Minuet Yachts: a 2m fun boat-can the design be improved?

[Doug Lord]

Version 2
This is basically the same system as in the previous post except that this is specifically for the boat where the bottom angle does not provide sufficient angle of incidence for the foil. The foil is still retained by the endplates and is mounted in a molded in recess in the hull rather than in a trunk. The control line system is the same. Any space in the trunk can be taken up by foam attached to the removable bottom plate. Additional points of contact can be added very simply if required to prevent foil bending. This system provides easy angle of incidence adjustment and easy access to the foil. The molded in trunk could use a dynamic drain as shown for any excess water.
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Originally Posted by Doug Lord

Version 1
This may be a drastic simplification of DSS for small boats like the L60 or even smaller. The foil is not in a trunk but "rests" in a molded in shape in the bottom of the hull. The ends of the foil are supported by a mounting plate/ fin/ bearing surface that fits into a recess on the side of the hull. This plate can be used to adjust the angle of incidence of the foil, if required. It is possible the bottom could be at the right angle to start with requiring little or no adjustment. By eliminating the trunk the system is vastly simplified at very little cost in drag-at least it seems that way now. A simple control line is run from the top of the foil outboard in the recess shown and then vertically up the inside side of the boat. This eliminates a lot of complication and makes controlling the foil a piece of cake.
Downside is that the foil will have to be the width of the bottom plus the usable span long-small price to pay.....

click on image--Version 1=left illustration;--Note: much smaller fin/sideplate on Version 2--right illustration :

[Doug Lord]

Because of recent info I've gotten from Hugh Welbourn that the DSS foil does not need to be 2-2.5 chords below the surface a smaller boat is possible. So instead of 12.5' I have asked my Styro lady to come up with a quote on cutting out a 10' boat. She says that it will be no problem but I have no idea on cost yet.
If I should do it at some point in the future I'd use a technique that others may have used but that I think could work real well for 80% of the boat.
I would use very thin .025" "Dragan plate" which is laminated carbon fiber with one side glossy and the other side bondable. The foam would be covered with it and it is approximately equivalent to two layers of 5.7oz woven carbon in weight-about 3oz per sq.ft. including bonding.Using this material would eliminate 90% of sanding and fairing and produce a professional looking finish very,very quickly. That plus reinforcing and other carbonating done by hand would allow a 10 footer to be done for about 55lb. all up.
This will probably be a relatively low cost and quick way to produce a good looking prototype that will allow me to evaluate the use of DSS on a very small boat.

[Doug Lord]

The idea of the L60 is for a "sit-in" boat but with the crew having a sliding "swivel and push" seat to be able to get to the weather side and maximize RM. The cockpit floor will be above the waterline and drain aft so its occured to me that there may be a relatively painless way to get even more RM while still sitting down. I haven't studied it enough to know whether its even feasible or practical but here is the gist of the idea:
1) Each side of the cockpit would have an opening "door" held closed by shock cord,
2) the sliding seat will "open" the windward door by sliding into it causing it to fold down which, in turn, allows the crew to move about 6"-8" outboard of the side of the boat and about 6"-8" above the water with the boat level,
3) while this adds significant RM and potential speed it also would allow the crew to be dunked fairly easily and be subject to being hit by waves. So the practicality of the idea is questionable. Its like a mini IC sliding seat
and, of course, has nothing in common with an Open 60! But the fun quotient would go up and so would the speed. RM would be improved and because of that the DSS foil would work better improving RM still more.

[rapscallion]

Originally Posted by Doug Lord

Because of recent info I've gotten from Hugh Welbourn that the DSS foil does not need to be 2-2.5 chords below the surface a smaller boat is possible. So instead of 12.5' I have asked my Styro lady to come up with a quote on cutting out a 10' boat. She says that it will be no problem but I have no idea on cost yet.
If I should do it at some point in the future I'd use a technique that others may have used but that I think could work real well for 80% of the boat.
I would use very thin .025" "Dragan plate" which is laminated carbon fiber with one side glossy and the other side bondable. The foam would be covered with it and it is approximately equivalent to two layers of 5.7oz woven carbon in weight-about 3oz per sq.ft. including bonding.Using this material would eliminate 90% of sanding and fairing and produce a professional looking finish very,very quickly. That plus reinforcing and other carbonating done by hand would allow a 10 footer to be done for about 55lb. all up.
This will probably be a relatively low cost and quick way to produce a good looking prototype that will allow me to evaluate the use of DSS on a very small boat.

any news?

