"T" foil rudders - Pitchpoling is History !

Hi all. "T" foil rudders are GREAT ! Dont know if you know but the Stealth has a "cartridge" style of rudder where it just slides up and down in its stock. Okay you have to pre-fit the rudders from the bottom up but the a shock cord holds them no problem. As for launching and retrieval you soon develop a method and (touch wood) i've not had any problems. I made my own "T"s out of balsa wood, skinned them in carbon then having checked their angle of incidence (God i'm starting to sound like Wouter) bonded them on with Epoxy and some carbon tape. The effect they have on the boat is astounding, the bow starts to go down, the rudders kick in and WHOOSH of you go faster than ever. They also contribute to a performance gain upwind as well. They act like a sort of "lateral damper" reducing the sort of "hobby horse" effect that you sometimes get on tidal estuaries. I dont use in light winds as i guess the drag outways any gain - i think (wheres my slide rule They are not covered by any patent and as far as i can acertain are legal for F16s - assuming they're not canted ....... no lets not go there ! Being painted white you can easily see if they have got any weed and its pretty simple to either reach down and clear it or remove the pin and lift them. I've maybe made it sound really simple but i was lucky in that i was able to check and measure Jon P's production items. If there's any other questions feel free to ask.

Hi Mike,
- Did you put glass the T-foil onto the existing rudder, or make a new rudder in Balsa, add the T-foil bit and then glass the whole thing ?
- Got any pics of the rudders, either finished or under construction ?
- Do the cassette type stocks ever get jammed, a big concern while surfing a 4ft wave towards the beach.....

Steve

I am looking at T foils for my next boat. No good in this situation as they do not kick up !

Mike added foils to an existing pair of blades. The Stealth originally used the same foils as rudders and daggerboards (I think they were actually 49er rudders) - then most owners got the bigger R dagger boards and so had a spare pair of rudders!

I've never had a problem with rudders sticking. As Simon says, they don't kick up. But the big advantage is that you can sailo with them well up without the steering becoming really heavy - because you still have the correct profile of blade in the water.

I'm still not entirely convinced by the T foils though - in light conditions I'm sure they must crate more drag.

What if you were able to change the angle of the horizontal blade slightly so that it holds the sterns down in heavy air and lifts them a little in light air? (Or be able to change the fore-and-aft angle of the whole rudder slightly to achieve those effects?)

I guess I am thinking of sort of how the fins/wings work on outboard motors to control trim of the boat.

Currently John (Mr Stealth) has a Set and leave set up with approx 2 degrees of drag (I think) on the Stealth range.

Hi all,

on Int.14' Skiffs Lindsay Irwin uses a twist grip type tiller extension to adjust the angle of the vanes on the bottom of the rudder blade. Angled down to lift bow pull transom down downwind, angled up to give lift to transom upwind. He swears by it and claims it is easy to operate once set up. But it must create more drag as it has more surface area than standard blade and when used to trim boat must create drag, I guess not as much as transom dragging or bow under water though.

Yet again played around with this sort of thing on sailboards years ago, but found for speed you couldn't beat a properly foiled straight fin with no extra bits on bottom. Of course sailboards weren't battling nosedive or transom drag though.

Maybe I will talk to Linsay some more? Definetly would be a weed catcher though a big problem on my home waters.

Regards Gary.

G'day All F16 Enthusiasts. This is my first post to cat sailor, so here goes....

My Name is Marcus Towell & live in South Australia.

I have been perusing some of the many posts within the F16 forum & have found the discussion interesting.

The Blade F18 was our project here in Aus & I am now looking to build two Blade F16 to replace my Marstrom Tornado.(If anybody is interested in any photo's of the blade just ask)The Blade F18 is going well & continues to improve when our development timetable allows.

I too am very keen to see some photo's of the T-foils as there some serious 14 ft skiffs at our club that use a similar system ( their trim foils are actually bigger than the steering foil !!)

Looking forward to reading future posts.

Marcus

The horizontal foils are bigger than the vertical rudders?! Bigger in what way -- in volume, in fore-and-aft dimension, in side-to-side dimension? (Sorry, but I don't know the correct terminology for describing these things in engineering terms.)

Marcus, Welcome! Look forward to hearing more from you in the future.



I'm interested. In fact I think I could speak for many here and say we're interested. Would appreciate it if you could post some picture here.

Thanks in advance.

Mark.

What a perfect time to use this image.

And here you have them :

Note the white foils are of 2002 the Black ones are newer and more faired.













And now for a work of art !

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I second Marks comments

Wouter

Wouter,
What are those pictures of? The Stealth?

Pictures are all of Stealth F16's; The white ones are off a UK based boats and the Black ones are off a US based Stealth F16 in California. Of Mark Talla. Eric Poulsen took them when he went up there for a sail in 2003 I believe.

There are quite a few T-foils in the F16 class at this moment. Currently all on Stealhs but a large portion of all of the Stealths produced have them. The other builders (except VWM) have looked at the setup and even had a test sail with them. I don't know wether they will go for the T-foils as well, maybe Marcus will. I personally still have to test sail these but that is planned for this spring at the Dutch Stealth Agent.

All very exiting.

Wouter

Welcome to the group Marcus,

It is a great honour to welcome you and your friends to the F16 class. To be honest; guys like you are very valuable especially at this time of growth. I'm thrilled with your decision to go with the F16's for your personal craft. And I'm quite sure the baby Blade (to the F18) will proof to be a little kitten with a big roar.

I've posted a few pictures of the T-foil rudder system in reply to your request. The foils on the stealth are much smaller than the I-14 because their function is a little different. The F16's are not as nervous as the 14's and more control can be left to the pilots. To foils on these cats only slow down the undesired movements to a level where the crews can adjust the trim in a comfortable way. That is all that is needed. Any excess funtionality will only lead to unnecessary drag and level-off the peak performance of the craft. Everything is a trade-off and one can loose as well by overdoing on a good thing. I really don't there is any benefit to large surfaces as the F16's are more controllable in basis and don't have to fear a wipe-out as much as the little skiffs.

And I second Marks comments that we all love to see pictures of boats in production/assembling.

Good luck,

Wouter

(co-founder & Chairman F16-class , 32, The Netherlands)

One thing you dont seem to have taken into account Wouter is the total surface area of the Stealths "T" foils, remember we have 4 (four) foils to an INT 14's 2 (two) so we're probably a lot closer than you think ! Also the Stealth is designed as a "PLANING" cat and the foils are angled to correspond with the optimum planing angle. As i'm from a Motor Racing background the beneficial side of the "T"s caught my attention although i was lucky to have a friend working for a F1 team who advised me on a more suitable section - glad i didnt have to pay for the use of their C.F.D. programming time ! anyway what are friends for ?

Mate,
The idea behind trim foils from a moth or a stealth is different to the original idea that inspired the 14's foils.
The International Moth is highly unstable in all directions. Without a trim foil the skipper needs to be somewhere behind and to windward of the hull. ie they are not the easiest to sail normally and downwind almost impossible. A trim foil makes the impossible almost possible (while still being impossible to old fat slow guys like me)

However the I14 while difficult beasty isnt that bad really. What the I14 has, is an issue with is length to power ratio. Biecker came up with the idea to use an assymetrical foil to modify the stern wave. Sort of similar to the bulb one sees on ocean carriers, but in reverse. By flattening out the stern wave, the theory goes the water "thinks" the hull is a much more acceptable 16 foot long. The longer the waterline length the faster the hull.. This is more important uphill than downhill. (Hopefully one doesnt have much hull in the water downhill). To accomplish this the trim foil needs to be the same width as the stern. Also the deeper the foil is below the stern wave the larger the surface area required to modify the surface wave.

Secondary is the anti mining aspect.

hope this makes sense.. I know what I mean anyway.

Stewart

Thanks for the welcome, this group seems to communicate very well.

I will dig out some mid to low resoltion photo's of the Blade F18 during construction & give some of the reasons why I belive the platform is very rigid.

I will attempt to create a new thread for this info & add my personal profile with all of yours.


I notice there is a good spread of people stretched to most corners of this planet & its good to see a couple of sailors close by ( Gipsland & WA).

Talk soon

Marcus

For clarification, the Stealth T foils are strictly for anti-pitchpole purposes. They do little for the stern wave--they're just too deep. When I sailed with the T-foils they did prove to be very potent at preventing nose diving. But they were also very unforgiving to any surface grass, fishing line, or as we encountered, rope from a crab pot. (At least we had the second rudder to steer us home.)

