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Tjarnold
Deckhand

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USA
24 Posts

Initially Posted - 06/18/2012 : 15:01:09

We have around a dozen C25's in our club. Most are std rigs with a mix of all three keel configs. We have two tall rig boats,one with a wing and one with a swing keel. We use the Portsmouth rating system for our club races. The system rates all the std rig boats the same regardless of keel configuration. The tall rig swing rates lower(faster) as you would expect. What is strange is that the tall rig wing rates higher (slower) than the std rig boats. This is very inconsistent with performance on the water. Has anyone dealt with thisq, and if so how?

Tom Arnold
1983 C25 SR/SK #3476 "Got Rum?"
1987 Hylas 44-21 "Farhaven"

Edited by - on

Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 06/19/2012 : 13:33:14

At the lake where I used to race my C25 TR/FK, we used Portsmouth ratings, and I don't recall specifically whether we had a TR/WK racing there, but we had every other C25 rig and keel configuration, and, although the wing can't point with the fin keel, I can't imagine how it could be rated slower than even standard rig boats in moderate winds.

But, as I recall, Portsmouth ratings take wind speed into account, and as the wind speed increases, there is a point where tall rigs do in fact become slower than standard rigs. That is because they have more sail area and their tall mast gives them more weight aloft, and that means they must reef earlier than standard rig boats. At that point, their tall mast becomes a disadvantage in relation to a standard rig boat that has less weight and windage aloft but the identical hull shape.

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 06/20/2012 : 04:01:03

Good answer Steve, I was pondering the benefits of the tall rig while looking at one's transome - through binoculars - during our last race.

Under PHRF-LO we rate 3 sec/mile slower than the TR, IIRC. No idea how Portsmouth works.

Edited by - on

NautiC25
Admiral

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USA
957 Posts

Response Posted - 06/20/2012 : 04:44:40

I've been trying to research the differences in the WK/FK's. All the opinions here say that the fin and swing point much higher than the wing, but phrf doesn't show that difference (or have a WK label at all). Does the wing make up the difference on the downwind?

Edited by - NautiC25 on 06/20/2012 04:46:03

Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 06/20/2012 : 06:26:13

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by NautiC25
 I've been trying to research the differences in the WK/FK's. All the opinions here say that the fin and swing point much higher than the wing, but phrf doesn't show that difference (or have a WK label at all). Does the wing make up the difference on the downwind?
<hr height="1" noshade id="quote"></blockquote id="quote">IMO, the wing keel is not as efficient as the fin or swing keel on any point of sail. The wing keel was originally devised as a rule beater, not because it was, in every respect, a more efficient keel design. But, designers quickly realized that, although it isn't the most efficient keel, it works well generally, and it has the added benefit that it permits a shallow draft without requiring all the machinery and frailties of a swing keel, so, it became popular for cruising.

We can't get inside the minds of the PHRF rule makers, but I'll bet they decided that Catalina offers so many optional keels and rigs with their various boat sizes that PHRF didn't want to try to provide different ratings for all the variations, so they lumped them together in broad categories and decided that was sufficient. In reality, anyone who was a serious racer would probably choose to buy a fin or swing keel, and people who bought a wing keel boat were probably casual racers. PHRF probably concluded, rightly or wrongly, that most owners of wing keels, not being serious racers, probably wouldn't particularly care. Racing ratings aren't intended to create perfect parity among different boats. On any given day, in the hands of any given sailor, any of the keel designs can probably be reasonably competitive.

I'm not defending Phrf. I'm just trying to understand and explain their likely thinking.

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 06/20/2012 : 09:33:12

What Steve said... AND with enough data behind it, the PHRF ratings should self-correct anyways. Since we are sailing these boats with 30 years of data behind the ratings, the ratings should by now show a really good sample of how well your boat ought to do.

The trouble is that PHRF keeps tweaking its mathematical model to try to reduce error, and that resets the clock on how well we are represented. The math behind PHRF tends to make people angry though.