[Doug Lord]

Originally Posted by rapscallion

any news?

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A bit: if I should do this(big if) Falcon Marine, who built Bradfields 18' foiler, has agreed to "build" this thing using the carbon sheet technique: thin(.025") sheets of carbon will be epoxied to the simple styro deck and hull. The edges will be carbonated . Would produce a strong structure and excellent, lightweight finish-quickly. But no cost there either-yet.

[rapscallion]

Hmmm.... This technique sounds interesting.... do you have a link that explains the method?

[Doug Lord]

Originally Posted by rapscallion

Hmmm.... This technique sounds interesting.... do you have a link that explains the method?

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No-other people may have done it but I'm not familiar with that. It's my technique based on a similar thing I did in the early 70's with glass. Without "dragan plate" carbon would have to be laid up on sheet window glass to get the perfect finish on one side with peel ply on the other side. It's about as simple as you can get to wind up with a good looking finish on a prototype quickly. Only problem may be the availability or not of "dragan plate" in a 45/45 configuration.

[rapscallion]

There is a very interesting airplane design called the facetmobile. The plane is made with 11flat surfaces on top and 3 on the bottom. Very angular, but flow stays attached even at low speeds. I have wondered if the principle could be applied to boat hulls. Perhaps.the Reynolds numbers are too low in the boat's case... but if I was more savvy with open foam I would be checking it out.

I don't believe humans know all there is to know about aerohydrodynamics.. the mercedes "boxfish" car proves my point... I bet one could design a low drag hull shape with flat surfaces..

[Doug Lord]

I've considered this for years and actually tried it on numerous rc model boats-it works and is fun. Previously, I had always considered a rather sophisticated system that used a molded wing and electric power to move the wing. Well, that is not necessary on a smaller system which can be built out of plywood and be covered by super high gloss carbon sheets. Basically, the wing is sealed except for a sealable center hatch that allows ballast to be added or removed. Inside, the ballast sits in a glass "tray" that slides inside the wing as the wing slides on deck. The ends of the wing are supported by "trapeze" wires(line) from the mast. The center mounting can be done in many ways just so it allows the wing to move side to side*. For a 12 footer, the wing could be 8' with buoyancy pods or even wider if the wing can be removed for transport. A 12 footer could use 60-80lb of lead in the "tray"-probably 1/8" lead sheets.
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UPDATE: Also a consideration for a small boat designed for maximum performance as a "sit-in" singlehander is that the DSS system will not help significantly upwind wheras the trapeze system would help a great deal.
*Fore and aft movement on a small boat may not be necessary since the crew can easily move.



Below are pictures of the "Trapwing Prototype" model showing one way to do it and one of the test models:
click on image-

[Doug Lord]

This is a sort of summary of the two boats that most interest me in this thread-The Minuet and the under 10' Little 60 :

1) The Minuet:

Originally Posted by Doug Lord

This thing just amazes me! Watch the video:

http://www.youtube.com/watch?v=tWRFd9kQmqY

http://www.youtube.com/watch?v=PZVSaTmqK3A

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New information on the Minuet:Crew: 1

Length: 2.2 m / 7.2'

Beam: 0.95 m / 3.1'

Hull Weight 30 kg / 66lb

Sail Area 2.96 sq m / 32 sq.ft.






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2) The Little 60:

Originally Posted by Doug Lord

Rough preliminary sketches on rough paper-Little 60: ( updated 11pm ,12/19/11)
--LOA 9'6"
--Beam 3.5'
--Displ w/crew 350(250lb crew-allows wide range of crew weight by adding ballast in center for lighter crew)-boat could be lighter
--Upwind SA 50 sq.ft.
--Downwind SA 115 sq.ft (asy spin or Hoyt-Lord system)
--DSS extended 2.5'to leeward. RM from foil at about 20 degrees angle of heel at 8 knots(just planing) : around 300ft.lb-more than a three foot keel with an 80lb bulb canted 90 degrees! DSS effectiveness on this boat much less upwind approx. 40ft.lb at 5-6 knots.
--DSS foil fits in sealed trunk in bottom of boat.
--Twin curved daggerboards. On the Minuet the crew has to sheet the jib every tack-on this boat the jib would be self-tending so racing workload for crew moving daggerboards tack to tack would not be excessive*. Daggerboards could be made in same mold as DSS foil.
--Bow sprit moves side to side. Main is similar to model main and does not require full battens. Upper "gaff" fits in bushings at top of mast.
--Boat would probably use twin rudders to go with the twin curved daggerboards.* If desired, windward rudder could be raised with same action as raising windward daggerboard.
--The boat would be designed to carry 50+lb of ballast but would be tested without it. Possibility of crew moving to weather-problem is opening cockpit wider and facilitating swamping in a knockdown- and holding crew in position a 30+ degrees angle of heel. A narrower-more or less "form fitting" cockpit would keep crew in center. Crew seating could be designed to allow crew to sit angled to weather?
--Rig "gaff" similar to smaller model in picture above. Allows an advance planform w/o requiring full battens but I'm leaning toward a simple peaked up square top instead.
--Spinnaker system could be asymmetrical roller reefed on long or short bowsprit and bowsprit could be moved side to side if desired. Spinnaker could be left up like the WETA trimaran. H/L spinnaker system from model may be easier to handle but requires trough in forward deck ahead of forestay and a tube under the deck sealed from the inside of the hull.

L to R-1) Rough Sketches of Little 60-click on image,2) Minuet:

[rapscallion]

Interesting design Doug! DSS on a boat like this makes sense. Imagine DSS on something like an international canoe, or a small sharpie. There might be an interesting EC design in there somewhere.

[Doug Lord]

Originally Posted by rapscallion

Interesting design Doug! DSS on a boat like this makes sense. Imagine DSS on something like an international canoe, or a small sharpie. There might be an interesting EC design in there somewhere.

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Raps, I'm using "DSSM" on the new tri-DSS for multihulls if it works( Dream Flyer fl-an 18' daysailing trimaran ). It would be a potentially great system for an EC multi because it would allow very small
amas with tremendous RM in a very shallow draft foil configuration. Thats also true for DSS on an EC mono designed for it. Lots of extra RM in a shallow water configuration that is retractable.....

[Doug Lord]

From another thread. The Illusion is interesting because it is 10' LOA and has a spinnaker-it's relevant to this thread as well:

Originally Posted by Doug Lord

Whats cool about this boat is that it is about the same amount longer than the Minuet as it is shorter than the International 2.4 meter, yet it carries a spinnaker. Pictures here: http://s197695124.websitehome.co.uk/...,0,1,5,800,740

LOA 3.27m / 10.7'
Beam .85m / 2.8'
SA:
--main 2.82sq.m / 30.3 sq.ft
--jib 2.46 sq.m / 26.46 sq.ft
--spin 5.6 sq.m / 60.25 sq.ft

[Paul B]

Originally Posted by Doug Lord

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Raps, I'm using "DSSM" on the new tri-DSS for multihulls

Congratulations. By publicly using the DSS term in this way you have dimished their ability to protect their IP.

[Doug Lord]

Just finished an interesting analysis of the original Minuet compared to an L60:
The Minuet has enough RM for approximately .9 LB per sq.ft pressure with a 170lb person sitting low in the boat @30 degrees angle of heel. The L60 has the crew raised up so that the cockpit is self bailing and has very little RM without additional ballast from a moving crew, keel, DSS and or a Trapwing (sliding ballast) system.
Of course, the L60( 10-14') would have the power to carry sail to allow it to plane and would be much, much faster than the Minuet with the enhanced sensation of speed from sitting "in" the boat-and low.
Also, a fixed version of DSS or (DSS-F) similar to the models Hugh Welbourn did, will probably be the best way to go on an L60. Well over 100ft.lb of RM
upwind at 4.7 knots.