading past posts, I felt, as well, that I would be able to open it up quite easily, to inspect the frame. I had not anticipated the thickened resin encasing the rudder shaft and its welds to the internal framework!

re: the movement between the top of the rudder skin, and the rudder post, as it passes through the skin - As i mentioned in my original post, it was an almost imperceivable movement - it was easier to see when we painted a small line accross the joint. Then when we turned the rudder hard (with the wheel tied), you could see the paint line distort a bit.

Although the lack of a perfect seal concerns me, due to possible water ingress, it does show that the post to internal framework can be strong, and yet there is enough flex in the combination of metal framework inside a glass shell, that you can see a slight flexing at the joint!

As you, and I felt though, this could have indicated possible water intrusion, and possible severe damage to the welds, etc.

When opened up, the inside (middle and top sections) were completely dry, and the welds (after iuncovering them) were strong.

I did not open up the lower section (yet, and may not), as the rudder post and internal framework stops 2/3 of the way down the rudder, as the bottom of the post is the pintle, that is mounted in the gudgeon on the skeg. Of course, the bottom of the rudder has top be sufficiently strong to move with the top of the rudder, when the wheel is turned. But, I am unsure as to whether it should be opend up, now that the top / middle sections showed in such good /dry shape.

Of course, any water that entered would have flowed to the bottom portion of the rudder, and most may have drained out the holes I drilled, as they are dry now. It's hard to say if there is much delamination of the skin, from the foam, but it may be more likely in the bottom. I rapped the whole rudder with the butt end of a screwdriver, and to my untrained ear, it sounded constantly sharp. I did not hit any dull sounding areas, that woudl cause me to suspect significant delamination!

As I will have some access from the opened middle section, I could pour epoxy resin down in the bottom section, and it should be absorbed by any pores in the foam, or spaces between the foam and skins.

Although this has caused me some "unnecessary" work, I would argue that it was necessary, given the age of the rudder, the signs of possible water intrusion, and the unknown condition inside. When I am done, I will know what I have!!
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Old 09-12-2008, 19:17   #23
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Quote:
As I do have a cheap IR temp gun, can you give some average temps that you would expect to encounter during the curing process.
85 to 100 degrees. Good luck
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Old 14-12-2008, 18:39   #24
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Here's a few pics of the rudder - opened up! I still haven't cut all of the glass away from the post / internal frame. I will do that soon, so I can weld some additional support in there, before suing epoxy / glass to fill the voids.
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Old 15-12-2008, 13:05   #25
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How far are the tangs apart from one another on the rudder post? How many are there? I think all the resin around your post and tangs was more for water intrusion than for strength and instead of welding another piece of stainless, I'd use a few layers of glass mat and cloth around the post and tangs (not 3" worth), fill the voids with foam and put your glass skin back on. Epoxy mat roving and cloth are very strong but just plain resin and fillers are not. If you feel your post and rudder are moving independently then you may want to gouge out about 1/8 to 1/4" at the top of your rudder where the post is and fill it with a flexible bedding caulk which will allow play and still keep it water tight. Something like Boat Life polysulfide?
These are just opinions and I'm certainly not an engineer just want to make less work for you.
I need to do what you have done but luckily my rudder is laying on my stone wall here next to the house so will be a bit easier. I know mine is in much worse shape than yours as I saw rusty water coming out the bottom when I hauled.
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Old 15-12-2008, 14:52   #26
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SkipR- the tangs are about 8-10" apart on the rudder post. 3 in total, top (which i haven't and will not be "uncovering" from beneath the resin), middle and lower. They are made up of longer SS tangs that are welded up against the post, with overlapping shorter ones, that are welded more on the sides of the post, and then scarfed on / welded to the longer ones, about 8" out from the post.

I agree with you, that the biggest reason for the encasing resin may have been to prevent water ingress, rather than strength. However, it did still add substantial strength, and there is cloth mixed in with the resin. It has not been an easy job to cut it away. Even when it is almost cut through, it is hanging on for dear life, as I try to pry, knock, and rip pieces out.

I am now just focusing on removing enough to allow me to add a couple more long tangs, to be placed in between the exising ones. Then I will place and weld a few solid plate pieces in between the tangs, and along the rudder post, tying most of them together.

I do think that 3" of epoxy and mat/ cloth wouyld be overkill, but I would rather fill the voids with this, and maybe some less strong thickened epoxy, instead of foam. I want to ensure that the side "skins" are bonded well, to the structure in the middle.
Just a thought, but what if:
After laying up several layers for strength, I may then start filling the void, a few inches up at a time, by filling the voids with some loosly folded cloth, (folds standing vertically) so that I could pour resin into it, filling the space. If I kept the new laminate work covered in peel-ply, just removing a few inches at a time, on my way up, I would still get a chemical bond between the more structural layers, and the more loosely placed layers of cloth and resin. I would use some type of cardboard, or flexible cutting board material to keep the outside shape as I worked / poured my way up. I could even have peel ply on this surface, so thaT I could lay up a few outside layers of cloth/ resin, to form the new skin.

Thoughts?
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Old 15-12-2008, 20:59   #27
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I was just looking at your pics and have a few comments.

First, S/S steel does not work well when it is starved of oxygen. What makes S/S stainless is a chemical process that requires oxygen to work.

Personally, I would have thru-bolted that gudgeon over the top of the skeg and not glassed over it. That would also allow you to service your rudder and inspect the gudgeon from time to time.

It really wouldn't be that hard to cut that glass off of that thing, Have a new gudgeon made (or not) and remove that rudder so that you can work on it.

Next, I am a little surprised at the size of the rudder stock. What size is your boat?

It's pretty hard to find a boat out there that doesn't have water inside the rudder. It has been my experience that every boat that I've ever drilled a hole in the bottom of the rudder drained water for quite some time. I don't feel that is a huge concern. The blade moving independently from the shaft is a big concern. The only way that can happen is if you have a broken weld or the F/G has become completely detached from the frame.
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Old 16-12-2008, 06:29   #28
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Kanani - Thanks for taking the time to look at the pics, and reply.

You do make very good points! I WILL ADD MY COMMENTS ON CAPITALS!



I was just looking at your pics and have a few comments.

First, S/S steel does not work well when it is starved of oxygen. What makes S/S stainless is a chemical process that requires oxygen to work.

Personally, I would have thru-bolted that gudgeon over the top of the skeg and not glassed over it. That would also allow you to service your rudder and inspect the gudgeon from time to time.

- IN HINDSIGHT, THROUGHBOLTING ON THE OUTSIDE WOULD HAVE BEEN A GREAT IDEA. I GUESS I NEVER THOUGHT OF IT, AS THE OLD ONE WAS GLASSED IN, AFTER BEING THROUGH BOLTED. ALTHOUGH YOUR IDEA IS BETTER, SINCE I PRACTICALLY DOUBLED THE THICKNESS AND SURFACE AREA OF THE OLD GUDGEON (WHICH HAD LASTED 20+ YEARS) I AM CONFIDENT, THAT THIS ONE IS GOOD FOR A LONG WHILE. THE OLD (TYPICAL) GUDGEON WAS MUCH BETTER FOR REMOVING AS IT WAS TWO PIECES, ONE BOLTED ON ONE OF THE SKEG, WITH A LOWER HALF TUBE FOR THE RUDDER STICK TO REST IN, AND THE OTHER SIDE BOLTED TO THE OTHER SIDE OF TEH SKEG, WITH AN UPPER HALF TUBE FOR THE STOCK TO PASS THROUGH. ALTHOUGH THIS MADE IT POSSIBLE TO UNBOLT THE TWO PIECES AND DROP THE RUDDER MORE EASILY, THE WELD AREA ON EACH SIDE TO THE TUBE PORTION WAS QUITE LIMITED. IM MADE A CONSCIOUS DECISION TO MAKE A ONE PIECE GUDGEON, THAT WOUDL BE MUCH STRONGER, ABLEIT MUCH TOUGHER TO GET OFF.

It really wouldn't be that hard to cut that glass off of that thing, Have a new gudgeon made (or not) and remove that rudder so that you can work on it.

SINCE THE GUDGEON IS VERY STRONG, AND WELL GLASSED, AS WELL AS THROUGH BOLTED TO THE SKEG, I DO NOT SEE ANY CURRENT BENEFIT FOR REMOVING IT, OTHER THAT MAKING IT EASIER TO WORK ON THE RUDDER, OFF THE BOAT. I DO FEEL THAT I CAN STILL DO A GOOD JOB ON THE RUDDER, WITH IT IN THE BOAT, AS LONG AS IT IS WELL THOUGHT OUT.

Next, I am a little surprised at the size of the rudder stock. What size is your boat?

RUDDER STOOCK IS ONLY 1" DIAMETER. BUT SINCE THE BULK OF THE FORCE IS TAKEN BY THE SKEG GUDGEON HOLDING THE BOTTOM OF THE RUDDER STOCK, IT SEEMS TO WORK WELL. OBVIOUSLY, IF IT WERE NOT SUPPORTED AT THE BOTTOM, LIKE SPADE RUDDERS, THE STOCK WOULD NEED TO BE CONSIDERABLY LARGER.

It's pretty hard to find a boat out there that doesn't have water inside the rudder. It has been my experience that every boat that I've ever drilled a hole in the bottom of the rudder drained water for quite some time. I don't feel that is a huge concern. The blade moving independently from the shaft is a big concern. The only way that can happen is if you have a broken weld or the F/G has become completely detached from the frame.

IT'S GOOD TO KNOW THAT WATER IS A COMMON PROBLEM!

RE: THE (BARELY PERCEIVABLE) MOVEMENT BETWEEN THE STOCK AND THE TOP OF THE RUDDER GLASS - IT IS JUST A BIT OF FLEX IN THE FRAMEWORK TO GLASS BODY OF THE RUDDER, ETC. THERE IS NO MOVEMENT (LIKE 1/8" OR MORE) AS WOULD BE THE CASE WITH A BROKEN WELD / FRAMEWORK!!
THE APPEARANCE OF A SLIGHT MOVEMENT MAY HAVE BEEN WORSENED BY THE FACT THAT THE TOP RUDDER BEARING BEING NOT VERY PRECISE (A BIT LOOSE -WILL BE REPLACING IT WITH A BETTER ONE). THIS ALLOWS THE STOCK TO MOVE A BIT, WHEN I AM PULLING / PUSHING ON THE RUDDER BLADE TO LOOK FOR MOVEMENT. RESULTS IN A BIT OF A TWIST OF THE BLADE AND STOCK!

THANKS AGAIN FOR THE IDEAS!! I WISH YOU HAD SUGGESTED THE OUTSIDE GUDGEON THROUGH-BOLTING LAST WINTER!!!
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Old 16-12-2008, 08:14   #29
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I suspect your idea of loosly folding glass in the cavity you created will quickly be discarded when you see all the air bubbles/spaces you can't get rid of while the rudder is vertical. Perhaps vacuum bagging would be an option, but I think your best bet is to rebuild with what was there--thickened epoxy that won't run and some glass. The bond with the edges of your cavity won't be strong unless you fair in your repair. Since that isn't an option, you are relying on the skin layer of glass to tie in your repair. Focus on strength for the glass you wrap over the cavity. Best of luck.

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Old 16-12-2008, 10:26   #30
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Brett - I really appreciate all of the advice and opinions that I am receiving. I am quite handy, but don't have alot of experience with fiberglass and / or epoxy, other than a half dozen projects like glassing over a through-hull, building new winch bases, the skeg repair, and a few fiberglass boat repairs years ago.

I hadn't thought that voids/ air bubbles would be an issue, as I could pour the resin in between the vertical folds of the cloth. But, I haven't tried it yet, so I will take your advice into consideration. I would still have access to the cloth /resin to move it about, and try to get rid of the bubbles.

Re: the adhesion to the outside layers - would unthickened ( or thickened, but having brushed all surfaces 1st with unthickened) epoxy not bond reasonably well to the rough inside surface of the outside skins???

I would think that it would bond better than simply filling the void (between the framework and the outside skins) with foam!! Feel free to correct me if I am wrong in this assumption!!!

I believe than when hull / decks are laid up, with a cored surface of balsa, or airx foam, the resin sinks into the pourous core, and therefore bonds the outside cloth layers to the core material very well. Of course, if it gets wet inside later, it will weaken the bond, and casue delamination, etc.

I do not think that just filling the void with foam would give me significant adhesion to the sides, unless the foam was somehow soaked in epoxy / glass resin.

In the end, I will beef up the internal framework , by welding in extra tangs / SS, and then I will use epoxy resin and glass to cover over the framework (thickness to be determined) to give it more strength and prevent water intrusion in the future).
Then i will have to fill the approx 1" void on each side (between the framework and the outer skin) with either foam, thickened epoxy, unthickened epoxy and cloth/mat, or a combination of those materials.

My main concern here is to adhere the skins to the middle framework as much as possible, and to prevent / minimize water intrusion in the future!
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