i am making a rudder

[AlanH]

Since no spare J-29/J-30 rudders seem to be forthcoming, I'm going to make my own new wood core rudder.

The basic idea is to build a core of 2 inch thich, 1 3/4 inch wide doug fir strips. They're cut from straight grain doug fir 2 x 8's. Then you randomize the strips by reversing a few and mixing them up so that the strength in the rudder goes everywhichway, and also, in case any water gets in there, any distortion in one strip isn't carried out through the whole rudder as it would be if it was all one piece of wood.

Glue the strips together into a 2-inch thick, 16 inch wide, 7 foot long board.

make a NACA foil jig for a the rudder, and use the router on the jig to form the foil.

Sand. Fair. Sand

overlay with epoxy in 8-10 oz cloth...maybe consider putting a layer of kevlar along the leading edge.

sand, fair sand..paint.

Make hardware... put on antifouling, mount on boat.

I will document all this with photographs, etc.

OK, $208 later, for straight grain doug fir, plus some re-sawing
$40 for two more bar clamps that are bigger than 1 foot span ( I had two already)
$50 for a Ryobi 1.75 hp router of of craigslist, and we are on our way.

 

[AZ Sailor]

Neat project. Looking forward to the pics and reports.

 

[AlanH]

Lookie what I generated....



The inner shape is the foil x-section itself, printed at real size. The outer line is the shape for the top of the router jig. The router bit needs to be set at a depth of 38 mm.

How did I get that? Look here.

http://www.duckworksmagazine.com/09/howto/foils/index.htm

This is what I'm doing. Read the article, download the foil generator and router-template generator.

 

[AlanH]

OK this weekend saw me do the rudder blank glue-up.




Rudder is 7 feet, 10 inches long, overall. Essentially, 50 inches of that will be submerged. The bit on the left is the trailing edge, which is thinner pieces than most of the rudder. I epoxied that on, tonight (sunday) along with two strips that will be the leading edge. This rudder will be about 12% balanced. The chord is 15.5 inches. That's close enough to 16, which is what I planned.

My shortest piece was 7 feet long. I cut everything to 7 feet, which was stupid, as I wanted a 7' 6" + rudder. Me=dummy. So I wound up offsetting some joints. The ones you see in the rudder closest to the camera don't worry me even though they line up a bit too closely, as that's the absolute bottom of the blade and the loads are minimal down there.

I wouldn't make a mast like that, though. Also, there are NO joints anywhere near the point of maximum load, which is right near where the bottom gudgeon will be.

 

[AlanH]

Here's the final glue up...leading edge and trailing edges are on. I ran out of wide clamps so I'm resorting to taping...yes, taping on a couple of small pieces that are really only there for shaping and fairing. There are a few bit of wood in there to support things while they dry. They're covered with wax paper so I don't glue them to the rudder. The leading edge is to the upper right in this picture, trailing edge to the lower left. There's a little strip in there between the main body of the rudder and the piece that will form most of the leading edge. I needed that to make the 12% balance. Without it, it would have been 10% and I wanted just a scooch more than that, but not 15%. Most of that wood will be removed by the router forming the leading edge of the foil, but if it's not perfect, I'll just fair it. It's going to be close, anyway, and there's a lot of gluing surface holding everything on..



I cut off a few bits along the bottom that I epoxied together...these are squares roughly 2 x 2... and I can't tear them apart. So that seems pretty strong.

The whole thing probably weighs about 45 pounds right now.

 

[AlanH]

On to the rudder foil templates. They're made out of plywood.

Look at this image-

This guy made his template foils out of particle board. I'm using plywood. No big deal. I mucked up the first foil template by not paying attention while running the jigsaw... moron mistake, so started over. The second one came out fine, but that meant a visit to Orchard Supply to get a cheap 2 x 2 piece of plywood for the other template. Since they had no 3/8th ply, I bought a sheet of 1/4 inch, cut two 5-inch widths to size and I'm glu'ing them together with Weldwood to make a 5" by 24" x 1/2" piece.. OK, so one side of the router carrier will be 3/8 and the other side will be 1/2. It's just the router carrier. While I was at OSH I bought a couple of new jigsaw blades, "many teeth" and narrow profile for cutting curves in wood. That worked like a charm and I now have one remarkably accurate foil template. Handholding the jigsaw and going slow was just fine, I didn't need a scrollsaw, which saved a drive up to San Bruno to get a used one off of Craigslist.

