Building a rudder

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Re: Building a rudder

Postby tc53 » Fri May 17, 2019 2:57 pm

After experimenting a bit with my router and a scrap piece of the 1/4" BB ply, I found that even with a minimal depression cut into the wood, the prongs of the torque washer extended through the other side once tapped in. So I tried simply tapping it into the surface of the ply without any depression, and the photo shows the result.
Washer.jpg
Washer.jpg (28.61 KiB) Viewed 1632 times

I suppose I could try glassing over that, but I am also wondering if I need that torque washer at all. Would a simple square hole, carefully drilled and filed through one of the cheeks (ply + 2 layers of glass on each side) be sufficient?

Greenlake, did you embed a squared off washer of some sort or just go with the square hole idea?
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Re: Building a rudder

Postby GreenLake » Fri May 17, 2019 4:04 pm

tc53 wrote:I am planning to use a 3/8" SS carriage bolt as my blade pivot bolt, and as part of that plan, I am hoping to glass in a 3/8" torque washer to hold the head of that bolt.


I am using a carriage bolt as well. I simply cut a square hole into the plywood and sealed it well with epoxy. The only torque this hole needs to withstand is the torque from (occasionally) tightening the wing nut.

This is different from the DS1 Centerboard, where the square hole is used to lift the board, which can take quite a bit of force on a long lever. That lever operated rather more frequently (and the friction to hold the CB in place may be partially on the mechanism, so that the square hole sees the torque from holding the CB in place. All factors that do not apply to the rudder.

That said, if you'd like to reinforce the cheek with a torque nut, why not. (I would "hide" it with glass/fairing compound a bit. You could also cut a depression, but then, as you noticed, you'd have to trim the prongs - nothing wrong with that, incidentally).

Question about the material. That nut does not look like it's stainless. That would concern me, as I have sailed in salt water.
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Re: Building a rudder

Postby GreenLake » Fri May 17, 2019 4:15 pm

On filling & fairing.

I would not bother trying to use additional layers of epoxy before gluing. Gel Magic like any epoxy glue is gap filling.

Clamping for epoxy: just watch that you do not squeeze out all the glue (as you would do for standard wood glue). Idea is to clamp just enough to hold pieces in place and perhaps to get extra glue out if you applied it way to liberally.

Regarding the top coat: I used a lot of QuickFair in getting a smooth foil shape. It looks like the chocolate kind of soft serve ice cream, something that I didn't feel would look good. That's why I ended up painting it.

If your rudder foil is shaped pretty well so that a careful fill coat or two will make it smooth, then I could see using WR-LPU and enjoying the varnished look.
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Re: Building a rudder

Postby tc53 » Fri May 17, 2019 4:58 pm

GreenLake wrote:Question about the material. That nut does not look like it's stainless. That would concern me, as I have sailed in salt water.

You're right, it is not stainless. I looked far and wide, online and in physical stores, and have not been able to find a SS torque washer. In the end, I picked up a few from Home Depot in "Rust Defender Grey," which they claim has "2X the corrosion resistance as hot dipped galvanized." I am hesitant about that too. Though I am strictly sailing in fresh water these days, who knows what the future holds?

I think I will go with the simpler "square hole method." Did you drill and file your square hole prior to glassing or after?

When I put my thin seal coat of epoxy on the core, I applied it with a 1/8" nap foam roller, per System Three's recommendation, but it did not come out very smooth. I wonder if a natural bristle brush would yield better results.

If I decide to stick with the blue Easy Poxy, I may use the container of Quick Fair that I have as I can get a smooth finishing surface with a single application, versus perhaps several fill coat layers with the epoxy. Until I looked carefully at the directions, I did not realize that the Quick Fair is (or appears to be) and "all at once" product. Is in not possible to use only a portion?
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Re: Building a rudder

Postby GreenLake » Fri May 17, 2019 5:13 pm

QuickFair: what I used was a two-part product, and yes, you need to use up anything you mix. The remainder (not mixed) keeps. So, don't mix all of it at once. If you mix to little for one application, just mix some more.

Not sure (unless I wrote it down in an earlier post here) about the details of drilling the holes for the cheeks. Most likely after glassing and before fairing/painting. Would be my guess.
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Re: Building a rudder

Postby tc53 » Tue May 28, 2019 10:43 am

Hi Greenlake. I have finished my fiberglassing and fill coats, and I am ready to drill my pivot bolt holes in the cheeks before gluing them to the core. Do you have any advice regarding how best to drill those holes. I want to avoid, if possible, any damage to the area around each hole. Will the cured fiberglass and epoxy help achieve a clean cut by the drill bit? When you drilled through your cheeks, did you start small with a pilot hole then gradually step up to the desired diameter, or is that not necessary? Did you drill outside to in, or the opposite?

Also, I think you said you embedded a SS washer on the outside of the cheek on the side where your butterfly nut is. Did you fiberglass that in? I did not, but I am wondering if I should apply a third fill coat and use that to "glue" a washer onto that side. Do you think that would work?

Thanks.
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Re: Building a rudder

Postby GreenLake » Tue May 28, 2019 2:25 pm

Don't recall any special drilling technique. Most likely used a "blade" drill, and those don't work with pilot holes. (However, not sure whether they work through fiberglass, so perhaps I used a different kind after all). Don't recall having trouble getting a clean cut. In any case, minor defects will not be visible once the bolt is in.

I rather doubt that I glued in the washer. Once you paint, the pressure will make it stick lightly to the paint, and anyways, if you are like me, you are never going to take that bolt out again (except for repairs). That washer isn't going anywhere.
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Re: Building a rudder

Postby tc53 » Tue Mar 03, 2020 8:12 pm

After breaking my rudder head on my last sail of the 2018 season, I built a new one in the spring of 2019. Following a design originally posted by Greenlake (plus a LOT of helpful advice from same), I used Russian Baltic Birch plywood (scrounged for free from an office furniture fabrication company, 1" thick for the "core" and 1/4" for the "cheeks." It was slow going, but I had it all put together and ready for sailing by the summer. Here are a few photos of my process and the finished product.

1 Core.jpg
Shaping the core
1 Core.jpg (22.92 KiB) Viewed 679 times


Using my old, broken head, I first created templates for the core and cheeks, outlining them with a sharpie onto some thin but stiff plastic sheets (with a graph-like grid on them; don't know what these are called, but they were invaluable in this step). Starting from scratch like this also gave me a chance to fix a problem I"d had for years with my old rudder head, which did not allow the blade to swing all of the way up to a 90 degree position because the curved cut-out in the bottom of the core portion of the head had not been cut properly. I used an old piece of 3/4" ply onto which I'd marked outlines of the core and cheeks, and through which I drilled a 3/8" hole for a blade pivot bolt so I could make sure I got that cut right. Both core and cheeks were cut on my band saw, then refined and faired edges on my belt sander.

3 Cheeks and core.jpg
3 Cheeks and core.jpg (21.48 KiB) Viewed 679 times



Once I had made sure the core and cheeks were properly shaped, I added two layers of 6 oz fiberglass (with System Three Epoxy Resin) to the insides and outsides of the cheeks for added stiffness.

4 Cheek Reinforce.jpg
4 Cheek Reinforce.jpg (20.97 KiB) Viewed 679 times
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Re: Building a rudder

Postby GreenLake » Tue Mar 03, 2020 8:18 pm

Looking good. Do you have any pictures with holes drilled, and assembled?
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Re: Building a rudder

Postby tc53 » Tue Mar 03, 2020 8:35 pm

Before assembling, I sealed the core with several layers of System Three Clear Coat and added a finish layer of epoxy resin to the fiberglass reinforced cheeks.
5 Core Finishing.jpg
5 Core Finishing.jpg (21.14 KiB) Viewed 678 times


6 Cheeks and Core Finished.jpg
6 Cheeks and Core Finished.jpg (21.78 KiB) Viewed 678 times


Then, after a light sanding of the sealed core, I glued the cheeks (one at a time) to the core using System Three Gel Magic (including a slight delay while I waited for a few extra Gel Magic nozzles to arrive; should have realized I would need more that the one it came with). Once all was solid, I added several layers of System Three WR-LPU to the entire head for UV protection.

Next, I added the pintles, the top one salvaged from my original head, the lower one a newly purchased one with wide (1.5") spacing between the straps so that I could avoid any compromising of the cheek stiffness. As luck would have it, both of these pintles still needed a good deal of reshaping (several hours with my vice and hammer) so each would fit properly. Also, again following very helpful advice from Greenlake, I created a "square hole" (making sure to seal it properly) in the starboard cheek to fit the 3/8" SS carriage bolt I would be using, with a thumb nut on the other end, for my blade pivot bolt. I also added a nylon bushing in the tiller bolt hole.

7 Finished Head.jpg
7 Finished Head.jpg (19.11 KiB) Viewed 678 times
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Re: Building a rudder

Postby tc53 » Tue Mar 03, 2020 8:50 pm

A couple of photos of the finished product, one alongside the old, broken head.
8 New Head with Blade.jpg
8 New Head with Blade.jpg (18.34 KiB) Viewed 678 times


9 Old and New.jpg
9 Old and New.jpg (21.24 KiB) Viewed 678 times


Because I repositioned the lower pintle, I had to change the position of the corresponding gudgeon on the transom. Also, in the spirit of "true confessions," I have to admit that I ended up having to drill a new tiller bolt hole once I tried installing the finished head and blade on the boat. I had used the old head as a template, but with all of my pintle repositioning, the first hole ended up being a bit low, not allowing the tiller to come down as low into the cockpit as I needed it to while still clearing the cam cleat I have on the transom deck for adjusting the traveler. The first hole (with its glued-in nylon bushing) serves as a constant humbling reminder to always measure twice, cut (or drill) once. :wink:

Finally, after sailing a few times and still seeing the underside of my tiller (recently refinished too) occasionally scraping that darned cam cleat, I added a stop for the tiller (a nylon busing held in place with a stainless screw) to prevent this.
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Re: Building a rudder

Postby GreenLake » Wed Mar 04, 2020 4:30 am

Hear you on the nylon stop. There's simply no way around it, if you want to keep your tiller from scraping. I don't have a cleat under the tiller, but I do put a piece of electrical tape on my coamings, because sometimes I lean on the tiller and the stop isn't enough to hold that much force. . .

Thanks for the pictures. Looking good and the 1.5" bracket for your pintle is something I wish I had been able to source when I built mine.

You don't mention it, or I missed it, but I hope you finished the epoxy with some UV blocking varnish. Clear is fine. I use untinted SystemThree WR-LPU which has worked well for me (while their paints based on the same chemical basis have failed for me on the hull). I like to use Satin or Semi-gloss because it is a tad more forgiving if your surfaces aren't perfect, but you should be able to get it in glossy as well. Applying it over epoxy is easy, per directions, and because sealed wood doesn't change dimensions with humidity, the varnish lasts much longer than if applied directly to the wood.
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