Rudder Issues

[jray]

Rocky, the single works great. I have pushed the limits on the Twist. By the time you loose rudder control the heel angle is so great that the boat isn't performing well at all. If you build a cassette single you could rig.it to lift on down wind runs. I leave mine lashed down and still have gotten on plane. Watch out for a very responsive helm when you get to that magic speed. It is a bit of a rush!

Back to the rudder, mine is built to the plan, height and cord measurements but is in a cassette and has a different foil shape then the plans.

[ryderp]

Rocky,

I gave a small bit of thought to double rudders since that's what I was used to with our e-scow, but went with the single retractable rudder in a cassette. I'm adding some ski-boot-like cable latches to the cassette this winter so that I can easily lock the rudder in any (vertical) position. I have a whole lot more authority with the single rudder than I do with the tiny rudders on the scow, but would guess that the doubles that you are talking about would be much larger and would give you good control.

Phil

[lohwaikin]

I notice there is not much discussion about rudder cassette design.
I love the simplicity of a fixed rudder, but it is highly likely I'll be sailing in or exploring shallow waters.
I am expecting some rudder strikes from unmarked sand bars, underwater trash (mostly abandoned fishing lines) and my ignorance of the tide....
With a fully trunked rudder cassette, I'm not sure if the assembly will be ripped apart during such encounter.
I was wondering if this design will work on the i550 (see image below)....

0.jpg

May I know if anyone care to share a view of your "rear end"?

I sailed the Laser Pico before and really love the forgiving nature of the flip-up rudder-tiller assembly.
Not sure if there is such rudder cassette commercially available for the i550 foil size.

Cheers,

[jray]

I thought hard about a kick-up rudder. Decided to go with a cassette and have been happy with the decision. I don't sail in areas that are shallow much. The only company I know of that advertises kick-up rudder systems is RudderCraft.com Might be you could purchase their hardware and use your own rudder.

[Big_Dog]

Yellow Canary had a similar rudder design.
http://www.epoxyworks.com/32/pdf/Buildi ... Canary.pdf
http://forums.sailinganarchy.com/index. ... pic=119477

Merry Christmas

[ryderp]

I don't have a photo of my rudder cassette, but I did cut the trailing edge of my cassette so that the rudder could pivot if it hit something. That feature worked, but it also started pivoting when I was going fast. The rudder also floated up a bit while I was sailing. The next thought was to use a large wide rubber band around the cassette to hold the rudder cassette closed but to still allow the rudder to pivot. That worked but it was ugly and it made it harder to raise the rudder whenever I wanted. My current project is to add a cable latch, much like you'd see on ski boots. This won't be as forgiving if I hit ground, but it should make it easy to raise and lower the rudder.

Phil

[Tim Ford]

I've decided I'll never get around to building a cassette, at least not this season, so I am beefing up the rudder, the top of it, to accommodate some strap-on pintles. It'll be like 87 oz of clothweight at the lower (longer) strap and 81 oz at the top. Any advice on how to attach a tiller? I was thinking about cutting a yoke out of some 4 inch x 5/4 thickness white oak I have left and fitting that over the top of the rudder. The yoke would have the top of my NACA 0012 foil shape cut out of the middle and it would (in theory) fit snugly over the top of the rudder and be taped and faired into the CF layup. To the oak yoke (oakyoke?) I could then pin in a hinged tiller.

Does this Make any sense? Anyone have a better idea and don't say, "yeah, build a cassette," please.

rudderBeef.jpg

[ryderp]

The picture below shows my rudder cassette before it was nicely finished. The pin for the rudder goes through the leading edge of the cassette and also through the end of the tiller. I later made a longer pin with a ring-ding on it (so that the pin wouldn't fall through), that I insert from the top. I don't see any reason why you couldn't have the same arrangement with a fixed rudder. It's actually very easy to remove the pin and the cassette.

Phil

RudderCassette.jpg

[ryderp]

P.S. I used a single fiberglass tube that I later cut to make room for the gudgeons so that the tubes would be aligned.

Phil

[Tim Ford]

Thanks Phil.
Maybe I am reading this wrong, but I'm not worried about the actual attachment of the rudder to the boat, I'm worried (maybe worried is the wrong word) about the attachment of the tiller to the rudd. Yours looks very simple, but I have found on small boats it's really nice to have the ability to tilt the rudder almost up to vertical, hence the need for a hinged set-up.

Gotta love the hinge.

[ryderp]

I see what you want now. You could easily have a pivot point on the tiller yoke which would allow the ruder to flip up. I think that you'd still have plenty of leverage to turn the tiller. I went with the design that I have because of some of the rudder failures on other boats, but there are many designs that could work.