Off the subject...a really nice aspect of the Stealth rudders is the cassette up/down design. This allows you to push the rudders only part way down in light air or shallow water. Of course, there's not way to do a kick up mechanism with the T foils. But a standard rudder that had both cassette up/down movement and a kick-up mechanism would be very handy and safe. I believe some of the new Farrier trimarans have such a rudder.

" Of course, there's not way to do a kick up mechanism with the T foils."

Eric, we use the Dotan rudders, the mechanism allows for very quick "pump-action" push down and pull up of the rudders. If you`re moving slowly i`d assume you could use T-foil rudders on a system like this. Then again that doesn`t allow you to sail into the beach in sizeable waves, since you can`t surf a wave slowly ! (I`ve tried.) Also can`t have rudders partially down for steerage while launching. OK, I`ve just explained to myself why the cassette stocks are the only option with T-foils. Thanks !
Steve

I have asked the Dotan people about being able to have the rudders partially up/down for launching and beaching, and they claim you can do it by keeping the tillers raised partway up (not locked either up or down). Are you saying this does not really work?

The Paper Tigers here for many years used the cassette type rudder stocks, But with a safety "kick up" system.
The stocks were similar to the Stealth BUT the aft end was not joined but open instead. there were two bands of shock cord fitted around the stock, one at the top of the stocks and one one at the bottom. This would allow the rudders to be pulled up and pushed down as per normal but if the rudders hit anything the shock cord would allow the rudders to pivot backwards and upwards in an arc without breaking. it worked exceedingly well.

Would there be any benefit or drawback to adding T foils to the dagger? They are already in a cartridge?

Many drawbacks, no advantages. Daggerboards are to close to center of bouyancy to have any damping effect on rocking about. Also the T-foils on teh daggers will lower and raise the boards automatically with different boattrim possibly you can see them move almost continiously. The T-foil rudders are pinned into place.

Wouter

"I have asked the Dotan people about being able to have the rudders partially up/down for launching and beaching, and they claim you can do it by keeping the tillers raised partway up (not locked either up or down). Are you saying this does not really work? "

No Mary, they do work like this, no problem. Only problem is with T-foils you`d have to put rudders down quickly and pull them up quickly if they are kick-up, since while the rudder is halfway down the T-foils would create excessive drag and would likely break off the rudder in this position.

That, I`m sure, is why Stealth have them in cassette type stocks.

Steve

Then it seems that a normal rudder system would work if the trim fins can be articulated so they stay level even when the rudder is tilted in a halfway up position. Gotta keep you engineers busy.

Bear in mind that cassette rudders have been a Stealth feature from the time the boat was put into production - which was some time before the T foils were added to the boards. I've always looked at it from the point of view that if you're going to hit something with the rudders, you'll have already hit it with the dagger boards....

Hi all,

is scratching of blades a big problem, many cats in OZ use to use dagger type boxes, but I thought one of the reasons they stopped was scratching of blades. As far as kick up is concerned this is easily fixed as Darryl Barrett suggests.

Many cats I have seen have deeper rudders than centreboards, I know on the mossie I have hit rudders on bottom without hitting centreboards. Mind you kick up rudders are not of upmost importance, I sailed a Contender dinghy with a 3' deep fixed rudder for years and survived, mind you a cat is harder to steer to deep water without the rudder than a dinghy.

Regards Gary.

It seems that everbody thinks the Stealths "T" foils are only a down wind advantage - NOT - Just to clarify things i had a chat with Jon Pierce (Stealth Designer) and this is what we came up with. Going upwind with the "T"s the boat adopts a rather "different" feeling about her, when a gust comes and the boat heels/accelerates and whereas before you had that feeling through the rudders that she was trying to "screw up" into the wind now you dont. Jon reckons that its a combination of a) by keeping the bow up you reduce the forward wetted area thus leaving the centre of effort and the centre of pressure pretty much where they were designed and b)because of the angle of inclination of the "T"s as the boat heels they operate like mini-rudders and try to keep the bows off the wind. All i know is that it just improves the overall feel of the boat.

Is it possible to design T-foils that are removable -- clamp on somehow?

Those T-foils are kind of wicked-looking. What happens to your body if you are on the trapeze and slip off the back of the boat and are trolling in the water right by or behind the rudder? I know...leave it to a woman to think about a thing like that -- but men might have more to lose.

