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

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Thanks, Sharpii-I'll think about it. I don't think we want very much heel on a small planing boat-at least downwind. I'm not 100% sold on the DeepDSS idea either. With any heel the top surface will be exposed to flow from leeway-and its supposed to be the low pressure side. In a lot of light, to maybe even moderate, conditions upwind the horizontal foil will be just drag especially if the DSS foil only partially retracts. And the area of the foil/trunk would be such that it would be too much in some conditions and might also require the DSS foil and the trunk foil to have two different angles of incidence! Not good.
The illustration below shows a larger keelboat with DSS and its heel angle is 10 degrees:

click on image--

 

L60 Deep DSS-RM-SA-Ratios

DSS foil+ the foil "trunk":
1) planform area 2.7sq.ft.
-
2)(using 63412 section & CI of .6) close approximation of lift of both foils @ 8 knots= 294lb.
--a. RM from DSS foil @ 8knots= (147lbs. @ 2.5' from CB)=367.5ft.lb.
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3)(using 63412 section & CI of .3) close approximation of lift of both foils @ 14 knots= 453lb.
--a. RM from DSS foil @ 14 knots= ( 226lb. @ 2.5' from CB)= 566ft.lb
-
4)(using 63412 section & CI of.2) close approximation of lift of both foils @ 14 knots= 302lb.
--a. RM from DSS foil @ 14 knots=( 151 @ 2.5' from CB)= 377ft.lb..
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--2 above: lifts 84% of total displacement, reduces wetted surface 11 sq.ft.(est.)= 4.07 times planform area.
--3 above: full flying(not good), 100% total displacement, reduces wetted surface 26 sq.ft., 9.6 times planform area.(unacceptable!)
--4 above: lifts 86% of total displacement, reduces wetted surface 13sq.ft.(est.)=4.8 times planform area.
=========================================
Conclusion:
The above is calculated from estimates but appears to show that
Coeficient of lift(and angle of incidence) would have to be lowered from
.6 to .2 from 8 knots to 14 knots to maintain a large percentage of hull lift without actually flying the whole boat.
This can be easily adjustable. I had feared that the angle of incidence of the DSS foil and center foil/trunk would have to operate at different Coeficients of Lift. That does not appear to be the case. But these are rough figures and would be explored much further during the actual design.
Another concern was that the foil area was too great and that also does not appear to be the case.
Added 12/31/11: as mentioned in a previous post the DeepDSS system has a drawback in the fact that upwind SA is small and the foil will mostly generate drag upwind-at least that appears to be the case now. It is the single biggest drawback of the system-and the preliminary design to this point.
==================================
Est. L60 Righting Moment:
--from 2& 4 above(8knots-14 knots) RM = 367-377ft. lb. So, lets say 372 ft.lb. max..
-add- 250lb(max crew) at 1.75'= 437.5 ft.lb
-add- 100lb(boat) at .5' = 50ft.lb.
Total RM off the wind= 859ft.lb. Max SA about 130sq.ft
Total RM upwind= 487.5 ft.lb. Max upwind SA about 70sq.ft.
====================
Ratios:

SA/D:
--upwind=22.5---LASER: 25.58
--downwind=41.8
---
DLR=79.97---LASER: 76
---
SA per ton(500 required to plane): (added 12/31/11)
--upwind= 448---LASER: 514
--downwind= 832

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L60 Rough sketch & DeepDSS rough sketch-Idea is to get DSS foil below the surface far enough to be very effective. Center foil is hollow allowing DSS foil to slide within it. Similar to Pi 28 foils shown on the previous page except* that this DeepDSS foil/trunk combination should be shown located some degree forward of the vertical fins to reduce drag.
*added 12/31/11
click on image-

 

Small sailboat performance design / L60 and ?

Anybody interested in small sailboat design -and their capabilities-should check out Mark Denzers site: http://hyccruisingsociety.com/Denzer.html

Also check out Marks modified Laser with racks and the video here: http://www.boatdesign.net/forums/sailboats/convert-laser-contender-40358-3.html

 

Micro Offshore Boats

You have some great designs. I will keep an eye on these. Best thing would be to come out to Hawaii and explain them and help me with my project. I am more hacker than designer. I have lots of room and lots of boats to sail.
Aloha,
Mark

 

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Thanks-one things for sure there is room for lots and lots of innovation in small boat design. That should suit us both well!

