here it is on a reach

I’ve stripped out the bunks, and sealed off the main bulkheads.  Those would have water tight hatches like the nice ones PT Watercraft makes for Scamps—a good place to put stores while conserving as much of the good space as possible.  Inside there would be sling chairs for two that convert into a single bunk.  Or maybe I’d just use a hammock to sleep inside.  We could rig a second one between the masts in nice weather.

Nice work Chris,

.............quote…...Of course, the stayed fractional sloop is probably always faster.  But for a cruising boat does the ease of handling and low center of effort make sense? ..........unquote….

Sorry to say but one thing I don’t like are the lugsails,  if you going to be hit by a nasty gust , best to have sails that are very tight at the leading edge, ie.you don’t want flutter and due high resistance. you need to be able to de-power very fast.

Thats probably why in the end [although higher CE] a sloopmain will always be quicker to depower, Further, the wishbone need to have a facility to depower ,as the leech is held tight by the wishbone.

————————————————————————-..........quote….......Sven, I have never seen a bendy masted, unstayed rig with an eliptical section mast.  From windsurfers to lasers to Wyliecats, they all have round sections.  I think some Freedoms had eliptical/wing section rotating masts, but I don’t think that they were too bendy.  And eliptical section stayed rotating masts, like on a beach cat, have diamond wires to stiffen them up in the small crossection direction.  I’d love to see what you have in mind….........unquote…........

Freestanding elliptical masts can be found at Eric Sponberg website. he really developed them properly.
On bendy masttips[ again difficult to engineer] I suggest Julian Bethwaite is the best source, [18foot skiff circuit]

Cheers Sven

if you going to be hit by a nasty gust , best to have sails that are very tight at the leading edge, ie.you don’t want flutter and due high resistance. you need to be able to de-power very fast.

Great point, Sven.  Your comment got me thinking about separating the bendy tip and the rest of the rig.  Lots of people have done sweet gunters.  And I’m a big fan of the PT Dinghy’s gaff-ish rig.  But this is a little simpler.  In essence, its a windsurfer rig, hoisted up like a topmast with a bunch of fully battened sail hanging down below it.  The mast could be a relatively cheap, very short and very stiff wood/composite.  The masts on this boat are only 14 feet long.  The topmast/gunter (a used windsurfer mast) is straight before the sail goes on, and is bent into shape by the fabric and the battens—just like a windsurfer rig.  There is room for four reefs before the topmast meets the boom.  And as you reef, you still have that forgiving bendy mast tip, all the way down.  Is the rest of the sail just laced on?  Are there strap “hoops” every few inches?  In any case, there’s no mast track and no mast rotation necessary.

I’m sure that there are some aerodynamic consequences to having the mast in front of the sail like that.  Maybe some can be mitigated with smaller sections (now, probably carbon).  But its an interesting direction that appeals to my retro-future sensibilities.

So many choices! I agree that the Presto sharpie style rig is going to be the most expensive, it’s similar to Evergreen’s twin masts and I was shocked by the time I priced out the mast track, full battens, and sails.

I like the windsurfer rig gunter, though the devil would be in the details to get it to set right, and to make it so raising and furling sail wouldn’t be too much of a chore. The PT Dinghy had a cool gunter-like rig though I noticed that only the first built was so rigged, the rest going to a normal fully battened marconi, draw your own conclusions.

Here’s a less high-tech schooner sharpie - Lady B - but still very nice. Free-standing carbon spars, the sprit booms are straight, not wishbones, the sail is more triangular with short battens, and it is lashed to the mast, no track or luff pocket.

BTW, you show your lugs with the fwd sail on the “bad tack” (mast to lee) and the aft sail on the “good tack” (mast to windward), which I think is backwards. For any twin masted rig, the fwd sail is doing the most work, being in clear air and not backwinded, and with the proa we want the fwd sail to be stronger anyway, to help pull the CE forward. My thinking is to give the foresail every advantage and put it on the “good tack”. The aft sail is mostly just along for the ride, anyway.

I’m glad you are testing the lug rig for yourself on the wa’apa, that will be really interesting.

The PT Dinghy had a cool gunter-like rig though I noticed that only the first built was so rigged, the rest going to a normal fully battened marconi, draw your own conclusions.

I really love the PT Dinghy rig, but noticed the same thing—that it was never replicated.  One big difference between that rig and my windsurfer/gunter is that the PT’s gaff was keyed to the mast, so that by controlling mast rotation, the twist in the top of the sail was controlled.  Mine is really just like a topmast—twist is controlled by the vang and the sheet.

Russell, what did you guys figure out there?  I loved the shrouds leading out the top of the mast—see the woodenboat article if you haven’t already!

I’m just hoisting the top half of a windsurfer rig, with a reefable bit attached to the mast below it.  Well, the reefable part is half the sail, actually.  The windsurfer/gunter would have a separate downhaul (attached to the gunter/topmast) to help shape that part of the sail.

Here’s a less high-tech schooner sharpie - Lady B - but still very nice. Free-standing carbon spars, the sprit booms are straight, not wishbones, the sail is more triangular with short battens, and it is lashed to the mast, no track or luff pocket.

An excellent point!  I saw this sharpie when I was looking for info on “strings”.  She’s a sweet looking boat, and maybe the “off the shelf” carbon tubing (is there such a thing?) might make it cheaper.  Here’s a question, how do you reef the main when the sail lacing interferes with the snuffer of the boom?  Do you unrig the boom?  One solution would be to reef to the boom, and leave the portion between the boom and the foot alone.  But that looks like it reefs to the foot.

What are the relative advantages of lacing the sail on vs. having strap “mast hoops” vs. having rigid “mast hoops vs having beaded rope mast hoops?  What’s the most reliable, reefable way to deal with the area of the sail below the windsurfer/gunter/topmast?

For any twin masted rig, the fwd sail is doing the most work, being in clear air and not backwinded, and with the proa we want the fwd sail to be stronger anyway, to help pull the CE forward. My thinking is to give the foresail every advantage and put it on the “good tack”. The aft sail is mostly just along for the ride, anyway.

I’m confused by your question, since on the other shunt, this is going to be the opposite way.  What I mean is that if you do not have a dipping lug (where you douse each shunt to keep the sails on the “good” tack) one sail will always be on the wrong tack.  Am I missing something?

This is a really great follow up and has definitely got me thinking. 

best,
Chris

Since the wind should always be coming over the ama, attach the sail with the yard and boom to leward for both.  Your aft sail will still be in dirty air, but the leading one will be set smoothly.  Apparently, it doesn’t make that much difference other than the looks.

Dan

dstgean - 27 February 2013 09:09 AM

Since the wind should always be coming over the ama, attach the sail with the yard and boom to leward for both.  Your aft sail will still be in dirty air, but the leading one will be set smoothly.  Apparently, it doesn’t make that much difference other than the looks.

Dan

Wait, but then won’t both sails/yards be leeward on one shunt and both sails/yards be to windward on the other?

Am I missing something?

chris

Hi Chris, you have obviously created a lot of interest in this design. Three dimensional drawings are definitely the way to go to get the message across. I looked at the twin sail arrangement and noted that the front sail is disposed behind its mast and the rear one is in front of its mast.

I had a similar arrangement on Pi, see photo of Pi and Piawatha, in that the sails did not finish at the booms but each had an “inverted” triangular extension which we tensioned to the pivot of the boom bridle.  My reasoning was that the sail at the back would be flattened by being pulled over the boom while the front one would be fuller.  This worked in practice but when racing someone would always go down to the float at the start of a new tack and put both sails outside the booms and adjust the tie-down tensions for the conditions, controlled by another crewmember or often members yelling out when the sail looked good. This gave a significant increase in performance but was often hazardous for the crew battling 20k spray in rough conditions trying to finalise the adjustment, always attached by a harness of course.

I suspect that the difference was not because the rear one was freed, but that obviously helped, and that selectively tensioning this inverted triangle made the bottom part of the sail (the large area part) and possibly the whole sail work very effectively.  The difference in performance for the tiny extra sail area was remarkable.