[Chad]

fwiw, if I were doing a pivoting tiller in wood then I'd:
-cast some low density epoxy around the aft, top inch of the foil (build a little box, prop the foil upside down in it, and fill with thickened resin).
-cut one strip of wood the width of the foil, two strips about 5/8" wide, 5/4 (1" net, or 1.25" rough) thick.
-shape the end of the center piece to match the foil pretty well.
-glue the side pieces to the center piece so the glue line is at least 8x the width of the side pieces (think of it as an 8:1 scarf), or use a cross bolt to keep the wood from splitting, or wrap the base of the throat area in fabric to keep the wood from splitting.
-place the tiller over the rudder and drill the hole for the pivot bolt through both parts (tiller and rudder), use a drill press or a long drill bit and some alignment lines to get it pretty straight.
-fit pivot bolt, and gently sand/file the nose of the tiller cutout to make sure it lifts cleanly.
-taper working end of tiller to maybe 7/8" wide, round over all edges (except foil contact area), sign name, and add varnish.
-add hiking stick hardware.

Here's a quick sketch of the words, in case that's easier to understand:

i550_WoodTiller.pdf

[Tim Ford]

excellent! Love the idea of the upside-down cast box. What sort of low-density would you recommend? 407 (microballoons) as opposed to 410? (WestSystem-speaking) And, why low-density?
thanks Chad, nice drawing and that'll be the plan!

tf

[Chad]

Either will work, micro balloons maybe a little better versus the softer 410. Low density filler added to make it lighter than straight resin, more easily shaped, cheaper (filler is less expensive per cubic inch than resin), and since the compressive strength of the wood is the limiting criteria- you're creating a large surface area of contact with the wood, so just matching the wood's dent resistance is all that is needed. Thickened until it's at the heavy cream/ketchup stage. Add some graphite powder if you like, to make it black and wear resistant. So pourable, barely, to avoid air bubbles. Use slow hardener to avoid exotherm, although there will probably be some anyway. Consider drilling an extra big hole through the rudder where the pivot will eventually go, so that hole gets filled in the same operation. Carefully measure and mark and record the location of the hole, so you have a chance of drilling in the same spot later with the smaller hole for the pivot.

[Tim Ford]

>"Carefully measure and mark and record the location of the hole, so you have a chance of drilling in the same spot later with the smaller hole for the pivot."

thanks!!...you obviously know what level of brain-deadedness I can descend to!

[Chad]

...only from my own personal experience of same!

[Kevin]

We have all been there. Trying to hit a previously created solid filled hole. Ahh the good old days.

[Tim Ford]

Without getting too personal, how long is your tiller? More specifically, how far forward does it extend, measuring from the leading (forward) edge of the rudder head?

thanks a heap, --TF

[jray]

32" from the front of the rudder to the attachment for the hoyt expandable stick. Seems to work fine and doesn't extend into the cockpit to much.

[Tim Ford]

Got some more work done on the "rutter." This is following Chad's idea, so if it fails, I know who I'll blame. It is rough and I still have some more CF to lay on and then fair the whole thing with 407.

IMG_2681.jpg

I built the mold and then figured out a way to secure the rutter, vertically, in the mold on a WARM, WINDLESS morning.

IMG_2689.JPG

IMG_2685.JPG

this is how it turned out, still needs some sanding on the tiller to fit more snuggly on the rutterhead.

Think this will last a season Mr. Chad?

[Chad]

The cast landing area on the rutter is perfect. Did you hog out a little of the foam foil and backfill with a hard filler or e-plate/G10? Something to keep the foil profile from collapsing if you squeeze really hard at about the 30% (fat) part of the foil, where the cast landing area tapers to nothing, where the forward part of the tiller cutout will bear?

Now about the tiller...
I'd get rid of those two aero-tipped cheek strips. They end before they can do any good, and the continuous tiller sides are already plenty big. Where the wood is in this pic (and where there isn't any) gives an idea of where the loads are:

WP_20131008_005 (1)-M.jpg

...except I like your longer, full-foil rutter cutout.

[Tim Ford]

Hah, OK thanks. Those silly little oaky doaky arrows are just some leftover stuff. What do you think of using another, longer, strip of hardwood of a different ilk? (different color)

What is that boat, above, a 420? I see they have an inspection port on a radius'ed surface. That'll go in OK, but you can forget about screwing/unscrewing the lid, as the curvy female receiver will make it extremely tight (and cross-threaded if it is bent enough). Unless it is laid in straight and faired to the rim?....hard to tell in the photo.

Thanks Chad!

[Chad]

If you want more wood there, just make sure it extends at least 8x its thickness, forward of the clamp bolt.
Tiller loads on an i550 with narrow foils and not-too-much pivot-to-leading-edge distance are pretty light; it's the rutters themselves that get loaded.
Pic is a 5o5.

[Kevin]

I like the look of progress there Tim.

The chine of the hull will drive the boat to weather when the boat is heeled significantly. The trick is to get the boat flatter (hike hard you blokes), de-powered and move the center of effort forward (more cunningham and drop the traveler) when the puff comes to combat that tendency. Fighting the chine with the tiller and lots of weather helm will be slow and will break something. To date, the rudder and/or tiller have been the weak link in the equation that has broken.

Kevin.

[noemar]

On a different note. There is a guy on e bay in Watertown, Ct selling dagger boards for $70.00 that could possibly be adapted for use as a rudder. He claim they were fabricated using s/s rods internally. May be worth checking out. I will try and find the item number and pass it on.
Noel