Uptip Foils

Nothing personal Doug.
Foiling is growing and it would be better if you guys had your own forum, that's all.

 

Foiling

The problem with that is that foiling applies to every segment of sailing from windsurfers, to dinghies, to small multihulls, to the Americas Cup, to offshore ocean racing ,to monohull keelboats, to 100' trimarans and more.
You would have to double the size of the sailing portions of the forum to cover all of it's aspects.
Now, everyone is free to choose what topics they are interested in and to ignore the ones they aren't interested in.

 

exactly right. All those basic hull variants are spread out over the traditional forums. Better to gather all of them into one place. I imagine that foilers are more interested in the foils than they are about specific hull variants. One stop shopping instead of being spread out all over.

 

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Thats simply not true. Any "slowness" as a result of the slightly(10 degrees) angled rig* could be remedied on a turbo version of the boat by simply using a canting rig while maintaining the advantages of the angle of heel relative to the use of UptiP foils.
The angle of heel greatly simplifies the handling of the boat.

* google "trimaran" and you'll see that the majority of tri's sail at an angle of heel......

 

Interesting that ALL(I think) of the new Ultim( 100' ) trimarans are using UptiP ama foils-mainly because these foils automatically maintain altitude with no or very little speed related variation. And most AC cats use a version of the UptiP foil:

Sketches by"darth reapius" :

 

One of the things thats been done in the AC 50 class is to allow 15 degrees of cant and that can allow the foil to work like a highspeed ,low drag foil or a super stable UptiP foil:

 

New UptiP foil configuration-note the horizontal tip-
Screen shot from DNA G4 cat from www.catsailingnews.com

 

UptiP/ "S"/AP Foils on AC Boats:
--all pictures by Ricardo Pinto/ACEA except BAR which is from the Team...
Artemis:

Oracle:

Team Japan:

TNZ:

BAR(UK) :

Groupama:

 

Simply saying something is "not true" isn't proof of anything. Look at any skiff sailing event and see how the boats are sailed: they're as flat as possible because it's faster. There are all sorts of physics to prove it, but there's no need. Just go to a skiff regatta and you'll see for yourself. Ask anyone who know anything about sailing high performance boats and they'll tell you.

There are some displacement boat classes that heal as it gives more righting moment and less wet surface, which compensates for the loss of sail efficiency and other effects of being healed. But that doesn't apply to skiffs or foilers as they don't gain anything from being healed to leeward. In fact, they not only lose rig efficiency but also righting moment as they get nothing from from hull stability. So healing to leeward is inefficient and why designing a foiling boat to sail healed to leeward makes no sense.

Displacement trimarans sail healed for the same reasons yachts do: it's impossible to prevent it without a canting keel (which has its limits). Some cant their rig upright because it makes the rig more efficient, so it's faster. They'd like to sail the whole boat flat and not cant the rig (because it's simpler), but it's a practical impossibility to sail a big trimaran flat in any sort of breeze, so they heal to leeward and cant the rig.

But a large foiler can sail flat, as shown in the AC. And they don't need a canting rig to stay efficient, so avoid that complexity as well.

So the best thing you could do for your trimaran is to make the beams anhedral and lift the center hull entirely out of the water, then just use two main foils—one in each float. Now it can be sailed like an AC catamaran, and be much faster for it.

 

Reply to previous post here: High Performance MPX Foil/Self-righting Trimaran-The Test Model https://www.boatdesign.net/threads/high-performance-mpx-foil-self-righting-trimaran-the-test-model.36058/page-171
post 2555

 

UptiP foil geometry- Oracle and TNZ Day 8: (picture by Ricardo Pinto from catsailingnews)

 

ULTIM UptiP ama foils: Both Gitana 17 and Banque Pop use UptiP foils on their amas because the foil can be designed to require little to no adjustment while automatically maintaining the ama at the designed flight altitude:

Gitana 17 UptiP ama foils:



Banque Pop UptiP ama foils: