T foils

Easy one this, your rudder sudenly starts to have no effect and you generally start to slide up the hull as the beams suddenly enter the water, as you can guess it is all too late to do very little about the out come.

That's my point, I want to know what (if any) feedback you get before it is all too late.

Can you feel the T's start to loose grip ?

Seems you could watch the bows, if they start going down, it's time to get back. It can't flip until the bows go under.

John may be able to shed some light on this one...

http://www.formula16.org/component/optio...;g2_itemId=1579

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Paul

Nice picture of a new

Wave Piercing

design! Did he recover?

Looks more like wave-ploughing than wave-piercing. <img src=

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Thought that was a submarine with a new *modern* periscope.

This modern periscope must be inverted. Have a close look at the forestay and mast, the first looks to be slack and the second looks bent. How nothing snapped under these loads I'll never know.

Nothing snapped because JP knows how to build strong boats! (plus - I flipped!! <img src=

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Simon - you really don't get time to react to any feedback (if you are able to discern any) It all just happens very suddenly. The bows will dip and then hold as the foils take hold. You can continue to push surprisingly hard and get away with it, but sometimes it's possible to simply overwhelm the foils. You get no real warning - one moment everything is at the limit, the next it's too late and the foils just let go of the water!!!

So far it's happened to me maybe 4 or 5 times in 2 years and I've been out in some pretty evil conditions. So I'd say that it's not really something to get hung up about.....

Not hung up about it; having pitched the 17 in big time when on the wire with the kite up in big winds it does not worry me; I was just wondering if there was much warning at all, or anything you can do about it.

To those who are using them. I am intending to use foils an a Taipan project and want to know if it is fair to say that the most obvious characteristic that suggests the foils will give way is wind strength, chop and probablity?
Also. I am strengthening the transoms of the Taipan for these and wings I am fitting. How much extra force on transom do you think is generated by foils?

John P, quotes the foils providing the equilivent of around 100KG on the back of the boat.

What I'd like to know is how these foils (and their attachment to the hulls) cope with hitting obstructions, such as sandbanks, shoreline and mooring lines... the point being that they are fixed down while in use. It's a serious question as I sail mostly on an estuary but would otherwise love to have T foils. ALso, if you allow them to rise up as you approach the shore, do you have any steerage?

I sail on the Thames Estuary at Leigh on Sea (where the tide goes out a mile and a half). So far I've had no problem with grounding, it just takes a bit of local knowledge and some planning.

Coming into and getting off the beach is also MUCH easier than you might think, once you've done it a few times. The rudders work as soon as they are free in the stocks, you can have just a few inches in the water and they're working enough for low speed manouvreing.

We have one racing mark where I can't get round with the rudders fully down if we have a particularly early start time. In that case (it's happened twice this year) I don't pin the rudders down for the first lap at that mark and they move up and down freely in the stocks but still provide really good steering.

David Tugwell could certainly tell you what happens if you pick up a mooring with a rudder <img src=

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Basically, it's a PITA. I've never done it, but I guess it would be incredibly difficult to get off without assistance. Thinking about it now, I think I'd probably opt to capsize the boat deliberately and then sort it out. (the Stealth comes back up VERY easily) Shouldn't take more than 4-5 minutes.....

Do you mind posting a photo of your rudder set up?
I am still sorting out what the boxes will look like.
Regards, Lester

Picture of 'old' style Stealth T-foil and stock:

Picture of current Stealth rudder arrangement:

Many thanks. the later one looks a very simple construction and the foils further forward will give them more protection at the beach. I thought I would cut the rudder stock up a bit to have the transome edge hit first.

Since we placed

T

foils on the Alpha Omega F14 we have hit many obstacles (mostly with the intention of testing them to the extreme) and we have had no failures of any kind to date except for the odd chip or scratch. In most cases the C/B’s will hit first any way. The T foils have never

let go

even under the most extreme of sailing conditions. We made them a larger surface area than those of the Stealth, which may be why they “grip” through the extremes. When we put them on the Alpha we never bothered to strengthen any part of the transom, in fact we just “dropped” them straight onto the same gudgeons. Although the effect load that they generate, would seem at first glance, to require a “stronger” transom construction, in fact it is not a primary loading only to the transom as the foils are “directing” the horizontal attitude of the hulls as they move forwards through the water and as such, only a relatively small amount of that “load” is absorbed by the transom, certainly not enough to require strengening the transom. The effect of sailing with the T foils has shown to offer a very noticeable performance increase over sailing without them in all conditions from 2 knots up to 20 plus knots.