As is well known by now I'm a big fan of T-foil rudders; especially when I can get these on my Taipan F16. I really do believe that these T-foils are one of the parts that will make the F16 platform "complete". The short hull length and large width do make pitching on the F16's an issue especially when singlehanding with an aluminium mast on the relatively confused North Sea.

Up till now I had 2 major issues with the T-foil designs as they stand now.

-1- The were fitted to non-kick-up rudders or when they were they would really slow down the boat when the rudders were kicked-up and dragged behind the boat.

-2- The are relatively hard to adjust to the sailing conditions.


Point -1- is a major concern as the surf at Zandvoort is often big enough to destroy major parts on your boat if you catch a breaker at the wrong time. Speed and manouvrability are paramount. Dragging the little winglets through the water perpendicular to their plane is not an attractive option. Neither are rudders that slide up and down.

Point -2- is important on my boat as you likes different attitudes in different sailing conditions. In light winds and flat water she like to sail on her bows, in rought weather or at speed she like to ride more on her sterns. The semi planing Blade design will probably show a similar behaviour. It is too much effort to pack the pintles each time you go our sailing.

I also wanted a setup that I could remove from the rudders entirely and that I could adjust on the water between races or even during a distance race like the 3 hour long NAM-REM race.

And of course it need to be simple and relatively inexpensive.

Basically what I've come up with it this :




The rudderboard is cut off at the bottom to get a flat surface. Half a circle is cut out there as well. This will take the axis (a tube) that is laminated into the T-foil. The T-foil is jammed between this cut-out and a plug that is screwed to the rudder (and the T-foil) from beneath. The T-foil is now fully secured but can still rotate its trailing edge downward and also a little bit upward but not by much. Just behind the opening in the T-foil that exposes its axis, a nut is laminated into the foil. This nut connects to the threaded rod that runs through the rudderboard in a relatively wide canal (some laminated in pvc or glass tube). On top of the rudderboard there is a little plate. On top of the threaded rod a nut and a winged nut are welded. These are spaced sufficiently far apart so that the little plate will just fit between them. The little plate is screwed to the top of the rudderboard and hold the threaded rod in place. Now by turning the winged nut the whole foil is adjusted in its trim. The rod is by far long enough to bend a little inside the tube so it can align itself properly to the nut in the foil even when angled. The kick-up rod of the rudderboard can still pass over the winged nut and so there is no interference with that mechanisme. Actually the rod will most likely act as a security against the wingnut/rod getting "undone". Nice double function of the rod !

A single turn of the winged nut will adjust the angle of attack of the foil by about 1 degree. Meaning that when you using half turns you get a range of 8 settings covering 0 to 4 degrees of trim. 16 if you count trimming the foil the other way as well.

How to beach and land ?

You simply unlock the rod of the kick-up system and turn the winged nut till the rod is detached of the foil. The foil will as a result have a couple of degrees upward trim. It will try to lift the sterns a little, but that is acceptable as you will be sitting far back on the boat with relaxed sails anyway when you get in through the surf. The foil is now free to rotate its trailing egde downward. The rudder stays down due to friction in it housing. You sail through the big breakers and at the first sandbar the rudder is un-jammed of its stock, the rudder will move back and up and the T-foil will automatically align itself to the flow of the water. As the axis is back from the leading edge the foil will also move clear of the rudders leading edge and thus prevent the foils from scrapping along the bottom.

When going out this procedure is covered in reverse.

During sailing the trim can be adjusted by quickly unlocking the kick-up rod (but leaving the rudderboard itself down) and turning the winged nut. This can easily be done between races. For long distance races with very long downwind legs, this can also be done. You take a 15 seconds hit but recover that on the way down.

I would prototype this setup using Catamaranparts rudders myself but I'm too much strapped for cash (when is that going to end ?) and so anybody may run with this and tell us all on the forum how it works. I'm seriously considering it for when I have play money again myself. I really do believe it will work well.

Wouter

You only need talk to the foiling Moth builders about how they are controling their T foil rudders, see if that can be adapted somehow to the double rudders we have. Or, use a cassette type rudder head as the Stealth does, and add some sort of tilt adjustment to that with three settings, nose down, neutral and nose up.

I already know and their setup is not sub-optimal. Their rudders are designed to be easily controlled by the skipper all the time, because they use there rudder foils to trim the main foil. Also their rudders don't kick-up. So I do not have a comparable setup nor similar requirements. For these reasons the design converges.

