Thursday, August 7, 2014

Software: NRace polar data issue (resolved)

This might trip others up so I thought I'd post it....

I haven't had much luck getting the farr design polar data into the Nexus race software.

Eventually I realised that the farr data for some of the downwind legs has different angles in the same column and this prevents the Nexus software from being able to deal with it.

I tried the minimal massage to keep some of the data (manual interpolating to fill in a bit, and deleting one of the columns) and it can now quantify TBS correctly. Still haven't had much luck driving the steer pilot though, that's next on my list of things to try and conquer.

Software: NMEAConnection v0.9

While away I got a chance to work on NMEAConnection. New features include:
- Finds tack and gybe points
- Generates data on these points - angle tacked, leeway, loss in boat lengths
- Has a spreadsheet
- Can draw histograms of data over sections of track
- Has a snazzy map courtesy or gmap.net
- Has a dialog box to connect to the boat
- Has a text log to help operate it outside the debugger
- Remembers core settings

On the horizon is the ability to enter meta data and a transition away from the original clunky window to something a bit sleeker. I've discovered its pretty easy to integrate C++ and managed C# so I can use winforms for the windows and integrate off the shelf applications like gmap.net, a big step forwards.





Gear: Wind Transducer Woes

Heading out on Monday to finally calibrate the wind transducer and log I was presented with a still propeller and system that told me there was no wind transducer.

Sinking feeling. Even more so when I started reading into the system and found I have the more expensive Nexus nRace model that would set me back a thousand dollars to replace.

Oh well, we calibrated the log then had a nice sail double handed. Upwind and down with a sprinkling of dolphins riding the bow and cavorting in deep blue waters. At no point did the prop consider moving.

On my return I started looking into it. Part of me wondered if an electrical fault could stop the prop like that, or if an electrical strike might have damaged it.

Looking at the server two LED lights were on under the wind connections and voltages were all pretty much zero, according to the manual this indicates a connection issue.

Climbing the mast I pushed the propeller around with a boat pole (it's a bit too high for me to safely get to with my climbing setup) but it didn't want too turn. I then pulled up the hose and sprayed it with water. Just as I was about to give up and look into removing the unit from the mast top for further maintenance it started turning and a minute of spray later was running freely.

Returning to a more sensible level I turned on the instruments with some trepidation and to my relief once again have readings!

Would probably be good for garmin / Nexus to update their manual to say the LED's and a stuck propeller could just mean go clean stuff.




The two lower lights were stuck on.

Thursday, July 17, 2014

Video:Other people having fun!

Not sailing Kraken this month, leaves me watching you tubes of others having fun.

This video was on Sailing anarchy and caught my eye, not sure I'd want to do this for 5 days but a few hours here and there would be awesome!

 

Saturday, June 28, 2014

Technique: Tacking

Tacking, on Kraken.

We have better tacking days and worse. In general they are getting better and better. We've tried a few ways of doing this but what follows seems to be the procedure that's working.

Tacking is a teamsport, and getting it right can make all the difference in upcoming crosses with our competitors.


  • Prep
    • As soon as we've tacked we get ready to tack again, the lazy sheet on the winch with no slack to the sail, the working sheet belayed ready to run free.
    • Ideally the helm gives some warning - "Tacking in five boat lengths", though this is not always posible
    • Helm: call "ready to tack". Everyone responds "Ready" of course... if not clearly call "NOT ready and give a time estimate, "NOT ready, need 30 seconds". Timing of tacks is normally critical happening either in response to the wind, or a tactical decision based on the fleet positions
    • Main: Secures the lazy traveller to prevent the main running across the boat
    • Trimmers: Makes sure enough wraps are on the new winch with the handle in place
    • Trimmers: Make sure the new jib lead is in the power position (#7 with our secondary #1 sail, #5 with our 3Di #1).
    • Helm: call "Helms a lee"
  • Tacking
    • Main: Release the backstay
    • Main: as the boat starts turning the main trimmer goes to the low side and releases the working jib sheet as the headsail luffs. This makes sure there is space for the trimmers and tailer who otherwise often pin the main trimmer highside.
    • Tailer: Start aggresively tailing, watching the clew position, when it reaches "just the right place" [which for a #1 headsail is around the shrouds on the new side and before the sail starts to fill] the tailer launches themselves to the new high side taking the line with them and continues applying pressure from the high side. If timed correctly this pulls the sail inside the lifelines and leaves it in about the power position. Thinking about it we should mark the lines so this is can be done consistently.
    • Grinder: Grind the drum as fast as possible, this makes sure overrides spin out and means there is no pause between tailing and trimming.
    • Bow: Skirt
    • Main: Bring the traveller up to the new side. Wait until the sail fills and then let a little sheet out (unless in strong winds) as the helm drives down to meet the headsail's power position. Use the fine tune to let this sheet out.
    • Helm: Drive down a little (sail to the headsail in it's power position)
    • Grinder: The grinder becomes the trimmer. We're looking for the head of the sail to be about a hands width outside the top spreader for the initial power position. 
  • Recovery
    • Trimmer: As speed builds (>5 knots) starts letting the jib lead come back to the pointing position, about #3 for the crappy headsail, perhaps #1 for the good sail. At the same time trim in further until the base is close to the shrouds and the top of the sail just about touching the shrouds. In low winds the tailer can manage the jib lead while the trimmer trims in the headsail to its final pointing position.
    • Helm: Bring the boat up as the headsail changes to its pointing positions
    • Main: Bring the fine tune in to close the leech and drive the boat up.
    • Main: As speed builds pull the backstay back on

The backbone of a good tack here is - start with full wraps on the winch and the handle in. Spin that handle and the grinder goes straight into trim mode.

Modifications
  • Light winds
    • Roll tacking, pit forwards shifts weight low at the start of the turn to help the boat around, swaps back to the original side (now the low side) as the sails fill and shift back high side to bring the boat back upwards.
    • Leave the sails a bit deeper, leave the jib lead forwards closer to the power position
  • Really light winds - just trying to get the boat moving.
    • Perhaps flatten the sails again
    • Take up another sport
  • Strong winds
    • Go straight to pointing trim rather than fighting the under powered jib lead (we're going to beef these up a bit but likely still a bit underpowered). Not roll tacking, weight goes highside and hikes as hard as possible
  • Waves
    • Trim: Leave a bit more twist in the main sails, don't sheet in quite so hard.
    • Helm: Time the tack so the next wave helps pull the bow down on the new side
  • Single handed
    • With autopilot:
      • Lock main traveller, get both jib sheets in hand
      • Trigger tack on AP (-1&-10 or +1&+10).
      • Sheet like mad to power position
      • Trim main quickly
      • Adjust AP to get sails pulling
      • Start fine tuning
      • Get back on helm and sail to the wind
    • Without autopilot
      • Same as above but using the wheel lock and stopping the tack from in front of the wheel

Wednesday, June 25, 2014

Technique: Don't luff all your telltales.... perhaps even stall a few

Our practice / casual race #1 sail has seen better days.

It's leech hooks horribly, even after some basic surgery.

It won't point.

It's teaching me how to sail upwind better, I think....

Traditionally you are taught to get all your tell tales to lift at the same time. Doing that with this sail leaves the foot loose, and sailing to the lower tell tales left us tacking through about 100 degrees.

So.... Forget the "all telltales luff at once" approach. I'm going to thank the North U trim book here, which honestly I need to thank on many many levels as it's generally awesome. Trim the foot in so the bottom telltale is bordering on stalling while the top tell tales are on the verge of luffing.

Having tried this, once, in light air, I can testify that we managed to point pretty well, better than we could before.

My guess is also that the twist this adds to the sail works two fold, firstly it allows the bottom to point higher as its sheeted tighter and secondly as the boat pitches it means there's some part of the sail that still works.

Three boats out in our class tonight. Two short WL legs in a dying breeze. Led through first WL then lost it on the second upwind. Came out deep from our first tack and then had to duck Shamen, if we hadn't messed up the first tack I think we'd have pretty much laid the mark in the persistent shift we were seeing, and won, but oh well.

I need to practice helming tacks, again, and again, and again....

This may or may not provide a link to the track.

Our baggy #1 has gone from a 8 -> 4 jib lead position. Our good #1 was sheeted at 5 before, what will it be now?

Going further with this....

The deep "all tell tales lift at the same time" is good for acceleration. So good off the line and good coming out of a tack, then bring leads back and sheet in at the same time to move to pointing mode.

Tuesday, June 24, 2014

Technique: Gybing - End for End

We spent some time with dip pole gybes but never got comfortable. We got a few to work pretty well but there were always snags, the new guy going into the jaw the wrong way, the pole getting caught up on the lazy sheet, the pole pulling the sail down as it was dipped etc and really it never got as quick as I know it can be done.

So we returned to end for end gybes and things got fast immediately. Kraken has a Carbon Fibre pole, which is pretty light but it still gets unwieldy at times, so we're probably about as big a boat as you can manage the end for end on. Luckily for us winds in Oceanside in particular, but also San Diego tend to be on the lighter side which I think helps.

End for end also seems easier to accomplish single handing.

The succinct(?) explanation is:

  • We turn the sail around the forestay and the boat through the wind at the same time keeping turning all the way to the new course. As the boat is passing dead down wind the sail should be past the front of the boat, will roll from one side to the other and the main is gybed. At the same time we release the pole, relying on the back of the boat to keep the sail flying as the boat continues to turn to its new course. Once the pole is set we switch control sheets / guys to the new side and high five as our competition sighs in appreciation of the awesomeness they just saw, though honestly they won't even know we've gybed until they hear the calls of starboard and have to luff horrendously rounding up in the procedure. Suckers!

More detail:

  • Preparation:
    • Helm: "Prepare to jibe!!"
    • Pit: Make sure foredeck is in agreement
    • Foredeck: We bring the lazy guy on the new side to the mast, ready to put in the jaws. [With one person, get it done. With two people, one is ready to snap in the new guy and one controls releasing the pole from the old guy at the right moment. With three the third person helps as needed, helping keep the sail flying as a human pole or communicating status back to the back of the boat and keeping an eye on things if hands are not needed.]
    • Helm: Call the start of the turn "Jibe Ho"
    • Everyone else: Critique as needed, the back of the boat is most likely to mess up the gybe so build some evidence to the contrary.
  • Initial Turn to DDW [Dead Down Wind]  - 10 seconds:
    • Foredeck: We bring the pole down to a height that is as high as possible while allowing the us to get the pole back on the mast. On Kraken the pole flies a couple of feet higher than you can reach comfortably. As the pole comes down the sail is less efficient and we are starting our turn.
    • Pit: Slack on the uphaul as needed for pole drop, in unison with foredeck, extra slack as needed for pole disconnect. Assist trimmers, make sure sheets are in place for new course.
    • Trim: The sail is rotated around to a deep configuration, pole back, sheet forwards. The sheet should be within a couple of feet of the forestay.
    • Helm: As the sail rotates we rotate the boat under it.
    • Main: Assist trimmers, making sure sheets are ready for new side
  • The Switchover- 10 seconds:
    • Foredeck: As the boat passes dead down wind we trip the pole, to allow the foredeck crew to work pit has given them some extra uphaul and down haul / foreguy slack. The sail will lean from one side of the boat to the other as the wind changes sides and this is the time to release the pole.
    • Foredeck: Communicate with the back of the boat
    • Pit: Communicate forwards and backwards. Call the trip when you see the sail rotate.
    • Trim: Keep the sail rotating to its new side, don't over trim, make sure it is around the forestay before we go DDW and communicate with the helm if we are turning to fast or can turn faster. Keep the sail flying and don't oversheet and flatten it against the side of the boat!
    • Helm: We don't stop rotating the boat but keep going through downwind to our course on the new gybe. Make sure we turn with the sail.
    • Main: Pull main over to new side, catch it as it goes to take a little shock out of  the gybe
  • The CleanUp - 20 seconds:
    • Foredeck: Attaches the lazy sheet in the jaw that came off the mast and pushes the pole out and forwards (about 45 degrees from the bow) in order to reattach the new base of the pole to the mast.
    • Foredeck: Gets pole back up to correct height
    • Pit: Pole back up to correct height, downhaul and uphaul nice and snug. Assist with trim
    • Trim: Switch control from old sheet to new guy (new guy in, then release old sheet).
    • Trim: Switch control from old guy too new sheet (new sheet in, the release old guy).
    • Main: Assist with trim as needed
    • Helm: Concentrate on new course, work with Trim to keep the sail flying

When single handing:

  • Use the autopilot!
  • Rotate the sail and turn deep but not DDW (say 160 to 170 depending on track AP can run and shiftyness of wind).
  • Gybe the boat and the main to new side. Sail deep again to keep the sail in front of the boat, but not so deep that epxected windshifts or autopilot wander will lead the boat below 170 true.
  • Slack the uphaul and downhaul and go forward to move the pole over (bring pole down, put to new side, take back up, take uphaul forwards to snug it)
  • Return to the cockpit, make sure I'm happy with the up / downhaul and adjust sheets
  • Get to proper new course according to polars.
When done correctly this takes about three minutes at the moment, so I'm not gybing on minor shifts but I often make mistakes and it can take up to 10 minutes to properly settle on the new course. Practice....