This was in Scuttlebutt:

HIGH PERFORMANCE SAILING
(Following is a brief excerpt from a feature on The Daily Sail subscription website presenting an update on the International 14 class from the UK perspective.)

Like the Moth class, the International 14s are entering a 'period of consolidation' after inclinable rudder T-foils became de rigeur a couple of years ago transforming the performance and the necessary technique required to sail the boat. After attempts at putting foils at the bottom of the rudder, the class norm is now to fit the foil half way up and there is a general trend towards thinner foils. At present there are still essentially two systems for altering the pitch of the rudder T-foil: the Paul Bieker set-up which contains an internal push rod, the foil moving independently of the rudder blade and the RMW Marine/Morrison system where the foil and rudder are one part that is inclined in its entirety relative to the hull. Bieker it seems may be moving towards the RMW system as at the Worlds he was trialing a one part system - the advantage of this is that with no moving parts to squeeze in and the foils can have a thinner section.

At present 'period of consolidation' does not equate with the 14s following the Moths in going fully foiling. At the Dinghy Show we spoke to the class' Dave Spragg who in fact has successfully tried fully foiling his 14 using the exact same gear as the Moths (lifting foils and the wand made by John Ilett's Flatacraft company in Perth) but all of it 50% bigger. "I've got one. I've flown it, but I don't think it is way forward for the class in the short and medium term," says Spragg. - The Daily Sail, full story and pictures: www.thedailysail.com

Marcus, Wouter and all,

Thanks for the info and pics.

If possible, could one of you provide a measure of some sort?

For example, the width of the rudder ( fore and aft) at the bottom.

From that data, we could approximate the rest of the dimensions.

Thanks again,

Bruce
I17
St. Croix

MAry and All,

1. The idea of 'removable' was interesting.

2. IF one were to make a fitting with rubber grommets and a 'pin'(s) to attach. Of course, it would have to be a nice job design to reduce induced turbulence.

3. IF this was possible, the one could fit to a rudder and/or a d-board.

..thanks again for a great line.

regards,
Bruce
St. Croix

in a word yes. David Lugg's fully foiling I 14 had plug in foils. Simply put two 1/4 inch rods into the foiling foil and two corresponding female 1/4 sockets. If the fit is tight enough you shouldn't lose the foiling foil. When one isnt using the foiling foil just put a piece of tape over the holes.

I guess locking grub screws could be used on this princple if one wants surity the foiling foils arent going to drop off in surf.

Sorry Brobu,

I can't help you here. Contact John Pierce Stealthmar@aol.com

Wouter

Hello All,

Once again, thanks to the sailing 'minds' out there....here comes a 'daaa' question,

1...does the foil need to be at the very tip of the rudder?

2. ..could it be ( say 25% up) and still function? (..for example, with a 2 foot rudder, could one place the foil at
1 foot 6 inches,..or 6 inches from the bottom?)


...this discussion will lead to another point..


regards

Bruce
St. Croix

Brobru,
See the post about high performance sailing (five or six posts back). International 14's are putting the foils halfway down the rudder.

Bruce

I would put the foils at the bottom.

Gives you just a little further to lift them out before you loose all "bite"

I've been told that sailing with them is fantastic untill you put the bows in so far that the T foil comes out of the water, at this point you instantly loose all the benefit of them and Splat, you are swimming.

Hello to All,

Mary, thanks for pointing me to the I14 post ( and answer),..I guess I should read closer.

Here is my question;

Could these folis be put on standard articulating rudder systems?

Granted, cartidge is best.

And, excluding braking beach wave condions.

I moved my boat from the y.c. beach back to a public beach this week. It was about a mile. I did not raise a sail, just threw the beach wheels on and floated down witht he wind. I sat on the rear crossbeam, pushing off with 1 leg when it got shallow.

Here is my observation. The rudder was locked in 'up' position. The rudder was horizontal. It was never more than 30-40% submerged ( I would steer with it).

Seeing where the foil is attached to the rudder, the aft aspect, in the 'up' position, the foil would safely not come in contact with the water ( get ripped off, etc). So. one is ok there.

