You could hinge it off the front beam, so you could retract it for launching/retrieving, then flip it down once in deep water. Might have to figure a way to work it around the spin pole, or have it pull up tight to the underside of the snuffer bag when up.

Timbo is on the right track here

Hinge it off the mainbeam with a retainer line of the spi pole. This line will allow the AoA to be set. Place the foil at the tip of a round alu tube and make a loose sitting fairing from foam that youbslide ove the tube. This fairing will weathervane around the tube and thus not act as a daggerboard. As a result this appendage will not be loaded up much in the sideways direction. Two dyneema line may be run from the mainbeam just inside the hulls to the tube just above the waterlevel and thus make for a low cost hinge mechanism and sideways support.

When traversing the surf and landing just pull the foil horinzontal towards the spi pole and clear of the water.

The T- foil may be made of a single 300 by 100 mm piece of multiplex shaped by hand and glassed over. Fit it to the end of the support tube in such a way that it can rotate freely downwards with its trailing edge but never upward past the horizontal. That way the foil can never pull you down. The hinge needs to relatively closevto the leading egde for this. About 25% - 30% down the foil.

A simple rubber end stop will suffice to prevent rotation upward.

At relatively slow speed you pull the assembly a little forward thus maximizing AoA, with increasing speed you relax the line progressively thus reducing AoA and preventing excessive drag and pranching. Fiddle about with a bungee in parallel with the retaining line and get an automated AoA sytem, one that also recognizes pranching by the excessive drag that is associated with it and adjusts the AoA accordingly.

Hell, this may actually work !

Note how even a small diameter tube will be able to withstand the 30-60 kg buckling load. And how a single foil in the middle off the boat with twice the area will have exactly the same overall behaviour with respecttomrighting moments etc as two foils half the size at the tips of the daggerboards.

With respect to foil area.

The total area of boat daggerboards will carry about 120 kg that is the sideways loading of the sails.

However it is best to start with relatively small assymetric foils.

Or make a "U" that just slides vertically in a cassette.

Ummmmm.......

Central mounted foil is a really bad idea. Any lift from it is going to act as negative righting moment against the leward hull so you have added a heap of drag and you have to depower sooner.. if it is tall enough to get both hulls out of the water, you have still almost halved your available righting moment and there for will need to carry much less power.

Having sailed a moth for a few years now, Wouter your T-foil solution won't be reliable. Once a boat is on foils, the pivot point for righting movement is now all on the foil as opposed to being on a 16ft hull touching the water. The foil has to be super strong and can't flex at all. Part of the reason why a Mach2 is faster than a Bladerider is due to the Bladerider foils flexing where Mach2 does not. Plus many many bladerider foils broke due to the loads. The mach2 foil can have a person jumping on them when suspending between 2 benches without any concern at all. And this is the lengths needed for a 30kg boat. Imagine now a boat that is 107kgs and has 2 persons onboard. Breakage city if not done correctly.

The other thing is that there can't be any slop in the system. Has to be rigid. The lengths we go to minimise slop is quite extensive. Reason is that slop means loss of control.

I'm figuring that the difference between full foiling a 30 + 70 kg moth and a partially lifted 107+ 140 kg F16 (for only < 30%) may be an important difference. The F16 will still be carried by the leeward hull for 70% and thus be stabilized. This is basically what the nacra20c and A-cats are doing as well.

Additionally what is the difference between the righting moment of a viper with both L- foils in the water and a single foil in the middle of the viper ? When it comes to righting moment both setups will result in the same overall moment.

Personally, I don't believe that foils are much of a performance gain in most conditions. Hwever the reason I'm interested in them is improved stability of my taipan under spi in big waves especially during long distance racing. For me it is either T-foil rudders or this. This is easier for me to make and try.

Apart from that I'm looking at th following calcs

170 kg crew on my 120 kg Taipan F16
45 kg lift of centrally placed foil
Combined weight carried by bouyancy will then be 245 kg or 110 kg + 135 kg crew.
New rightingmoment will be transformed from 170*3.5+120*2.5*0.5 = 745 kgm
Into 745-45 = 700 kgm = 157*3.5 + 120*2.5*0.5

basically by adding the central foil I expect to get a boat that will partially lift its bows at speed then without thus reduce the dependence of bouyancy to carry to sail loads and wave action.

Secondly I expect to get a boat that thinks that it sailed by a 45 kg lighter crew with the righting moment of a crew that is only 13 kg lighter. The reduction in overall weight ( by 15%) is more then the reduction in righting moment by ( by 6 %).

However, I still don't expect much if any perormance gain except for what is th result if increases stability under spi in waves/ chop

Consider the angle how the t-foil lifts. There is a reason why moths heel to windward. Heeling to leeward like a normal boat just doesn't work.

How about two cassettes(think rudder cassettes) on either side of the mast attached to the front cross bar, with a T foil between the two. You could use the dolphin striker for additional support. Just lower the foil down and raise it back up when not in use. Maybe using a V shaped foil to increase stability and allow the foil to shape around the spin pole.

Doesn't work or doesn't work as well ... ?

I feel flying moths have very little daggerboard in the water and dependent on the Veal-heel canting of the lifting foil to compensate for that.

Doesn't seem the partially lifted cats have the same issues (nacra 20c, A-cats, New Viper)

Wouter. trying to do what you want by hinging off the beam would be an engineering nightmare to get that all important tolerance free fitting, any movement at the beam will be lots of movement at the tip. By engineering a solution will mean lots of extra weight which is going to mean larger foils, more induced drag, even bigger foils to overcome the drag and weight penalties, its a vicious spiral ending in failing to acheive what you wanted in the first place.

Wouter, can you instead use your time and computer model skills to design some nice J boards, they overcome most of the problems, giving good lateral support and some lift. Getting them in and out of the boat is actually quite easy if you think things through a bit. It would mean making up a new case but then even fitting assymetric boards will mean making new cases.

Doesn't work.

We have little daggerboard in the water but this is because you don't need much. When you turn, you aren't trying to turn a 16ft hull that is in the water hence very small amount of vertical foil in the water.

But as for leeward heel being bad, the foils will lift you in the direction of the heel. So if you are heeled to leeward, then when you start foiling they lift more to leeward and on the moth no amount of hiking can counteract this as the foil forces are too high. You have to drop the mainsheet and get the boat flat and then try again being flat or slight to windward. It is a classic newbie moth mistake.

So if you are going to try a t-foil on a cat, the boat has to be sailed flat. But how to get power to foil? The Canadian c-class guys tried all this and brought in Veal but couldn't get it going faster than normal c-class.

J or S foil on each hull a better solution I think.

From above assuming partial lift, an upside down 'Y' appears better than a 'T' ?
Then again assuming partial lift, V or U from the inside shear of each hull at the main beam?

I think the bigger question we need to address is;

1. Do we want to sail in the traditional sense, ie. no foiling, no lifing boards, etc.? (call it Old School)

2. Or do we want to go down the path of full foiling?

(the C cats and Moths have already figured it out, Dave Carlson was foiling his A cat 20 years ago)

3. Or some half-way, in-between measure, ie. C-boards, L boards, J boards... or what have you?

As a class what does the F16 want to be?

1. To even semi foil we add expense and complexity. We further separate the guys who can sail from any potential “new blood”. How many people would we attract, vs. how many would fade away if the class goes on this path? I’m too old to effectively run a spin against younger athletic teams, never mind trying to balance on foils.
2. Do we want to go completely generic and have a heavy 16 footer as being promoted by a number of builders rushing off to Asia. Hack 2 feet off the hulls and recycle all your parts and call it a new thing.
3. For me the excitement in the F16 is what was promised when the rule set first was presented. A light weight fast platform that allowed versatility for its members. Purpose designed and built F16’s can be light. It is still new and the potential for this has not been realized yet, but for a few.
The 16 class has flexibility, where it is not so likely to get caught up in the quagmire the F18 class has going for itself now. There are though, some reasonably thought out restrictions that allow for experimentation, but from a practical standpoint does not force high tech to be mandatory.

If you want foils go join the moths. Every other combination already exists as well somewhere else. You want heavy racing go F18, semi lift foils go A, Line honor racing C20-M20 etc. What is the constant fascination with people to want to f - up the rules all the time.

Just to be clear, I prefer Option 1 from my above post, and fully agree with Mini's last paragraph above.

If it is foiling, it is something else than an F16

Timbo, mini, Rolf,
I thought we already went over the issue of foils in this thread?
http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=232988&page=1
or is there something new here?

Thanks for the reminder, that was 10 months ago.

Ahhh...the Good Old Days.

My memory is good, but it's short!

Foiling is Dangerous!

And YOU guys are Dangerous!

http://www.funnyordie.com/videos/8afa50b440/iceman-the-later-years-from-nino

At work, they call me Ice Man...but sometimes it sounds a lot like butt-Man!

http://www.youtube.com/watch?v=o2X_XNdmWws

haven't we already answered that in our class rules ?