Portsmouth Yardstick and which boat is faster?

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Portsmouth Yardstick and which boat is faster?

Postby seandwyer » Mon Jun 03, 2013 1:53 pm

I have begun to try my hand at a little racing and so far, things are, well, disappointing. But I expected that--at least at first. But here is what I am trying to decide--is my tardy arrival time at the finish due mostly to the nature of the DS or is it mostly my sailing skills? Unfortunately I sail in an area where there are no other Daysailers on the water, so I am generally up against a bunch of Sunfish. That said, as I look at those boats I feel their size and nature make them a quicker boat from the start, but just to make sure I checked the centerboard class of the Portsmouth Yardstick and the numbers not only confused me, but made me wonder if actually the DS is considered a faster boat than the Sunfish. If the DS has a D-PN of 98.5 and the Sunfish 99.6, would not the DS be considered the faster vessel? My impression is that the lower a boats number, the faster it is considered to be. I haven't factored in the wind handicap yet because that just makes things more confusing, but if someone knows an easy way to explain it that'd be great! So what do you guys think?
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Re: Portsmouth Yardstick and which boat is faster?

Postby K.C. Walker » Mon Jun 03, 2013 7:07 pm

It's my understanding of the Portsmouth rating that it is not, nor can it be precise. However, it does give a pretty good handicap guideline for each boat. There is no question that the sailor makes by far the biggest difference in boat speed. If there was such a thing as two identical DaySailer's and I was to sail against, let's say Mike Gillum. There is pretty much zero chance that I would be able to keep up with him. I think that a Portsmouth rating that differs by 5 is pretty insignificant. Meaning, if Mike had the slower boat, he'd still trounce me.

I view sailboat racing as a game of minimizing mistakes, and there are so many to make that it's sort of overwhelming. Each one adds up rather quickly if you're sailing against someone who makes few mistakes.

I'm not an experienced racer. When I do race, my strategy is to work on boat speed and handling and then pick the best sailor in the fleet to chase and try to learn something from them. Remember it's a game of skill. It's not like you'd expect, as a beginner, to go to a tennis club and be able to keep up with the regulars, no matter which racket you had.
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Re: Portsmouth Yardstick and which boat is faster?

Postby seandwyer » Tue Jun 04, 2013 12:28 am

K.C. Walker wrote:It's not like you'd expect, as a beginner, to go to a tennis club and be able to keep up with the regulars, no matter which racket you had.


That's a great analogy! And I sure don't have the best racket, or boat, and certainly don't have the skills. I guess what I am trying to figure out is...COULD there ever be a day when I can at least keep up with some of these Sunfish or will I always feel in the way? As it is, if the race involves two laps around marks, they want to start the next race before I'm finished with the first lap--which sort of makes a guy feel like he's mostly a nuisance. If there is hope of working towards not being in the way then I'll keep trying, but if not I might try to find more similar boats to race against and learn from.

All that taken into consideration, I still don't understand the Portsmouth Yardstick. I studied it a bit this evening and noticed the wind handicap has categories of 0-1, 2-3, 4, and 5-9. Is that supposed to be knots? I know I sound like a bone head. :?
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Re: Portsmouth Yardstick and which boat is faster?

Postby GreenLake » Tue Jun 04, 2013 2:43 am

I looked at those numbers once and they are for different wind speeds. I'm pretty sure they are not in knots, but possibly in the Beaufort scale. Check that one out - you can get translations into knots in many places. Very few people sail dinghies in Bft 9, so that really means "5 and higher".

The idea is that based on design, sail carrying ability and ballast (hiking or trapeze) some boats do better in higher winds while others do better in lower winds. If your sailing venue doesn't have a good mix, then using one of the specialized numbers will be slightly more fair.

Having the right boat for the conditions helps. I was in a winning boat on a night where unusually heavy winds allowed us to profit from being too heavy in a slightly undercanvassed boat. The guys in the fast boat had to dump excess power, which made them slow.

What K.C. said.

Sailboat racing, to quote somebody I read recently, is different in that there's no "sprint' at the end. Most of the time, instead of making a big push to secure the finish, you focus early on, on not giving away your chance at victory, what K.C. calls minimizing mistakes. You try to be early at the start (not over early, but not in the 2nd rank), early at the first mark, early at the second mark and so on. You do this by optimizing boat and boat handling, but also optimizing the tactical and strategic decisions that are based on the state of the wind or the presence of "traffic".

After dabbling in "fun" races with the DS and another boat for a few seasons (as well as crewing at times on bigger boats in slightly more formal races), I find these statements a rather accurate summary. In addition, because wind-shifts can separate a fleet dramatically, sailboat racing really forces boats to stick together - gambling on a wildly different course rarely pays off (unless you have some very reliable expectation of where wind will appear, for example, because you happen to understand an unfolding weather pattern, while your competition does not).

Now, there are some "mistakes" that you can learn to avoid that don't require big expenditures.

The cheap thing to do is to put telltales on all your sails - so you can see the state of the trim. What Arvel Gentry writes on the subject of telltales (and aerodynamics) is quite readable and illuminating. Or you can get a more basic "recipe" for sail trim and sailing to telltales in many places now. A wind indicator (windex) on top of your mast is most helpful in getting the basic relation of boat / sails / wind right, for fine control the telltales will let you know immediately whether your sails are working optimally.

On a DS hat has correct mast rake, you should have a balanced boat (not much weather helm, which means not fighting the boat's tendency to round up). Too much rudder is like a parking brake. Another parking brake is sitting so far back that the transom squats.
967
Fixing that might mean getting a tiller extension, if you don't have one already, otherwise it's free. I take it that you are hiking hard enough to keep the boat level.

Those are a few elementary things that affect straight line boat speed.

When it comes to tacking, there's a particular rate of turn that you'll find will preserve more of you boat speed. A really sharp turn will dump speed, a really shallow/gentle turn will have you use momentum for an extended period of going up wind. Experiment with an optimum - and read or learn about "roll tacking".

If you work on these, and your starts, you should be able to keep up with more of the other boats up to the first mark.

At some point, you would take critical stock of your hull and foils. If they are rough, scratched, banged up, they may need some TLC.

960

If you've practiced boat speed, you would learn to appreciate the difference even moderate improvements can make. Every winter season, you can do some project, like replacing a stock rudder with a better design:
945
or simply fair your CB and add some shape to it (several threads here).

The fastest boat on our lake doesn't always win. The local winds are tricky, and being in the right place at the right time isn't obvious. Sailors who figure out how to sail based on the wind and how to get around other boats better will often beat the "faster" boat. This effect is stronger in places with quirky winds and lots of traffic.

At some point, if you haven't already, you might want to make sure you have a decent set of sails. I think the sails that came with the boat may well have been several decades old. It was simply impossible to trim the jib w/o getting a flutter. If you are in this situation, spending a bit of money is advisable. If you race only occasionally and mainly for fun, sails will last longer than they will for serious racers, also longer if you don't race often in high winds.

I found that the trim for a decent set of sail was rather different than for my old sails, and had to unlearn some bad habits. So I would encourage you to make sure yours are at least adequate.
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Re: Portsmouth Yardstick and which boat is faster?

Postby seandwyer » Tue Jun 04, 2013 2:10 pm

Thanks Greenlake. All good points. My rudder and centerboard are both in rough shape, as is the bottom of my hull, as is my sailing abilities. I guess I will polish them all in methodical order. I'd still love to understand that chart though.

Thanks guys
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Re: Portsmouth Yardstick and which boat is faster?

Postby GreenLake » Tue Jun 04, 2013 3:57 pm

If your CB, rudder and hull are banged up, that's going to cost you a fraction of a knot in boatspeed - it's instructive to figure out how much difference a quarter of a knot makes in terms of boat lengths at the end of the course. Same for pointing angle. The CB for the DS is small-ish for the size, and any improvement there that results in more 'lift' is something that you can notice. Keep things in perspective. If you sail in a mixed fleet, your boat doesn't respond like for like with the other boats, even if you polished everything. But you want to be in a place that, if conditions favor you for the night, you can give a good showing.

About the Beaufort scale. Here's an excerpt up to force 9.
Attachments
beaufort0-9.jpg
Beaufort scale, up to force 9
beaufort0-9.jpg (66.18 KiB) Viewed 15601 times
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Re: Portsmouth Yardstick and which boat is faster?

Postby GreenLake » Tue Jun 04, 2013 4:09 pm

And here are the yardstick numbers

Code: Select all
Centerboard Classes    NAPY    D-PN    Wind HC For Handicap Range
                       Code             0-1      2-3      4      5-9
Day Sailer (O'Day 17)    DS    98.5    101.3     98.5    96.9    96.3
Sunfish (Int.)           SF    99.6    103.0    100.4    97.8    95.8


The way I'd read these tables is that of two boats with new sails and maintained to perfection, sailed by expert racers, the DS should sail away from the sunfish in all conditions except if the winds are above 19 knots (Beaufort 5-9).

If you (and crew) are lighter or heavier than a normal DS crew or, conversely your competitors don't have normal "race" weights for their class, then these numbers can be off in both directions - they are so close anyway that local knowledge and experience, conditions and/or traffic should make big(ger) differences.

But if you are simply inexperienced, the others will just seemingly inexplicably manage to sail away - the skill is subtle enough that it won't be obvious "how" you managed to lose ground. That's what makes it challenging.

If you keep this up for a few seasons, you'll notice definite improvements.
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Re: Portsmouth Yardstick and which boat is faster?

Postby seandwyer » Tue Jun 04, 2013 4:24 pm

Thanks--thanks very much Greenlake. This now puts everything in perspective--the things I can improve upon and the things I can just try to minimize. It's good to know that I have a chance at this and that the Sunfish should only be beating a DS in weather that no normal human could sail a Sunfish in :D
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Re: Portsmouth Yardstick and which boat is faster?

Postby Moose » Tue Jun 04, 2013 5:41 pm

How does the yardstick certification process work? do you just need to have a boat or do you need a class measurement certificate?
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Re: Portsmouth Yardstick and which boat is faster?

Postby GreenLake » Tue Jun 04, 2013 6:12 pm

I think for class boats, it assumes that your boat measures to class specifications. So you would have to have a measurement certificate from DSA. For the type of race that Sean is in, they may not even use corrected time, so in that case the yardstick is just approximate to tell you how much better you need to be as a sailor to make your boat compete with the other ones.

I've seen people round here beat boats that had a difference of ten in the yardstick number on uncorrected time. Not always, but often enough to keep the game interesting. There's also a bit of a culture of clever upgrades that aren't legal for the class, but generally not expensive and that tend to act as equalizers, like adding a discard spinnaker from some other class to boats that don't have one by class rules. In total "race what you brung" contests like that, adding something like the Doyle UPS to your boat (which will also be fun when cruising) might make things more fun. (Purists will shudder, but they don't have to sail where you do).
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Re: Portsmouth Yardstick and which boat is faster?

Postby GreenLake » Wed Jun 05, 2013 1:51 am

seandwyer wrote:Thanks--thanks very much Greenlake. This now puts everything in perspective--the things I can improve upon and the things I can just try to minimize. It's good to know that I have a chance at this and that the Sunfish should only be beating a DS in weather that no normal human could sail a Sunfish in :D


Yeah, I'd say, accept the competitive challenge and go for it!

I've only tried my hand at this for a few seasons, after being content just cruisin' and daysailin' around. The jump was bigger than I expected - just to get the hang out of maneuvering among a hundred boats (9' to 65'+) on a small lake. But even after I got the hang of the way things were organized, it took further effort to improve my game. I'm still relatively fresh in the learning experience - the only leg up that I had was a rather thorough knowledge of the lake. I must have picked up on things like typical wind patterns etc. even when I was just sailing around.

I was, in a way, surprised how much fun it can be to sail around a bunch of floating fluorescent rubber balls. More so, if it's in a crowd where being competitive for its own sake is frowned upon (that is, without it being a fun event, even if you don't win). So I hope I'm not inadvertently killing the fun you are having matching your skills, boat and wits against those nefarious sunfish sailors! (Pointing out the long list wasn't intended to intimidate - just pick whichever item you'd like to improve yourself or your boat off that list and give it a try. You might find you like fairing foils, or reading about and then trying out starting tactics. Whatever.)

Thanks for sharing your adventure and posting some good questions.
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Re: Portsmouth Yardstick and which boat is faster?

Postby K.C. Walker » Wed Jun 05, 2013 8:56 pm

So, the Portsmouth yardstick numbers are relative, in the centerboard section to the Thistle class, I believe. As I recall, the data is collected from participating yacht clubs. So it has to be a number of races with mixed fleets and people taking times and reporting them. It is a system fraught with error, but it does allow racing with mixed fleets on a somewhat more even basis.

The Thistle has a rating of 83. Phill Root, former DaySailer national champion, once posted that he often races Wednesday nights in mixed fleets and starts with Thistles sailed by national contenders. He said that even with his 19-year-old club sails he was rarely more than 50 yards behind after a half mile beat to the first mark. I believe he also said that one blown tack was more significant than the difference in the ratings between the two boats.

The difference between the ratings for the Sunfish and the DaySailer are insignificant. However it does not state whether or not the spinnaker is being used on the DaySailer, so I am going to guess that it is, because that's how it's raced. If you weren't using a spinnaker and the Sunfishs were using the North racing sail and had the new version foils they should easily have sailed away from you.

Now if you want to get serious about racing, it takes quite a commitment to win. It still takes a lot of commitment if you want to move from the end of the fleet to the middle. There's a lot you can work on to practice. If you can get good boat speed and handling it's a great foundation. You can do things like go out and practice tacking. Like, do 20 tacks in a row with five seconds between. Of course reading helps but getting out there and doing it is essential. I think taking lessons would speed up your progression tremendously. If you're a somewhat inexperienced sailor, this is the best way to learn good habits from the get-go.
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