Pointing Ability - SailNet Community
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post #1 of 7 Old 04-23-2005 Thread Starter
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Pointing Ability

I would be most interested in hearing how others test pointing ability when testing out a new boat.

My very untechnical way has been to determine the true wind direction when stopped and then with the sails sheeted find the highest speed on a close haul and compair the heading.

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Ken
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post #2 of 7 Old 04-24-2005
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Pointing Ability

I haven''t found a very reliable way to quickly test pointing ability on a boat that I have not sailed enough to know how to dial in (by which I mean optimize sail trim and steering for the conditions).If the boat is instrumented with a compass, masthead fly and knotmeter, it is a little easier. The difficulty in getting to an accrate assessment has never stopped me from trying.

When I want to evaluate pointing ability on a strange boat, I typically spend time getting to know the boat and figuring out how to get the boat dialed in on one tack by experimenting with sheet leads and tension, watching the knotmeter and masthead fly, looking at the position of the jib relative to the lower shrouds and at spreaders, and tracking the general relative wind direction on the compass. Over time I begin to get a general sense of the proper set up to optimize pointing ability on that tack. I do this again on the other tacks because many boats are assymetrical in performance or instrment readings, and because sailing conditions such as current may effect the settings on one tack versus the other. Once I feel like I have an understanding of the settings that optimize the pointing for the given conditions I sail on a tack until dialed in to maximize VMG, then tack and sail on that tack until dialed in, and then go back again, over and over again. With each tack I record the sailing heading from the compass until I have a sense of the relative compass courses between tacks.

Of course that is only a part of the story. Being able tack through some given compass angle is a big piece of the puzzle but so is leeway. many boats can be pinched and achieve reasonable speed and narrow tacking angles but are making so much leeway that the VMG achieved is slower than pointing a few degrees lower would achieve. I check leeway in a number of ways. The quickest is to simply back sight your own wake. If you are steering a straight course, you can usually see the angle of the wake relative boat. This is not a particularly accurate indicator since wind driven surface current can come into play here, but if you get into the habit of back sighting your wake on a regular basis, you develop a sense of what larger and smaller amounts of leeway look like.

Another way to evaluate leeway to sail up to another boat from astern (Far enough back to avoid their dirty air). By sighting over that boat to an object on the horizon you can get a relative sense of that boat''s leeway relative to your leeway. Again, the problem is calibrating what you see, and again, if you get in the habit of doing this on a regular basis with a boat that you are familiar with, you begin to end up with a kind of mental database of how different boats behave in terms of tacking angles and leeway.

Of course the best way to see how well a boat points is on the race course. There you typically have crews and skippers who have a reasonable understanding how to dial in their boats and they are sailing in a pretty confined area so that you can watch trends over the course of the windward leg.

Jeff
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post #3 of 7 Old 04-26-2005 Thread Starter
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Pointing Ability

Unfortunately, during a "sea trial" there are so many things to test out, that one really doesn''t have time to get into the detail your describing, Jeff. Would be interested in how you went about the sea trials when you were shopping and finally found the Farr 38 (as I recall).

Yours,

Ken
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post #4 of 7 Old 04-27-2005
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Pointing Ability

My advise on developing an understanding of a boat''s pointing capabilities was specifically aimed at developing a more detailed understanding of the pointing ability of a particular boat than one would necessarily expect to do at a sea trial. I had interpreted the question to be an owner of a new boat learning about the boat rather than during a sea trial. I agree with you that there is rarely adequate time during a sea trial to come to detailed conclusions about the pointing ability of a boat. That said, with a boat that is unusual in some way, it is not unreasonable to expect to spend the necessary time experimenting enough to get a general sense of the sailing ability of the boat.

My last boat purchase was a case of not following my own advice. In the case of the Farr 38 that I ended up buying, I had researched Farr 38''s sailing ability pretty extensively, and had sailed a sistership, and so had a reasonably accurate sense of their sailing ability. As things worked out I never did a sea trial on the boat that I eneded up buying(the boat was sitting in a field at a private residence in Maine unrigged and somewhat taken apart.) We did escrow funds to cover the condition of the engine, transmission, and electronics all of which turned out to be in good shape. There were a number of minor issues that came up once I had sailed the boat in terms of deck hardware in need of replacement but that was certainly within the rhelm of what I expected for a boat of the type, age and price range.

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post #5 of 7 Old 06-05-2012
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Re: Pointing Ability

With GPS you should be abe torun acourse and see the actual track made good over the bottom. This is far more accurate than trying to estimate VMG by looking at masthead flies, compass headings and so on. It is very easy to be optimistic when feeling the wind in your face, but the GPS (usually) tells you the truth. (Bob Dylan song)

Another technique I used, long before GPS was to sail to windward in a relatively narrow channel (the Oakland Estuary) and carefully plot the location of each tack by some identifiable landmarks on the shores. The plot of your course will give you an accurate measure of your real pointing ability. Do this Or the GPS method on open water numerous times with different sail sets and trims, wind and sea conditions, and so on.

Yeah, it will take a lifetime ... you got something better to do?
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post #6 of 7 Old 06-09-2012
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Re: Pointing Ability

Modern GPS with a VMG to windward function. Slowly bring the boat from jib reaching up until the vmg starts to fall. That's your fastest upwind angle, regardless of pointing ability. A lot of boats can claw upwind tighter than this at reasonable speed.

A lot of people worry more about point than speed made good, but that is the slow way to get anywhere.

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post #7 of 7 Old 06-09-2012
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Re: Pointing Ability

The minor exception I take to Jeff's statements in no way detract from my overall agreement with his points.

If you have a chartplotter you can off set up a databar to show heading and course over ground (COG). This can be illuminating. Setting a waypoint and watching VMG can be similarly helpful. Without a chartplotter a handheld GPS or even most smartphones can provide a lot of useful data when coupled with a compass.

With regard to sea trials, a sea trial takes however long it takes. In two major boat purchases of my own and several I have participated in a pretty detailed sea trial test plan was submitted as part of the offer and was accepted. Auspicious took two days; my previous boat one long day. I had polars from Frers for Auspicious so I just checked a few points. It doesn't hurt to be a naval architect... *grin*

sail fast and eat well, dave
S/V Auspicious
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beware "cut and paste" sailors.


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