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Thread: Interested in a boat for 2018 TransPac

  1. #581
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    May 2015
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    Redwood City
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    Quote Originally Posted by The Smokester View Post
    How do you calibrate your boat speed and wind speed? I am struggling with this, myself.
    Ah ... I don't ... And I do realize that it may not be accurate. In Santa Cruz I recall cross-checking with SOG on the VHF and it seemed mostly accurate. With tides it seems mostly impossible in the Bay. As for the wind I compared my experience with what would read on some of the anemometers in Santa Cruz and I was in the ball park. I'd love to hear other folks' approach in the Bay.

    Accurate or not it does help provide a reference for my own setup.
    P___/)___J
    Solo RTW

  2. #582
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    Sep 2007
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    There's a measured nautical mile in the Oakland Estuary that can be used to calibrate the speed, the markers are located in the Oakland estruary entrance channel, on the Alameda side (south side) up against what used to be the Naval air station. The markers themselves are two pairs of small triangles (yellow, I seem to recall) on posts set up as range markers with one triangle inverted and located above the other - when the two triangle tops line up you're on the line. You run east/west in the channel at a constant RPM and you can time the run then work out how fast you were going. Hopefully the markers are still in place.

    The difficulty with using the range is being there with no current and without a lot of other boat traffic.

    You could probably do well using a GPS and an area with no current - you need to keep the boat running in a straight line, that's where the estuary helps as it's straight there, just follow the armored shoreline.

    My instruments are the by-now quite old B&G Network and there's no facility for calibrating the wind speed. I know that it's off, I've learned to do the subtraction in my head to arrive at useful numbers. To compare boat performance polars to what the instruments are telling me I tweak the wind speed numbers slightly to fit the instruments. Though I don't look at the polars any more, after enough time on the boat you kind of learn when you're slow.

    My expectation is that most folks don't do a lot of dead reckoning, which is when you really do want an accurate compass, speed, and time. I used to do that before I got my first Loran receiver, and having all three working well was important. Today I just look at the GPS and it tells me how far I've come in what direction and even better it gives me the distance/bearing to where I want to go and then tells me how I'm doing.

    When racing by yourself in the ocean it is not so easy to tell how you're doing as you can't see any competitors to gauge performance against and there's not a lot of landmarks to get a feel for the boat's speed - the scale of everything changes enormously. That's when the instruments become important, at least in relative terms; having accurate numbers would be great, but consistent precise numbers will let you gauge relative performance as you change trim, course, sails, etc.

    - rob/beetle

  3. #583
    Join Date
    May 2015
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    Redwood City
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    D-72

    I don't have much to show for these past two days. I did some writing to help organize my thoughts.

    Here's a link to a draft "20 days before race start" plan: https://docs.google.com/spreadsheets...it?usp=sharing

    I'm sharing all this in the spirit to get feedback but also to encourage other participants to get organized in which ever way will work for them, and my stuff could give you a head start.

    I had the opportunity to speak with Jiri over the phone (who was first in Hanalei in 2016). The key take aways from our conversation were:

    1. Mostly he did not get out of the cabin at night. He would instead adjust course using the auto-pilot (even with the spinnaker up). I decided to buy a spare remote for the auto-pilot.
    2. He got a routing plan from Commander Weather but did not want to point as high as suggested. That seemed to have helped him big time as apparently folks to the North weren't as lucky with wind.

    When I hear him speak of speed of 20+ kts running before big swell with the spinnaker up in 40 kts of wind I realize I'm woefully under prepared when it comes to colored sails.

    I cut off a few feet of an old hose and sliced it up along its belly. That may come handy as chafe protection for sheets or anchoring.

    On to Round The Rocks next then ...
    P___/)___J
    Solo RTW

  4. #584
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    May 2015
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    Redwood City
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    Quote Originally Posted by tiger beetle View Post
    When racing by yourself in the ocean it is not so easy to tell how you're doing as you can't see any competitors to gauge performance against and there's not a lot of landmarks to get a feel for the boat's speed - the scale of everything changes enormously.
    - rob/beetle
    What I think I will struggle with most is sail plan vs heading decisions. Should I take it easy with the #2 poled out and full main up going straight to HI, or should I put a spinnaker up and go faster, hoping for nothing to go wrong ... Each sail plan change is likely to be tiring, if not downright risky. This is the part that baffles me most. Add to the mix that conditions are changing and it becomes a puzzle that I'm not sure I'll be mentally equipped to solve ... heck, I don't even think I can here, on land, rested.

    I've watched a few of Idefix' YouTube videos about his trip to HI and a few others while riding my bike indoor. A boat is small; being on this tiny white spot bobbing out there is an interesting thought.
    P___/)___J
    Solo RTW

  5. #585
    Join Date
    Sep 2007
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    520

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    Quote Originally Posted by The Smokester View Post
    Does anyone have a photo of their spinnaker net? I'm in the process of making one from webbing but sounds like there are some subtleties.
    Here's mine. Very simple, I threw it together in a hurry from the luff tape of an old jib and my old jacklines. A ring at each corner and lines at the tack and clew to tie them down.

    The foot is only about half of my J dimension, so it didn't get in the way of the pole during end-for-end jibes.
    If you go back to the photo thread in this forum, you can see the net in use - the photo with the black and white Spinnaker.

    As I recall, Synthia has a very clever means of clipping
    it down helically in a bag to keep it from tangling. But I found that if I flaked it carefully on the deck as it came down, it stayed tidy.

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  6. #586
    Join Date
    Jan 2013
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    Berkeley Marina
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    What are the decision parameters for using a net? All the time, even during a short run in a bay race, or only when the spinnaker will be up for hours/days?
    Or is it purely conditions-dependent, i.e. when winds exceed your spin-wrap likelihood threshold?

  7. #587
    Join Date
    Jan 2015
    Location
    San Francisco Bay
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    156

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    Quote Originally Posted by Critter View Post
    Here's mine. Very simple, I threw it together in a hurry from the luff tape of an old jib and my old jacklines. A ring at each corner and lines at the tack and clew to tie them down.

    The foot is only about half of my J dimension, so it didn't get in the way of the pole during end-for-end jibes.
    If you go back to the photo thread in this forum, you can see the net in use - the photo with the black and white Spinnaker.

    As I recall, Synthia has a very clever means of clipping
    it down helically in a bag to keep it from tangling. But I found that if I flaked it carefully on the deck as it came down, it stayed tidy...
    Thank you Max. One question: Is it important/necessary to have the luff attached to the headstay (as you would a jib)? I have roller reefing and don't see an easy way to do this. Or can I just put a lot of tension on between tack and head?

  8. #588
    Join Date
    Sep 2007
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    Capitola,CA
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    2,091

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    Quote Originally Posted by Lanikai View Post
    What are the decision parameters for using a net? All the time, even during a short run in a bay race, or only when the spinnaker will be up for hours/days?
    Or is it purely conditions-dependent, i.e. when winds exceed your spin-wrap likelihood threshold?
    Spinnys are more likely to wrap when windy, running downwind, using a symmetrical spinny, using a sock, jibeing, and at night. Spinnys are less likely to wrap when reaching, during the day, using an asymmetrical, and using an outgrabber.

    One parameter for using a net is how long it takes to rig and unrig, time you are likely at the bow. Rigging a net in daylight can take 15-20 minutes. One reason why nets are never used in closed course or SF Bay races.

    A big cause of spinnaker wraps is getting by-the-lee. This often happens when mistaking a spinnaker collapse for being too high (too close to the wind) and turning down. When in fact the spinnaker is collapsing because you are by-the-lee, and the spinny is blanketed by the main. Turning down even more causes the spinnaker to blow through the foretriangle, unless there is a net in place.

    Socked spinnys can wrap when the sock's weight begins a rotation around the headstay as the boat rolls.

    If there is a spinnaker wrap and no net, a possible remedy is to jibe. Sailing on the opposite jibe reverses the wrap rotation.

    A possible substitute for a spinnaker net is using a #3, or a #4 or storm jib on a long tack pennant. Even partially unrolling a furled jib will work, although a net needs to be higher, rather than lower in the foretriangle for best effect.
    Last edited by sleddog; 04-14-2018 at 10:44 AM.

  9. #589
    Join Date
    Jan 2015
    Location
    San Francisco Bay
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    Speaking of outgrabbers, my understanding is that their purpose is to pull the clew in closer to the boat thus depowering an asym. Are they recommended/essential?

  10. #590
    Join Date
    Sep 2007
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    Capitola,CA
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    Outgrabbers pull the spinny clew further outboard, thereby flattening and stabilizing the spinnaker. If one understands their function and use, they are recommended, but not essential. Outgrabbers also double as a preventer. http://honeynav.com/outgrabber-on-spinnaker-sheet/

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