Planing Trimarans

With respect to Philips-Birt, is that definition actually of any use?

With the typical hull, as soon as the boat moves at .0000000000001 knots there must be SOME upward pressure created by motion. There'd be no way of working out whether that was the case on any particular hull at any particular speed.

Take a sheet of thin aluminium. Hold it by the edge at 45 degrees. Move it very slowly through the water.......at the speed type moves across the page when it's being typed. "A proportion" of the alloy sheet's weight will be carried by upward pressure created by the motion - even when the whole sheet is fully underwater.

Is a tugboat getting a gramme's lift when it squats at hull speed? Surely it is. Then is it a planing tugboat? What is the definition of "nearly flat"?

Doesn't it define the problem of this thread, when we are arguing over something that is not defined and where there is no agreement over which definition we are using to get the criteria for the discussion?

 

Can we get a definition!?

Thanks CT...This is what I am getting at... Obviously, there have been multiple definitions listed, but non agreed upon. After 14 pages of this thread, can we please get a definition of 'planing'?

 

planing tri

CT & Fhr,I think you may be missing the point to some extent. There are numerous threads on this forum that discuss the definition of planing and the definitions given here are not too dissimilar.
1) The crux of the problem seems to me to be the viability of planing UNDER ANY DEFINITION if the hull doing the planing(by any definition) is unloaded due to heel. That started in the very first post where it was clear from the numbers that the F22 would NOT plane unless the main hull was unloaded by some amount. That was backed up by Mr. Farrier who said the same thing about other F-boats.
2) I've trying to figure out the mindset that says the hull unloaded by heel is NOT planing when it fullfills every criterion of planing( by any definition). Seems to be something like: with heel the F-boat main hull is being "supported" and can therefore not be planing-I guess. The fact is that in the example in the first post, in Mr. Farriers post(s) and in the picture of Parliers Cat(where there is an excellent illustration of the concept) the main hull(and Parliers windward hull) are still supporting some of the weight of the boat. The whole controversy hinges on whether
the F-boat main hull can EVER plane BY ANY DEFINITION when part of the boat's weight is supported by the immersion of the ama. In the picture of Parlier's boat it is abundantly clear(to me ,at least) that the windward hull is planing while the leeward hull is not-the best illustration I've seen yet of this concept.From the angle of heel of the cat it should be obvious that the windward hull is still supporting a substantial proportion of the weight of the boat but because it is "lighter" than the lee hull and because it is a stepped planing hull and because the wake is flat it is planing while the lee hull still has one crest forward and one crest aft.
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The problem in this thread is NOT the definition of planing but whether or not a hull being lightened by heel can ever plane by any definition.
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One other thing: the Parlier picture has additional value because in it you see two IDENTICAL stepped planing hulls: one planing and one not. Part of the problem for some in understanding the Farrier is that in that case when the main hull is planing(by any definition) the leehull is NOT and never will be no matter how fast the boat goes. The Parlier picture catches the two hulls at a perfect transition: the lighter windward hull is planing and the heavier leeward hull is at max displacement speed with one crest at the bow and one at the stern.And we know with that boat as it goes faster the lee hull will plane even with the windward hull in the air. Again, it is NOT the definition of planing that is causing the angst here it is the application of any definition of planing to a hull that is lighter due to heel.....

 

Why does it matter? If you consider the windward hull to be planing or not has no effect on the boat.

I think it comes from the association of planing hulls with higher speed. No one is claiming that a "planing" tri is faster than one that is not "planing", so what's the point of the discussion?

Getting the leeward hull to plane might create a speed advantage, but there would be no argument whether or not it *was* planing.

 

planing tri

I think you're probably wrong: it has a major effect on the boat from the standpoint of interior space since a planing main hull will be wider than a "traditional" narrow main hull.
And the discussion is important from a design perspective because in order to be able to utilize a concept similar to Mr. Farriers F-boat or Mr. Antrim's planing ama's in your own design you would(should) first have to understand exactly how the concept works and why.

 

It is very obvious what forces are involved, what does it matter if they are labeled "planing" or not? The interior space does not change depending on whether the boat is "planing" or not. The boat does not change shape when sailing.

The F-Boats sail the way they do, no matter what you call it. There is little doubt that they use dynamic lift to support some portion of their displacement. "Planing" or not is a label that can be proved to lead to argument, while boats care not what label is placed on them, they sail anyway.

It is exactly like arguing if the boat is red or not.

That boat is red.

No it's not.

Yes it is.

That boat is planing.

No it's not.

Yes it is.

Same nonsense argument.

Thus, "Planing" or not has no effect on how the boat sails.

 

planing tri

Yeah, but those who fall in love with practice without science are like a sailor who steers a ship without a helm or compass, and who can never be certain whither he is going.
(Thanks, Leonardo)

 

Yup.

The reverse is also true ...

Those that fall in love with science without practice are like a sailor who has no boat to sail.

How are things in the Fantasy Boat Works? Still waiting for ol' Rube to come up with "practical" solutions to make the "science" work?

