Wayne,
She looks beautiful! What is the final blk with the cam cleat? I don't recognize it. At the rear you've got single/becket at the clew, a double at the traveller, what's inside the boom? What's the sheave inside the boom that turns the sheet forward? I like your simple rotation control arm. Thanks!
Dave
Dave, sorry I can't remember what the final block manufacturer, it was an Ebay special I bought some time ago for about £20.00 brand new, I think Lewmar springs to mind. Most of the blocks I use have been Holt Allen, great blocks at low low prices. The through deck block is http:/
Inside the boom I have a 30mm at the front against the gooseneck and a 30mm with becket at the rear creating a 3:1. Not really sure whether this is a 12:1 or 9:1 you can discount the last block at the front as it has very little effect, but it is nice and easy on the forearms.
There are a number of do's and don'ts with cascade systems, they can be a bitch to set up to get maximum travel, but worth while.
The biggest don't is to make the rear boom block at the back fixed inside the boom. The mainsail with tension on can grip the boom and turn it just a few degrees beyond the best working angles causing alsorts of binding problems. I solved this by using a tie on block mounted onto the outhaul pulley, the tie on allows the block to always be at the best angle.
There is an interesting discussion on SA re the mid mounted sheets for A classes, lots of interesting litle nuggets of info there.
All excellent, thanks Wayne! I'll give SA a view.
Dave
Well a relatively interesting season racing at Datchet, without breakage. Despite my best efforts at knocking the main cleat out repeatidly and forgetting to release the downhaul, the A mast is still intact.
Another racer commented on just how flexible the top of the mast above the hounds was one night whilst racing, for me to realise that I had been both forgetting to release the downhaul and the mast rotation and having problems with the main jammer seizing open. Virtually every reason to break the mast.
Changed the mainsail as the sail I had clearly was not suiting both my porky frame and the older style stiffer mast I have and what a revelation. Very much now able to fly the hull from about 6 - 8 knots of wind and downhauling pretty hard now when into the 15 - 20's. Despite only 14msq in area, the high aspect and the years of design knowledge far surpass the F16 compliant sails I had been used to.
This really is something the class needs to address or should consider perhaps within its rules to help the solo sailor. In direct comparison to the equivalent sailor on a Nacra F16, Bitsa probably is faster upwind, something it shouldn't be and I put that down to the sail mast combination. I am very much a believer that we should be allowing the A mast and sail combo on single handed F16's. Cost is not the issue with there being very little difference in price between an equivalent F16 and an A carbon mast. The upside is all that free development that has taken place. On handicap terms it makes virtually no differnce with the higher aspect rating cancelling the 1 less sqm of sail.
Learning all the time and really starting to notice the angled dagger boards. Bitsa is probably too old fashioned in hull design and has too little volume, but at speed with both upwind and downwind, I need to move far less around the boat than I did with the Stealth and one would seem to be further foward in the boat. That could be due to a number of reasons such as the beam and COE is further back, certainly upwind I have to be nearly as far foward as the front beam to get the bow down and use the full water line length, which seems to get the boat into a nice groove, downwind its faster to stay off the wire and fly the hull going more downwind than to try and hot the boat up on the wire, again probably something to do with hull volume I would suspect. What is very evident though is that you cannot be more than a foot out of position in the boat as it simply will either lift the front out or try and dive the bow, those angled boards are having quite a bit of effect.
Lots of design ideas going on in Bitsa and it is quite contrary to a lot of modern design, but its no slouch and certainly the Nacra and Bitsa are pretty evenly matched with the Nacra being faster downwind. The snuffer is certainly causing a lot of head turning and seems to work very reliably when going downwind and doing everything as a single hander should. The minute you turn upwind that fraction too much such as leaving it a bit late at the mark, it turns into a real horror story. The need to bring the spinnaker around the stays just slows the retrieve enough to suddenly wet the sail and then cause it to drag just slightly. The boat then over runs it and you end up trying to pull in a great big wet blanket. I have a simple mod, that of fitting a snuffer ring just ahead of the stays on the spinny pole, that should solve it, but then we are suddenly increasing wind drag.
So learning Bitsa's foibles, and probably in all truth its a better sailor than I, very very balanced now that I have shortened the spinny pole a tad and can upwind, almost put the tiller down whilst adjusting the downhaul etc,downwind a bit of lee helm but not significant and probably means that I have put the dagger boards a touch too far to the rear.
