Foiling Keelboat: 30'

Version Two--fixed keel plus sliding(or pumped) on-deck waterballast:

Modifications from Version 1 in red--

1) Beam 18'--6.17' racks on each side and designed to ensure that the boat is regarded as a monohull and can meet other rule parameters.
--
2) Displacement:

--a. hull + rig= 882lb

--b. fixed keel-bulb 440lb. At fin/foil juncture.

--c. max. sliding(or pumped) on-deck water ballast(not used at earliest takeoff) 1180lb*

--d. takeoff displacement(min) 1847lb( 3-crew-no waterballast-min.)

--e. crew-3@ 175lb 525lb

--f. Max displ. 3029 lb.( 3 crew + waterballast) OR 2856lb with crew on trapezes.

3) SA 680 sq.ft( @ 21' with designed max pressure at approx. 15-30 degrees veal heel= 1.8lb. sq.ft.)

4) SA/D ((w/o water ballast) 72 (Moth 78, 60' Moth 66 )

5) Mainfoil area(supports 80% of total weight)- 8.11 sq. ft( supports new max weight at 15 knots with a .6CI)
--a. 83.8 sq.ft. SA per sq. ft main foil (Moth 78.2, 60' Moth 83, Mirabaud 91)

6) HM(est Heeling Moment) :

--a. SA= 680 sq.ft at 21'
--b. est. design wind pressure before depowering: 1.8lb. per sq.ft.
--c. TOTAL HM--[680 X 1.8] X 21 = 25704 ft. lbs.

7) RM (est Righting Moment) Note: Veal Heel moves hull CG(and everything else) to weather about 4'.

--a. hull-882 X 4= 3528 ft. lb.

--b. 3 crew-( 9+4) X 525 = 6825 ft.lb.

--c. waterballast (9+4) X 1180lb(158 gal.)* = 15340 ft. lb.

--d. TOTAL RM= 25693ft.lb(essentially equal to HM) NOTE: 40.2% of RM is due to Veal Heel.

*Or 1028lb(137gal) if three crew on trapeze( 200lb total increase over canting keel version)

8) Takeoff at 8 knots boat speed, approx 6-7 knots wind speed. Uses bi-foiler configuration-one foil on daggerboard, one foil on rudder. Uses mechanical(wand), electronic and/or manual altitude control. Much discussion of foil configuration since the owner had his own ideas about foils. Wanted to use double mainfoils with adjustable dihedral tips. Essentially, a semi-surface-piercing ladder configuration that would ,he hoped, enhance RM. Discarded after illustration of the extra drag such a system would engender(and the poor performance of such systems in the past) and after showing the impractical nature(both hydrodynamicly and engineering wise) of using adjustable tips for righting moment.

* A system similar to the one on Hydroptere will also be looked at. That system requires no pumps and water comes in thru an intake on the rudder. The biggest question with this kind of system is how fast can the ballast be moved(in or out) and how does that compare with a sliding tank.

=================
See Versions 3(canting keel) & 4(fixed keel) to follow at 10 knot* take off speed-SA and max weight dramatically reduced.*
-hull shape will have to be carefully analyzed.

 

Dane is still around a good bit, went to the last Olympics, and got spanked. I know the other names well, though I haven't seen them since Katrina. I am not sure if they are around, or just given up sailing.

The boat I mentioned uses very wide wings like racks but solid, and 13 sailors running side to side to keep the boat flat. Check out http://www.cravensells.com/index.ph...s&id=67:taylor32&option=com_content&Itemid=21 It is radically fast, but takes very skilled crew to keep on its feet. No canting keel, but if I were looing for a prototype to mount foils on DangerZone might be interesting. The keel could be easily removed, a dagger board installed, and then toss on some foils to see. Assuming the boat can be kept flat it planes upwind in 8-10kn.

 

Foiling Keelboat

============
Thanks Greg! Must be a ***** in the Lake Ponchatrain chop-the worst I've ever sailed in.

DIMENSIONS-Danger Zone:

• LOA 32.
• LWL 28.9'
• Beam 14.8'
• Draft (Deep) 5.6
• Displacement 1962 Lbs.
• Ballast 551 Lbs.

•Rated SA 470.6 Sq.Ft
• PHRF -30

 

Actually the boat is fine in the chop. Downwind it just skips over them, upwind you are planing in chop conditions, so maybe it is slower, but oh so much fun.

And ya, the Lake is brutal. But thats why we generate such good sailors. Constantly varying conditions with all sorts of holes to sail into.

 

------
My memory is sailing a Fish class gaffer in those conditions. I would have thought Danger Zone would be bothered a bit-glad to hear it's not.
Do you know why it's for sale?
Naleans is a factory for great sailors!

 

Fins, on the lake can be brutal! I think we have Fin nationals next year, and we already have some contenders practicing on the lake getting ready for it. Something about needing to drink more beer, do more sit ups, and prepare to keep up with the local crews when it comes to partying.

DZ was bought by a friend of mine as a race boat to match his Columbia 50. But to take DZ out just takes more work (stepping and unstepping the keel every time), than he was willing to put in every week. This of course led to evaporating crew... So he bought a Martin 243 instead and has been racing that. I can tell you other than new sails DZ is really ready to go play. The owner doesn't believe in defered maintenance (he also owns a push boat company on the mississippi river).

 

Foiling Keelboat: 30---Veal Heel

There are some who would like to use a foiler configuration like Hydroptere to create a foiling keelboat-this is to help in that discussion. The rationale here is not the only reason a bi-foiler configuration is better but it is the primary one:
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One of the MOST important reasons a bi-foiler(just two lifting foils) is so important for a keelboat foiler is because it is the only foiler configuration capable of Veal Heel.
Veal Heel is a technique developed in the Moth class where a foiler can be sailed with up to 30 degrees of windward heel. It is the only form of windward heel where the CG of the hull physically moves to windward along with the crew, rig and on a foiling keelboat, the ballast.
No other foiler configuration allows Veal Heel. See the numbers on Version One and Version Two for the proportion of total Righting Moment that is due to Veal Heel. The following is a summary:

Version One--41.3% of total RM is due to Veal Heel.

Version Two-- 40.2% of total RM is due to Veal Heal.

Those numbers are extremely significant because if you didn't have 40+ % of the RM you couldn't carry the 680 sq.ft. required for early takeoff which translates to 83 sq.ft. of Sail Area per sq.ft. of main foil area which is a Sail Area to wetted surface ratio for foilers. Further, you wouldn't have the power(RM) to carry that SA in more than 1lb per sq.ft. pressure!
----
The bottom line is, as best I can tell, that a keelboat foiler that was incapable of Veal Heel would not work! That means that for a full flying keelboat foiler that will take off in 6-7 knots of wind the boat must be a bi-foiler configuration.

 

Help in the discussion? You've basically made your choice and wish to end discussion.

Most folks here are familiar with windward heel, and applying the mathematics to windward heel and righting moment isn't hard. Yes, in Moths windward heel has worked out to be the best technique on the race course. No one sat down and defined the Moth foiler around the concept of windward heel - rather Rohan Veal tried it (along with everything else) and found it worked best. Empirical testing, data collection and conclusions derived from results, rather than defining the result before testing and designing to a premise.

To some degree, you are defining this proposed 30' foiler around the windward heel concept because it worked for the Moth. Just because oranges are round fruit grown on trees does not make them apples. The helm on a Moth is a huge percentage of the overall boat weight. Helms on Moths are actively moving to balance a fundamentally unstable platform to maintain windward heel, and that huge proportion of overall weight is critical to the process. The moving weight on a Moth is intelligent, can anticipate condition changes before they happen and also can tolerate big mistakes and crashes because it is after all an 11' dinghy. I think that no matter how sophisticated you plan the control systems for sliding water ballast to be they may not achieve the same functional sophistication a Moth helm does.

These numbers also indicate that a very significant part of overall righting moment is transient and only real when the windward heel is achieved. This means if windward heel disappears due to a gust, so does 40% of your righting moment just when you need it the most. This isn't an 11' dinghy, and crashes will involve a lot more kinetic energy due to the huge scale difference.

If a full flying 30' keel boat MUST be a bi-foiler for 6-7 knot take off, it may just not be practical, safe or reliable enough for people to sail.