 

Wow, this is an interesting thread!

Can you guys apply these ideas to a boat that would sail a trans ocean race unmanned?

Although, to me, the beauty of the boat is the fact that he just picked it up, set it in the water, got in and went sailing. It may not be as fast as a laser, but it looked like it would be easier to sail and handle.

 

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Sure-even smaller. Take a look at the links in the first post here: http://www.rcgroups.com/forums/showthread.php?t=865134

 

UnManned Race Boats

An un-manned Laser would certainly be more comfortable and drier than a manned one. I could be home drinking my beer. What a concept.

 

Ya, while your illegal drugs headed across the border!

-Tom

 

The Micro Transat Rules

Raps: The Micro Transat: http://www.microtransat.org/?lang=en

Rules
Safety Rules:
1.Safety should take priority over winning.
2.Competitors may not attempt to inhibit other competitors by intentionally colliding with or obstructing their boat or by interfering with radio and electronic equipment.
3.All radio equipment must comply with appropriate International regulations.
4.Each boat must be equipped with a navigation light which is turned one during the hours of darkness. It should be visible from all directions and from a distance of at least 2 miles. The light maybe a single white light or a tri-colour red/white/green light.
5.Boats must take appropriate precautions to avoid collisions. This might include the use of radar reflectors, brightly coloured panels, warning labels/flags or AIS transponders and avoiding known shipping lanes. Each team must decide the exact precautions they wish to take.
6.The boat owner is liable for any damage caused to their boat or by their boat. The organisers take no responsibility for any damage caused.
7.Boats must remain outside any defined exclusion zones.
8.Competitors must arrange permission for the boats to operate in the waters of their chosen country of departure. Competitors are also responsible for arranging permission for their boat to enter the waters of their destination country and other countries along the way. Competitors are recommended to remain in international waters where possible.
Tracking of boats and transmission on data:
1.Each competitor will be required to provide their boat's position to the organisers via a web or email interface every 24 hours. Competitors are free to decide how this information is obtained and transmitted. A map showing each boat's position will be provided on this website. Any boat which fails to transmit for more than 10 consecutive days will be disqualified.
2.In adition to transmiting position data, each boat should keep a record onboard of its position at least once every 24 hours. A copy of this must be presented to the jury upon completion.
3.Competitors may transmit status information such as battery state from their boats.
4.During the race competitors may not transmit any information to their boats, including new waypoints, weather information or software updates. Any competitor which does will be disqualified. However if a competitor wishes to implement such features for use in an emergency or after the race, then they may do so on the understanding that their use during the race will result in disqualification. The jury may request to examine satellite phone bills, log files or computer code if they suspect data has been sent to the boat.
Criteria for entry:
Every boat entered must fulfill the following criteria:

1.No source of propulsion other than wind.
2.The sailboat must be fully autonomous, no operator control is allowed.
3.The sailboat must be energetically autonomous, carrying on board any required batteries and electricity generating equipment.
4.The length of the boat must not exceed four metres.
The competition:
1.The aim of the competition is simple, to sail an autonomous sailing boat between Europe and the Caribbean in the fastest possible time.
2.The competition will start between January 1st and December 31st 2012. Competitors may launch at any time during this time.
3.The start point is between 48 and 51 degrees north, along the line of 7 degrees and 30 minutes west.
4.Competitors are responsible for transporting themselves and their boat to the starting line.
5.An approach of at least 40 nautical miles to the start line must be sailed autonomously. This is approximately along the line of 6 degrees and 30 minutes west.
6.The finishing line is the line of longitude between 10.00 degrees North, 60.00 degrees West and 25.00 degrees North 60.00 degrees West. Before departing, each team must choose a target area of 50km diameter along this line. A boat will only be considered to have finished the race when it reaches this 50km target, even if it has already crossed the finish line.
Judging Criteria:
1.How quickly the boat crosses the Atlantic between the designated start point and the team's target end point.
2.A handicap will be calculated by the jury based on the boat's hull length using the following formula: Time Corrected = Time * square root(length in metres)/square root(4 metres)
3.In the event of no boat reaching the finishing line, no winner will be declared.
4.The result will be given by the jury within one week of the last boat arriving or giving up. During this time each competitor will submit a complete log of positions (minimum of 1 every 24 hours) along with any contest or comment to the jury and to all other teams.
Notifiying the organisers of your attempt:
1.Before departing please email registration@microtransat.org with the following details:
◦Organisation Name and location (town/city and country)
◦A link to your website
◦Boat Name(s)
◦Measurements (length, beam and draft) in metres
◦Weight in kilograms
◦Details of your power source(s), actuators, computers and communications systems
◦Details of your hull and rig design
◦Any other interesting information about your boat
◦A photograph of your boat
◦A link to a video of your boat sailing autonomously
You may send in these details as a sign of your intention to compete, long before departure. This may help to improve publicity and show potential sponsors that you are registered.
2.As soon as possible after you launch email the date, time and GPS co-ordinates of the position where you launched the boat to registration@microtransat.org

