Rudder Upgrade; Performance Tips Needed

[tomsayres]

When I trained for my US Sailing Keelboat certification in Coconut Grove, FL earlier this year, I was astounded by how agile the Pearson 24' Ensign was. Instructor Richard Crisler (the best you could imagine) had us get within 6' of huge yachts in 20 knot wind, before he allowed us to tack... which quickly built confidence in the agility of that vessel.

As a new sailor, I can grasp the topside sail comparison to an airplane wing and the drag and lift concepts. My Spirit 21' has a swing keel which is pretty much "unmodifiable" I suppose, but are there practical ways to make my tiller's rudder more efficient so it is more Ensign-like?

I have the original wooden assembly and I keep stored out of the water to keep it in the best condition I can, and was wondering if anyone has experience in making their steering better beyond keeping it clean, free of algae and waxed? Any advice would be appreciated.

Can the shape be modified to be optimal or are other materials better, or is it such a minor issue that a rudder is a rudder, is a rudder?

[SimonV]

Quote"Instructor Richard Crisler (the best you could imagine) had us get within 6' of huge yachts in 20 knot wind, before he allowed us to tack." End quote.

This does not make a good instructor in fact makes him a bit of a dick. Very poor form.

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[UNCIVILIZED]

tomsayres, welcome to CF!
To answer your question on rudders (& keels), yes, they definitely can be modified. And such can make a HUGE difference. I'll try & add some links later, but go over to Sailing Anarchy Forums, & do some research there on the subject. As foils are a BIG topic in the racing crowd.

That, & I did some writing on rudders over there (where my post count's a lot lower than here). But my handle's the same, so you should be able to find some stuff.

Also, there's www.AYRS.org the Amateur Yacht Research Society, which has loads of info on all kinds of topics. Things most of us couldn't dream up on our wildest days, & of course, the more mundane.
Another good site is www.L-36.com

Enjoy your studying!

[tomsayres]

Awesome advice Uncivilized- I will do as you suggested.

[Cheechako]

Obviously rudder shape does make a difference, but it's part of the whole design also; where the rudder is placed, what the best heel is for the rudder etc. Changing the shape on your particular boat may do very little or a lot.
I upgraded the rudder on an old semi full keel boat once. The older versions of this boat had a crescent moon shape rudder, the new versions had a more modern trapezoid shape.. larger at the bottom. After modification, I found very little difference, if any, in weather helm or handling.

[Snowpetrel]

Ha, funny that the long keeled Pearson seems more "nimble" than the fin keel spirit.

Looking at the plans of the spirit the rudder seems like it's the appropriate size, shape and geometery. A decent foil shape will help some, but I think the real issue lies elsewhere.

The boats are very different. The Pearson is narrower , heavy and has significant momentum. This can give some certainty when tacking, and maneuvering in close quarters. My old folkboat type was similar. Very predictable and reliable in close quarters under sail. And not at all skittish, she would deal with gusts and lulls in a stately progressive manner. And even at slow speeds she would behave. But she didn't turn quickly , or stop quickly. I sailed her for years with no engine, in and out of marinas in all sorts of conditions.

The spirit looks like a much wider, lighter , and higher boat, with a very skinny swinging keel. These boats are much more skittery. They excellerate fast, turn fast, but also lose way (speed) quickly. At a certain speed the keel and rudder is more likely to stall and the boat will go sideways quickly until enough speed is regained. The rudders can also stall at times, loosing steerage.

These light boats are very maneuverable if sailed well, but they need different techniques to a heavier boat. You can't let them slow down too much. And in gusty conditions you need to carefully handle the mainsheet to depower and avoid round ups. And with less momentum you have less ability to "shoot" into the wind or through a lull. But they should be able to spin tack, and stop very quickly.

I'd also check the keel is going all the way down. Lee helm is a killer when sailing in tight spots. Use a smaller headsail as well. Dont over do the amount of helm. Throwing it hard over often just stops you faster than it turns you.



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[tomsayres]

Thank you very much Snowpetrel. Such great insight.

The winds here have been almost non-existent so maybe when they pickup- and they will- the little Spirit will be more responsive.

I here you loud and clear on the lack-of-weight and stalling- I'll be real careful with that.

Appreciatively,

Tom

[Snowpetrel]

Ha, yes you need wind to be nimble! A few other big difference's are the ballast ratio. 25% with probably a fair portion in the bilge for your boat, and 40% or so on the Pearson. This should make the Pearson much stiffer, and more powerful in a breeze. Also the fractional rig is pretty handy, and easier to tack than your big masthead rig.

I'm guessing in 20 knots your boats a bit of a handful without a reef and a smaller headsail?

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[tomsayres]

I hope to find out this winter, Snowpetrel. The low water racing begins tomorrow at my yacht club and I've only had her our a few times since her rehab, so this is all very new; the boat & racing. After I learn what she can or cannot do the next few months, we'll take her down to the Keys this winter a few times.

[UNCIVILIZED]

Firstly, what the other posters have said has great merit. As a boat’s performance & handling is far from dictated by it’s rudder alone. Some other aspects of which I’ll try & cover.

As to your boat, & options to boost her performance, & or reshape the keel. There are options, depending on the amount of $, time, & effort which you want to put into things. Plus, there’s always a point of diminishing returns.
For instance, you could prep the surface of your keel for bonding, & then epoxy it, while wrapping it in one type of cloth or another. And then add a templated (see below), faired shape & surface on top of that.

Also, with your transom hung rudder, if you know your way around tools, it wouldn’t be hard to alter/upgrade it a lot. But changing it’s; foil section, blade shape, amount of counter balance, size etc.
Though it’d probably be wise to read up on the boat, & what modifications others have done to them, first. Perhaps via; the class association, the manual on said boat, various online forums discussing it, or just a general online search.
american spirit yachts 6.5 manual - Bing
american spirit yachts 6.5 - Bing

Regarding this topic, if you really want to get up to speed on it, you're probably going to need to do a bit of learning about; foil shape/sections (NACA), center of effort, center of lateral resistance (CLR), counter balance, lead (pronounced leed), plus a few other terms & items. And what follows, is a Foils 101 knowledge dump.

A couple of key things:
~ Much of a rudder's feel is dictated by the hull shape, sail plan, & relation of the sailplan's center of effort in relation to the hull's CLR. With some boats inherently having loads of weather helm, others a bit of lee helm, & many, the ability to adjust how much weather helm there is.
Much to most of that, depending on what the boat has in the way of sail trim, & rig tuning controls.

For example, a J24's helm has a totally dead feel when the boat, sails, & rig are tuned properly. Almost to the degree that you could let go of it & let it steer itself (not that you can on this design). Yet it's a very responsive boat. Still, it has a very "neutral" helm, generally.

~ Fatter foils, in relation to their length fore & aft, tend to be more stall resistant, & recover more quickly from stalls when they happen.
An example of a heavy duty rudder stall would be where it completely loses it's bite/grip on the water, & the boat will want to spin out to weather.
~ Slimmer foils tend to have less drag, & thus are faster. But require more attention to one's helmsmanship.
~ The amount of counterbalance which a rudder has built into it plays a HUGE factor in how much pressure there is on the helm regardless of the circumstances. As with a rudder with no counterbalance, you feel the entire load of the rudder in the helming mechanism, be it tiller or wheel.
Which, with a wheel system, can be dialed down to reasonable levels, but it’s still not the most efficient form of rudder (or system).

The counterbalance in a rudder is usually primarily affected by how much of the rudder is ahead of it's center of rotation... typically; where the rudder post is, where the rudder’s attached to the stern (and if part of the foil extends forward of this line), & or the fattest point in it's foil section.
- A rudder with insufficient counterbalance will be a beast to steer, especially if it's a tiller steered boat. Plus, it'll be incredibly sensitive regarding needing balanced sail trim.

If it isn’t obvious, a full keeled boat is going to be less responsive to helm inputs than will a fin keeled boat. And the former will also be more inclined to suffer from rudder stall, for a couple of reasons:
~ The common response when a boat’s not turning/responding “fast enough”, is to use more rudder. Which puts it at a higher risk of stalling, as it becomes more of a drag device, vs. using the lift generated by it, to induce a turn.
~ Rudders on such boats generally tend to have poorer, if any foil shape at all as compared to spade rudders.
~ There’s much less lift generated, by long, often shallower, low aspect ratio keels. And relatively speaking, they also have very little foil shape, with which to generate lift. And significantly more drag.

So then, to varying degrees, the reverse is true in terms of most performance aspects of higher performance boat designs. Especially fin, or foil keeled boats, with spade rudders.

But again, all of the components of a boat; hull shape, foils, & rig design, are interconnected.
Still, hanging a well-designed spade rudder on a full keeled boat will make it handle a good bit better, if the NA does his homework. Just as well cut & trimmed sails will make her sail, & handle a lot better too.

Now, many would have you believe otherwise, or that it doesn’t matter… “Because they’re cruising”.
But such things are Fact.
That, & it takes (or can) a good bit of time, money, & effort to do a good bottom job on a boat, or to template & fair a keel or rudder.

