X18-T ---Experimental 18'/Movable Ballast/Foiler

X18-T ---Experimental 18'/Movable Ballast/Foiler/Keelboat

I've decided to update this thread under a new heading since I can't change the old one. This is the original incarnation:
Address:http://www.boatdesign.net/forums/showthread.php?t=12131
I've been working on the design for some time and think I've settled on the final boat. But it will be a while before I can start building so I'm not ruling out changes but they should be minor compared to the change from the original idea. I have some sketches and I'll get them posted sooner or later.
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X18T--- Trapwing / Canting Keel/ Offwind Foiler
Conception:
This boat will be highly experimental and will use a Trapwing which is just a carbon wing shape part that contains 110lb./50kg. of lead(the amount is easily adjustable) that slides inside the wing.
The whole Trapwing slides from side to side with the weight sliding inside it as well.The wing and guide unit slide on a carbon tube allowing the whole assembly to move fore and aft. It will start life with a 16'/4.88m span, about a 10.75"/270mm chord and somewhat of an elliptical section. The wing is supported from the mast by trapeze wires. Initially it will move manually along with the canting daggerboard(25° max cant angle). This is to allow a crew up to 220lb./100kg. or so to sit inside like a 2.4 meter yet have incredible power to carry sail especially offwind. The boat will use a main hydrofoil and a rudder t-foil. Upwind the hydrofoil provides lateral resistance when the board is canted; downwind the board is locked on the centerline to allow foiling.
The two main experimental areas are:
1) the trapwing/canting keel system.
2) the hydrofoil system for downwind foiing only.
Since the original post the boat has grown as I researched building methods and weights. The IC method Phil Stevenson used was a big influence allowing me to lengthen the boat to take advantage of a more favorable beam to length ratio since the earlier 14 would have had the same waterline beam as this boat.Additionally, though this boat is now 18'/5.49m that INCLUDES the rudder in the doublended hull with the trunk faired in so it will appear as though the whole backend(1'/.3m or so) moves for improved manouverability in certain conditions. The boat retains it's self righting capability in this configuration.
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But there is one more big change: because it is an experimental boat I want to be able to try as many different things as possible. So the boat is designed to have molded in rack tube receptacles so the Trapwing,it's ballast and the canting keel can be removed and side racks like a Moth or I14 can be simply plugged in. The sideracks will include buoyancy pods and a sliding seat system-a system that is extremely unique and light. When the boat is configured this way it will use the SAME rig and initially the same foils though, for highest performance, I will have to buy a new set of 6.5"/165mm chord Fastacraft foils using the H105 section. So I get two different types of boat for very little extra money.Plenty of things to test and that will be fun and interesting.As mentioned in the previous thread the new boat will intially use much of the equipment used on my original 16 foot foiler saving some big bucks.
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X18-T Specifications as of 10/13/06
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LOA-18'/5.5m
Hull beam at wl= 1.67' (20")/ .5m
Beam overall-SDB configuration 16'/4.88m
Sail Area upwind- 171 sq.ft./15.9sq.m
downwind- 300sq.ft./27.9sq.m
---Daggerboard ballast- 150lb./68kg
---Trapwing 16'/4.88m Span; 10.75"/270mm chord approx 30% t/c ratio; 14'/4.27m cl-cl inside ballast.
---Mainfoil area 3 sq.ft./.28sq.m
---Mainfoil loading 169.3lb.per sq.ft.(approx. same as Moth)828kg./sq.m
---SA/sq.ft. foil area= 100(approx 25% greater than Moth-downwind only for this configuration.) 100sq. meters SA per sq.meter of foil area.
---Foil footprint ,both versions-10' 6"/3.2m( defined here as the distance from the leading edge of the main foil to the trailing edge of the rudder foil)
---Trapwing will utilize removable pods with approx. 64lb(29kg) buoyancy on each end.
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WEIGHTS
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-hull, rig, foils 130 lb./59kg.
-daggrboard+ballast= 150lb./68.2kg.
-wing=25lb./11.4kg.
wing ballast= 110lb./50kg.
-crew= 220 lb./100kg. --can be sailed by much lighter crew since crew does not contribute to righting moment.
ALL UP-635lb./288.6kg.
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Ratio's
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1) SCP/total weight=26.9% ( FD, Tasar)
2) Bruce Number-upwind 1.59(Moth 1.57); downwind 2.11
3) "Wing Loading"(weight/SA)=upwind 3.71 ;downwind 2.11(Moth 2.4)
4) SA/D- upwind 37(Moth 39.6); downwind 65
5) D/L- 53
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Foiler(upwind and downwind) conversion weights
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-hull, rig, foils 130lb./59kg.
-racks and pods=35lb/16kg.
crew=220lb/100kg.
ALL UP= 385/175kg.
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--Main foil area-new foil set=1.82 sq.ft./.169sq.m H105 section Fastacraft foils.Foil Loading 169lb. sq.ft./828kg. per sq.m
--SA/sq.ft. foil area-93(Moth approx. 82)
93sq.m SA per sq.m foil area
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Foiler version Ratio's
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-SCP/total weight=44% (Moth 39%) higher better
-Bruce Number=1.78 (Moth 1.57) higher better
-"Wing Loading"= 2.25 (Moth 2.4-rohan) -lower better
-SA/D = 51 (Moth 39.6) higher better
-D/L= 33 (Moth 75) lower better
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---Thanks to the guys here for helping me think out the canting trunk for this boat:
Canting Keel Trunk Within a Trunk Idea - Boat Design Forums
Address:http://www.boatdesign.net/forums/showthread.php?t=14018
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---Where is all this going to lead? Right here:
60' Moth-A Preliminary Detailed Design Exploration - Boat Design Forums
Address:http://www.boatdesign.net/forums/showthread.php?t=13654
The thread may have been killed but the idea lives on......

 

X18T-notes

Minor change-foil loading will be reduced from 169 to 158 lb. per sq. ft.
Sq. ft. sail area per sq.ft foil area will stay above that of the Moth on both versions: movable ballast version downwind only; foiler version upwind and downwind.
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Tentative decision to build hull out of 3mm Okume plywood glassed with epoxy+ 5.7oz carbon.
Not satisfied with finish; also considering foam+carbon laid up on real glass sheet for side and deck pannels-extraordinary finish with minimum sanding. Any better ideas??
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Ballast "wing"-all carbon/foam-must be light and strong to carry 110lb slug of lead sliding athwhartship-details of best way to slide weight still being worked; probably will slide on delrin runners-or something better....
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Great sketches to be done by Eric Sponberg from my originals for this thread and new website-a month or so away......
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Do the foils have flaps or other controls? Operated by hand or sensor wand?

 

Foils

Stephen, since this boat will be sailed in two versions with the same sail area-one as a high powered keelboat, two as a high powered unballasted foiler there are two foil sets:
1) Keelboat foilset- already have these foils, made by John Ilett at Fastacraft, 63412 section, upturned "winglets" and a fairly large flap in the center third of the foil. This foil will also carry ballast.Upwind this set is canted with the foil helping to generate lateral resistance. The rudder foil on this set is symetrical with a large flap in center third of foil.
2) Foiler-new foil set(less area than above) to be made by John, H105 section(Tom Speer) with nearly full flap and extendable foil tips. Rudder foil same section less area with a full flap.
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Both foil sets can be adjusted in angle of attack while sailing and while the wand(same for both) is controlling altitude;the mainfoil and rudder foil can be varied in angle of attack together or separately-or simultaneously at different rates. The wand can be neutralized for zero drag in light air and shock cord tension on it as well as altitude can be adjusted. The wand can be bypassed on both versions(used on the foiler version for re-entry after jumping). Both foil sets are retractable-mainfoil and rudder. And both fit into the same "trunks" in the boat that allow for a wide range of adjustment. Changing foilsets/boat configuration should not take more than a few minutes.
This boat allows two completely different configurations which will give me the chance to try numerous experiments over a long period of time-and that's what I call fun. It is not a production boat but a boat designed specifically to allow me to try a whole lot of different things.
I want to give some credit for this dual configuration idea to an old nemesis on this forum-"Frosh" : it was a comment made in his inimitable way that started me thinking that I could design this thing to be more than one boat and test much more than I originally planned to be able to do. Numerous others have helped me think this out in ways they may never suspect and I appreciate all the help!

 

Best wishes with it, Doug! It sounds like an exciting project. Once construction has advanced enough, I'd be interested to know what you intend to do with it, where you intend to take it, and/or who you intend to race!