But and a big but, its bloody great when someone asks is that an A Class and I say no, an F16, upon which they will immediately ask, which make then, upon which I say Bitsa.
Never heard of them
they often reply and I guess that must be the case as there just aren't many around.
Hi Wayne,
what is the mast length of the rig you are currently running? Is it class legal?
Last night Frode and myself cut down the mast section we are going to use from 9.2 meters to 8.49 meters. It hurts but after crying a bit we tossed the cut-off into the alu scrap bin and started drilling new holes for the fittings.
Looking at your pics and the rudder forward rake, it seems like quite a bit of rake there?
Apart from the user errors on the snuffer, do you think the reduction in drag from the snuffer is worthwhile?
Very interesting post you made!
Sadly the 9.1m mast I have would take me outside of class limits but then the 13.95sqm total of mast and sail combo, under SCHRS handicap will give a slightly lower handicap than the 15m F16 so all is fair (approx). Bitsa is slightly underweight at 100kgs and only 2.3m wide as well so it balances out nicely to just under the true F16 handicap, under SCHRS.
Why only 2.3m wide, I think we have gone over wide on the solo boats as with a low aspect 15m main at 95kgs I found it really difficult to fly the hull in anything less than 7-9 knots of wind. Less RM will allow that hull to fly earlier and on the water I would say I have substantiated that with both Bitsa and the early Stealth ( which was only 2.3m wide ) flying the hull earlier than their wider brothers. I think also there is something about less tripping and diving also with the narrower boats.
Its been long known that I feel the jib gives the dual handed boats more drive than the weight penalty of another body on board and that really shows at low speed where the jib smooths the flow over the main. All the knitters loom of wires and snuffer etc can only make the bottom of the uni main even less effective, anything we can do to at least give something back to the bottom of the main can only be a good thing. This winter I plan to build a blade jib and fit it to Bitsa to test out my theory's.
Why the foward angled rudders. Most vintage aircraft with leading edge pivots on their rudders have foward angled rudders to balance the rudder and prevent flutter. Water being a lot denser means much lower speeds before the potential of flutter. How many times have you sailed some of the Hobies to simply feel the rudder
spin out
and you have to slow somewhat before you get full rudder control back, thats flutter setting off ventilation. On Bitsa I tried to get as much board ahead of the pivot as behind to try and prevent this and give a nice feel to the rudder. As a bonus the foward lean prevents a lot of the ventilation problems we often see, the moths certainly have had to do this to prevent air leaking down the leading edge and getting to the hydrofoil. There is a really good You tube clip made by a guy called Bulgari which shows this happening. I'm sure SmithCats would be able to put a more finite analysis on whether I'm right or just luckily wrong as the rudders are really light and nicely balanced at the moment.
Interesting what you say about flutter. On the Tornado we regularly lost grip with the leeward rudder when flying a hull and hauling the main tight when going upwind. I dont think there were any flutter as there were no noticable vibrations and no escalation. Rudder loads were light and we did have positive rake on rudders vs pintles/angle. However we were sailing with 200kg on the trapeze and class standard mast rake. This problem went mostly away when we used less mast rake. My conclusion back then was that we overloaded the rudders and experienced loss of lift as the poor rudder was asked to balance too much total load.
I am fully with you on the foil balancing to avoid a heavy helm and flutter as it is defined here: https:/
Cudos for your willingness to experiment! Wires are a worst case for drag I think. But seriously, we should look at our bodies and how we dress onboard as well. Drag reduction is the game for optimization!
For width I always enjoyed the curves showing righting moment vs angle of heel. Decreasing the max widt also decreases max potential RM. By going less wide the boat should in theory not be faster and heel angle should, again in theory, be controlled by crew positioning. What I think you imply is that we, the sailors, are not good enough at getting our positioning correct (we dont move our
behinds
inwards from the hulls)? Where do you notice the most difference with a less wide boat. Upwind, downwind or even?
We drilled the beams for max width when assembling the platform, but beams are affordable <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
Thanks for sharing Wayne!
As virtually all my racing is based around SCHRS handicap racing then Bitsa has to conform to the pecularities of a rather antiquated one calculation fits all system. We as solo sailors are penalised in my opinion and few Uni boats can conform to their ratings, one only has to look at the F16 rating between solo and dual, both being the same rating. Can a solo boat beat a dual boat, I think with the new powerful rigs and sail handling systems available, it is now very very very unlikely.
So how do I
trick
the boat out to try and get any sort of advantage. The only real way in my view is to use very well developed mast and sail combos ( A Class ) and hull design to suit the Uni sailor rather than the hull designs which suit the dual sailors weight ( RM ) and extra drive of the jib.
I chose to go to the narrower beam for a number of reasons, pricipally it helps a lot in reducing the handicap rating in SCHRS, enough to allow a lighter boat and more high aspect rig. Secondly to get a faster hull ( in theory although I think some of the new designs are proving otherwise )one has to increase the hull width to waterline length ratio. Once we go to a finer hull as I have tried to do, immersion from the RM becomes a problem ( drag through the water )however by using angled boards creating lift this can be reduced somewhat ( think A class with their new C boards ). So lots of design factors here being influenced by a handicap calculation.
Last but not least, when I moved from the Stealth 2.3 to fitting the full 2.5m beams, it was very noticable in the handling at just how that 200mm effects the boat. The boat became much easier to control the heel, it became much more likely to bury the nose in a tripping sort of way, it became much more sluggish in handling,it became possible to over load the boards and start going sideways rather than tracking true.
So by choice wishing to compete under SCHRS handicap, I went narrower and probably would go narrower even further on real life experiance. It would certainly make for a very lively boat and probably only the very experianced sailor would be able to get the best out of it, but it would lower the handicap significantly and allow even finer hulls that would benefit from C boards.
Bitsa has become about the package under SCHRS I'm afraid to say, one cannot compete at F16 meets due to the anomoly of our class rules so one has to compete on handicap.
Hi Wayne,
I dont know your rating system. But if it is formula based a coefficient for solo F16 might be a solution? Dont know how to incorperate this though..
Rules are what they are. Some parts are excellent, others are not. But the rule is what makes this interesting and at the same time frustrating?
We need friction brakes on the spi halyard for non-solo boats. <img src="<>/wink.gif" alt="wink" title="wink" height="15" width="15" /> To be serious, it would be very good to see some statistics on the performance of solo vs. 2-up with boats and sailors of comparable skill. Perhaps there are some things that can be done?
Interesting that you have optimized BITZA for your rating system instead of just getting an old A class. I bet you have learnt a lot during the progress.
The SCHRS is the official ISAF handicap system and although it is good, like all handicap systems, some boats seem to pop out the side of the system and flag up errors. Its been long proved that single handed F16's cannot now compete with the duals, when one of the top A Class sailors in the world tried at the 2010 Europeans ( ? ) at Garda to sail solo when his crew became ill, it was very noted that he went from top 3 to 17th. That was certainly an eye opener and in later discussions with SCHRS it was very apparant that even they consider that the duals have some advantage. But hey thats another story.
I did sail an A Class for the 2010 season just to learn the basics about mainsail control and have learnt a lot. However the A is no match for all the spinny boats at my club and for that reason have moved back to Bitsa. A single Uni sail cannot compete with the spinny boats in just one small part of the race, just as you transition from upwind to downwind. The spinny allows them to just slide slightly below you whislt you are trying to hot the A up onto one hull, at that point they are in control and you inevitably lose 1 or 2 places on every leg. The power of the new mains on the likes of the Hurricane 5.9's which predominate at my club, means they are a near match on the upwind legs which always means that you are slowly but surely going down the fleet. I think the very good guys are perhaps able though to sail the downwind legs on the A's far better than I, where the spinny on Bitsa at least gives you a chance to maintain your position.
So what areas does the uni need to improve to be on like with the two handers? (assuming same level of skill and gear between boats).
In order of priority it looks to me as this:
1: Upwind
2: Transitions (upwind to downwind, downwind to upwind)
3: Downwind in trapeezeing conditions
Rolf
This is getting way way away from the original thread, that of Bitsa's build. Perhaps you may want to start a new thread on this very subject as then you may get a few more coming into the frame to discuss.
It will be very un PC as the Uni v Dual being even is what our class is based on. From real world data that is now no longer the case in my view and that is supported by the disintegation of the fleet of F16 single handers at my club, which probably was the biggest in Europe at the time. Some have retired, most just got tired of coming last in the handicap fleet racing which we predominately have.
At some time this subject is going to have to be discussed and not on the F16 web forum which is closed to those who do not have a F16 boat.
Thanks Wayne,
I'll cede the topic to somebody else. I am fitting out an F16 to be solo sailed mostly just now so this is highly interesting.
Please do keep up the BITSA info flow!