Templating being when you literally get the ideal, theoretical NACA shapes for your keel or rudder. Print them out, full sized, & transfer them to a hard, dimensionally stable material. And then, using fairing compound, & or other materials, shape your foils to conform as closely as possible to said templates.

NACA foil sections, essentially, tell you how much depth of shape a foil should have, at any given point, vs. that of a flat plate. And there’s a whole spectrum of sections from which to choose. Each having a window of applications for which it works well. Which is a whole ‘nother dissertation/tome.

Depending on the boat, who made it, how much care & attention to detail she’s had along the way, doing this can make a lot of difference or only a little. Much as a good bottom job on a boat who’s underside looks like a s**t hammered washboard, can easily add 1/4 – 1/2 a knot or more.
And if your foil(s) was poorly done, or poorly chosen by the designer, then tuning them up, or switching to a different one can yield big dividends.
Witness the AC boats, or developments in; foiling craft, & IMOCA boats of the last half decade.

There's more to it than this, or even what's on the websites which I suggested. But if you’re truly interested, I’d suggest reading/picking up some boat & rig tuning guides. Which often include sections on setting up, & or templating one’s foils.
And to get a taste of such, some are available for free. Albeit they can seem highly technical. But many are found on various sailmaker's websites. Where one can download the tuning guides for many different designs of boats. Though, likely the best source would be various one-design class websites. And of course, Amazon has enough technical sailing reference books to fill a fleet of trucks.

This one is fairly good http://www.amazon.com/Sail-Rig-Tunin...g+tuning+guide

My apologies for the PhD sized headache, from the data dump. But hopefully some of the knowledge therein will stick, & or prove useful.

[tomsayres]

Very awesome advice, UNCIVILIZED. I especially like your suggestion of not falling into the realm of diminishing returns. I can see from the outset, that could be very easy to do!

I will try, the best I can, to digest what you have provided- point by point- and buy a couple of books to really sink my teeth into the efficiency and balance concepts.

It seems practical to learn how the various aspects are interconnected, check how my particular set of components currently interplay with each other under sail, try some subtle modifications and note any changes... and explore all of the various "more drastic" possible improvements from there. One reason I started with a light weight trailerable yacht is to take it to different places and get exposed to different conditions to know how fast or how far to move up the various avenues of yachting bliss; racing, coastal cruising, etc..

The good thing is that once I learn the various working parts better on a small digestible scale, that knowledge can not only be used on dinky 21' little Spirit, as I hopefully progress, the enjoyment factor will keep keep on keeping on if I move to a larger yacht in the future.

'Really appreciate the time and thought you gave to this effort!!

[UNCIVILIZED]

Given that you already have foils that, dimensionally, are already so close to daggerboards (like on catamarans) or the foils on racing boats, you have a Lot of lattitude when it comes to modifying them into high performance units.

For example, a friend had an O'day 25 for a toy & Wednesday night Beer Can Races. Being that he was a semi-retired pro racer with ties to the America's Cup. And we broke the transom hung rudder on it, twice.

It was a crappy design to begin with, as the bolts for the pintles & gudgeons were just bolted straight through the skins of said foam cored rudder. And there were no extra reinforcements in those areas for the bolts, & the enhanced loads there. So it was a built in recipe for failure.
Plus, it was a slab sided design, wiith no foil shape, nor tip shape to it. Ergo, a slow profile, & low performance design.

Anyway, we got the thumbs up from the local racing board, to go ahead & replace the broken stock rudder, with a "tuned" one.
And we decided on a semi-eliptical foil shape. With a good bit of counterbalance extending forward underneath of the hull. Along with choosing a nice, moderate NACA section for it. And it took about 30 man hours to put together (by pro's), including templating & fairing. Made from marine plywood, epoxy, glass, & microballoons.

The results were great! Where as with the OEM rudder, with a kite up, there were definitely times that we had to muscle the tiller in order to keep the boat underneath of the chute, & on course. Which was slow, in needing to use so much helm input.
But with the new one, steering was almost fingertip like, control wise, under the exact same conditions (with a tiller no less). And it was impossible to make the rudder lose it's grip on the water, even when we intentionally did every dumb thing to try & induce such that we could think up.

So all, in all, it was a great success... paid for by the insurance company to boot
And I'm thinking that you could do something akin to this, with your current rudder. Although, if it's of the type where it retracts vertically, into a box cassette, you might have to skip the extended counterbalance, & just work some magic on blade & foil shaping.

