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| The fastest points of sail for the islands http://www.hobie.com/au/en/forums/viewtopic.php?f=71&t=57205 |
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| Author: | vetgam [ Fri Mar 25, 2016 7:38 pm ] |
| Post subject: | The fastest points of sail for the islands |
I've always heard people say that the beam reach is our fastest point of sail. That's not what I'm finding. Although I haven't measured for sure my close haul feels faster. Anyone do the measurements? Below are my impressions. Anyone measure and know for sure? 1st in speed=close hauled 2nd=close reach 3rd= broad reach 4th= beam reach 5th= running Again, I'm going by feel not by measurement. Do others find a true beam reach slower than close hauled. Maybe I'm not trimming the main correctly, I'll have to pay more attention. |
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| Author: | tonystott [ Sat Mar 26, 2016 12:51 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
Greg, I also "feel" like close-hauled is faster, but this couod just be because apparent wind is at its strongest. I suspect the ultimate determinant is the sea state (direction and shape of the waves-does surfing down swells count? lol). I will also keen a closer watch on my GPS on future outings and try to get a definitive answer. Of course, relative speeds would need another look once a reacher is in the mix! 
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| Author: | vetgam [ Sat Mar 26, 2016 7:13 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
Thanks Tony. I bring this knowing the new sail could change things. I'm trying to determine which point of sail to choose if you are headed for your mark on a beam reach. Trying to determine should I tack using close reach or a broad reach on the longest point of sail? Should I just stay on the beam reach. With the regatta coming up soon, I an finding that I can't really plot my ideal course until I work this out using my boat with my rigging. Time for some GPS work. But I was curious on what others may have already worked out. |
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| Author: | chadbach [ Sat Mar 26, 2016 7:59 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
In order of fastest to slowest, for me it's: Broad reach - this is where I've reached my top speeds Close reach Beam reach Close haul Run It's interesting that you guys are faster close hauled. Tony, do you have an AI or TI? I wonder if the two boats have different fastest points of sail. |
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| Author: | tonystott [ Sat Mar 26, 2016 8:11 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
I had a real-life encounter with this dilemna... I was sailing my 25' yacht against a sister ship (in a 150 mile race), and I worked out that I could lay the mark (30 miles away!) by sailing closed hauled. My competitor decided that he could increase boat speed by laying off a few degrees, and putting in a small tack at the end. It was just after sunset when we arrived at our mark, and I recognised the stern light of my friend's yacht 25 yards in front of me! I suspect our Islands would benefit more by not pinching too high... Just a gut feeling. Chadbach, I suspect I have been conflating the issue by considering VMG (velocity made good) with SOG (speed over ground).. But it is a close call when sailing upwind in flat water. I will; have to take more notes. (My example above certainly showed that boat speed of my competitor was greater, as he covered more distance in the same time). |
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| Author: | vetgam [ Sat Mar 26, 2016 10:59 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
VMG is an interesting topic. I read where VMG to windward or downwind is more important to consider than VMG to mark. I've concluded that I would be best to focus on VMG to mark as I initiate each point of sail and just focus on making minor adjustments based on wind changes and not over shooting my laylines. Not sure how someone can measure VMG to windward with a GPS without making constant mark changes to the gps. Are there some sailing tools/tricks to make VMG to wind position? |
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| Author: | tonystott [ Sat Mar 26, 2016 11:37 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
Sorry, I have never got into the nitty-gritty, as most of my prior experience was pre-GPS. Taking sightings via hand bearing compass, and then going below to try and work things out on the chart just to confirm where we actually were, was quite enough science! VMG has always been something in my mind. Instead, I tended to work navigation in the big picture only, and instead concentrate on optimising boatspeed for the given conditions. I think there is a danger of overthinking it |
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| Author: | Chekika [ Sat Mar 26, 2016 11:59 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
vetgam wrote: VMG is an interesting topic. I read where VMG to windward or downwind is more important to consider than VMG to mark. I've concluded that I would be best to focus on VMG to mark as I initiate each point of sail and just focus on making minor adjustments based on wind changes and not over shooting my laylines. Not sure how someone can measure VMG to windward with a GPS without making constant mark changes to the gps. Are there some sailing tools/tricks to make VMG to wind position? You boys are confusing me. VMG is always towards a mark, waypoint. What do you mean by "VMG to windward?" Keith |
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| Author: | vetgam [ Sat Mar 26, 2016 4:06 pm ] |
| Post subject: | Re: The fastest points of sail for the islands |
Here's an article that discusses the difference. http://www.sailtimerapp.com/VMG.html I'm not seeing a whole lot of use for VMG to wind other than as a concept. It constantly changes so my point was that VMG to mark is all we can measure in practice. Even then, VMG to mark seems only to be useful as you set out on the beginning of any tack to determine the optimum course. Once you get close to the layline it becomes a moving target and meaningless. It all makes my head spin and hurt.  Next thing I'd like to get help with is how not to overshoot a layline other than by site. That's how I do it now but I have been known to overshoot it occasionally. I see that sailtimer makes a free app and I have downloaded it but yet to figure it out. I imagine if I took the time to learn how to use a compass I would have no trouble with this. Just too lazy. Compasses hurt my head too. |
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| Author: | Chekika [ Sat Mar 26, 2016 6:13 pm ] |
| Post subject: | Re: The fastest points of sail for the islands |
Frankly, Vetgam, I found that article totally worthless. Garbage. Here is what Wikipedia says about VMG. ==Concept== Boats cannot sail directly into the wind, requiring the sailor to alternate between headings, which are commonly called "tacks." On a sailing tack, the sailor will generally point the sailboat as close to the wind as possible while still keeping the winds blowing through the sails in a manner that provides aerodynamic lift to propel the boat. Then the sailor turns slightly away from the wind to create more forward wind pressure on the sails and better balance the boat, which allows it to move with greater speed, but less directly toward the mark. Determining the velocity made good (VMG) usually requires computation and instrumentation. For example, in a northerly (wind coming from the north) on a heading of 60 degrees NE, the speed of the boat is 5.0 knots. Falling off to 65 degrees NE accelerates the boat to 5.2 knots. Turning up into the wind to a heading of 55 degrees NE causes the boat speed to drop to 4.0 knots. These data indicate the trade-off between speed and progress toward the upwind mark (to the north in this case). Finding the heading that moves the boat most quickly towards the mark requires basic trigonometry. The northward component of the boat's velocity vector is found by multiplying the boat speed by the cosine of the angle between the true wind direction (north) and the sailboat's heading. cos(55) * 4.0 = 2.3 knots made north (VMG) cos(60) * 5.0 = 2.5 knots made north (VMG) cos(65) * 5.2 = 2.2 knots made north (VMG) In this case, the optimal VMG is obtained on a heading of 60 degrees off of the true wind (60 degrees NE or 300 degrees NW). Turning up into the wind (more towards the mark) makes less progress towards the mark because the boat slows down too much. Turning downwind speeds up the boat, but yields a course that leads too far away from the mark for the increased speed to be a benefit. ======== GPS units are small computers which can do the required calculations to determine your VMG independent of your tack. Because of the wind conditions, you can be on a tack which takes you away from your destination. In which case, your VMG will register a negative speed, say -1.1 knots. Your actual speed over the water may be 4.3 knots, but your VMG says you are going away from your destination--not much gain in that. The GPS is doing its job. VMG is a great tool for the average sailor trying to make progress to a windward destination. Keith |
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| Author: | hawk232 [ Sat Mar 26, 2016 7:51 pm ] |
| Post subject: | Re: The fastest points of sail for the islands |
I take my gps out everytime. fastest point of sail depends on the wind. in REALLY light air, close hauled is fastest due to increased apparent wind. in anything over about 10mph beam reach to broad reach are always faster. my best top speed was 12.8mph on a beam reach, I have been 10mph numerous times on a broad reach, fastest I have ever been (in those same winds) was 8.5 or so close hauled. it just feels fast due to the increased wind speed from the apparent wind as well as the splashing and spray from usually running into a sea vs with it. |
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| Author: | vetgam [ Sat Mar 26, 2016 8:24 pm ] |
| Post subject: | Re: The fastest points of sail for the islands |
Thank you for that post hawk232. That makes a lot of sense and as I recall sailing in winds of different strengths, I would agree with your findings. Never looked at it that way before. Replaced my dead GPS so now I need to test my boat with its rigging to see if this is the case for me. I wonder what other factors might come into play. Currents and tides probably make a difference too but unless I'm in a channel I can't imagine much. |
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| Author: | hawk232 [ Sun Mar 27, 2016 6:10 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
current and tides will obviously slow down your SOG (speed over ground) if you are going into the current, or speed you up if going down current. shouldn't affect you speed over water though (not that any of us measure that, we all use GPS with is SOG) |
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| Author: | tonystott [ Sun Mar 27, 2016 7:24 am ] |
| Post subject: | Re: The fastest points of sail for the islands |
Not forgetting of course, wave height and direction. When the waves are coming from other than dead ahead, one tack is going to be appreciably slower. (take two aspirin!) |
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