Ultimate 18' Tri ?

On the 18 it would be done by removing a pin, rotating the hull by hand, and then reinserting the pin. It could also be done by using a gear drivebelt and pin. The rotating structure itself would be engineered so that the hull had the same longitudinal bending strength as a normal hull. This would result in slightly more weight than a normal hull but that is offset by the smaller size(and volume) of the whole ama(as compared to a displacement ama).

 

The rotating ama mechanism.

On the 18 it would be done by removing a pin, rotating the hull by hand, and then reinserting the pin. QUOTE- DOUG LORD

OK it could be done be two guys on the shore, but on the water this would be impossible or at a minimum the stuff of legends. If you have been out on a short board sailboard in strong winds and you suffer a rig from hull separation which is not all that uncommon, the subsequent seemingly very simple re-assembly required to save one's self and get back to the beach requires exhausting and almost super human effort in rough water. But guess what? the motivation to fix it and save you self is an over whelmingly huge motivation.

 

Well, I have been designing, building, sailing, and successfully selling commercially, my high performance catamarans now for over 40 years, and over that time I have never produced any multihull that did not actually exceed its design brief! The last cat that I designed and produced is the Alpha Omega F14 which has now shown to be the fastest 14’ cat in the world and they compete “head to head” for “across the line first wins” against much larger cats such as the NACRA 5.8, A class, formula 18’s, F16’s, etc, etc. The all up sailing weight of the Alpha Omega F14 is 75kg and this foiling tri is based on the centre hull being from and Alpha F14, The foils I have been studying and working on for over 40 years, The Alpha F14 already sails with “T” foils on the bottom of the rudders which have proven to be very advantageous to it’s performance.

 

Hi Darryl, You have made very very big claims for the alpha omega 4.3 cat. being quicker that A cats at times etc. etc. Easy to say on a forum, where are some results that are convincing? Also I asked in my posting #15 to give more specifications. Your sketch (schematic only?) in your posting is so rudimentary as to convey almost no information. Can we get some more details of the new tri design?
Regards, Sam

 

I see that you are in Australia? And you have not heard of the performance of the Alpha Omega F14??? Just look up the Yachting Victoria web site and have a look at the YA yardstick for the F14 in comparison to the other cats mentioned then come back and resume your cynicism. Just where in Aust’ are you if you haven’t hear about the performance of the AO F14?
Do you or don’t you sail? Is all that you talk about here confined to “theory” with no actual practical experience??? Do a little research on my name and the 5000 odd multihull craft that I have designed, manufactured and sold throughout Australia over the last 40 odd years, then come back and ask some appropriate questions instead of attempting to cast aspersions.

 

Foiler tri

Darryl, as I've said before your boat looks very interesting. I have some questions:
1) Why four hydrofoils? One of the big advantages of the bifoiler configuraton, as you know, is the ability to heel the boat to weather to unload the vertical fin. Would something like that be possible with your configuration? I've always been taught that surface penetrations in a hydrofoil design should be minimized-and you have four-what is your theory?
2) Do the outboard foils generate righting moment? How do you control altitude?
3) Why did you choose swept foils; isn't there an efficiency penalty for that much sweep?
4) How much sail area do you envision?

 

Darryl, You have a manner about you that is somewhat odious and with an air of supremacy which comes across very strongly. I have been sailing for 41 years and my first boat, something similar to the original Sailfish design, was self designed and built, and was a very successful one off. Since then I have sailed in Intervarsity Lightweight Sharpies, Skates, Moths and extensively in sailboards. I have been published in 'Windsurfing Magazine" out of the USA in March 2002 (page 22). It is feature article with large photo published in the section of the mag entitled LEADING EDGE.
What is being featured is a 20ft. tandem high performance sailboard being sailed by me and my son. This is a unique design and constuction for a sailboard.
I have never owned a catamaran although have sailed on them at times including the Tornado. I have not found catamarans to my taste as sailboat I want to own.
By the way, I have lived in Perth for many years, and do most of my sailing on the Swan River, but have raced and windsurfed on the Indian Ocean many times as well.
I am not going to go on about this stuff, as after almost 600 postings on this forum I have hardly ever blown my own trumpet until now.
I only asked you a couple of normal questions, to which you could have graciously provided the requested information. Now I suggest you go and think about your response and try again later.

 

Well, thank you for your comments as to your assessment of my “attitude”, “Frosh” read and noted.
To answer your queries DL.
There are only three lifting foils, one at the bow of the centre hull and one each at the extremities of each ama. The foil on the rudder is a pre set, parallel to the average water level, “T” foil and its sole purpose is as a pitch control, although its function is somewhat negated by having three automatically adjustable lifting foils I still like it for that pitch control function. I think what you are referring to by “the ability to heel the boat to weather to unload the vertical fin”, is something that may be applicable to something like the Moth supported on a single central main foil (and to a lesser degree the single asymmetrical rudder foil) than it is to this type of foiler where the pitch and heel all come under the influence of a dramatically larger support “base”
All three lifting foils are symmetrical (as opposed to “wing” like asymmetrical) and they are all controlled independently by a “wand”, meaning that all are capable of positive lift either upwards or downwards which ever is appropriate depending on the height that the craft is airborne and its “roll” or as you say “heel” attitude. The object of a high performance foiler is to have as little heel as possible as heel would indicate a greater difference than desired between the lift being generated by the sails and the speed of the craft across the water, so yes the outboard foils generate “righting” moments (as does the centre foil as well when the leeward foil generates enough lift to support the entire load of the craft and them some) angled or raked foils are more efficient when it comes to foil cavitation prevention and as well as for other reasons, they automatically shed weed and a foil when raked for all intents and purposes becomes a much higher aspect ratio foil than when straight as it exposes a much greater length to the direction of the water that it is travelling through with the same chord height. The entire foil rotates not just a trailing flap so giving them great directional controllability of lift as well as increasing the efficiency of lift generation (either up or down) greatly over fixed foils with trailing flaps. (Particularly asymmetric foils)
This craft carries a 25’ rotating carbon fibre mast and is cat rigged with a mainsail area of 13 sqm (including half the area of the mast bounded by the luff length of the main sail) and an 11sqm spinnaker.

 

These are the "plugs" that the molds were made from for the adjustable foils and the second is a photo of the T foil rudder already in use on the Alpha Omega F14
The third is a photo of an Alpha Omega F14, this has the same rig and sail plan as the foiler and the centre hull of the foiler is the same hull (finished weight per hull 15.5kgs)

 

Thanks Darryl, now I think we can be friends and exchange ideas for our mutual benefit. Looks very very good. Please keep us informed with photos and info. as you make progress.
Regards, Sam

 

Ultimate 18 / ROH hull

The "ROH" hull referenced in the first post of
this thread is shown in rough model form here-second row down:
X21
Address:http://www.monofoiler.com/x21.html Changed:12:38 PM on Friday, September 21, 2007
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The model shows the concept in both displacement and stepped planing hull configurations. These are the same model with the hull simply rotated. The idea is to be able to sail on the displacement hull until the right speed is reached to rotate both amas and effectively utilize the stepped planing hull configuration. The windward ama is rotated first then the boat is tacked and the other one rotated. Should conditions change to where the planing hull is not suitable the process can be reversed back to the displacement hull(L/B=20/1). It is envisioned that the process would be very quick-less than 3 minutes. The concept is actually going to be tried in about a year or so on my experimental X21-T. See that thread under "sailboats". As mentioned in the earler part of this thread the ROH concept depends on the use of two fairly small hydrofoils on the main hull daggerboard and rudder-primarily for pitch control.

 

Nice to see some photos of the work in progress, Doug. You'll potentially engender so many positive outside contributions to your effort by exhibiting it in this fashion.

There is potential in this approach, but there are also a mountain of technical issues to solve if it is going to proceed to functional fulfillment.

What is going to ensure that water flow over the displacement surface is not disrupted by the "slots" for the rotating mechanism? Isn't the drag associated with this tranverse slot going to hamper the potential to get the boat up to speed where the possibility of a planing surface can be of an advantage?

How are you going to waterproof the pivot point in the hull to avoid the entry of high pressure water?

In the foiling model, you show the mast stepped well forward and the drawings show it in a more conventional location? Which is it going to be on the full sized craft? If it is well forward, what has been done to the Hobie hull to resist torsional loading into the structure that far forward?

Other questions to follow.

Good luck with the process.

Chris

 

Thanks ,Chris. The ROH model was done to allow me to visualize the geometry of the concept and it has potential but there are problems that need to be solved experimentally-on the X21-T platform. I think the seam can be worked out to be virtually no problem but time will tell.
The little red model is of the aeroSKIFF™ 14 and it has much more rake than does the X21 so the mast is further forward.You can see the first sketches of it done by Eric Sponberg on the original Peoples Foiler thread...The rough sketches posted as of this date show the X21-T -not the aeroSKIFF™.
The X21-T will have a carbon tube structure to reinforce the standard Hobie hull and may have an additional 45/45 layer of 5.7oz carbon inside and out-not finalized yet. But the preferred system is to use the tubular structure to take the mast loads.

 

And here are a couple of pictures that illustrate the concept with a rough balsa model: