Profile to F21 lifting rudder

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newt2u
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Re: Profile to F21 lifting rudder

Post by newt2u »

Now for the layup. I plan to use two layers of 50mm tape on the leading edge and a single layer of biaxial glass on each side. The biaxial cloth is sewn and works out at 480gsm. So first job today was to lay down the first layer of tape on the LE. I needed to clean off any dust and grease before I laid down the tape but you have to be careful with blue foam. I normally use acetone as a cleaner but look what it does to the foam. This is a test patch on one of the offcuts, where I dabbed it with acetone and methyl alcohol. The acetone patch is on the right.
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For this weight I weigh the glass and use about 120% by weight in resin. I laid it uo using a small brush working from the top to the bottom.
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The finished job. I'l have to wait until at least this evening in order to lay up one of the sides.
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Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

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drcscruggs
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Re: Profile to F21 lifting rudder

Post by drcscruggs »

Looks good!

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newt2u
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Re: Profile to F21 lifting rudder

Post by newt2u »

The leading edge is now cured enough to lay up the first side. I had enough biaxial cloth from a previous job to cover both sides. I used the offcuts from the foam to measure up and cut to size.
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One of the things I like about this biaxial cloth is that it is stable (its stiched) and drapes well over curves. It was a bit tricky getting getting it in place because the roughness of the foam tends to catch the weave. It must be lifted and replaced to get it in position. Then I wetted it out, again using the small brush but this time pouring and brushing rather than dipping and brushing.
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Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

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newt2u
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Location: UK

Re: Profile to F21 lifting rudder

Post by newt2u »

Today I trimmed of the excess glass from the first side and laid up the second.
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Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

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newt2u
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Re: Profile to F21 lifting rudder

Post by newt2u »

This morning I tidied up the excess glass around the edges of the rudder and then sanded the leading and trailing edges. On the trailing edge I just sanded it back square to the plate edge and I re-profiled the leading edge and tip. I also smoothed off the base of the rudder where it runs out to the plate.
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Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

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newt2u
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Location: UK

Re: Profile to F21 lifting rudder

Post by newt2u »

Structurally the rudder is now pretty much complete. The last step was to reinforce the leading edge with one more length of fibreglass tape.
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Tomorrow I will add a little filler to the edge of the tape and fair that off, then I have to think about how to finish it. Currently the layup has quite a rough finish from the weight of the cloth and its stitches. I want to finish with a gelcoat made from epoxy and fumed silica. This produces a thixotropic liquid, i.e. one that can be brushed on but becomes gel-like or viscous when left. It will also adhere to vertical surfaces. However I may also cover the whole rudder with a single sheet of lightweight cloth. I'll run a test on some of the off-cut bits of glass from the edge later today and see whether I can get a good finish as is.
Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

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newt2u
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Joined: Wed Sep 11, 2019 11:24 am
Location: UK

Re: Profile to F21 lifting rudder

Post by newt2u »

First a warning. Fumed silica is very nasty stuff, wear a good filter mask when using it as it is a very fine powder and isn'y good for your lungs. Anyway warning over, I mixed up 1 part Thixotropic Silica to 3 parts epoxy resin (by volume) and it seems to have done the job nicely. Its thick enough to cover up the stitching...
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... now I need to see if I can do the job in one go with the rudder sitting vertically. So I proped up my little off-cut and have left it to see if it works as described on the tin. I.e. does not run.
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Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

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newt2u
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Re: Profile to F21 lifting rudder

Post by newt2u »

Well it seems it was not as viscous as I thought; it did run slowly and although it left a few mm of coating on the vertical surface it was not thick enough to hide the rows of stitches. So it looks as if I'll be laying on the gelcoat one side at a time with the blade horizontal.
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Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

bad
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Re: Profile to F21 lifting rudder

Post by bad »

Do you have any experience with peel ply? You might find it is good at helping fill in the weave, plus it creates an excellent finish to glass on top or to paint. You also avoid amine blush.

Your can also try some taffeta or other nylon or poly cloth from the fabric store instead of peel ply.

Nice work and thanks for sharing. I've had good luck doing the tape under the biax. Seems like less fairing then.

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newt2u
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Re: Profile to F21 lifting rudder

Post by newt2u »

I’ve never used it. I do have some but never really had the confidence to try it. Maybe I should give it a try. Most of my experience has been in covering glider wings, where lightness is the biggest issue; lightweight glass and as little resin as necessary.
Rockin - F21 twin drop keels - located Milford Haven
Wintered in Shropshire where I am when I’m not sailing

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