New Trimaran Foilers

[Doug Lord]

F101 Foiling Trimaran

Fairly high take off speed given that the Quant 23 foiling keelboat takes off in around 5 knots and the same for the Whisper cat and around 6 for the UFO.
No specs giving length and beam so far-unless I missed it somewhere......

More info: http://www.foiling101.com/

DESIGN
Long central hull gets the rudder and main foil further apart, removing some of the limitations and bad habits that other foiling boats suffer from.
All carbon construction: main hull, foils, floats, beams, 2 piece mast.
Very simple, well thought out control systems.
All up weight: 80 kg ( 176lb dl)
Length 5m (16.4' dl)
Beam 2.55m (8.4' dl)
Sail area: 8.5m2 main ( 91 sq' dl) + 7m2 gennaker ( 75sq' dl)
Target crew weight range: 70-120 kg ( 154- 264lb dl)
Take off wind speed: 8kts
Target boat speed range: 10-25kts

 

[Doug Lord]

This is what the F101 people say about a couple of features of their boat:

SO WHY THREE HULLS?

Many Moths use buoyancy in the wings to help sailors get to grips with the boat, but this buoyancy is limited to helping the helm recover the boat from a capsize and does nothing to prevent the capsize in the first place. The F101 Tri configuration allows for a slender hull with enough length to prevent pitch poling, while at the same time creating a stable platform to allow novices to get out on the water with no previous foiling experience. The super slender wave-piercing outer hulls are set at an optimum angle to initiate foiling - simply sit on the windward hull, which will cant the boat to windward, then sheet in and take off! If the F101 does pitch forward, the main hull is designed to recover straight back onto the foils; the hull’s additional length keeps the angle of incidence shallow. Its rocker is matched to the angle of incidence – and the additional buoyancy forwards help lift the bow. The benefit applies to the outer hulls too - if the F101 falls in to windward, the windward hull lifts the boat back onto the foils. If the boat falls in to leeward there is enough buoyancy to prevent a capsize and the boat is quickly back on the foils.

WHY IS THE WAND ON THE TRAILING EDGE OF THE MAIN FOIL?

The F101 has its control wand fixed to the back of the trailing edge of the main foil, as opposed to the mounted at the bow which is where Moth’s mount the foil. There are a number of advantages to the trailing edge position, the most important of which is that the wand measures the ride height of the boat irrespective of pitch. This important factor can help to eliminate the porpoise effect which many beginners experience when learning to sail a Moth.

 

[Lurch723]

This looks like a well thought out answer to a safer and slightly less demanding foiling question. The price tag is what it is, after all there's so much developement cost that needs to be clawed back and anything too radical just won't do that.

I think I would buy one as an aging skiff sailor but my money is tied up else where for now. I like the location of the height sensor, I think my main question is just how many of us want to go foiling? For me I like the interaction with the waves and surface, this is sailing for me. but I certainly wouldn't mind owning an F101 and going for a blast now and then.

 

[myszek]

Just a thought: did anybody try a T-foil with ailerons?
Instead of a single flap and a single wand, two side wands and two ailerons to maintain the desired heel. That could make ballasting much easier.

regards

krzys

 

[Doug Lord]

I'm thinking that if one side of the T-foil was capable of downforce it might neutralize the other side or at the very least reduce the total vertical lift available from the foil?

 

[myszek]

I'm thinking that if one side of the T-foil was capable of downforce it might neutralize the other side or at the very least reduce the total vertical lift available from the foil?

Of course it would - so the boat should be ballasted to keep the ailerons close to their neutral position. I hope, however, that the ballasting could be easier with them. Worth test, anyway.

regards

krzys

 

[Doug Lord]

Maserati-Giovani Soldini

Giovani Soldini--from Scuttlebutt: http://www.sailingscuttlebutt.com/2...er&utm_term=A Fascinating Voyage of Discovery

https://www.youtube.com/watch?v=KBdFHBWk0F4

 

[OzFred]

Just a thought: did anybody try a T-foil with ailerons?
Instead of a single flap and a single wand, two side wands and two ailerons to maintain the desired heel. That could make ballasting much easier.

It's been tried on at least one Moth that I know of, however not successfully. It introduces some engineering challenges (such as lateral bending of the vertical foil, dual vertical pushrods in a single strut, dual sets of control mechanisms) that are difficult to overcome with practical solutions. Same for the huge stresses the horizontal foil generates.