Just an observation you may be interested in.

I had previously tried a similar sail on Protoproa hanked to a stay from a similar bridle arrangement and with a massive wishbone about 15ft long which pushed such a big kink in the forestay that its life was short.  The sail was a modified old 18ft skiff sail.  Still, done properly on a headsail it could be beneficial.

Best regards

John Pizzey

I’m confused by your question, since on the other shunt, this is going to be the opposite way.  What I mean is that if you do not have a dipping lug (where you douse each shunt to keep the sails on the “good” tack) one sail will always be on the wrong tack.  Am I missing something?

Here’s a little info graphic of the schooner standing lug proa.

1. Wind coming from the right, proa heading up to the top of the page. Fwd sail on “good” tack, aft sail on “bad” tack.

2. The shunt, with booms and yards pivoting around masts.

3. Proa heading down to bottom of page, fwd sail on good tack, aft sail on bad tack. I think this little bit of lug rig magic can only be accomplished on a shunting craft.

Very interesting, John.  Are you talking about the lug rigged versions?  Or are you talking about a sprit boomed triangular sail?

I’ve gotten pretty worked up about this fully battened, fatheaded windsurfer gunter topmast thing.  I’ve put regular, boom at the foot of the sail booms on this because I don’t know how you would reef it otherwise.  But if I were to forego a rope vang (as currently designed) and do a sprit boom, the tackable foot (like you are talking about) is a very interesting option!  At least for racing…

Any thoughts about the viability of the windsurfer/gunter/topmast idea?  Does it even make sense?

By the way, I thought I invented your Pi rig (albeit backwards) on my snelson’s canoe design. 

http://proafile.com/forums/viewthread/135/

I am really dig that general idea—but I’m worried about the tension required.  There are LOTS of spreaders and wires on Pi—was it har to get enough luff tension.

Thanks for your thoughts!  Its great to see you on this forum.

chris

Hi Chris, sorry not a comment on any of your versions really just an observation that a conventional sail which terminates along a boom may work a lot better if the abrupt termination of the curved sail shape at the boom is eliminated by utilising a tapered continuation of the sail. A wishbone windsurfer rig is a perfect example.
On a flying proa when one is trying to minimise size but maintain performance and reduce overall rig height this may be an important consideration.  If you like what you have designed, go for it, it doesn’t seem too radical.  I can’t see any problems reefing a windsurfer type sail but you would need a vang to pull down the boom when the bottom part of the sail is gathered, probably also need a topping lift. You could take an old windsurfer sail add the rectangular panel in the middle to give the required area and give it a go at little cost.
As regards Pi, the structural design ensured that we kept a tight luff. The basic structure was an H frame made from fibreglass I beams about 30” deep in the region of the mast loads with flanges incorporating continuous rovings.  The transverse beams ran from the outer cabin side to and including a float bulkhead, both formed as one piece fibreglass beams as was the fore and aft beam on which the mast was centrally located, all glassed up into a monolithic structure. During initial overload testing the web of this central beam deformed with stretch corrugations, interesting to see in 1/4”+ thick glass web 30” deep.  I beefed it up and had no further problems.
The ends of this H frame provided the anchors for the stays and the sails so the stress was kept out of the rest of the boat or mostly so. As you alluded to, unless the structure can take the loads without significant deflection the forestay will sag off badly and the boat probably won’t point very high.
However I did build a spindly 30ft cat with 3/4 rig rotating mast, battened main and a very saggy forestay.  The sailmaker eventually put a “cunning seam” up the luff (he gathered in a significant portion of the luff and sewed it together) and it then performed very well to windward, but it was extreme.
There really aren’t lots of spreaders and stays on Pi.  One spreader with diamond stay, two masthead stays two intermediate stays all going to the upwind ends of the H beam and two booms with bridles going to the downwind ends of the H beam and the two forestay and backstays.  More than a freestanding rig obviously but when sailing the forestays became part of the sails and each backstay equated to a topping lift so effectively no fixed rigging downwind of the mast.
Thanks for your interest
John Pizzey

Here’s a little info graphic of the schooner standing lug proa.