 

X18T notes

1)Following practice closer to the Rave system than the Moth system the wand will be mounted just forward of the center of the boat, and viewed from forward the pivot axis of the wand will be lower outboard than inboard with that angle adjustable. The hub of the wand mount will allow the wand itself to be adjustable in length.
The wand will be able to add input to the rudder foil flap as well as to the main flap and as I think I mentioned before be able to be entirely bypassed/neutralized.
2)The wing containing ballast is the main source for RM on this boat. It slides to side as the ballast moves inside it. Consideration is being given to testing the concept on a smaller boat in order to work out the bugs before the 18 is built. This will add cost and time to the project so it's very much up in the air. The basic system has been tested on 5' and smaller rc models.But there are aspects of manual control of this wing physically that may need special attention.The wing must be able to carry over 100 pounds while sliding side to side , pivoting side to side and moving fore and aft.
3) The idea of this boat- in both versions- is to be able to beach launch at Kelly Park in Merrit Island Fla.and other similar places. In considering the launching of the keelboat version with keel retracted it has become clear that with the crew sitting inside the thing may be too tippy for comfort between the beach and where it's deep enough to lower the keel. The wing will be "active" during this period and may be ok but some kind of retractable and /or molded tip float may be used as well. I don't care too much for this idea but it may be required-testing it will prove it one way or the other.
Happy New Year!

 

Doug,

Have you considered using an existing hull as a test bed for the ballast system? It might save time and money to have one of the systems sorted out before you finalize the design. If you were to take something small and cheap like a Cal 20, you could test the ballast system, then replace the keel with a simple daggerboard to evaluate the the need for side pods.

Once you were through with the Cal, you could bolt the keel back on and sell it for what you paid. It would be a near zero R&D expense.

If you decide that tip floats are needed to get off the beach, the ballast pod could have hinged tips (Like a WWII PBY). If the tips were hollow, they would only limit the ballast travel during launch. Once underway, the tips fold up and the ballast can move the whole length of the beam.

Happy New Year.

Randy

 

X18t

Thanks for the suggestions.

 

Movable Ballast / Trapwing

This exchange was moved from the "Rig moving laterally" thread to avoid any further hijacking of that thread as much as possible.
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Steve(Sail Design) Baker quoted me responding to an inane comment by Chris Ostlind:

And Steve follows with his comment:

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My answer:
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Steve, of my two on-deck movable ballast versions one is on a 60' monofoiler and would, in essence, use a tank of water sliding side to side in a fixed wing/tube-easily emptied at any point. The other is on an 18' "sit in" keelboat where the ballast is inside a hollow wing with buoyancy pods on each end. The wing and ballast moves. In this application the boat should be self-righting yet have the righting moment to foil offwind. The wing ballast is neutralized by the buoyancy of the wing and the ballast in the keel. I'm actualy building it to test the practicality of the idea. Hope it works well since it could conceivably allow tremendous performance from a "sit in" keelboat....
I think Bethwaites version(60') was to be water and or solid ballast sliding in a fixed hollow wing.

 

X18-T

As per post #6 I tried to find a suitable small boat within a specific budget to modify with a larger rig and the Trapwing.The boat I wanted was a US 1 which is a splash of the Windmill hull -with the sides already cut down-it would have allowed testing the Trapwing very quickly. Since I couldn't find one I'm going ahead with the original plan to build the 18 hull as soon as possible-probably several months before I can start.
In the meantime, the hull,rig and foils have been designed and the final details are being worked out on the Trapwing. For anyone interested in the Trapwing concept an illustration of the same basic concept can be found here-although for model boats I'm sure you'll get the idea:
Address:http://www.microsail.com/pbs.html Changed:2:35 AM on Tuesday, January 9, 2007
I may go ahead with a much simpler version of the Trapwing done almost exactly like it is on the model of a Melges 24 I built using carbon tubes. The Trapwing is supported by trapeze wires and the "rack" and ballast both move. The final version will be a molded wing to take advantage of the low windage and high buoyancy of such a shape.
So at this point I have three options for the Trapwing System: 1) Build the tooling for the final version,2) build a Okume+carbon prototype, 3) build a twin tube version using ready made carbon tubes identical to the model. As on the model, whichever version I go with first will be able to be pivoted 90° for trailering and will be fitted with outboard buoyancy pods.
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One of the options is to make the first proto Trapwing just like it is shown here on the model:

Address:http://www.microsail.com/ Changed:2:35 AM on Tuesday, January 9, 2007

 

the begining!

