4 Meter mono foiler project

I have worked quite a bit with mdf, no grain related tare out, because there is no grain, but I will wet out the 14'' plywood, thanks for the tip.

The guy today said that they have a vac table, I'll be sure to make it a point that accuracy is very important.

Tonights side note......New bow lines.

Thanks to Bruce Mcleod (respected Aussie moth builder)for pointing out the fact that my boat would tack better if I rounded the tip of the bow a little, so I did Now I need to change it on all the drawings and change the bow mold frames. (I'll do that tomorrow night). anyway.........

Pic 1 - Old pointy bow, Pic 2 - new rounded bow (it looks better in Higher res pics)

 

Its so rigged......

Well, its been a week or so, alot of works been going on, I drew up a guestimated rig (the mast and boom are the right length, and the bend is about right). Have all the hull mold stanchions, the nose cone mold stanchions, and the deck stanchion plans all drawn up and ready to take to the cnc, of course I have to leave town for a couple of weeks so it'll have to be on hold for a while, but its coming along very nicely, I don't want to go to fast anyway, because there is no way I'm going to beat winter, so steady as she goes. now for the fun part, Foil design, looks like its time to go back to school (not very much info out there about homebuilt foils, not like there is about hulls)

(If anyone out there has any pictures or info, it would be greatly appriciated)

I'm thinking double feeler wands mounted on the crossbar like a couple of the mothies and mirabaud are using, same feel on both tacks, I would also like to use a flapless rudder like the bladerider, but not really sure how that system works.

like I said, time to go to school, I would be happy to just get the vertical for the main foil going, so that I can make the case to put in the hull.

anyway, the latest Rhino osx update lets me do things like this.......(ah the joys of high res quality pics)

******its a quick sketch, need more mast bend, haveto put the spreaders and the prodder in the right place, I know I know......its just so I could get an idea******

 

Crossbar mounted wand(s)

Sam:

There was some great needles to be found in a ridiculously large haystack thread on Sailing Anarchy / Dinghy Anarchy regarding wand placement. Our good friend Doug Lord was expounding on the horrors of bow mounted wands, and quite a few experienced foilers (people that actually sail full size boats) presented strong arguments to the contrary. It may be worth a read, as some of the logic regarding timing of flap induced lift adjustments at speed made sense.

In a manually controlled system anticipation of lift requirement is the operator's responsibility, as as he can see what's coming at him. In an automated system, the system has to be located enough distance forward of the main lifting foil to allow for system hysteresis so the lift change arrives in time to respond to the actual change in the surface condition.

The hypothesis was that if the wand and the foil were at the same place lengthwise on the boat, lift changes would be happening after the surface condition requiring the change had passed by. The control rods & bell crank added a small but measurable lag to the system.

I know that this comment will probably cause a torrent of rebuttal (I can already hear "pitch coupling"), but at the end of the day I would do your own research and form your own opinions. Bladerider and Prowler both implement bow wands for reasons that seem to be justified to them. Andrew McDougall and John Illett aren't exactly people that should be ignored.

Cheers,

--
Bill


BTW, the sketch looks cool. It is always nice to get a vision in your head of where you are going.

 

Hmm ... from an idealistic point of view if you are sailing the boat flat, there should be no need for dual wands. I do however realize that the world is far from ideal. Personally, I fail to meet ideal in many ways (which my wife would be happy to elucidate), so as a helm I deviate from flat far too much.

I chose to go with the end boom split bridle, and boom sheeting for a bunch of reasons, speed of tacks and gybes being one of the major ones. I just hate tripping over crap when running across. Since you are foiling, you'll be a lot more sensitive to fore/aft weight shifts where being out of place could blow a foiling gybe or tack.

I also ran the mainsheet inside the boom from the aft block end to the gooseneck, turning it there on a block and running it back to the rachet and boom mounted cleats. This took the dangling sheet away as well and contributed to better mobility without getting hung up.

The other major benefit of the boom end split bridle and 1:1 sheeting is that there is far less mainsheet in the boat, and far better responsiveness to control movements. I can go from fully extended to centerline in one arm pull without using my teeth and two hands. Big necessity for a singlehander. The long lever arm of the full boom length has the same kind of effective purchase as a multi block mainsheet setup. You do have to get used to sensitive movements - i.e. six inches of accidental sheet release can cause a swim.

 

There is this crazy idea in foiling called "veal heal" where you sail the boat as much as 15deg to windward when up on the foils, that being said, Dual wands might be nice because it would add simitry. might not be needed, but might work out well? Might not be worth the drag, still thinking about it.

as far as end boom sheeting, got any pics?

thanks again.

 

I'll take some better pictures and post them. This one shows the split bridle and the entry into the boom tube. There is a Harken block at both ends of the boom, with the lower part of the boom cut away to allow the blocks. The rear block is mounted to the boom and the forward block is attached to the mast luff track.

The forward block turns the rope 180 and it goes back to the rachet block underneath the boom. The vang strap leaves a space where the sheet passes through. The split bridle legs meet right at the block when the boom is at centerline.

The rachet block at the boom has a clam cleat on a plate on either side, as with the spinnaker I need to cleat and drop the main. In your case a cleating system would not be necessary (and maybe dangerous).

(And yes, I've retensioned the battens to eliminate the creases)

Regarding the Veal Heel - yeah, I forgot about it. If the wand is on centerline it isn't relevent, except the disturbance wake of the wand tip may cause issues with the leading edge of the foil. I'm not sold on this completely, as I think there would be enough leeway to make the wake not hit the foil leading edge (but that's just a shot in the dark guess). I could imagine the linkage could get complex on a dual wand system. Complexity is the enemy, but if it can't be avoided, so be it.

 

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WA, this is absolute BS. It's very easy to prove as well: Look at the speed of the boat and the distance it moves every second. Keep in mind that the wand hits the water 3-4' ahead of the main foil:
--boat speed 5 knots=8.43 ft.per second
--boat speed 7 knots=11.8 ft. per second
--boat speed 10 knots=16.86 ft. per second
As you can see there is absolutely no"anticipation of lift"! In other words there is NO advantage to a bow wand "so the lift change arrives in time to respond to the actual change in the surface condition." Lift changes ARE ALREADY happening after the surface condition requiring the change has
passed by!
Further, my main point was that it makes NO DIFFERENCE to altitude control -for the most part-where the wand is-since it is a mechanical averaging system. I say for the most part because there is some evidence that there can be a coupling between the pitching of the boat and unwanted wand movement for a bow mounted wand.
The advantage of a midship wand is that it can be integral to the top of the daggerboard-requiring no cable etc. and therefore be lighter.
I made the point that I believe will prove to be accurate as time goes by: a manual system would eliminate the rapid wand(flap) movement associated with a wand, be lighter still and therefore have less drag. For racing this may be the best way to go-time will tell.
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Probably your MOST IMPORTANT consideration now is where you are going to put the daggerboard because that will have the most dramatic effect on pitch stability. Take a look at Jundts early AET video and then at his most recent Mirabaud video-you'll see a dramatic improvement in pitch stability.
-
Your sketch looks great. Have you been able to contact Thomas? Let me know...
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I have been taking that "complex linkage" thing to heart, and after thinking about my wand system all day, I think it would be best to just go with a bow mount, its hard enough to get the systems sorted without making them difficult. I can always mess with it later. Its best to go with conventional things that work, then try to improve them. really I just want to get the thing up in the air, then I'll worry about being "trick" I was thinking of putting the wand out in front of the bow on a little rig of its own to keep with simitry, and so that the wake at least hits the leading edge consistantly. still thinking about it. I really like the way your sheeting system works, right along the lines of what I want, can't wait to see more pics. (that and I just love the way your boat looks) while your out there with your camera would you mind clicking a couple pics of your Trapeze System as well?

 

never really thought about that, I was just going to have a really short linkage on my midships wands, but I already have ideas of ways to do it....more to think about.:?: It will probably come down to doing a couple or of different control systems and then trying them out, go back and forth right now as I think about it more and more and as I gather more info and insight. good thing is, as long as I don't hardwire my boat for any one of them I can try them all.

I plan on putting the vertical through the deck between my crossbar and my kingpin, have to change my rack build a little, but I can actually use this to my advantage by using it as an excuse to put in one more anchor point on my kingpin. (stronger = better ) Then have the vertical angled about 7deg forward to help with ventilation. that should put my forward foil right under and behind where my mast is. (tentitive) Unfortunately that will make a retractable foil improbable because of the boomvang, but oh well ( I do have thoughts of a clip on vang that I could clip onto the boom after lowering the foil, but I'll worry about that later. I recieved information today about the bladerider flapless foil, so I want to use that Nylon wormdrive pin system for my rudder. ( a friend turned that Mirabaud video into a screen saver for me)

I'm going at the sketch again tomorrow, I've been looking at it all week letting the rig evolve in my mind, its not that far off. a little more mast bend , round the foot, and lower the boom in the stern some because I'm not going to be back there on the tacks anyway. Haven't contacted Thomas yet because I want to have my brain wrapped around what I'm talking about before I get in over my head with someone already seeped in this stuff.

 

Keep in mind that the original reason John angled his board was to get the mainfoil further forward -nothing to do with ventilation(popular myth). If you can't retract your board you will be unhappy.....
Consider the 49er type vang that comes down from on TOP of the boom-makes a lot of room.

 

I'm a big fan of sticking to things that have been proven to work - it just takes some tough variables off the table. I would not want to be the proving ground for theories considered and rejected by the most successful platforms out there like Bladerider and Prowler. You've got enough on your plate to resolve without adding more question marks.

It is amazing how much time I've spent sorting out trivial stuff on my boat, and it has got a lot less technology risk than yours.

I'll get some pictures of the trap setup as well. Nothing exotic there at all - typical I-14 style setup. Placement fore and aft of the retainer bungee has been an issue for me - do I optimize for upwind tacking or place it further aft for gybe speed? I would not want to have to move weight forward on a gybe too much and cause a slow down and rig loading, but I also don't want the trap retainer in the way of upwind tacking. Every little detail is a debate and compromise.

