# Planing Trimarans

Discussion in 'Multihulls' started by Doug Lord, Sep 30, 2006.

1. ### Doug LordGuest

This post is an answer to a question posed in post # 4 of the "Best Design for Minimalist Trailerable Coastal Cruising" under Boat Design.
The question asked for a definition of a planing tri.Examples of "Definition 1" below that I know are sailing are the Farrier boats including the F22:

From Farrier on the F22:
"Main hull lines have been optimized further with a higher displacement being achieved, but with a lower wetted surface area while it has a slightly flatter bottom with less rocker so it will plane earlier."
A planing F22 has two ama's that are displacement hulls while the main hull is designed to plane. Planing can be defined as the reduction of displacement due to dynamic lift or maybe better as the reduction of wetted surface due to dynamic lift.
A rudimentry analysis of the F22 sailing in 1lb. per sq.ft. pressure shows that it requires approximately 600 pounds of bouyancy(max buoyancy around 3500 pounds) from the ama leaving the main hull still needing to support 1200 pounds. Since planing requires about 500 sq.ft. per long ton(2200lb.) and the F22 has 294 sq.ft. not including a screecher or spinnaker-2200 divided by 1200 gives 1.83 multiplied by 294 = 539-easily enough SA/ton for planing. Because of the high beam to length ratio of the displacement ama's they wouldn't retard planing of the main hull significantly.
I had two small planing trimarans one 14' which would begin planing in around 8-10 knots of wind with the leeward ama barely touching.The twenty footer would plane in around the 12 knots of wind and the ama provided some righting moment reducing main hull weight a bit.
--------------
Definition(at least my best shot at it)--
1)A planing tri: A trimaran with high beam to length ratio ama's with a main hull having flat planing sections coupled with a SA/ton of 500 sq.ft. or over for main hull displacement.This may be designed as a static condition or occur as the boat is powered up and the ama absorbs some of the boat's displacement in effect reducing the load the main hull is carrying.
2) A planing tri: a trimaran with ama's designed to plane as the relatively high beam to length ratio displacement main hull begins to lift and eventually flies just clear of the water.(new type)

2. ### Chris OstlindPrevious Member

I am not of the opinion that a Farrier trimaran can plane on its own, with or without the functional use of its ama to support any part of the total displaced weight of the boat.

I do believe that there is a partial, dynamic lift scenario developed by the amas and also by the vaka hull in certain conditions, but it is a far, far distance from lifting the entire hull onto the surface of the water beyond its displacement bonds.

Let's face it, these are commercial boats in which certain parties have vested interests in their potential as performance products. Performance oriented sailboats have a holy grail that puts them into a select group of fast designs. That holy grail is the ability to get up on a plane, so the pressure for a performance boat is very strong to enter that arena. It is true that Farrier boats do perform very nicely as trimarans, which are generally very fast boats for their length. Like any boat, however, they do need to be sailed well in order to achieve their full potential.

Planing is not when the bow busts through the crest of a wave and you see half the hull jutting forward. It's also not when the stern is lifted by a passing wave and the boat briefly accelerates down the face of the wave, well beyond its hull speed, only to return to normal sailing. The last description is actually "surfing" and that is not planing.

What I have never seen either on the water, or in video proof, is a Farrier trimaran main hull actually planing, on it's own, with absolutely no support of any of the weight on either of the amas.

I know that Mr. Lord likes to embrace all things technical in nature and that he has a small interest in the technical aspects of multihulls in deference to the techno-foilers, which are his real passion. So be it. What is typically ignored, along with all the marketing claims that are put forth regarding any performance oriented object, is the fact that there needs to be a collection of proofs in order for the claim to be recognized. Science is not a word-smithing exercise. There’s a process to adhere to and it isn’t being done in this case.

This isn't wizardry. There is a serious scientific order to the presentation of claims of this sort and without that observable, recordable set of proofs, all the puffy words in the world are not going to allow the claim to jump the chasm to the recognized reality. The claims have to be documented and repeatable via the same conditions by anyone else who performs the experiment.