X18T
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The last few days have been very interesting and the project has taken a giant leap forward. It occured to me that perhaps a single cat hull 18-20' LOA might be suitable to be converted to an X18T prototype and I've looked into it fairly thoroughly. The best candidates would be a Hobie Miracle, NACRA 6.0 or Inter 20 -all of which can carry the weight of the keelboat version as described in post #1(with a much better length to beam ratio). I found a Miracle hull here and looked at it today-maybe 100 pounds and a symetrical hull. Scott Hubel of Performance Sailing is going to see if he can find a lighter NACRA or Inter hull but I WILL be picking up a hull next weekend. It will still be a long time before I get sailing since there are going to be substantial modifications for the "sit-in" cockpit ect. The board location will have to go forward etc. But the rig and the foils are ready to go.
This boat is being put together to do a number of experiments; going with this hull will get me on the water sooner than doing the hull from scratch so I'm going for it. Still looking at options to do the Trapwing. I've postponed the drawings from Eric until after this proto has been sailed.
Initially, I'll be using the relatively small rig I have now( plus a new spin) followed soon by a larger main only rig and newer, smaller foils. As mentioned before the boat will eventually be able to be configured in just a few minutes either as a self-righting canting keel/Trapwing offwind only foiler or as an unballasted very light upwind/downwind foiler.
I'm excited about getting started ; it should be a fun project with some really interesting results.
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2/17/07
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Just picked up the 19'6" Hobie Miracle hull; it's
the begining of the build part of this project.Most of the design work I've already done
will apply to this new hull and the time and money saved is enormous(to me).
First thing I did was cut access holes in the deck to be able to see inside and to have a way to put the test ballast in the boat.
Next weekend a friend and I will take the boat and 535 pounds of lead (in 44lb pieces) to Kelly Park on Merritt Island to make a displacement test.(we'll take and post digital pix) The point is to determine the boats exact static waterline fully loaded as per the keelboat version in the first post. Remarkably, the boat as is weighs only 99lb!( LOA 19'6" Beam 16" ) So we'll bring it up to 635 for the test. I'll be able then to determine the exact center of
buoyancy and design the mods to the hull. The Hobie Miracle is designed to sail with a load of
around 720lb on one hull so the heavy version at 635 will be just fine.
The mods will include: moving the board position significantly forward; reinforcing the hull for two unstayed mast locations(small intial rig-143 sq.ft. and 2nd rig 171 sq.ft.*); bulding the "sit in" cockpit; installing the rack mounts and Trapwing mounts. The gudgeons are not satisfactory for the rudder loads when foiling so they'll have to be replaced. The added hull structure minus the current structure comes out to an estimated final hull weight of 130 pounds-a little more than the 18 but insignificant given the longer hull. One mod I didn't mention is the reverse bow which will extend the length to about 20' from 19.5' LOA. The boat will have an almost identical shape to the origninal X18T design just be a little bigger with a narrower length to beam ratio.

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* SA may go to 185-2nd rig

 

X21t

Slow,painstaking progress has been made in the continuing evolution of the design with limited work on the boat. But that is changing as business pressures are easing and I will be able to devote many more hours and dollars to this exciting boat.
Again, the whole idea is an experimental boat that will be capable of changing configurations fairly dramatically with a minimum of effort.
The boat will have the ability to be configured as:
1) A downwind only foiling keelboat with on-deck movable ballast and canting keel.
2) An unballasted full tilt foiler with numbers equal to or better than a Moth foiler designed specifically for a 220lb crew. This version will utilize sliding bench seats and buoyancy pods and a number of experimental ideas in foil control and in manual altitude control combined with a wand.
3)An experimental version of #1 above capable of foiling upwind.
4) An experimental trimaran version using rotable amas with planing hulls and two small hydrofoils.
5) All versions use the same main foil and rudder position and same rack/cross arm positions.
6) The first rig used on this boat of approx three (including an A class cat rig) will be the one on the first aeroskiff here: www.monofoiler.com Most of the "stuff" in those pictures will be used to one degree or another on this boat including the first set of foils built by John Ilett.
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The boat is designed to make changing confiurations easy but it will be a long time beore each configuration is available.

 

Which one is it going to be?

More questions and coments to follow, Doug, but two quickies while I'm here...

If the LOA, even after pulling the bow out, is only going to be 20', why are you calling the project the X21t?

Where are the promised photos of the waterline to load test on the H20 hull?

 

X Twenty One T

No load test; did a Simpsons instead.
The overall length of the final design with the reverse bow is a couple inches under 21'.
I'm going to post some pix of the hull and parts as they are and then follow up with progress shots over time.Will probably post them on monofoiler.com on a new X21T page.

 

X Twenty One T

This is a shot of the rig on my first foiler. It will be the first(and interchangeable) rig on the new boat with two mods:
1) the boom will be a modified mid-boom mainsheet horizontal wishbone to allow the forward third of the foot of the main to come right down to the deck.
2) the masthead crane/backstay will be eliminated and the jib will still be square-topped but fractional.
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aeroskiff 1 rig