 

Microtransat

Microtransat boats: (see website link for more)

click on image

 

How about a registration fee, proportional to the weight of the boat and refundable if and when the boat is recovered? Think of it as an ocean dumping fee. There's enough junk in the oceans already so it would be nice if there was at least a nominal effort to ensure only serious and sincere entries hit the water, and a nice addition to the publicity too.

 

L60-DSS breakthru

Major breakthru in considering DSS for the L60:
1) Hugh Welbourn just said he will help in every way possible and thinks this is very workable,
2) I've had trouble in the design of a small boat getting the foil low enough because I have been operating on assumptions I learned such as keeping the foil 2-2.5 chord lengths below the surface. Well, turns out that is not required-in extensive testing Hugh has determined that keeping the foil one chord length below the surface is sufficient,
3) I have been operating on a the assumption of a 6/1 or greater aspect ratio for the deployed foil but Hugh has found that using a foil with less aspect ratio may be the way to go.
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2 & 3 above represent a major breakthru in using DSS on a small boat, particulary the L60 but there are other small boat applications as well.
I just want to publically thank Hugh Welbourn for his generous help!
Note: this means that the "DeepDSS" in post 77 above is no longer necessary or beneficial for the L60-which is great news. The simplicity of DSS is what attracted me to it in the first place and the added complexity of the "DeepDSS" system was discouraging.

 

L60

So at this point(that is,tentatively) the L60 specs:

--LOA 12.5'
-
--Beam 4'
-
--at waterline: 3'
-
--SA-
upwind: 70sq.ft.
downwind: 130 sq.ft
-
--Boat weight all up 120lb
-
--Crew weight: 230lb(at all times-lighter crew carries weight in sliding seat)
-
All up sailing displacement: 350lb
-
--Dual,asymetric, toed in curved lifting daggerboards
-
--Rudder t-foil(to be tested)
-
--Canting mast-could be tied into to seat and/or daggerboard movement
-
--Swiveling,sliding seat with ballast compartment/self-draining cockpit
-
--DSS foil -may be tied in to movement of daggerboards and/or movement of sliding seat.
-------------------------
Estimated L60 Righting Moment(updated) :
- DSS downwind (1.5 sq.ft./257lb. lift) @ 10 knots = 643 ft.lb., plus:
-add- 230lb(max crew) at 1.75'= 437.5 ft.lb
-add- 100lb(boat) at .5' = 50ft.lb.
Total RM off the wind= 1130.5ft.lb. Max SA about 145sq.ft
------
-DSS upwind (.75sq.ft./ 30.87lb lift) @ 4.8knots=46 ft.lb
Total RM upwind= 533.5 ft.lb. Max upwind SA about 75 sq.ft.
====================
Ratios:

SA/D:
--upwind=24.1---LASER: 25.58 / National 12: 30
--downwind=46.62
---
DLR=79.87---LASER: 76 / National 12: 119
---
SA per ton(500 required to plane) :
--upwind= 480---LASER: 514 / National 12: 539
--downwind= 832

 

Possible DSS Simplification for small boats

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: