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All things related to sailing: tips, howto, pictures of sailing boats, sailors, pirates and all

Docking in Low Tide

Docking in Low Tide

I posted while ago on launching in low tides. The idea was close attention to sail trim. The common mistake is to over-sheet the main leaving the dock, and even with full centerboard you'll drift sideways into the Cal Adventures dock.

Here I want to talk about docking in low tide. 

There are several problems. One is recognizing that it's low tide. It's easy going out with a "fresh" boat (you push the centerboard/rudder down and feel the mud, so you bring it up a few inches). But coming back you have to recognize and plan it. My rule of thumb for Bahias is that a tide of under +2.0 means you have to raise the centerboard and/or rudder. Plan for it, and raise both on the way in. When it's all the way down, the centerboard is about a foot lower than the rudder fully down, so you can adjust the two differently.  In very low tides, the rudder will be just below the water, horizontal. It will work, but it will be very  hard to use, and hard to turn quickly. Also, the stress on the rudder when it's parallel to the water surface is in a direction it's not designed for. So it's best to limit the amount of time you sail with the rudder in that position.

You will find that the boat handles differently with the centerboard up (or raised above the normal, fully down position). An important thing in docking is that the pivot point of the boat is farther aft, which means that where the boat actually turns in the water will also be farther aft.

The dock approach will be different in low tides. You can't use the standard "come in on a beam reach and slow sail to the dock". Your leeway with the centerboard up will be too much. Even if you aim for the south end of the dock, you'll be lucky not to hit the sea-wall (painful personal lesson here).

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Recent Comments
Michael Sherrell
Alternate technique: Uncleat the rudder, keep your speed up, let the mud raise your centerboard, and plow through the mud! (Note J... Read More
Tuesday, 09 June 2015 11:20
John Bongiovanni
In a south wind, you'd be toast. Right into the seawall. The centerboard will still be dragging a bit in the mud, preventing you f... Read More
Tuesday, 09 June 2015 22:56
Michael Sherrell
That's probably true, but the idea would be to be on a line into the dock before you hit mud. A south wind would help drive you th... Read More
Friday, 26 June 2015 17:15
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Advanced Boat Handling - Another Great Advanced Dinghy Lesson

Advanced Boat Handling - Another Great Advanced Dinghy Lesson

The Advanced Dinghy lessons this year have been uniformly great.

This week's was no exception - boat handling by Jonas Kellner, a club member who's been sailing for over 30 years and teaching sailing and racing for almost as long.

Someone asked Jonas before the class whether he'd be teaching racing tactics. He said that he could, but knowing the best tactic for a given situation is useless if you can't execute the maneuver. He'd be focusing on the latter.

We had a pre-sail briefing, where Jonas explained what we'd be doing. 8 exercises around a set of buoys in a line perpendicular to the wind (so basically beam reach). The first and last exercises were slalom course, where we were to keep as tight to each buoy as we could.

The intermediate exercises were ovals around the set of buoys (counter-clockwise in all cases). They were technical exercises, designed to improve boat handling skills:

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Downwind sailing and the evils of rounding up

Downwind sailing and the evils of rounding up
One of the common pitfalls of sailing a dinghy downwind is that in a sudden gust, the boat will start to head up, leading to a capsize. In this blog post, I'd like to share some of my thoughts on the factors in play and how to best deal with them. This discussion applies to sailing with just main and jib, as well as to those thrill-seekers using a gennaker.
 
To begin with, why does your dinghy insist on heading up in a gust? There are (at least) two factors involved. To begin with, your dinghy typically has a bit of weather helm: to get technical, the center of effort (COE) on your sails lies slightly behind the center of lateral resistance (CLR) created by your dinghy's foils. In normal conditions, a bit of weather helm makes for a nice responsive tiller that helps you to better "feel" the boat and the wind. However, as the force on the sails increases as happens during a gust, the discrepancy between the COE and CLR is amplified, causing more and more weather helm. This effect will cause your boat to want to head up more strongly during a gust.
 
However, the natural weather helm caused by the discrepancy between COE and CLR isn't typically what will cause you problems. Instead, it is the additional weather helm caused by excessive heeling. Indeed, as the boat heels more, the hull's interaction with the water creates extra weather helm. Furthermore, your rudder is now only partially submerged, giving you less control over rounding up. And that is just the beginning: assuming that you are sailing below a beam reach, the more the boat rounds up, the more the heeling force on the sails increase. This causes more rounding up, which causes more heeling which causes... you can see that this will probably end with you getting wet.
 
Now that we know two of the main factors in play, let's consider three different scenarios.
  • First scenario: you're sailing on a dead run when a gust hits. The force of the wind on the main will indeed cause the boat to want to round up a bit. However, since you're on a run, it won't cause much heeling, so you only have the first aforementioned factor to deal with.
  • Second scenario: you're on a broad reach when a gust hits. Now you're in trouble -- you have both excessive weather helm coming from the force on the main, as well as weather helm caused by heeling. As you round up towards a beam reach, you can't depower the main, and you may end up capsizing.
  • Third scenario: you're on a beam reach when the gust hits. Again, both factors will apply, but as the boat rounds up above a beam, the main will start to depower, reducing heeling and weather helm and saving your bacon.
From the above analysis, we see that the danger of rounding up and capsizing is greatest when sailing close to a broad reach. But never fear: we have some powerful weapons at hand in combating the evil demon of weather helm.
 
First, we would like to be able to depower the main sail while sailing on a broad reach; this will decrease both natural weather helm and excessive heeling. Our first weapon for doing this is the vang or gnav. Easing this control in a gust lets the top portion of the sail twist away from the wind. While crewing for one of our club's most experienced dinghy sailors during the infamous Fast Track squall of May '12, my skipper had me blowing the gnav in every gust, and this is what let us limp back to the club in (more or less) once piece.
 
Our second weapon in depowering the main is of course the main sheet. If the wind is howling 20 knots and your Bahia is screaming along on a broad reach, chances are that your high boat speed is shifting the apparent wind far enough forwards that your main sheet should not be all the way out. The added bonus is that when the gust comes, you can now ease the sheet to help balance the boat and depower the main. If you instead neglected to sheet your mainsail in at all, you can't depower  by easing the main! 
 
Apart from depowering the main sail, the above analysis tells us that we want to do everything possible to keep the boat flat. Anticipating the gusts and aggressively falling off is key. Likewise, hard, aggressive hiking (or even sending crew out on the wire) are also important. Keep in mind, though, that if you are already hiking out hard before the gust hits, you won't be able to up the ante when you need to. Just as with the main sheet, it is highly advantageous to have a bit of room to make adjustment during gusts. Finally, aggressively sheeting in the jib (or gennaker) in gusts so that it stalls a bit will shift the COE forward in the boat, which will also decrease weather helm. Likewise, raking the centerboard aft slightly will shift CLR aft, also decreasing weather helm.
Recent Comments
John Bongiovanni
Great post, Nathan. One thing that I can't figure out is sheeting in the main on a broad reach. I guess the apparent wind has to ... Read More
Saturday, 09 May 2015 17:55
Nathan Ilten
John: Thanks! First of all, let's suppose that you've sheeted in the main "too far" so that the sail is stalling a bit. You are a... Read More
Saturday, 09 May 2015 22:41
John Bongiovanni
To reinforce something you mentioned but didn't highlight. I was out today with James C (great, wet experience), and he showed me... Read More
Saturday, 13 June 2015 20:37
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Advanced Dinghy Lessons Start with a Bang!

Philippe on the subject of sail trimming and especially use of the gnav (according to him, an under-used tool).

Philippe is an an incredible sailor and an amazing instructor.  We spent about half of the time on land with an RS Venture looking how the various sail controls affected sail shape and talking about what sail shape you want for what conditions (it was blowing over 15 kt. this evening, by the way, with pretty big seas - we  had a lot of weight on the boat on land to make sure it didn't capsize into the cars parked near the clubhouse). On land, it was much easier to see the effects of various controls on the sail shape.

This is my lesson summary (feel free to comment):

Scope: Dinghies which generally don't have travelers.

  1. Sail shape is very important. The usual things about depth and power, and location of sail draft. With lighter winds, you want a fuller sail and a draft a bit aft. With heavier winds, you want a tighter sail and a draft forward.
  2. In heavier seas, you want more power, even with stronger winds.
  3. Tensioning the Cunningham brings the draft forward.
  4. The outhall affects the lower third of the sail.
  5. Several controls bend the mast aft, which tighten the sail and move the draft forward. Tightening the mainsheet and the gnav do this.
  6. In high winds, you don't want the boom near the center of the boat, as the lift from the sail is mostly sideways to the boat. But just easing the mainsheet induces twist in the sail. Tightening the gnav overcomes this, allowing the mainsail to go to a better angle, but preserving the sail tightness.
  7. Bearing off from close-hauled, you want to do several things.  One is ease the mainsheet. Another is to keep weight on the windward side to help turn the boat downwind. A third is to ease the gnav (and then tighten it when on course).
  8. Gybe-ing:
    1. Blow the gnav before the gybe (this will depower the sail and cause the top of the sail to back-wind before the bottom of the sail, producing a gentler gybe).
    2. Weight the boat to windward to turn it down-wind through the wind. If you reach across to pull the boom across, you'll mess this up.
    3. If done correctly, the wind will gently pull the mainsail across. Grab the sheets as this happens to buffer it.
    4. Power up after the gybe by tightening the gnav

Then we went out and did it, both upwind and downwind. And it worked. I was prepared for hikiing really far out with the winds we had, but we didn't have to. And it was amazing how gentle the gybes were with this technique. Note that in bearing off and gbye-ing, you're doing what you would do rudder-less - moving weight to turn the boat. After the class, I discussed that with Philippe, and  his opinion (as a racer of some renown) is that the more you can use your weight to  maneuver the boat, the better (i.e. faster) you'll sail.

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Recent Comments
John Bongiovanni
I want to add a couple of things to this. One is that I talked with Philippe today and asked hiim if I got it all right. He said ... Read More
Wednesday, 22 April 2015 19:52
Francisco Kattan
Thanks to John and Philippe for the great writeup and lesson. I've got some new things to try, especially releasing the gnab du... Read More
Thursday, 23 April 2015 18:07
Christian
Great stuff. Thank for the post!
Thursday, 23 April 2015 18:56
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There be dragons here!

There be dragons here!

While you spoiled Californians may have been venturing out onto the water all winter long, most of us in Vancouver are just starting our sailing season -- we don't like frostbitten toes! This past Saturday, I had the pleasure of crewing on a Dragon in a one-design regatta. The Dragon is a "modern classic": designed in 1929 with extremely elegant lines, this 29 footer has been updated again and again to remain an exciting keelboat. She has a furling jib, a symmetric spinnaker which launches from a chute below deck (very similar to our Bahias), and really feels more like an incredibly large dinghy than a keelboat. Her RYA handicap puts her just a bit slower than a 470, so she would destroy one of our Bahias in a race.

This was my first time racing on a keelboat, and I don't know why I waited so long to do it! It was fascinating to see a keelboat set up for racing, in contrast to our Commanders which are set up for, well, pretty much the exact opposite of racing. Did somebody say "spinnaker practice?" I must have hoisted and doused the kite ten times, and I can't even count the number of times we gybed with it up. At the beginning of the day I was just concentrating on not wrapping the jib sheets around the spinnaker pole, but by the end of the day I was doing end for end gybes on the foredeck fairly smoothly. As they say, practice makes perfect. Even with my bumbling help, our Dragon "Rum 'n' Monkey" managed to place solidly in the middle of the fleet. I look forward to honing my skills throughout the summer; I think once our crew of three gets dialed in, we'll be unstoppable (or at least close to it).

If you ever get a chance to sail a Dragon, I recommend you take it -- they are pretty fun boats! But even more importantly, all you aspiring dinghy sailors should take any opportunity you can to crew during keelboat races. It's fun, and you'll learn a lot, including many things which will improve on your dinghy sailing. Fortunately, Friday evening racing at Berkeley Yacht Club has just started up for the season. If you show up at O-dock at the Berkeley marina around 5:30pm any Friday evening (dressed to sail and with a six-pack for after the races) chances are you'll get a crew spot on a boat. It's a chance too good to miss.

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Lester Gee
Dragons are gorgeous boats. Saw them racing during my brief stay in Seattle. Similar boat you can find here locally are the Colu... Read More
Thursday, 16 April 2015 08:34
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