I've had this same conversation with Tom Speer. (a couple of times, actually, to no avail) While he makes the accompanying argument regarding this planing Farrier phenomenon through words and testimony, he has still not produced one single motor drive sequence of still photos or even a video to support his claims to this fact. Since Tom is a scientist by practice, completely engaged in the process of recognizing proofs, I marvel at the nearly complete lack of objective proofs that can be examined by a group of his peers.

I'm not highly qualified to be a hydrodynamicist or naval architect for these purposes. If this claim of having either of the amas in the water while the main hull is skimming along on the surface is the position that justifies the planing claim, I feel it is marketing hype and ultimately without merit in its position. If this is the game, then virtually every catamaran on the planet can also plane and we all know that claim to be false.

I see the argument for dynamic lift as a function that can partially unweight the vaka hull through a combination of form characteristics as well as surface and wind conditions. To extend this condition to the identifier of "up on a plane" is beyond my willingness to recognize the position.

I'm not the only one who regards this "planing" claim as nothing more than marketing position. I would ask that the proponents of this position produce an unedited video with continuous, camera original, time code so that the visual component of the proofs can be examined by appropriate professionals who have unquestioned credentials in the matter.

I have great number of sailing friends in San Francisco who have seen many Farrier trimarans sailing in what could be called optimal conditions for a high performance sailing craft. ( protected waters, remarkably high and very steady winds and long stretches of water to get all the various boat components dialed-in to maximum output) Not one of them has ever seen an F-Boat get up on a plane and leave the other boats in the dust.

Certainly you would have to say that any sailboat that could routinely plane and severely reduce its wetted surface drag component, while the rest of the class multihulls struggle along in displacement mode, would completely dominate the fleet by large margins. Yet, this is not happening. One can only wonder why.

Mr. Lord likes to use the capability of the Foiling Moth to rise above its displacement brethren as the single most important issue in its apparent ability to blow by otherwise fast, displacement craft who are still saddled with the wetted surface drag component. In this argument, however, Mr. Lord will have to substantiate why a boat type that can also seriously reduce its wetted surface, has not delivered the same, blistering domination of the local, fast multihulls against which they race.

There's a very quick 31' trimaran in San Francisco designed by Naval Architect, Jim Antrim, named Erin, that has routinely smoked the "planing" F-Boat fleet, Yet, it is a displacement design with no accompanying claims otherwise. Why can't the F-boat fleet absolutely obliterate the efforts of Erin in every race it enters when they should be so much faster in the water by the planing claims?

I am afraid there is a long way to go before these marketing claims will be substantiated on behalf of the F-boats.

So, here's the take for Mr. Lord, Mr. Speer and even Mr. Farrier... Show us the untouched, camera original video containing unbroken time code and no, "after the fact", edits that demonstrate multiple proofs. Let me get it before a group of respected professionals for their examination and I'll reconsider the position I hold. The collective opinion is open to the potential, so gather your proofs and not just the words or the desire.

3. ### Doug LordGuest

Actually, Mr. Ostlind you may need to see video but an analysis of the speed of the boat under the 1lb. per sq.ft pressure I mentioned in the first post should give you irrefutable evidence. I'll try to find speeds achieved in those conditions. I don't remember the waterline length of the boat and it will be slightly shorter under the conditions I mentioned anyway so lets just use 22' as the waterline length for the F22 main hull. Another definition of planing is when the boat exceeds a speed length ratio of two; at 22' that would be 9.38MPH or 8.15 knots. Now, I'd bet that the F22 in conditions of 1 lb.sq.ft pressure is likely to be going faster than that. The real "thing" about the Farrier hull is that since it IS a planing hull it can use wider sections on the main hull than would be possible on a high beam to length ratio hull- the only other alternative to fast(speed length ratio of 2 or more) speeds. If the main hull on the Farrier was not a planing hull than the boat would be a dog since it's beam to length ratio would be too high to allow it to easily exceed hull speed. So, you see, for the boat to be fast(see definition above) the main hull MUST be a planing hull. And everybody agrees that Farrier tri's are fast.
I'll try to find more facts for you.
I do think you go too far when you accuse an eminent trimaran designer like Ian Farrier of "cooking the books" by saying that the main hull of the boats he designs planes-Farrier would have far too much to lose by making such a claim if it wasn't true.

4. ### Chris OstlindPrevious Member

I want everyone to take notice of Doug's position with the deliberate misspelling issues regarding my name and mark it down as the point when the otherwise respectful discussion went south. It's on you Doug. Maybe you'd like to apologize for the deliberate act while all the readers are watching?

Now, on with the points I will make...

First of all, Ian Farrier has designed a truly wonderful series of boats in his career and will be respected for that contribution to the craft of sailboat design, for as long as folks can remember it. I respect his work and the place he holds in the trade to that end.

I'm not accusing anyone of anything, Doug, just doing what anyone would do, demand the proofs in an irrefutable fashion. If there are so many F-Boats flying around on plane, then the videos should be oozing out of the woodwork, don't ya think? Yet Speer couldn't produce one and neither could Ian. Here's the designer, himself with a full-blown, F-Boats website with dozens of promo tidbits floating around and not one single video clip of a planing F-Boat anywhere on the entire site. Yet the claims are rampant. Something is mighty weird about that discrepancy, if you ask me.

I don't care what your hypothetical numbers say. I'm a real world guy, show me the visual proof on an unedited tape directly out of the camera with continuous time code. These are called camera originals in the trade, Doug, and they are easily read for second generation data.

Interestingly enough, when I asked this same question of Ian about two years ago, he provided me with a set of photos showing a pair of F31's up on one hull. Now, that's impressive as all get out, but it's not planing anymore than a jumper from the Golden Gate.

I'm not disputing Ian's skill or his accomplishments. I'm doubting Ian's claims... or are you of the mind set that Ian is above being called on his position statements? Ian's an engineer and engineers tend to take things on a numerical basis. Now that you say there is proof in the numbers, I say prove it in the real world and produce said proofs so all of us can see it and know it for what it is. Get a qualified, professional cameraman who can hold the camera steady for proper anaylsis. Get a high quality camera with adjustable, electronic shutter speeds so that the image is as clear as possible. You should know the drill by now.

In your own last posting, you say "another definition of planing..." So, which one would you like to endorse and then promise to not deviate from in future discussions. No, really... pick one, since there seems to be about a half dozen, so-called definitions with significant elements of difference between them. The definition has now been expanded to include the use of amas in the planing capacity and I find that to be a huge stretch of semantic arguing in odrder to sorta kinda get the discussion turned around your way.

Tell me something... Is a foiling boat actually planing when it is supported on its foils. You know, the time when the boat is just barely lifted up on the surface but there just isn't enough wind to get it to fly completely. Virtually the entire weight of the boat is borne by the foils and you would like to suggest that the hull is planing and the hull is supporting all the weight on its bottom surface? Or... is it in fact foiling?

And no, Ian's amas do not plane either. Dynamic lift... maybe/probably... planing, no way. Go look at the shapes.

So, what about the cat argument? You know, the one where the cat gets to say it is planing when the weight is borne by the leeward hull just because the windward hull is skimming the surface?

What about the Erin argument in which a displacement trimaran busts the planing F-Boat paradigm when the boats are equally matched in LOA, BOA and Sail Area. Antrim states that his boat gets dynamic lift from the amas and the form of the main hull, yet he makes no such claims about planing.

Are you saying that you know more about trimaran design than Jim Antrim?

From your own use of the numbers to determine performance, you'd have to assume that a non-planing tri would be absolutely sluggish compared to a planing design with equal specs. Yet, not only is Erin not sluggish, it still routinely beats the F31's and the F9R's and the design is going on 12 years old now. How is that when the F-Boats can plane so easily? One would think they can just flat fly away from Erin?

In the 2005 Farrallones Double Handed race, Erin beat a Farrier designed, C31 on elapsed time as first multihull to finish. Shouldn't a planing boat have won that race and been first to finish just because it was incurring so much less drag with the same sail area available? Yet Erin won handily and has been winning that event since it first hit the water. Why is that with so many high performance F-Boats in the water in the SF Bay area? doesn't anyone know how to beat Erin, that funky displacement boat that pushes so much water out of the way wherever it goes?

Could it be that the elusive, drag reduction planing potential of the F-Boat is not all that it's cracked up to be? Could it be that the desire to stretch the definition of planing has finally gotten the boat design and marketing world so dilute with these claims that now all of them are specious?

And, Doug, be so kind as to stop with the name spelling games unless you'd like to open-up the criticisms again to anything on your personal side of the ledger? I've played this totally clean and you are resorting to lo-ball tactics.

5. ### Doug LordGuest

name

I would NEVER deliberately mispell your name and have corrected it. I apologize for missing it.

6. ### Chris OstlindPrevious Member

Actually, the list below is the precise number of threads in which you have NEVER deliberately misspelled my name. You've even gone so far as to make it bold and put it in red

While I do appreciate the attention that lends to my Swedish heritage, it would be tough to say it wasn't deliberate after all the heavy graphic treatment.

The angelic routine is for the reader's benefit and those who give you reputation points.

Catamaran vs Trimaran

60' Moth-A Preliminary Detailed Design Exploration

Foiler Moth World Championship Standings

FOILER 1 Grand Prix

I do, however, take heart when you show the grace to apologize, even if it is something akin to crocodile tears.

Now, would you be so kind as to prepare a series of answers to all of the questions I posed on the matter at hand? Feel free to consult the Antrim website for data on Erin. Jim is quite free with his knowledge in that way.

www.antrimdesign.com

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### FiggySenior Member

Chris, with all due respect, where are you going with this? I want to get involved in the topic, but if your not listening to Tspeer, why would you listen to me? (I'm not being sarcasic)
I do agree with you about the market being flooded with "planing hull" claims, but I dont know how anyone can stop that trend. Its marketing, and people want boats that plane.

1 person likes this.
8. ### Doug LordGuest

Excuse me?! Jim Antrim "replies": Antrim30+ "Erin"

Jim Antrim makes no claim that I can find about a planing main hull. No, actually this design seems to fit Definition 2 in post #1.
"The high buoyancy, planing geometry[ of the ama]
is highly resistant to burying the bow at any speed."
"...attribute this to a wonderfull synergistic effect between canted boards and the planing hull shapes.High static buoyancy, planing ama shapes and canted daggerboards form the holy Trinity of anti-nosedive safety." Jim Antrim
Antrim 30+
Address:http://www.antrimdesign.com/trimarans/erin/ Changed:1:17 PM on Friday, September 30, 2005
++++++++++++++++++++++++
So what we have here are TWO major TRIMARAN DESIGNERS claiming that planing hulls are INTEGRAL to their design philosophy! One uses a planing main hull ; one uses planing ama's.
I tend to think that these two designers know what they are talking about.....

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10. ### Chris OstlindPrevious Member

Figgy,

I'm not going anywhere with it, Figgy. Doug brought it up on another thread and directed it over here. I just want it (the claim) to be supported by substance and not pure marketing hype. Like you, I'd like to see these kinds of "my boat can plane" claims removed from the hyperbole. They disrupt the buying process for the uninformed and don't contribute to anything like a consistent picture of what multihulls are all about.

Is that all it takes...? Speer says its so and the deal is done. Please wake me when the dream is over. He's just another guy who is prone to doing and saying stuff outside of reality once in awhile... just like the rest of us. If Tom could have produced the proofs beyond his saying so, then I'd be saying nothing right now.

Tom typically goes to great lengths to provide data derived from repeatable maths, laws of physics and other scientific applications. Suddenly, here, about this well known and somewhat easily tossed type of claim, he goes blank. Why don't you tell me what that means? I suspect he does not like to be challenged, but that's not a new issue for human beings. I don't like it either, but it doesn't make the issue go away, just because one gets uncomfortable.

I've enjoyed his contributions here and elsewhere and I think he's a very sharp guy in his element. I don't know anything else about him, so that's the fact of the matter. He could be a total dunce about any number of things he needs to do in his life, or he could be a genius in everything he does. What difference does it make?

If you can make the claim, you should be able to support it. What's the big deal with asking for visual proof regarding this very visual issue? So far, it's not on the table and that, in itself, is a proof.

On this issue, perhaps Tom could calculate just how much faster an F-Boat should be when, and if, it planes over an F-Boat that is locked in a purely displacement mode of sailing. Like I said before, one wonders why F-Boats have not absolutely mopped the floor with all the displacement multihulls like Erin? Geez, even Mike Leneman's L7 is kicking the crap out of F-Boats and he makes no such planing claims at all. What's up with that?

Doug: before you get all excited on this, the indication by Antrim is not that his boat planes. It's simply a comment about the shapes of the forms themselves and how they help to create dynamic lift in concert with other elements of the design.

If you read it again, Antrim never claims the boat planes on the amas, he states that the planing shapes of the amas contribute to the whole of the efficiency of the design along with the assy. boards and the static buoyancy. The two statements are not the same, no matter how much you would like that to happen. Having planing forms does not mean the boat actually planes on them. Ask a guy with a powerboat with too small of an engine if he knows about that reality.

I know you'd love to see Antrim come out and concur with Farrier, as it would help your argument, but I'm of the impression that he has not made that claim for a reason. Then, again, you could always ask Jim and post the answer here.

Farrier, by comparison, makes entirely different claims.

From the F22 page:
"Hulls: Main hull lines have been optimized further with a higher displacement being achieved, but with a lower wetted surface area, while it has a slightly flatter bottom with less rocker so it will plane earlier..."

This isn't a comment about planing shapes and their contribution to the whole effect. Its a direct claim of the boat planing on the main hull. What I suspect it omits is the reality that in order for the main hull to plane, the rest of the boat weight has to be supported by the leeward ama. And therein lies the trick to the tale.

Get the video, get a clip of it on the air and verifiable, as I shared, and the commentary can shift, like I also said. I'm open to the potential, I've just never seen it, nor have many extremely well versed sailors who know multihulls better than do I.

Tom says he has had his own boat on plane, though he has no documented proof. Perhaps you could fly up to Des Moines, WA and arrange to shoot him while he powers his planing F-Boat across the bay? I know he'd love to spend a few days with you if the conditions are not just right for that particular event.

11. ### Doug LordGuest

Planing hull shapes that don't plane?

======================================
"Planing hull shapes" &"Planing ama shapes" is not clear? It seems so utterly clear to me but who knows, I guess.....

12. ### Chris OstlindPrevious Member

Wordsmithing will not fix the issue, Doug, and you know it.

Why not exercise the courtesy of answering all the questions I asked that clearly place the planing question on another footing?

You know what they are and this business of twisting Antrim's intent is not going to make them go away.

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### Dan SJunior Member

Just because a boat has a planning hull or ama shape, doesn’t mean it will plane. Secondly, the numbers from your first post are all based on linear relationships; and while linear relationships will get you in the ballpark, they can hardly be considered a good way of determining if a boat will or will not plane.

14. ### Doug LordGuest

F22

Factors indicating that the boat will plane:
1)D/L ratio around 50(at 1lb. sq.ft. pressure with ama supporting some of the weight.
2) SA/D ratio 42(27 required to plane according to Pierre Gutelle in "Design of Saling Yachts"). This is with UPWIND sail area only. Downwind SA increaes this number and reduces the wind pressure required to plane.
3) Has over 500sq.ft.SA per metric ton just in upwind SA. 400 requred according to Douglas Phillips-Birt(Sailing Yacht Design)
4) Should easily exceed speed length ratio of 2-the threshold of planing according to Skenes and others..
Pierre Gutelle in "Design of Sailing Yachts" second edition says a sailboat will begin to plane at a speed length ratio of 1.5
5) Ian Farrier says the boat will plane.
6) Tom Speer who has spent many hours ACTUALLY SAILING on a Farrier designed tri(if I remember correctly) says it is a planing(main hull) design.

15. ### Chris OstlindPrevious Member

Ian says it's so

Yes, and George Bush said there were WMD's in Iraq.

I trust my folks more than Ian and they told me there was a Santa Claus and I still have nightmares about coming to terms with that issue.

Get a proper video, Doug, and quit fooling around with the calculator and wads of paper. Eventually, even the Apollo Space Program had to launch a few rockets to get their butts to the moon. That's called proof of concept.

Make it so and quit hypothesizing.

I'll be down at the shop working while you pull your act together with the camera. Take your time.

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