Has anyone experiences issues where the top of the main was inverting on them?
We were racing last Friday and had an issue where the top of the main was inverting on port tack but not on starboard. Since it was happening only on one tack and the jib cars were the same position I am thinking it may be a rigging issue. Uppers were set at 37 on the gauge, lowers were well slacked. True wind was ~17 knts.
Brian Bennet here, http://www.youtube.com/watch?v=_zJ0TH9UL9k says that too little lower shroud tension could cause overbend and cause the main to invert. I thought this may be the problem but when I watched some videos with Paul Young, he seemed to not care about the lowers at all.
Perhaps if the main sheet bridle was offset to one side then the main would be out on one tack more than the other which would cause it to get more backwind from the jib?
It seemed to be inverting just at the top two battens and not the rest of the main.
Any Suggestions?
Thanks,
Pete
What kind of sail is it, and how old is it? Were you seeing inversion with the main sheet full "on", or only when you eased out some?
I've seen the top of my main invert when dumping the main in big puffs, but never when sheeted in hard. And I don't think the lowers are going to cause the top two battens to invert - the bend they control is much lower down.
And as you've noticed, Brian and Paul have very different views on the lower shrouds. Thing is, they are probably both right. And it depends on your sail cut.
Jay,
They are Hyde sails (2008), we were at the stage of vang sheeting so the main was off centerline, but that was true for both tacks.
A little off topic, with your main bridle setup are you able to sheet the main on centerline?
Yes they seem to have very different views on that. I see Brian's point about the over bending may cause the main to invert but it doesn't seem Paul has any issues since he sometimes sails without the lowers.
As usual, as the class gets more experience with the carbon mast views have met somewhere in the middle. Brian wrote a very good tuning guide late in 2009 where he advocates looser lowers.
I was at CORK in August and Brian suggested loosening my lowers (I had tightened them when launching the boat, because the keel was suspended from my main halyard and I often put 4 turns on the lowers to keep the mast in column. Forgot to take them off). I loosened them and the boat sprang to life in the gusty conditions and I started going forward very nicely. But I dont go as loose as Paul Young. Paul likes his mast to be very dynamic like the aussie 5-0-5 sailors. With
I'm am not sure what you are noticing that the main is inverting. The 2008 Hyde sails are cut very deep and it is very difficult to invert the main. I suffered inversion on an experimental sail from Quantum once. The sail goes flat as a board, no power and the leech falls off. Its distinctly weird and slow. Ive never managed to invert the early Hydes.
If you are seeing the Hyde main bubble and stall at the front, this can be caused by jib backwinding the main or too much depth. I used 2007/8 Hydes in the 2008 NAs very effectively. I used a fair bit of of prebend but the key was to use the mainsheet on hard to get a tight leech.
Do not oversheet the jib in any sail combination. Viper is slow if you pinch.
Since then, Hyde have slightly reduced the depth of their mainsail.
I strongly recommend to all Viper owners that you make the shift to split end main sheeting. (Mark McNamara from Dinghy Locker can get you set up, so can Juan Mauri from Mauri Pro Sailing + you're supporting Viper owners). The split end mainsheeting does away with having to alter the length of your bridle for different wind conditions and trying to precisley center the bridle. You can split end to the center or aft. It is much easier and faster.
Justin,
Thanks for the good info.
I know what you mean when you say the main bubble stall at the front, this seems to be common during high wind beats where the main may not be centerlined on the boat.
This was definitely not like that, the main was inverting and like I had mentioned early, it seemed to be only on one tack. I think we are going to check the rig make sure it is symmetrical and try and get it close to the tuning guide #'s. If it happens again maybe I can sight up the mast to see if it is doing anything weird.
For the lowers I keep reading stuff like "I can touch the uppers 3' above the turnbuckles". Is this usually just by taking the slack out of the lowers you able to have them touch the uppers this high up or does one have to pull hard on the lowers to achieve this?
Thanks again,
Pete
I bet you did not have enough vang on. Vang is your friend, I know that when it is really windy, on Jackpot, both Brad and Eric put together to get enough vang.
that is what it sounds like to me. you actually did not have enough mast bend to suck the luff curve out of the main.
Tac
Tac,
Could be right, but we did pull what I felt was a lot of vang on although we didn't have two people trying at the same time. Do you find that you need two people pulling with the main luffing to get it right? Although I don't know how that would explain it happening on one tack and not he other. We are going to take it out on Friday and Saturday so I will report back.
For 18-20 TWS do you guys find that you have more than 37 on the gauge for the uppers?
Out boat speed was pretty good (I think and comparing with Norths "polars") as we were holding 6.0-6.2 knts pretty consistantly.
Quote from: Peter Ruggiero on September 28, 2010, 09:28:32 AM
Tac,
Could be right, but we did pull what I felt was a lot of vang on although we didn't have two people trying at the same time. Do you find that you need two people pulling with the main luffing to get it right? Although I don't know how that would explain it happening on one tack and not he other. We are going to take it out on Friday and Saturday so I will report back.
For 18-20 TWS do you guys find that you have more than 37 on the gauge for the uppers?
Out boat speed was pretty good (I think and comparing with Norths "polars") as we were holding 6.0-6.2 knts pretty consistantly.
The Gen II Hydes had lots of luff curve and were damn near impossible to invert. The Gen III's are considerably flatter and can invert with more than the normal 4.5" of prebend.
Garett and I will be making a 'bend' gauge that will give you a real measurement of mast bend. This is all working towards an updated tuning guide. I think each of the sailmakers should put one out there and it'd be great to incorporate some polars as part of their guide.
Here's North Sails Viper Tuning Guide...for review.
Drew,
Thanks for the info, what is the easiest way to found out what gen of hyde sails we may have. The boat is #76 if that helps. I could see if the port upper shroud was tighter than the starboard one then maybe it was trying to flatten out the sail too much.
The 4.5" prebend is measured at the spreaders correct? I was thinking it may be useful to put a mark on the spreaders that is 4.5" back from the mast (not 4.5" along the spreader) this way you could use the main halyard and see where you are relative to the marks on the spreaders.
If they are original, then they're Gen 1. Just shy of 7 inches of luff curve.
Prebend is just so damn subjective...that's why we're making the gauge. It'll become a real number/look.
Yes, measure at the spreaders. Do remember that blocking at the partners changes where the bend happens though.
Man 7" of luff curve, that would help to explain the feeling of being over powered in those conditions.
I sailed Gen II main a LOT in SF Bay. 7 1/4" luff. 50+ days in over 25. I just wind on turns and it's all good.
Pretty common for me to carry 6" of prebend to counter the occasional 30 knot puff and the 4' square chop we get here on ebb days.
Sounds like the mast can take some serious pre bend, when you were running that high of pre bend how loose did you have the lowers?
Pete, I am thinking we may have had the uppers to tight and uneven, coupled with the jib cars too far forward.
Yeah I think something in the rigging (probably the uppers) were uneven, even though I did check them with the gauge.
I am curious as to what sails the Bennet tuning guide was made for if even the different generations of Hyde sails vary that much.
If they are Gen I sails with a lot of luff curve then it may of been an issue of having the main too full.
Tuning guide was a broad range document. Tuning guides REALLY should be issued by each sailmaker. It's the best way to get up to speed with the particular cut/fabric/mold of the sails you're using.
Drew,
I agree and it is a very nice document to have, espcecially when you are just getting started with the boat.
I was just thinking out loud that perhaps since these are earlier gen Hyde sails that they may require more pre bend to de power than later gen hyde sails.
The guide is really a starting point and everyone needs to do their own testing to find out what works for their particular boat, crew, sails, etc.
Quote from: Peter Ruggiero on September 29, 2010, 12:29:06 PM
The guide is really a starting point and everyone needs to do their own testing to find out what works for their particular boat, crew, sails, etc.
What works reasonably well for me is the ol ass-elerometer. Full hike and not flat? Wind on the uppers, blocks out. Sitting upright and inboard? Wind off the uppers & blocks in.
I'm usually not slow upwind, relying on the ass-elerometer. Stupid is another story... :-O
Thought I'd update what we found. When we went to take the boat out yesterday for the race we found that the port lower was tighter than the starboard lower by a good amount. I'm guessing this played a role in the main inverting on us.
Quote from: Peter Ruggiero on October 02, 2010, 11:02:01 AM
Thought I'd update what we found. When we went to take the boat out yesterday for the race we found that the port lower was tighter than the starboard lower by a good amount. I'm guessing this played a role in the main inverting on us.
Time to do a quick check on your geometry. Measure the mast butt, side to side. Measure your chainplates stern to plate. Mast butt from stern.
Make sure you are keeping your masthead square....the old main halyard trick on this one.
You may not have exact same numbers on the Loos, port vs starboard and have the mast in column.
I'm not sure how the lowers are affecting inversion. Usually that is a case of overbend in the mast....maybe Tac will chime in. Lowers restrict mastbend.
You guys have the tuning guide...yes? Run through your setup against the guide and verify your positions.
What kind of nominal breeze is this happening in?
Drew,
Those are all things we will have to pay better attention to.
I may not of been clear early on, the inversion has only happened to us once, winds were ~15
When we took the boat out yesterday (wind ~6-8knts), we set it up better (per tuning guide) and the boat handled real well; fast and had neutral helm. We were racing phrf against J24's, S2's, etc.
Upwind we believe we were doing good, we seemed to be out pointing the other boats while at the same time having a slight speed advantage on them.
Downwind was a little different as we heated up to gain speed they were able to point ddw at the mark. This is something we will have to work on, finding the sweet spot for different wind conditions.
6-8 you'll find yourself sailing pretty deep. Probably in the 140-155 range, depending on sea state. You just don't get enough speed when you heat up to offset the extra distance.
Wish some others would pipe in here. I'd like to hear what else folks are doing.
Drew,
I think you're right, the boat does like to be heated up some but I don't think the serious extra distance is worth it. I'm going to try and get a boat speed vs TWA sheet together for different wind conditions and setups. I think it will really help out sailing the boat PHRF.
Pretty easy to do. Borrow a hand held anenomter...take a wind reading..direction and velocity.
Drop two buoys...dead upwind/downind from each other about 1/4 mile apart.
Sail upwind to the polars..about 5.8 in 9 TWS inhauled and main mostly centered. Check your angles off true wind direction. Make sure you sail approximately the same angle off TWD.
Sail downwind at 170 off TWD from top to bottom of course (1/4 mile marks) Clock your time for this..start to finish.
Do same for 160, then 150, then 140 then 120.
This will give you real data and is kind of fun.
Quote from: Peter Ruggiero on October 02, 2010, 03:23:58 PM
Drew,
I think you're right, the boat does like to be heated up some but I don't think the serious extra distance is worth it. I'm going to try and get a boat speed vs TWA sheet together for different wind conditions and setups. I think it will really help out sailing the boat PHRF.
I had a J80 sailor recommend getting weight to windward to heal the boat slightly to windward so the spinnaker would drift around slightly and allow the boat to sail a lower angle. I'm not sure this will work on our boats. Anyone else?
Quote from: Robert Bernard on October 02, 2010, 10:52:42 PM
I had a J80 sailor recommend getting weight to windward to heal the boat slightly to windward so the spinnaker would drift around slightly and allow the boat to sail a lower angle. I'm not sure this will work on our boats. Anyone else?
In my experience this completely puts the brakes on a Viper. The Kites could be cut with larger shoulders then we'd lose considerable 'heat' speed. The raked rudder on the Viper is unhappy with windward heal. The boat gets a nasty leehelm which is slow. I've tried every rig variation, sail variation and weight placement to remove the leehelm on weather heal...unsuccessfully. We always keep the boat healing and if it's light (under 6 knots TWS) we always drop the jib.
The Viper is shaped completely different from the J80. It has a really big butt and if you hear gurgling, that's bad. Get weight forward..INCLUDING the driver.
Drew,
This depends on the kite... A Hyde can't do it. A North, Q/Dieball can. Only in light, and be careful not to overdo it, but it can be devastating. One trick is to ease the pole in a couple of inches to allow a softer luff, like easing the tackline on some Assy boats...
Weight forward in the light stuff, ABSOLUTELY.
We have a well sailed boat on the West Coast with new Norths. We've eyed those pretty hard and they just aren't much different than the latest Gen Hyde. North's don't seem to soak any better than the Hydes, Doyles, Ullmans or Q's. I sail J120's which are the queens of rolling to weather and tossing that big-ole-luff to windward. Don't reach up worth a squat though. Luff's are ridiculously long which works well soaking.
On thing that does work well on a Viper is Wing and Wing. It's important to ease the pole in but it's loads of fun at the bottom mark to come in on starboard tack with the kite on starboard side...deep. Really gets some interesting conversations happening at the corners (lol) and the boat moves well and remains remarkably balanced.
Quote from: Dan Tucker on October 04, 2010, 10:23:12 AM
Drew,
This depends on the kite... A Hyde can't do it. A North, Q/Dieball can. Only in light, and be careful not to overdo it, but it can be devastating. One trick is to ease the pole in a couple of inches to allow a softer luff, like easing the tackline on some Assy boats...
Weight forward in the light stuff, ABSOLUTELY.
Quote from: Drew Harper on October 04, 2010, 11:47:10 AM
We have a well sailed boat on the West Coast with new Norths. We've eyed those pretty hard and they just aren't much different than the latest Gen Hyde. North's don't seem to soak any better than the Hydes, Doyles, Ullmans or Q's. I sail J120's which are the queens of rolling to weather and tossing that big-ole-luff to windward. Don't reach up worth a squat though. Luff's are ridiculously long which works well soaking.
On thing that does work well on a Viper is Wing and Wing. It's important to ease the pole in but it's loads of fun at the bottom mark to come in on starboard tack with the kite on starboard side...deep. Really gets some interesting conversations happening at the corners (lol) and the boat moves well and remains remarkably balanced.
Quote from: Dan Tucker on October 04, 2010, 10:23:12 AM
Drew,
This depends on the kite... A Hyde can't do it. A North, Q/Dieball can. Only in light, and be careful not to overdo it, but it can be devastating. One trick is to ease the pole in a couple of inches to allow a softer luff, like easing the tackline on some Assy boats...
Weight forward in the light stuff, ABSOLUTELY.
I wasn't going to mention that one! ;)
Oooooops [-)
Quote from: Robert Bernard on October 02, 2010, 10:52:42 PM
I had a J80 sailor recommend getting weight to windward to heal the boat slightly to windward so the spinnaker would drift around slightly and allow the boat to sail a lower angle. I'm not sure this will work on our boats. Anyone else?
Windward heel in the light is tricky to do, but in right conditions it can work. one reason is that reduces depth of keel. The tricky bit is keeping the main working.
Chute can certainly curve to windward in medium to light medium breeze. In super lighter stuff its just key to keep the flow moving so sheeting a bit harder for a flatter shape seems to work for me (or sometimes not)