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9089 Posts

Response Posted - 06/20/2012 : 20:59:21

US Sailing lists 10 configuration combinations for the C-25 (including inboards) in their [url="http://offshore.ussailing.org/Assets/Offshore/PHRF/High+Low+Mean+PHRF+Handicaps.pdf"]national PHRF listing[/url]. Note that the WK generally rates slower (higher) for both masts. You can also see some variation in the variations (low-high-average) between the configurations, suggesting local organizations see these things differently. For example, some committees consider the TR/SK to be 6 seconds faster than the TR/WK, but the national average does not.

I would expect the wing to be faster downwind--less drag than the fin or swing, but less lift upwind. Do they cancel out?? The jury's out.

Edited by - on

NautiC25
Admiral

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USA
957 Posts

Response Posted - 06/21/2012 : 04:45:40

Edited by - on

Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 06/21/2012 : 06:44:11

IMO, the problem with wing keels is that they are not used, on production boats, in the manner that they were originally intended. The America's Cup 12 meter design parameters essentially limited the depth of a boat's keel. The original intent of a wing keel was to increase the amount of lift created by the keel, when the boat was heeled, so that the keel produced more lift than a fin keel of equal depth. Theoretically, that would improve the boat's performance to windward. But, designers of production boats adapted the theory of a wing keel, and used it to reduce the draft of their boats. In doing so, they transformed wing keels into stubby, shoal-draft things, which generate less lift than fin keels of equal depth. Thus, even though, in theory, wing keels have greater lift than fin keels of equal depth, in practice, they have less lift than fin keels, because of the fact that, on production boats, they are made much shorter, in order to achieve shoal draft.

Thus, because they are shorter than a fin keel, they can't generate the lift of a fin keel that typically has deeper draft, and are slower sailing to windward, and, because they have more wetted surface than a fin keel, for their size, they tend to be slower off the wind.

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9089 Posts

Response Posted - 06/21/2012 : 07:04:06

For boats as old as the C-25, I suspect the relative ratings from 2008 are valid in 2012--they've had a lot of time to accumulate data. Winds and racecourses are going to create their own variations. Tall rigs want lighter air (not accounted for in PHRF), and wing keels probably want windward-leeward courses over triangles, so they can sail dead-downwind. Wings might also suffer a little in choppy seas, with turbulence around the keel... (But they go nicely on a trailer!)

Edited by - on

Stinkpotter
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Djibouti
9089 Posts

Response Posted - 06/21/2012 : 07:18:54

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 ...and, because they [wings] have more wetted surface than a fin keel, for their size, they tend to be slower off the wind.<hr height="1" noshade id="quote"></blockquote id="quote">I recall Jim Baumgart in his SR/FK could hold his own against Gary Norgan's TR/WK to windward, but was eaten up by it downwind. They sailed together a number of times--once with me aboard Jim's boat. Too bad they didn't both have the same mast.

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awetmore
Master Marine Consultant

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USA
1144 Posts

Response Posted - 06/21/2012 : 10:09:21

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 US Sailing lists 10 configuration combinations for the C-25 (including inboards) in their [url="http://offshore.ussailing.org/Assets/Offshore/PHRF/High+Low+Mean+PHRF+Handicaps.pdf"]national PHRF listing[/url].
<hr height="1" noshade id="quote"></blockquote id="quote">

Why does the TM FK IB do such much better than the TM FK? I would expect the reverse, the IB should add some drag under sail that the outboard boat doesn't have.

On the standard mast they don't list such a large difference, so I have to assume that this is a mistake or that the boat tested with the inboard had some other helpful features (a very well faired bottom, a larger headsail, or something else).

I've been doing the casual races on Lake Union every week (Duck Dodge, http://duckdodge.org) and the ratings seem pretty fair otherwise based on my limited experience. My C-25 TM FK seems pretty well matched to the Erickson 25+ and O'Day 25 that we see often. We've passed a San Juan 28 on downwind runs (neither flying a kite), but can't point quite as well as them upwind. Some weeks we do better than a Cal 2-27, some weeks they do better than us. In the lighter winds that we normally race in the tall mast does seem to do better than the standard (there are often two standard rig C-25s at Duck Dodge along with our tall, none of us have spinnakers). Of course Duck Dodge isn't very serious so I can't always tell which boats are trying hard and which ones aren't.

We're in the background of this photo passing (slowly) a Cal 2-27 on a upwind run:
http://janpix.smugmug.com/Boats/Duck-Dodge-Pirate-Night-2012/23542856_3MCVmZ#!i=1903973158&k=3Gf8gh4&lb=1&s=XL

This is the photo from my boat maybe a minute later:
http://alexandchristine.smugmug.com/Sailing/Duck-Dodge-2012/23397725_jKtRXf#!i=1903618943&k=rX5TrRb

They did quite a bit better than us this week though (in somewhat lighter winds).

Duck Dodge is a lot of fun and pretty choatic with 50+ sailboats on a small lake, some of them very fast and some of them like ours.

Edited by - awetmore on 06/21/2012 10:24:58

Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 06/21/2012 : 11:33:14

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by awetmore
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 US Sailing lists 10 configuration combinations for the C-25 (including inboards) in their [url="http://offshore.ussailing.org/Assets/Offshore/PHRF/High+Low+Mean+PHRF+Handicaps.pdf"]national PHRF listing[/url].
<hr height="1" noshade id="quote"></blockquote id="quote">

Why does the TM FK IB do such much better than the TM FK? I would expect the reverse, the IB should add some drag under sail that the outboard boat doesn't have.
<hr height="1" noshade id="quote"></blockquote id="quote">I'd guess it's a statistical anomaly, because IBs aren't usually rated as faster than OBs. Maybe the only data for a TM FK IB came from an especially skilled skipper competing against casual racers. There can't be many IB C25s racing, so one well-sailed boat winning 2-3 races or regattas might be enough to skew the statistics.

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Stinkpotter
Master Marine Consultant

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Djibouti
9089 Posts

Response Posted - 06/21/2012 : 14:26:21

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 I'd guess it's a statistical anomaly...<hr height="1" noshade id="quote"></blockquote id="quote">That's what I assumed when I saw it. One boat... dark sails... skilled racers... lucky wind shift...

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Tjarnold
Deckhand

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USA
24 Posts

Response Posted - 06/25/2012 : 15:53:29

So my take away from all this is to race under PHRF. I don't buy the weight aloft issue on the TR or the WK making that big a difference upwind. More than offset by off the wind performance. I would guess that the portsmouth rating for the TR/WK is based on a very minimal data set (one fleet, single boat, inexperienced sailor/racer). PHRF rates the TM lower in all keel configurations and has much more data points/fleets reporting.

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Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 06/25/2012 : 17:24:23

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Tjarnold
 So my take away from all this is to race under PHRF. <hr height="1" noshade id="quote"></blockquote id="quote">
You don't usually get to choose the rating system under which you race. The club that sponsors the races chooses their rating system. I have raced under both Portsmouth and PHRF, and found that I could win about the same percentage of races and regattas under either system, if I sailed the boat well enough to win. Choosing a rating system isn't what wins races. Saiing well wins races.

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Tjarnold
Deckhand

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USA
24 Posts

Response Posted - 06/25/2012 : 20:33:20

Well that was a really helpful post. Do you get another star on your badge for that? I am out of here.

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NautiC25
Admiral

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USA
957 Posts

Response Posted - 06/26/2012 : 07:02:30

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Tjarnold
 Well that was a really helpful post. Do you get another star on your badge for that? I am out of here.
<hr height="1" noshade id="quote"></blockquote id="quote">
Wait....whaaa??

Edited by - NautiC25 on 06/26/2012 07:05:10

Derek Crawford
Master Marine Consultant

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USA
3323 Posts

Response Posted - 06/26/2012 : 07:35:46

There used to be a C250 WK (rated at 231)racing in our fleet and it was never any competition although sailed by an experienced sailor and racer.
We won't have any C25 WK's racing until Nauti25 starts to race his own boat (and I'll lose a damn good foredeck crew

Our experience on Canyon Lake shows that the swing is faster to weather (tacks quicker, less leeway) but slower off the wind. Thus their ratings are the same. Where the WK will fit in remains to be seen.

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NautiC25
Admiral

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USA
957 Posts

Response Posted - 06/26/2012 : 11:12:45

No way, you've always got dibs. On the other hand, our lake could use a lot more competitors to really clutter up that starting line.

We'll see how I do against Pete's Cal on the 4th.

Edited by - NautiC25 on 06/26/2012 11:23:57

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