Therein lies the reason I don't think the Hydroptere style-option should dismissed out of hand - it achieves the speed goals without the same potential for problems. It may not be able to foil in 6-7 knot winds, and it may not have the same top-end speed potential of the theoretical bi-foiler configuration but it is a proven functional concept that could be refined.

Although I'm certain you will fail to objectively consider these comments, perhaps the people spending the money will. Oh, well. There was no scoreboard between Don Quixote and the windmills.

--
CutOnce

 

Foiling Keelboat: 30' Version 3

In continuing to look at this I've found that there could be significant benefits to increasing takeoff speed from 8 to 10 knots. The original "I wish" was for 6-7 knots take off which was impractical but Version One describes the requirements for a canting keel(110 degree each side) + sliding on deck ballast with an 8 knot takeoff.
The problem with this is that "hull speed" for a normal 30 footer is 7.34 knots.
However, the target hull is quite narrow on the wl so may be able to reach 10 fairly easily. It is worth looking at very closely. I think that in most cases early takeoff is the best solution but for a boat to be sailed and raced in the ocean this may be satisfactory. The foils will be lifting a majority of the weight at 6-7 knots boat speed and therefore contribute to reaching the higher takeoff sooner than the hull would w/o foil assist. Continuing analysis of beam vs max waterballast is beneficial.

====================================

Version Three--canting keel plus sliding on-deck waterballast*:

Modifications(see post #1) in red--
blue= mods from Version One to Version 3

1) Beam 12' (cl of crew and waterballast CG)--approx. 2' racks on each side and designed to ensure that the boat is regarded as a monohull and can meet other rule parameters.
--
2) Displacement:

--a. hull + rig= 882lb

--b. canting keel(110 degree) 440lb. 10' canting keel strut.

--c. max. sliding on-deck water ballast(not used at earliest takeoff) 452 lb

--d. takeoff displacement(min) 1847lb( 3-crew-no waterballast-min.)

--e. crew-3@ 175lb 525lb

--f. Max displ. 2299 lb.( 3 crew + waterballast)

3) SA 467 sq.ft( @ 21' with designed max pressure at approx. 15-30 degrees veal heel= 1.8lb. sq.ft.)

4) SA/D ((w/o water ballast) 72 (Moth 78, 60' Moth 66 )

5) Mainfoil area(supports 80% of total weight)- 5.19 sq. ft

--a. 90 sq.ft. SA per sq. ft main foil (Moth 78.2, 60' Moth 83, Mirabaud 91)

6) HM(est Heeling Moment) :

--a. SA= 467 sq.ft at 21'
--b. est. design wind pressure before depowering: 1.8lb. per sq.ft.
--c. TOTAL HM--[467 X 1.8] X 21 = 17652 ft. lbs.

7) RM (est Righting Moment) Note: Veal Heel moves hull CG(and everything else) to weather about 4'

--a. hull-882 X 4= 3528 ft. lb.

--b. canting keel-(10+ 4) X 440= 6160 ft. lb.

--c. 3 crew-( 6+4) X 525 = 5250 ft.lb.

--d. waterballast (6+4) X 452 = 2714 ft. lb.

--e. TOTAL RM= 17652ft.lb(essentially equal to HM)
Note: Veal Heel is essential to the performance of a keelboat foiler.

8) Takeoff at 10 knots** boat speed, approx 7-9 knots wind speed. Uses bi-foiler configuration-one foil on daggerboard, one foil on rudder. Uses mechanical(wand), electronic and/or manual altitude control. Much discussion of foil configuration since the owner had his own ideas about foils. Wanted to use double mainfoils with adjustable dihedral tips. Essentially, a semi-surface-piercing ladder configuration that would ,he hoped, enhance RM. Discarded after illustration of the extra drag such a system would engender(and the poor performance of such systems in the past) and after showing the impractical nature(both hydrodynamicly and engineering wise) of using adjustable tips for righting moment.

* A water ballast system similar to the one on Hydroptere will also be looked at. That system requires no pumps and water comes in thru an intake on the rudder. The biggest question with this kind of system is how fast can the ballast be moved(in or out) and how does that compare with a sliding tank.
** In the drag bucket at 13 knots(63412 foil); in drag bucket at approx. 22 knots with max ballast.
=================
Version 3-Quick View Summary

1) takeoff at 10 knots(approx.7-9 knots windspeed)
2) SA from 680 down to 467
3) max displ. significantly reduced-2299 from 2656lb.
4) beam reduced from 16' to 12'

 

Foiling Keelboat:30' Surface piercer(?) owner concept

The sketch below illustrates the surface piercing concept put forward by the owner. It is done(by me) to scale showing the equivalent foil area as required in Version 3 above which is 5.13 sq.ft of lifting area. Because the surface piercing foils are angled at 45 degrees , the immersed area of each foil right at takeoff is 5.13 sq.ft.. Theoretically as the boat speeds up the immersed area would decrease-at some point becoming less area than the fully submerged t-foil(daggerboard + lifting foil) on the bi-foiler.
A careful analysis needs to be done here but a few things are apparent now:
1) Note the direction of sail force. That means that the top(outboard) side of foil "A" would be subjected to high pressure from leeway and should have Low pressure from lift. This is a MAJOR problem resulting in very high drag. Foil "B" is ok in this regard.
--
2) Total foil length(2 foils) is 19.5'. Total foil length of the bi-foiler with a 10' vertical fin(not firm yet-may be shorter) is 15.13'. The surface piercing foiler has 1.29 times the foil area of the bi-foiler pre takeoff.
--
3) Sketch shows a nominal 3' flight altitude where the bi-foiler could fly twice as high ,if desired, in waves.
--
4) The owner has suggested that the foils could have manual angle of incidence change to allow differential lift in order to create righting moment. This requires extensive analysis but right now we know that the foils have to develop around 1477lbs of lift to takeoff. It is not clear that differential foil control would work but it might- especially at higher speeds BUT there is a big problem: surface piercing foils change their immersed area with speed. If you throw a differential lift variable into the mix it would probably have to the same on each foil-+ on one, - on the other. Doing it like this would not(I think) affect the natural "surface piercing" altitude control with speed. An electronic system could make this automatic as it can automate Veal Heel on the bi-foiler. My gut feeling is that that there would not be a lot of RM possible within the drag bucket of a foil like a 63412-but that is a guess. Serious analysis is the only way to answer this. Drag would undoubtedly increase.
--
5) Veal Heel, that accounts for about 40% of the RM on the bi-foiler, is 100% impossible on this configuration. Veal Heel is a low cost system in terms of drag(no resultant extra drag) whereas developing RM from the foils, in addition to lift, will have a drag penalty particularly with foils whose centers of lift are so close together.
--
6) On-deck water ballast would be required just as on the bi-foiler-but substantially more to make up for the inability to use Veal Heel. This amount could be reduced by a successful application of differential lift as in #4 above(see conclusion, below).
============
Conclusion, for now: This has some interesting elements but #1 above trumps the configuration as shown below and I don't believe it is worth pursuing.

click on image:

 

After 9 days of evolution of this thread, it is pretty apparent that the mystical "owner" doesn't have much experience regarding what his/her role is arriving at a final product that meets it's goals.

First, defining construction techniques, dimensions, proportions and major technical issues prior to design is a mistake. Those are issues for the Naval Architect. Your role as owner's consultant should be to steer the owner to the items they should be defining:

1) Clear performance objectives (i.e. fastest thing on my lake, target competitive boats);
2) Owner's requirements - required crew, sailing skills required, storage, transport, accommodations (on board portapotty? etc.);
3) Rules and restrictions regarding racing and competition;
4) Budget and timeframe;
5) Level of acceptable failure (self recovered knockdown, pitchpole with breakage, capsize with aided recovery etc.)
6) Milestones to be defined for testing, budget etc.
7) What's the point? Corporate advertising platform? (promotional tax deduction?), ego?, personal sailing satisfaction?

Your "research" on foil configuration(s) can be submitted, but becomes 100% the responsibility of the Naval Architect firm, as they are the ones responsible for system function. No real engineering professional will accept working with pre-defined technology approaches, unless they get a complete release from responsibility for the outcome and failure.

Once you have the above items defined, you and the owner are in a much better position to approach the Naval Architecture firm with a realistic idea of requirements. Technical details of construction are their responsibility. Budgetary plans to meet the owner's objectives will be produced by them after agreeing on requirements.

Basically, if I were you I'd also want some type of binding agreement regarding your lack of liability - as you represent yourself as a foiling expert advocate and "guru", you do not want to become liable for failure of the final product to meet it's goals as defined here on a public forum with your name instead of the owner's.

Before you go a lot further Doug, you should get a clear handle on exactly who is playing what roles in this unfolding drama. Your role as owner's expert consultant has to be clearly defined and documented. Notice how no Naval Architects or industry professionals are commenting on this thread - they know better than to go for a long walk on this particular quicksand.

--
CutOnce

 

Foiling keelboat: 30'---bi-foiler non foiling drag/ self-righting

This is where the bi-foiler hull design needs to be looked at very closely. Since the boat requires zero form stability(stability due to hull shape) the hull can be
optimized for the best combination of lowest wetted surface and lowest wavemaking drag comensurate with its displacement and takeoff speed. Just this, compared to a "normal" 30' keelboat, will cover the drag of the main foil and then some.
But non-foiling drag can be even further reduced:
1) on Version 1-4 the daggerboard supporting the main foil is 10' below the bottom of the hull. This is particularly important on Version 2 & 4 where there is 440lb of ballast at the bottom of the daggerboard along with the main foil.
In non-foiling conditions, the daggerboard could be retracted 3-5'(depending on board chord) reducing wetted surface by the total area(both sides) of the main foil. Further, the main foil would be set up to develop zero lift at all speeds before take off speed. This would be accomplished by adjusting the foil and flap for a zero lift angle of attack while disabling the electronic or mechanical wand(altitude control system).
2) On all versions a very simple, robust system could be incorporated allowing the 100% retraction of the rudder hydrofoil while still leaving the appropriate vertical rudder fin.
3) On all versions, in non foiling conditions, no water ballast would be required allowing for minimum sailing weight in that speed range.
======
By utilizing these measures the SA/WS ratio of the boat will be superior to a "normal" 30' hull in non-foiling conditions while allowing blast out, unmatched monohull keelboat performance after lift-off.

++++++++++++++++++++++++++++++++++++++++++++++++++

At this point I'm convinced that the best foiler configuration for a keelboat is a bi-foiler. Further, if the 10 knot takeoff is acceptable, then the best configuration for a keelboat bi-foiler is Version 4(not shown yet but eliminates the canting keel from version three and uses fixed ballast as described in Version 2). This is a bit heavier than Version 3 at max ballast, but will take off in the same wind since the ballast isn't (generally)required for takeoff. Further, the boat will beself-righting from a capsize or pitchpole. That is, it will self-right w/o crew intervention with the caveat that the crew may have to empty the waterballast or have an automatic system to do that with manual overide. This configuration is the version that will meet the least rulemaking hassle since it will be self-righting. It will be extraordinarilly fast both on and off foils.

 

Foiling Keelboat: 30'----Control Systems

These are the control systems that I'd like to see developed for use on a foiling keelboat:
1) Master autopilot:
-- maintains veal heel angle @ 10, 20, or 30 degrees-will probably involve computer based control of rudder, ballast system and sail sheeting. Will always require human standby and/or allow direct overide of sail trim function.
There are people/companies I know capable of doing this now.
-- maintains altitude as preset and/or auto changes for conditions.
--maintains and optimizes pitch trim w/ manual overide
-- maintains heading while on foils
-----
2) A system similar to one believed to have been developed for Hydroptere that can spot small floating or partially submerged objects in time for the skipper and/or autopilot to avoid. This kind of system will be critical ,in my opinion, to facillitate racing foilers in the ocean.
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3) Panic button-automatically transmits last will and testament of crew, sets off epirb, deploys raft subject to manual setting of thresholds and so forth and so on.

Picture: from Bill Beaver's paper on the Moth, this is an illustration of how veal heel works to:
a. increase RM,
b. develop lift from rig,
c. unload the vertical fin using the lifting foils for lateral resistance.

 

looks like a lot like the front view of the Flying Camel....

 

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What's the Flying Camel?