I'm contemplating whether I need to run my whole rudder blank through a planer to take down the high spots. Hmmm. Who's got a 16 inch wide planer, I wonder.

Progress!

 

[AlanH]

It occurred to me that this would be a great way for someone to knock out a simple emergency rudder for the TransPac for a smaller boat. You could "go simple".... Three dry and straight 5.5 - 6 foot 2 x 4's plus a 2 x 2 would give you a 12 inch chord with a rudder thickness of 1.75 inches. That's very roughly J-24 size, and significantly thicker. If you wanted a bigger chord, just use another 2 x 4 instead of a 2 x 2. Glue all the pieces edge-to-edge with epoxy. Make a foil template like what I'm doing if you're hardcore, or even rough one out with the table saw, a surform plane and a bunch of sanding. Just shape the leading edge to be nice and round, and taper the back half of the blade to about a 1/8 inch wide at the back. It won't be perfect, but it's easy to do, just time consuming. So, in summary, shape the bottom half into some sort of foil, leave the top half un-shaped...just rectangular. Front and back should be straight up and down...parallel.


Cut the leading edge, in the unshaped top half of the rudder back about 20%. That's right, 20%, which will be about 2.5 inches for a 12 inch chord. That's a lot. Why so much? Read on. Put a layer of 8oz glass in epoxy over the whole thing. Sand, and sand some more. Now you probably have a rudder blade with a 12.25 inch chord and almost 2 inches thick. That's pretty bluidy strong. Epoxy/bolt something to the top so the rudder doesn't slip all the way through the cassette. Paint, and admire.

Now build a cassette that will accept a rudder that's the thickness of the upper half of your blade, but with an fore-and -aft dimension big enough that you can slide the bottom half down inside. When it's all the way in, it will wobble fore and aft because the top half of the rudder is 2.5 inches smaller in chord than the bottom half. Now, make a 2.5 inch wedge/spacer out of some 2 x 4. Tap that into the cassette behind the rudder so that it pushes the rudder forward in the cassette and jams it into place. No more wobble.

Upshot...semi-balanced emergency rudder in cassette, U-Bild-It-At-Home-4-Cheep

The major problem with my e-rudder from 2008 was that while it steered the SC27 just fine, the leading edge was a good 3-4 inches behind the rotational axis. It was horribly UN-balanced and loaded up immediately. This system I outline above would make a somewhat balanced rudder, depend on exactly how you fit the cassette to the pintles on the back of the boat.

For reference, my S-2 7.9 has a kick-up rudder (until I finish this one). That's the stock, 1-D rudder. The rudder is 3 inches thick, about 20 inches chord at the top and 13 inches chord at the bottom. Top to bottom of the submerged part is about 44 inches. The cassette is made up of hardwood, basically 2 x 4's at the front and back, and approx. 1/4 inch aluminum plates for the sides. It's all held together with about 5, 5/16ths through-bolts at the front, and 5 more bolts at the back. The gudgeons are massive custom stuff that wrap around the front 1/3rd of the whole thing. Any metal shop can make them up but they'd cost a mint. I can think of other ways to make gudgeons that would cost a LOT less.

This is an ENORMOUS rudder. It's bigger than a J-29 rudder, on a 26 foot, 4500 pound boat.

 

[Submarino]

That is neat! I would love to see a seminar on how to make your own.

 

[AlanH]

You can buy foam "blanks" from flyingfoam.com

That's what I did in 2003, to get ready for my disastrous 2004 attempt. I got one of those and then glassed the snot out of it.... like used this stuff that I can't name right now...it's heavy mat and roving stitched together... two layers of that with Unidirectional carbon in between.

Then I made a cassette out of doorskins, reinforced with carbon. I did all this in my garage.

It's do-able. ---just a lot of work. Or you can do this, what I'm doing here, which is also a fair bit of work but it's at least half wood-work and not so much epoxy-yucky-work.

 

[AlanH]

Today I made the router carrier/foil template for the project. I cut the foil shape in one piece of plywood the other day with the jigsaw, as explained a couple of posts, above. I then used the printed pattern from the Excel spreadsheet to mark the cutouts where the plywood foil template has to fit over the unsawn board. Then, fortunately before I cut that out, I went and compared it to the rudder. It was a good 3/4 of an inch too big. Not only that, but the offset for the router bit depth was 4-5 mm too big. What the heck?

Come to find out that apparently the Excel program works great, but just because it generates an accurate foil and router-offset pattern does NOT mean that your printer will print the exact dimensions. BE WARNED....print your pattern and compare it before cutting! I had to go back and enter new numbers in the Excel spreadsheet to generate an exactly-sized paper pattern to work from. This is trial and error, but I guessed well, and the second time I taped the printed pieces of paper together, I hit the right sizes.

Once I did that, I re-marked the plywood I'd already cut, which was fine as the new template is smaller than the earlier, wrong one. So I cut out two plywood foil templates, and two blocks, exactly half the thickness of the rudder blank for the foil templates to ride on. Add Weldwood glue and clamps and....




Here's the router carrier/foil template...the dark wood was cut from a lap tray I made for Joan when she got her hips replaced a couple of years ago. I didn't need the plywood or the tray, so now it's been re-used. The other stuff is junky plywood and scrap, cut-up 2 x 4's. It bugs me that the two templates are different thicknesses, but it totally doesn't matter.

 

[AlanH]

So this rudder will be comparable to a J-29 or J-30 rudder except that this one will be balanced and the One Design rudders for those boats are not balanced. The entirety of the One Design rudder blades for those boats are behind the axis of rotation of the rudders; the entire rudder is aft of the gudgeon/pintle pin axis. Balanced rudders are not class-legal...though maybe the classes should make them legal as those guys all talk about how their rudders load up something fierce on a long, heavy-air reach.

Anyway, Competition Composites..aka "Phils Foils" makes a balanced rudder for the J-29/J-30. It's a beauty.

http://www.fastcomposites.ca/site/wp-content/uploads/2013/06/J30BR-gallery-2.jpg

...It's also $2400 (Canadian dollars) cha-chiiinnnnggggg....though honestly probably worth every loonie you pay for it.

Rudder Craft also makes a balanced J-30/J-29 wood-core rudder. It's $2100 USA. Waterline Systems makes a class rudder theoretically for $1400, but it's not balanced and they didn't return either of my e-mails. Larry Tuttle at Waterrat quoted me $2K for a much "hotter" elliptical rudder, and I thought about that but two thousand dollars is a lot of moolah for this guy.

Rudder Craft makes rudders which are somewhat smaller than these which would probably work for my boat, but the largest one they make and market for 24-26 footers is made of machined HDPE plastic. That stuff bends under load. If I was just cruising around I might not care, but.... They also make an $895 wood core rudder, but it was just a scooch smaller and thinner- aka "less robust" than I wanted. It probably would work, but it would suck to find out that it didn't on the LongPac Racae, 185 miles out. On the other hand that $895 plus shipping includes custom rudder gudgeons for 5/8th inch pins, and those are about $350, right there. But still, their wood core rudder was just a bit too small and thin for what I wanted. I wanted ridiculous BEEF.

So here I am, making a rudder. I should also add that I am NOT a "fine woodworker". I have Orchard Supply level tools...a small table saw, hand drill, cheapo jigaw, cheapo circular saw, and now a pretty decent router, but seriously...I'm making this on my garage floor.

 

[AlanH]

Today I made the *Flat* surface/table that the rudder and router guide rest on. That was pretty straightforward, glued-together particle board and 2 x 4's, with outdoor deck screws. it rests on the sawhorses that I use for working on cabers.



I then "microadjusted" the router guide/template with the table saw so it fit to close tolerances over the rudder. It's great at the top and to about 2/3rds of the way down the submerged part. I'll have to shim it below that. This photo is taken just where it's starting to get a bit loose. I also had to plane down some of the epoxy dribbles, since this was the underside, while I glued it. That wasn't bad, though.





Then I started to set up the router. I'd bought a nice 3/8 round router blade at Home Deport, so after futzing around, trying to figure out how to change bits, I finally got it in the chuck, only to discover that it's not long enough. Come to find out that there are "router bits" and there are "extra long router bits"..... GRRRRR. That's $20 shot, as I destroyed the packaging getting it open. Oh well, now I have a router, and I expect that I'll need some bits someday. So no foil shaping today. Instead, I trimmed off the top and cut the angle in the back edge, above the waterline.

 

[AlanH]

I was going to post a video of myself, happily routering-away, removing wood at a great pace and forming a perfect foil. Haha! One of the guys on the Wooden Boat Forum said that he'd made his centerboard in 45 minutes, each side. Haha!

NOT.

After 4 hours of work I have about 3/5ths of one side done.You know how it is, about 1/3rd of the way through the job you figure out the best way to do the job.

Gaaaa.... I discovered that router bits drift in the chuck after a while. You have to check them every 10-15 minutes. Imagine how I figured that out. Except for the godawful area where the bit moved, which will have to be faired, bigtime, most of the body of the thing is tolerable. The trailing edge is OK. The leading edge is disgraceful. Now I know why the guy in the YouTube video used an elliptical edging bit for his leading edge. I'll be able to fill with epoxy and wood dough and it will be fine, but yeeeecccchhhh.

I refuse to show you all photographs of this mess.

 

[AlanH]

All this stuff about emergency rudders got me inspired. I grabbed some lumber that's been sitting down the street, in an empty lot that used to have a house on it, a few years ago. This stuff has been outside for 18 months-plus. I thought it was doug fir, or "construction hemlock" but when I cut it, come to find out that it's redwood. Hmm. This is for an emergency rudder, that will go in a low-tech cassette.

Anyway, I cut the bits out and put in two pieces of mahogany from Home Depot to add some stiffness. I carefully chose bits of redwood with the fewest knots, and actually scored pretty well, there are almost none in the rudder. And then in a fit of cheap, I edge-glued them with Loctite PL100 polyurethane because I had a tube of that lying around but no epoxy.

Before everybody loses their minds over the PL100 I have to say that I use the stuff to fix cabers for the Scottish Highland Games and that stuff is strong. The cabers stay out in the rain and weather until we finally bust 'em and invariably the wood goes before the PL100- wood bond breaks. AND, the stuff is $6 a tube. Cheapo home-builder dudes who knock together semi-disposable plywood boats use PL100 to seal seams and glue stuff together all the time.

I dunno about redwood. It's light, I'll say that. This will be an experiment. The blade is now 7 feet long overall, but that's because I have to cut the top off at an angle so the rudder can get over my transom. The thing may get used on George McKay's Capo 30, too. The foil part of the blade is going to be about 40 inches. While I was at TAP plastics today they had 4 1/2 feet of linear carbon, 12 inches wide in the "2/3rds off" bin. WTF, I bought it, it was $7.. I'll cut some 2 inch wide strips and lay on there, to reinforce the rudder/cassette line to help the redwood. Then laminate over it all with bi-directional glass in epoxy. The chord is 13 inches, the stuff is 1.75 inches thick, by the time I fair it and glass it, it will probably be close to 2 inches thick. Beef, I think. It might not be pretty when it's done but it will be strong. I'm sort of mentally assuming that the redwood will contribute minimal strength. It will be more than foam, for sure, but way less than douglas fir.

 

[AlanH]

Actually, turns out that it's not that bad. --- looking here: http://www.woodworkweb.com/woodwork-topics/wood/146-wood-strengths.html

I'm guess that "compressive strength perpendicular to grain", is probably the most likely thing that would be applicable to shearing off a rudder with side loads..

Doug Fir, depending on where it grows, is 1100 - 1400 psi
Young growth Redwood - is 1100 psi. so, in the ballpark.

 

[Lanikai]

Sounds like progress to me.

On an only ever-so-slightly related note, TechShop just shuttered operations with zero notice. Bay-Area-Tech-Shop-announces-closure-of-locations The place was a major boon to us apartment dwelling sailors. I had all sorts of boat project hopes based on the tools I learned to use there, including e-rudder and windvane foils on the CNC, but alas.
There are other "maker spaces" around the bay, but nothing I've seen yet really compares.
This event has me considering - god forbid - putting my priorities in their proper order: home ownership (+garage+basement+yard workshop space), THEN boat ownership!

 

[AlanH]

Sounds like progress to me.

On an only ever-so-slightly related note, TechShop just shuttered operations with zero notice. Bay-Area-Tech-Shop-announces-closure-of-locations The place was a major boon to us apartment dwelling sailors. I had all sorts of boat project hopes based on the tools I learned to use there, including e-rudder and windvane foils on the CNC, but alas.
There are other "maker spaces" around the bay, but nothing I've seen yet really compares.
This event has me considering - god forbid - putting my priorities in their proper order: home ownership (+garage+basement+yard workshop space), THEN boat ownership!

Oh, man. that SUCKS. I know a dozen people with memberships, who will be upset by this.

On the home front, I smoothed over the worst of the part that I gouged up pretty badly with the router, when I first started. This is on my primary rudder. The leading edge is now acceptable for this stage. I built up the worst gouges with epoxy and sawdust...not even wood dough, sawdust. They're back to acceptable now, but for one dollar-sized high spot and a ragged inch on the trailing edge. I'm going to need another box of wood dough.

Tomorrow, back to the router.

 

[AlanH]

Today I finished off routing one side of the blade, flipped it over and did the leading edge of the other side. It's not turning out as thick as I'd wanted, so I'm scabbing on some"cheater" 3/16ths inch fir strips, which I will rout and belt sand. I also got the first "fairing" coat of epoxy and sawdust on the leading edge side that I did today.

Tomorrow I'll use the surform plane to even out the leading edge on that side, and then fair some more with epoxy and wood dough. If I can, I'll route out the trailing edge. If that's the case, then the basic forming of the overall shape will be done.

 

[AlanH]

OK, I used the router for about 2 hours again today, and finished the essential shaping of the foil. I'm adding on some thickness at the thickest part, as that's undersized, but the basic shape is done.

Here's my setup in my "workshop" aka, the driveway.



and some close-ups of the process, showing the degree of smoothness (not much) and accuracy (so-so) that I'mm getting on the trailing faces.

 

[AlanH]

Work has been progressing, but nothing big until today. The little stuff? After doing my thing with the router I noticed that it was cutting almost nothing at the thickest point of the chord. That seemed odd so I did some measuring. I decided to glue a couple of 3/16th strips, 2 inches wide, most of the length of the rudder, at the thickest point of the chord (on both sides of course). Then I went over it with the router again. --MUCH better. Also, since I'd developed some technique with the router/template, and I was using a larger ball-shaped-bit, I went over the back 1/3 of the chord over most of the rudder and cleaned it up. That really made a difference on one side, in the bottom 1/3rd of the foil.

Anyway, that was yesterday. Today was belt-sanding out all the router grooves, which went very fast. Then I blopped in some spooge of wood dough and epoxy and filled in the worst of the gouges, faired part of the leading edge to the first "strip" and shaped the bottom of the rudder.

The bottom was an issue...what to do? Should I leave it more or less square, like and old-skool J-24/29/30 rudder or an an "elliptical" (haha!) trailing edge to the bottom? OK, well "elliptical" I don't know but this is what I have. It still needs a lot of smoothing, but the shape is there.



And here's a view of the "One-side-is-wood-dough/epoxy faired-step one" setup on my workbench. The chain is holding down a strip of the extra wood that got lifted during the routing process. There's a piece of plastic between the chain and the wood/epoxy.



The "really brown" part in the lower right is where I did the very first few passes with the router. I cut way too deep so there's a LOT of epoxy/sawdust or epoxy/wood dough in there to build it up. It needs one more "go" with the wood dough/epoxy and then some sanding before I'll call it good.