Also the Moth rudder foils and even the mainsail are not very efficient. They only adjust the trailing egde of their foils and not the whole foil. This is a suboptimal setup, but works for them because adjusting the whole foil is far to aggressive on the twitchy moths and leads to major control problems.

In case you hadn't noticed. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> The Moth sailors are carrying their boats, mast layed horizontal, into the water then have to swim it out to sufficiently deep water before righting their boat and sailing away. I'm NOT going to do that with my F16 in the North Sea breakers.



Don't want the Stealth setup for the reasons specified in my earlier posting. Basically, non kick-up rudders, non adjustable to sailing conditions and not possible to adjust trim when on the water.

For the second part of your statement, "some sort of" is the key component, without specifying what that exactly means we are left with basically nothing.

It is exactly the "some sort of" that is detailed in my proposal.

Also a "tilt mechanisme" still doesn't allow the rudders to be kick-up and the foils to weathervane when hitting the beach or to allow the foil to weathervane itself freely in light winds and flat water where you don't need them.

My proposal is intended to be a step up in design with respect to the Moth setups.

Wouter

I like the thinking. I'd really like to have T-foils on my Spitfire, but I sail in an estuary that has many moorings, as well as sandbanks. It is the mooring lines that worry me. Kick up rudders have done their job too often for me to go with 'fixed' ones. However, I still think kick-up rudders with T-foils will still leave me tangled. Is there any reason that the T-foils have to be at the bottom of the rudder?

stealth type rudders are great sailed with them for 2 yrs now and work a treat , I sailed out and in through breaking waves dumping on a steep shingle beach at loch ness , was far easier than last time i sailed a boat with rear pivotting blades that nearly got snapped off when launching on a H5.9SX , as for controllability with blades raised , it works no trouble at low speeds as John Pierce always has said .
Developement as suggested would be to be able to rock the cassette back and forth , think I read in latest Yachts and Yachting that this is what the latest Int 14s are doing , that would be interesting and relatively simple I pressume .

However unless you can adjust the wings whilst sailing I cant see much point in adjusting attack , conditions throughout a whole race raely stay the same to get a benefit from any other sort of adjustment . Stealth rudders are nuetral untill bows try to go down , then they maintain the constant waterline plane

That was one of the first things I thought of when I was coming up with my kickup T foil idea see
http://www.catsailor.com/forums/showflat...true#Post107486

I rejected it early on as for me one of the main points of a kick up system is for when you hit something unexpectedly. I thought that having to undo a bolt before the foil can kick up was not a good idea.

Gareth

In fact having re-read my thread haven't you just described what John initially described in post #107737 of at the end of the first page of my thread?

Gareth

Gareth, I think you meant Phill?

I'm not sure why you are going to such mechanical means of allowing the rudder to flip up, the Stealths have been sold in sufficient numbers to flag up whether the cassette rudder used is a problem and likely to get broken. All the Stealth owners I know seem to have had some stage or rather a dagger board broken or damaged by hitting something which seems to indicate that its not the rudder that takes the impact but the dagger board.

If you want to make the T foil adjustable then I would suggest that you take a look at an older fibreglass glider which has an all flying tailplane, the principals are the same and open to inspection. Its interesting that the all flying tailplane was quickly dropped due to quite a number of problems at higher speeds ( uncontrollable flutter ), they are all now like a conventional wing with only the very last part of the wing adjustable.

In the surf I know many Stealth owners simply put a small elastic section around the back of the rudder locking it into the cassette, any bangs from below simply drive the rudder upwards out of the way and is retained there by the elastics friction, rather crude but seems to be effective.

Your right, Phill should get the credit, Thanks

I shared the same view till I heard the experience that Darryl Barret gained using the T-foils on his Alpha-Omega F14. He used normal rudder pintles (with a retainer clip) and normal rudder stocks that allowed the rudders to kick-up. Basically he took a conventional rudder system and just bolted some T-foils to them. After sailing with it for a while and having them kick-up a few times he found that the T-foils would just kick-up as normal rudders would.

This lead me to the idea to just accept the drag and decelleration when they kick-up after hitting an object floating in deep water. Pretty much the initial "give" is what saves the rudder and sterns not the upswing to the horizontal. Taking a calculated risk here, which apparently isn't much of a risk afterall, I was only left with the problem of kicking them up in shallow water with a surf, i.e. when running the boat up a beach. And that is what the system does well. As you know when you'll be returning to shore you can unlock them.

When running aground in the middle of a large body of water then I just have them kick-up as if they are hitting an object in deep water. There will not be a surf there to smash your boat when you make an unintended turn or whatever. I there is then I'm a dumb fool for trying to sail through such a patch without unlocking my rudders.

That is the thinking behind the proposal.

Wouter

Come to Zandvoort one time and you'll know.

Besides your are also overlooking the fact that I what to be able to adjust the trim of the foils for different conditions/courses. You can't do the latter with the fixed foils.




What a nonsense, who says Phill was first ? Besides his design was strikingly vague. The real designing is hardly ever in the concept but rather in getting the details right. One of those problems was to find a simple way to fit the foils to the rudder so it can turn about its axis. Simply bolting it through won't work.

Now I'm not claiming to have done something special here, but I'm also not accepting any claims by others who wrote statements like:"if you use a rod in some way, so that it adjusts the angle somehow then it could be designed such that it would be adjustable if you find a way to somehow control it from the top of the rudder board."

YEAH DUHHH ! My granny could have thought that one up.

Wouter

Hi Wouter,

The whole thing would be easier, if you use Stealth type rudders. If you want to have an adjustment for the foils, you could use a flexible trailing edge (aluminium strip) or even a fixed Gurney Flap. The first solution can be seen on many light aircraft, as an aileron trim device. The first big advantage is: no moving parts apart from the sliding rudder itself. The second (maybe even bigger) advantage: No edges, gaps, slots, etc. between rudder and horizontal foil, which easily could create drag and cavitation (I have had servere problems with cavitation on my Dart rudders, when I rebuilt the rudder nose).
If you seriously consider the solution with fixed foil and adjustable trailing foil edge, you can contact me directly for more information about this trailing edge devices.

Cheers,

Smiths Cat

By the way: If you balance the pitch trim of your boat with such a device, you do nothing else than putting additional weight on the stern of it, which causes drag... and I am wondering that foils are legal in F16. Maybe the F16 scene will be dominated by hydro foil cats in a few years.

Forgive me for saying so everybody, but please read the posts carefully and try to understand what is said.

Alot of you are simply guessing at things I already looked at in some detail.

The reason why I disgarded the fixed foils with an adjustable trailing edge is given in my initial posting.



That is not what I mean by T-foil trim. Basically I'm trying to get a certain attitude of the boat in different conditions and ADJUST the foils so they do not fight this. That is why I want adjustable foils. My trim in light winds and flat water is different from strong winds and rought water. All this has already been written in my initial posting.



T-foils are.

Wouter,

I think you are underestimating the force these foils will have when they kick up.

I had a foil (approx 350 wide x 200 long) on the bottom of a pivoting centreboard about 15 years ago & the first time I pivoted the board down was fine & the attachment seemed to work really well. But when it came time to pull the centreboard up the foil simply ripped off the bottom & caused a bit of damage to the centrboard & pin. The boat actually lunged quiet badly when this happened.

So I can see your transoms taking a beating no matter how well the design.

Just my 2 cents worth (or 0.01 euro).

Marcus

Was this a foil that could weathervan itself to the waterflow by turning on its axis or was it a foil completely fixed to the daggerboard ?

Wouter

What a nonsense, who says Phill was first ? Besides his design was strikingly vague. The real designing is hardly ever in the concept but rather in getting the details right. One of those problems was to find a simple way to fit the foils to the rudder so it can turn about its axis. Simply bolting it through won't work.

Now I'm not claiming to have done something special here, but I'm also not accepting any claims by others who wrote statements like:"if you use a rod in some way, so that it adjusts the angle somehow then it could be designed such that it would be adjustable if you find a way to somehow control it from the top of the rudder board."

YEAH DUHHH ! My granny could have thought that one up.

Wouter [/quote]

Calm Down Wouter, if you read the post properly you will see I was giving Phill credit for his post not your invention, I had wrongly said "John" had come up with the idea and John pointed out it was in fact Phill, I was simply admitting my error and giving Phill proper credit.

There was no need for the hissy fit.

Of course if your Granny had in fact thought of it first then I should have given her the credit but I didn't know at the time.

Gareth

Just make it a pin with a line you can pull in an emergency.

Gareth,
I was thinking the same thing. Although I only had a short chat with Wouter's Granny about it.

I suppose she should get the credit.

Wouter, how about you?
Have you been talking to your Granny lately?

No I think that was his wife...