As I referred to in a previous post, about your keel, odds are, that if you wanted to, you could prep it for bonding a composite skin to it, & then add a high performance foil section on top of that if you liked.
The catch(es) being;
- Choosing a thin enough foil section so that it would still easily fit into your (stub) keel trunk.
- Sealing the bond of the composites to the fin, where they'd end, such that water doesn't get into the laminated on bits. As on rudders, it's common for water to get into their cores via the area where the stainless shaft enters the glass blade. But with intelligent materials choices, workmanship, & design, it can be done.

Also, trailer sailers needn't be poor sailers, even in stock form. As, growing up, for a while we had a Chrysler 22'. With foils & a swing keel much like yours. But of all of our boats (half a dozen), it was the best sailing of all of them.
Cruising at between 5-7kts (sometimes more), often in weather which caused a lot of fixed keel 30'+ boats to stay tied to the dock. Though, admittedly, part of her speed, when not hard on the wind, was due to a big, hank on, Drifter/Reacher/Spinnaker. With perhaps twice the sail area of a working jib.

But the boat was so controllable, especially via tuning her CLR by altering the Keel/centerboard's depth, that we could fly it in winds up to 20-25kts.
For an inexpensive boat, it rocked!

Some other helpful tips, especially to help you with racing your boat. Take it out, from time to time, & tie the tiller of to centerline. And then learn how to steer her with changes in weight placement & sail trim.

By learning to balance, as well as steer her this way, you'll go a long way to reducing excess drag due to poor boat balance or sail trim. And I think that there's info on how to do this on www.BethandEvans.com - titled "how to steer home if you loose your rudder". And if the article's not on there, there are similar ones on here, as well as on the Internet in general.
That, & you might query Evans Starzinger (on here) directly, about it.

[tomsayres]

Love all of the tips Uncivilized!

As you unfolded all of the steps necessary to make a better performing rudder I began thinking about possibly having one made… is there a company you could recommend that does that type of work? Or would it be so costly that rudder works belongs in "a labor of love" category.

If I couldn't afford having one made to my boat specs, I think I'd be too chicken to tear up a perfectly usable rudder and would likely opt for starting from scratch on a second one and keep both on board, in case one did break.

LOVED your idea for tying the tiller to the centerline and trimming!

Bought the book you recommended and can't wait to get it.

THANKS for all of the time and high skill investment you have made in this project for me!

[UNCIVILIZED]

There's a company called Phil's Foils which builds rudders. But likely they'd charge you more for a rudder than your entire boat cost.

The rudder which we built was pretty simple. Being primarily, several layers of marine plywood epoxied together. Then cut to shape, & the foil section was cut into it by planing off wood to the appropriate depth/thickness, checking our work with templates as we went.

It was pretty quick & easy to get it really close to perfect, between the power planer & the templates. Plus, the layers & glue lines in the layers of plywood serve to make shaping such a thing Much easier than say, a foam & glass rudder.
- You can see some examples of foils made in a similar manner, here http://ptwatercraft.com/ptwatercraft/PT11_Options.html
There's all kinds of applicable building knowledge & links here http://dixdesign.com/ Check out some of the builder's blogs too.

Then, once her foil shape was close enough, she got a couple of layers of woven cloth set in epoxy. Followed by some fairing compound/blend, in the appropriate areas. Which were then sanded to perfection; to match the templates, & smoothness requirements.

Finally, we did a couple of flow coats of epoxy to seal things, => prime & paint. Plus, somewhere along the way, we put in a couple of G10 compression tubes where the hardware was to be bolted to it, so as to minimize any chances of water intrusion into the wood. And to spread out the mounting/bearing loads a bit.

PS: A Power Planer isn't a requirement, but it makes things easy & simple. And there are a number of other ways of removing the appropriate amounts of material.
Even setting one's table saw for the correct depths of cut, & running the rudder over it in progressive passes, to "mill" away the wood that you don't need. Well, to get things close anyway. And then switch to a grinder or belt sander from there.

Honestly, such projects are quite fun! Even before you get to put them onto the boat, & feel the results of your giving her some love.
And as perks; it adds to your skill sets, & confidence as well.

[tomsayres]

Uncivilized, I like that strategy A LOT! If I do something accidentally wrong, I supposed I could sand and fill to correct. I'm going to try to hit a boat junk yard to buy the fittings to use, then make this a winter project I think.

If I do, it is likely that the community will benefit greatly from your very detailed and generous advice and if I can actually pull it off, maybe other newbies will give it a try... so I plan to take pics along the way.

Bravo! Thanks you so much!