Tiller extensions and how to keep them from dragging has been a debate. The split bridle somewhat handles a lot of this, but I tried a couple different methods of using bungee to keep them from dragging and they didn't work well. The SwiftSolo style bungee on tiller wasn't effective at all - it didn't prevent dragging and actually exasperated problems in recovering the extension on tacking. A 29er-X style bungee added a hell of a lot of friction to the steering - nice if you don't want to turn! The 29er-X style was strong enough to cause the leeward extension to drag quite hard laterally - keeping it from dragging back but not helping at all. I'm currently using nothing, and working from the principle that the split bridle bounces the windward extension forward automatically when it tensions. The leeward extension now drags straight back and doesn't add lateral drag.

Rig setup and tuning is a big gray area. We originally set up the rig with turnbuckles on the shrouds for simplicity, and manually tensioned the rig on the forestay. This isn't optimal. There is no repeatability or consistency as I don't like leaving the rig under tension.

I'm buying a Loos gauge to measure things. We've added lowers (really needed), and I'm changing the turnbuckles to 29er-style multi-hole chainplates. I'll probably make a built-in boatbreaker-style tensioning system on the forestay to set up rig tension as well. Probably have to add the same style chainplates to the lowers as well. This rig really responds to and requires tuning. I would guess yours will be similar.

Since you are starting a completely new platform here, to reiterate, complexity is the enemy and I would stick to as much proven systems as possible. I can guarantee that there will be plenty of issues sorting out things without adding huge question marks to the equation. You will find out quickly what systems need more sophisticated methods and what things work well enough without.

 

In true Doug Lord fashion you have done half the work and reached a firm conclusion - "absolute BS" - without experimentation, measurement, testing, a data set, analysis and conclusions. It is wonderful that you may be able convert knots to feet per second - a good challenge for a fourth grader using Google. You may have forgotten to determine the reaction time of the wand controls to see how it affects the wand placement. As I've said before, your science & engineering skills and objectivity are lacking. If the wand system hysteresis is 500 milliseconds, your feet per second speeds certainly seem to allow changes in time for reaction to conditions happening in a timely fashion.

Doug, the issue I have is that some of your adopted theories from other people's ideas may have merit, and some may not. Without scientific experimentation, measurement and repeatability they are just theories. Scholars publish their thesis and put them up for peer review - the publishing process allows other experts to review and comment on the work done. If the work passes muster, the review process adds credibility tothe body of work, and allows others to build upon it.

You confuse anecdotal and potentially biased third party reports on the Internet with academic works, and reach conclusions skipping the whole annoying "work" part of science. The worst part is you selectively choose the third party Internet posts that re-inforce your pre-decided conclusion, ignoring or deriding those that oppose. I'm certain this call for you to think about how you conclude things will be ignored and held in contempt.

Nobody can "see" anything here. You may be able to envision things in your head, but that is not the real world. Measurement of the wand position, measurement of the foil height, flap angle, depth of foil, wave state pooled together would give a data set that could be used to reach some theories regarding the efficacy of various wand systems. Any other method is more voodoo than science. You can't just throw **** at the wall and reach conclusions based on what sticks and what falls off.

I'm not doubting that there may be lots of room for improvement in how things are handled. I think there may be merit in investigating a lot of the ideas brought forth over the past two years - including Mr. Jundt's.

Doug, the most important consideration here is getting a working foiler on the water, not daggerboard placement for pitch stability. Stop confusing your personal pet theories with someone else's project goals.

I know this post will probably generate a torrent of continued abuse, capitalized letter shouting and red text, accompanied by other people's photographs and Internet blog posts as evidence of your conclusions. I'd like to politely ask you skip it, as I've seen all your tripe before, as has everyone else. Show me your academic credentials, your professional engineer accreditation, your published papers, your raw data and your experimentation plans. Show me peer reviews, show me repeatability.

The funny thing is, I think some of your seat-of-the-pants anecdotal experience and shade tree mechanics may have merit. I just think you need to step up academically and prove things yourself. Welcome to peer review.

 

I'm using a single bow wand and linkage, thats that, not even going to think about it anymore until I run out of important stuff to mess with.

Amen.....

I would also like to ask you to skip it, there are about 4 other "foiler wand placement" pissing contests going on at other forums, take your beefs there.

I will be using the current single wand bow linkage system, end of story, I will be putting 7deg of angle on my vertical, end of story, flapless rudder control, end of story.

Foil controls and shapes have now been sorted, moving on to cool rigging, sail, and control ideas (tiller, trap set, prodder, spreaders, stay adjusters, outhaul, downhaul, vang, main sheet, gantry,ect.)


Time to draw......

 

Are you eliminating retractable main and rudder foils?

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From the aardvark site(axiom moth)"
Moth Hydrofoil Daggerboard with Flap
Carbon fibre Moth daggerboard with trailing edge flap. NACA 66014 vertical section with 7 degrees forward rake for increased foil seperation. Large chord flap for increased control. H105 lifting section section
Product Details
Price: 850.00 GBP