 

planning an F-31

New to the list but read the discussion between Chris and Lord.......
Having sailed my F-31 RL for 12 years and being the winningest multihull sailor on the West Coast (sorry to brag but I needed some cashe here), and having sailed multihulls all my life........
I have to agree with Chris.
The f-boats do not plan on their own. True, when you drive the leeward float down enough so that a great percentage of the weight of the boat is borne by the floats, then the main hull "breaks" through it's displacement mode and their is an increase in speed. This is the same as a catamaran beginning to lift it's weather hull. I wouldn't call this planning.
The only case I would call planning is when the boat goes dead downwind and then exceeds it's hull speed........this may happen when the wind is over 30 kts. or so......
What I don't like about the flat bottoms on the Farrier design is the pounding the boat takes going to weather.........but in the interest of full discloseur (sp?).....I designed the L-7 which doesn't plane, but easily beats the f boats which are larger. How? We're lighter and have bigger bouyancy and less draggy floats.

 

interesting

Leneman and Ostlind vs Doug Lord and Ian Farrier-hey, I like my odds...
Mike, the L7 seems like a fantastic boat-great job!
Seems like quite a few people on the F boat forum say their boats plane-why do you think that is?
Interesting website: Mike Leneman=Multi Marine
Multi Marine, a Multi Hull Boat Dealer, Marina del Rey, Calif. - Home
Address:http://www.multimarine.com/ Changed:8:45 PM on Monday, June 26, 2006

 

Someone told them they do and they never question it?

They haven't read this thread and don't know what definition of planing to accept?

It sounds kewl and it impresses the chix at the bar?

 

That's funny, Doug

What I mean by the title is this:

There you are, in the middle of a Sunday afternoon with the weather in the mid 60's, about 6 knots of breeze and you're typing madly on the computer and not out sailing (or whatever, just to get on the water instead of slovenly-glued to the computer chair.

While I was out on the water today paddling and testing the new rigging setup for an expedition canoe I designed and built, you were posing hypothetical matchups for credibility.

I'll take the match-up anyday you'd like. In fact, since you are in the business of issuing rhetorical challenges, I'll go you one better.

Since sailing itself is the only real means for determining a boat's ability to plane (or not in this case) I'd much rather have the dominant sailing experience of Mike and myself over your partnership with Ian.

I'm calling you out, Doug: You get Ian to join you the next time he finds himself in the West Coast of the USA and get your butts on an F31 and Mike and I will meet you for a sailing race. The loser will shut the ---- up and acknowledge the position of the other as to planing hulls and that will be the end of it. Simple

I'm sure you'll have no problem whatsoever standing by your man in a match race.

You may love that planing has a definition, but the only place where the proof is in the making is on the water. Since planing is a uniquely powerful claim for boats that are being used actively, why not decide the issue on the water like gentlemen and end this stupid exchange of meaningless drivel?

I'm really confident that Mike can handle an F-boat with supreme skill... are you as sure that Ian can still compete on that level? What's your experience in F-Boats, Doug. Are you a competent racer? If your skill in getting an F31 to plane is so secure, then you should be able to beat us handily.

I'm saying F31 here, because Mike knows them well and they are pretty damn fast trimarans. If any boat in the fleet is capable of planing and subsequently sprinting away from our entry, it would be an F31 driven by Ian and yourself. That is, if your claims are legitimate.

What do you say to series of races with best of seven winning the match?

All this, of course, is dependent on your willingness as well as that of Ian and Mike.

Take it or leave it, Doug. Are you a sailor or a computer geek? Have you got what it takes to back up your claims?

Chris

 

planing tri

Let's see : you want to race two identical trimarans to prove that a Farrer tri does or does not plane? That's absurd-why not just ask Ian Farrier, the designer?
I don't need to be convinced:I know from personal experience that a tri can be designed with a planing main hull having designed, built and extensively sailed two such boats.

 

Planning

Doug, thanks for the compliment on the L-7.
To answer your question of why do people say it planes? Because that is what it appears to do and if you stretch the definition of planning maybe one could say it does........at this point it's a game of symantics. The main hull lifts and all of a sudden the wake almost disappears......but this is exactly what also happens on a round bottom hull as well.
The real question or point......and probably why Chris is so adamant, is: Does a flat bottomed main hull on a trimaran make the boat go any faster than a rounded bottom main hull?
Isn't that really the question? Ian claims it does. Ian claims his boats go faster because they have this flat bottom. Ian claims his boats are better because of this. BUT: Ian has not sailed on other boats. When other boats beat his he makes unfounded claims of the other boats being unseaworthy or over-powered, etc. The proof is in the pudding though........do ORMA 60 trimarans have flat bottoms? No. Does the very fast Seacart 30 have flat bottoms? No. Does the faster L-7 have flat bottoms, No. Does the Antrim trimaran have flat bottoms? No. What other proof does one need?
As for a sail off? In all fun.......no problems. I've already challenged Ian to a sail off......his F-22 and my L-7. He said we would have to sail in the roaring 40's off New Zealand........what a ****** !!!! He hasn't raced one of his own boats in years.....I'd race him with one hand tied behind my back
Cheers,
Mike

 

This quote comprises two points I was trying to make earlier in this thread! The definition of planing is certainly stretched to say the mainhull or windward hull is planing , when it is actually being lifted by the rig. The other point is regarding the hull and hull shapes....being that a deep V'd asymmetric hull just skimming across the top of the water, ready to fly but not quite, is hardly the definition of planing.

Mike, thanks for sending the RI gentleman my way...:!: