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Pourable foam for a rudder


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1 minute ago, Black Panther said:

Broken because stressed or broken because corrosion? 

Looks like foam got wet via inadequate shaft seal. Foam broke down unevenly, allowing excess strain on tangs, which work hardened and broke. Little corrosion evident, except for one small patch of galvanic corrosion on shaft....

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And bedded, then glassed... next, when this is gone off, the first of the pourable foam, just to see how that goes. Then side on the rudder, then fill with pourable epoxy foam. It'll be a couple of days....

20211120_115631.jpg

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Next stage, most of the foam done, decided to pour, and roughly shape,  as its pretty thick and I wasn't certain it would fill the space without voids around the tangs and edges.  Several manual pours, with brush/spatula to push into all corners. The idea is to get it close to shape, then paint on some more, clamp on the side panel,  and let the foam ooze out the seams...

received_836270660377684.jpeg

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Well, the result was not perfect. I should have drilled a few holes thru the top skin, as the foam trapped some air in there, and made 2 quite large voids (found with the hammer test). Now drilled the holes (DOH! would have been way better before) and had to inject some epoxy to fill them. Extra weight that's not needed :-( . Anyway, solid now. The foam is very tough - if you hit it with a hammer, it leaves a small mark.

I think the foam is a good solution, but definitely needs a breather at the top point to allow the air out! The foam, unlike urethane, does not produce lots of pressure, and when still soft is easy to compress...  

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Well,  done. Reinstall tomorrow. 

The cut in the side panel was V'd with a grinder, 2 x 400oz bi-axial cloth, faired, whole rudder covered with 2x 10oz boat cloth, faired again, 3 coats epoxy barrier coat. Just antifouling to go in this pic.

Install will be in water. We'll see how that goes!

20211126_093720.jpg

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Be interested to see pics of how you get it to sink the pointy end rather than the heavy end

lm sure you’ve got this sorted 

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31 minutes ago, Black Panther said:

When he was pouring the foam he added lead at the bottom. Smart.

Wasn’t that the keel ?

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all done and working. The rudder went back on in the water more easily than expected. This is how we did it;

Pin thru the top of the rudder shaft, no overlap, so the shaft can still be fed thru the bearings. Pin an interference fit, so it does not move. 

Rope loop on the pin, then thru the water, thru the rudder tube, tied off so I don't lose it!

Another line fed thru the loop, doubled so it can be removed when needed. 

Shorten the lines so only about 1m of slack...

Push the rudder off the dock by boat.  With the stock held at about a meter below the surface, the rudder is slightly buoyant, but easy to submerge further. 

Pull in the line fed thru the rudder tube, easing the doubled line as it goes, so that it doesn't swing around too much.

The end of the stock appeared in the bottom of the rudder tube, pretty sideways. Pulling on tube line, can lift it a little. Rudder itself out back of boat. Removed doubled line, pushed foot of rudder down hard with a boat hook, while tension on tube line. Rudder shaft came up passed 1st bearing, and with a little manipulation of the tube line, all the way in. :-)  Way easier than I thought  it would be, but then took a few hours to reinstall the mechanical quadrant, steering cables, hydraulic ram tiller, AP rudder sensor etc. 

All works fine, but the rudder fwd of the stock is a little too close to the hull when straight ahead. It scraped off some antifoul. I must has built it up a little too high, but its ok for now, and next time she is out I'll take a mm or 2 off that area - it's plenty thick there and wont matter.

All in all pretty happy. If I'd got a boat builder to do it, I'd have had no boat for Xmas, and had a big bill...

Oh, and while it was still opened up, I got the local Cat 1 inspector to have a look at it, so it shouldn't be a problem next time we want a cat 1...

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