Using just the flap to generate downforce is not very efficient.

 

[Doug Lord]

Daggerboard main foil

It's been tried on at least one Moth that I know of, however not successfully. It introduces some engineering challenges (such as lateral bending of the vertical foil, dual vertical pushrods in a single strut, dual sets of control mechanisms) that are difficult to overcome with practical solutions. Same for the huge stresses the horizontal foil generates.

Using just the flap to generate downforce is not very efficient.

===========================
Somewhat true in a split configuration: one flap up ,the other down. However, using a single flap that is deflected up to create downforce is very efficient particularly on the Fire Arrow main foil. Maserati has a similar result creating downforce with the main foil by changing the AOI of the whole mainfoil.

 

[Doug Lord]

Maserati with Fire Arrow Configuration

See here for the story of Maserati doing 33-36 knots at night in the Atlantic on her Fire Arrow type foil system designed by Guillaume Verdier.

http://www.boatdesign.net/forums/multihulls/rorc-transatlantic-race-56808.html

 

[OzFred]

===========================
Somewhat true in a split configuration: one flap up ,the other down. However, using a single flap that is deflected up to create downforce is very efficient particularly on the Fire Arrow main foil. Maserati has a similar result creating downforce with the main foil by changing the AOI of the whole mainfoil.

Not sure an example that doesn't use a flap is much support in a discussion about using a flap.

I guess you determined that your 5' model is "very efficient" at creating down force based on testing, so you should have some measurements or comparisons with alternatives. That the designers of Maserati's foils have chosen to adjust the entire foil rather than use a flap might provide a hint about the comparative efficiency.

 

[Doug Lord]

Fire Arrow Foil System / Maserati

The main difference between the test model , the new 14' version and Maserati is simply size. The smaller boats use flaps to change the lift of the foil because they have automatic systems controlled by wands and/or manually for testing.
A wand would probably not be practical on an ocean going boat the size of Maserati so the choice was between using a manually(hydraulically) controlled flap or hydraulically moving the whole foil. There is plenty of history for the choice of a flap on a wand controlled foil where downforce is critical such as the Rave, Osprey, SKAT, Whisper and S9.

 

[OzFred]

You have not addressed your claim of "very efficient" regarding flaps and downforce. How the flap is controlled is irrelevant in that regard.

There are many considerations when choosing how to implement a design feature, one is that wand controlled appendages breach RRS 52 so unless a boat specifically gets an exemption (such as in the class rules or event sailing instructions) it can't use that system in events covered by those rules whether the wand adjusts a flap or the whole foil.

As far as I'm aware, your "new 14' version" exists only in your head.

 

[Doug Lord]

I beg to differ:

You have not addressed your claim of "very efficient" regarding flaps and downforce.Yes I did by showing the number of existing foilers that use a foil with a flap for downforce.So many boats would not be using a wand controlled flap for downforce if it was not "very efficient". How the flap is controlled is irrelevant in that regard.No its not.

There are many considerations when choosing how to implement a design feature, one is that wand controlled appendages breach RRS 52 so unless a boat specifically gets an exemption (such as in the class rules or event sailing instructions) it can't use that system in events covered by those rules whether the wand adjusts a flap or the whole foil.An absolutely ridiculous statement because of the ease with which it can be-and has been-gotten around(or ignored).

As far as I'm aware, your "new 14' version" exists only in your head. Well,it has to start somewhere. And there's 6 years worth of detailed development notes that have laid the foundation for the 14 footer based, as it is, on the Fire Arrow Foil System, a basic version of which has recently been used successfully in over 5000 miles of ocean testing on the 70' Maserati including the use of downforce by the adjustable mainfoil.

http://www.boatdesign.net/forums/mu...f-righting-trimaran-test-model-36058-162.html

 

[OzFred]

Lots of red ink, but not one single fact in support of anything you said.

Supporting the statement that a particular feature of your model is "very efficient" because some other very different, real life boats use a similar feature is only proof that they share a similar feature, not that it's "very efficient".

Referring to a boat that doesn't exist is even less substantive.

Your assertion that downforce is "critical" to the boats you mention is also unsubstantiated, particularly the S9. There is serious doubt that it generates downforce at all. Even if it did, that doesn't mean using a flap is "very efficient".

Facts may not suit your opinion, but that does not make them "absolutely ridiculous".