Yup, I was missing something!  Thanks for drawing me a picture—it seems so obvious now that I feel silly for not having seen it.

a conventional sail which terminates along a boom may work a lot better if the abrupt termination of the curved sail shape at the boom is eliminated by utilising a tapered continuation of the sail. A wishbone windsurfer rig is a perfect example.

I totally agree, John.  I love sprits and wishbone rigs.  But part of the windsufer/gunter idea is to eliminate the sail track (replacing it with lacing, straps, hoops, beaded loops—TBD) to make it cheaper.  My understanding is that the snuffer (outhaul/vang between the mast and sprit or wishbone) will not allow that kind of sail to reef down to the foot.  Now you could reef to the boom..that should work..but there’s something unsatisfying about having all that sail bunched up above the foot.

Some might argue that having a separate outhaul and vang is tunable.  But its hard to argue that the snuffer isn’t more simple.  Its just that sail lowering thing—if you don’t use a mast track.

Seriously though, does anyone know how they reef a rig like Lady B’s?  Do they have to re-rig the boom each reef?

thanks,
Chris

Hi Chris,

I’ve been lurking for a while, but I couldn’t stand it anymore, I had to join to say how much I really love this boat.  My favorite incarnation is the orange/brown one back in post 74.  I’ve been sketching what I thought would be my ideal boat for the past year or so, and in many ways it resembles what you have shown here, but my scribblings don’t hold a candle to the fantastic renderings you have here!

What I love:
- I think 24-ft is the perfect length for what you’re going for.  It can be light, but still fairly seaworthy.
- The sail plan is great, I’ve sailed some wyliecat 30s before also, and the wishbone boom is so easy.  The only downside is gybing in heavy air can be dicey, but proas don’t have that problem!
- I like the jib option, especially when it is accessible from the cockpit.  If it were on a track so that it could slide up to weather for reaches or runs, that might work, and it would also be an option for moving the jib to weather and out of the way of the main when on the other tack.  An alternative to moving the tack to windward might be to sail wing-on-wing downwind, with the jib sheeted to the aka, but then you wouldn’t get all the sheeting angles for reaching.
- Like nearly everyone else here, it seems to me like the brown style proa makes a ton of sense.  I would LOVE to sail on one someday.  That includes the pod, Newick style rudders, single mast stepped a bit to weather, etc.

Some other thoughts:
I think with +200-sqft of sail area, that is still pretty sporty for a boat this size, and the option of body ballast is a good thing.  I know that the design brief was to sail in the cozy comfort of the cockpit, but from what sailing I’ve done, I can’t help but envision sailing upwind in 15-knots of wind and some light chop, sitting with my feet on the seat, and my butt on the top of the seat back.  That would get me a little higher (better visibility) and a little farther outboard where my body weight would help keep the boat a little more powered up.  The hiking stick would need to be freed from the hull to make that happen.  The thought of sitting up there flying upwind at 10-knots with the breeze in my face just makes me smile.

For when the wind is not blowing, I think the Hobie mirage drive is a pretty cool option.  I had the pleasure of using one in a kayak not too long ago, and I was blown away at how well they work.  With a self-draining cockpit, the floor would need to be a bit above the waterline, and a mirage drive might install very neatly into the floor in the center of the vaka.  When not in use, it would be light, and would easily stow in either the pod, or in one of the bows.  There could be a plug that would fit into the hole in the hull when not in use, and it could also double as the drain for the cockpit with the floors sloped towards the penetration.

Last, since the mast is now supported by stays, and is stepped on the corner where the hull meets the seat, I wonder if the mast still needs to be supported by the deck coming across from the pod?  That adds some weight, and prevents a bit of mobility when tacking.  You could still have a soft cover in that area that connects from the pod deck to the mast to keep things dry, which might make things a bit more flexible depending on weather. 

Anyway, I’m in love.  Thank you for putting this out there.
-Kimbal.