I do not know about you, but when I launch, my rudders stay up until I clear the mooring area or until I have a 'clear path', or deep water( in the locked up position, and weight to the back, enough of the rudder is in the water for steerage)......when I do set the rudders, the boat is stopped or at a crawl,...down goes the rudder, then I check that they are 'locked',....and I power up and go.

Knowing this,.....could one safely use the foils on a standard 'articulating' rudder system?

I respect your ideas, comments and opinions.

regards,
Bruce
I-17
St. Croix

Bruce

I think the answer to this is no, the only way I can see is that you can fit them to kick up rudders is if you pin them down before you go out, so you must have the boat in deep enough water to be able to have the rudders fully down before you get on. I doubt you will be able to get enough rudder in the water to steer with the T completely clear of the water.

I can see no way that you will be able to steer the boat with these on unless the rudder is fully down.

If you do manage to make it work, you will have to pin them down, the loads get quite high when they are working hard, it would be a disaster if the rudders kicked up just when you were flat out and the only thing stopping you from pitchpoling is the foils.

Depends on what the reason is for the foil. If it is to create a negative wave. Then it needs to be high up on the rudder.. Im sure Bieker has a mathematical model as to exactly where..

If the foil is anti-pitchpoling then a long as it is in the water it will work. Remembering that the base of the rudder means you have only one drag creating interface. Higher up and up and you have two.

I want it all. I want cassette rudders, but I want the whole cassette to be able to kick up (like the new Farrier system). And I want T-foils, but I want them to be removable and movable to different locations. And I want the T-foils to be able to be angulated up or down depending upon what works best in different conditions and points of sail.

Am I asking too much?

I want it all. I want cassette rudders, but I want the whole cassette to be able to kick up (like the new Farrier system). And I want T-foils, but I want them to be removable and movable to different locations. And I want the T-foils to be able to be angulated up or down depending upon what works best in different conditions and points of sail.

Am I asking too much?

Nope, not if you intend building them yourself !
While you`re at it, Mary, I`ll have a set. Make them black, please.

What you`re asking for is probably do-able, with a huge amount of engineering, design and fiddling. Once you`ve built 7 prototypes and tested them thoroughly in all sorts of conditions, you`ll probably end up with something remarkably similar to the Stealth foils as the best solution. Everything has a beginning and an end, and they`re usually in the same place.

Cheers
Steve

Except for the T-foils, you might take a look at the Topcat rudder design. This might not the most fancy but has excactly what you want. I attach a page from the F2 page showing it.

Mary

You are not asking too much, but you might think that I was if I gave you a quote to build your rudders. To give you an idea, the int. 14 rudders that have been talked about cost in the region of $2000 each and you will need 2 of them, and these rudders don't have all the features that you want.

"I want it all..." OK Mary, now you are sounding like MY wife!

Timbo, your wife is interested in rudders? How lucky can a sailor be?

Just thought I'd add my two pence worth to the debate. Having sailed a Stealth for two seasons on tradition rudders I've recently purchased the new Stealth F16 with T-Foils. It was noticable from earlier light wind outings that the boat is very stable for/aft particularly downwind. A very planted feel with no noticable side affects.
However last weekend saw some decent wind and the chance to see what they could really do. Twin trapeezing everywhere, try as we might we just could get the boat to stuff the bow in. On one occassion when lossing my footing downwind and swinging forward into my crew I was sure it was cartwheel time and would have been on my old boat but nothing more than a slight bury with no water over the top of the hull.
There is another Stealth F16 at my club who has been racing with the standard rudders while waiting for his new T-Foils. There is no difference in performance between the two setups. Until it gets scary downhill that is!

John Pierce took a load of photo's and some video of the weekend so will post when we get organised.

Wouter - If you're there, I've very regretably had to pull out of Texel. Maybe see you next year.

Aaron,

Are you going to Marconi for the ECPR ?

I'm planning to be there

Cheers

Simon

Simon,

Yes, should be there for both days hopefully. John Pierce mentioned he may be going and a couple of other Stealth's from Datchet as well by the looks. I'll probably only manage Colne Pt as sailing 1-up.
See you there.

Aaron

Got a CD in the post today from John P with 150+ photo's from the weekend. Won't bore you with all of them.
Aaron

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[img]http://www.catsailor.com/bb_files/51094-Stealth%20Photo%20Shoot%20114.jpg[/img]



Wouter