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Catalina/Capri 25/250 Sailor's Forums

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Wing Keel question

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raulpou
Navigator

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144 Posts

Initially Posted - 03/28/2006 : 21:34:35

Due to the long hours behind the wheel of my car with radio stations that only south Georgia can provide, I have time to think about things like this.

Has anyone looked into the effects (hydrodynamically) of the wing keel when going down wind? Does the angle of the boat make the wing point down, therefore slowing it down? What if you overload the stern, do you have the reverse effects?

Just thinking...

Edited by - on

djn
Master Marine Consultant

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USA
1561 Posts

Response Posted - 03/28/2006 : 21:58:51

If you take that thinking a little further. Get the the boat going fast enough with the weight in the back and you could call it a hydrofoil. Cheers.

Edited by - on

lcharlot
Master Marine Consultant

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Antigua and Barbuda
1301 Posts

Response Posted - 03/28/2006 : 22:51:58

The consensus of Forum members seems to be that the Wing has a small performance "edge" over the Swing and Fin on a broad reach or dead downwind, but there are so many variables that can influence this, like overall condition, size, and shape of the sails, and smoothness of the bottom paint (if any), that I would hesitate to add my own blanket endorsement for the wing's performance, despite the fact that my own boat is a Mk. IV wing. Frankly, the Catalina 25 seems to be miserable on a dead downwind run unless you have a spinnaker, which I don't. Practically every other sailboat at Folsom Lake can blow past the Catalina 25's downwind, especially the Santana 20's. I have even been passed on a light air day by Catalina 22's flying 150's (I had only a 110 on board that day). My Catalina 25 is the most fun to sail on a close reach, Starboard tack, in about 8~10 mph of wind. Boat speed is in the upper 4's to low 5's, and heel angle is about 15º~20º. However, I can say from personal comparison between hull #1205 (my '79 SK) and hull #5857 (my '89 wing) that the wing "crabs" significantly more than the swing or fin when sailed close to the wind, so much so that if it were up to me, the 1-design racing rule for the Catalina 25 would NOT include the wing in the same class with the fin and swing. A wing keel 25 will be hopelessly out-pointed by fin and swing keels on the upwind legs of a race. Not to mention the fact that the wing keel didn't become a factory option until the advent of the Mk. III hull in 1986, and the Mk. III's and Mk. IV's are hundreds of pounds heavier than the '77-80 MK. I hulls.

Bottom Line: for pure performance, the Mk. I and Mk. II Fin Keels are the best Catalina 25 made. The Mk II has a non-corrosive lead keel with stainless steel keel bolts, which makes it a better choice than the MK. I (which had a cast iron keel) for use in salt water. If ease of trailerability and ramp-launching is a prime factor in your buying equation, the Mk. III and Mk. IV wing keels are best. These are no more difficult to ramp launch than the swing keel, since they are only 2 or 3 inches higher on the trailer (vs 28" higher for the fin), and since all wing keels are lead with stainless keel bolts, you can keep them in salt water with no concern about rust. The one environment where the swing keel might be considered the best choice would be shallow waters, like many lakes and reservoirs, the Sacramento/San Joaquin River Delta, Chesapeake Bay, Florida Keys, etc. In these places, the ability to easily crank up the keel from 6' draft to 2.5' draft can mean the difference between simply turning around and retreating from a shoal grounding under your own power, vs. a very expensive visit from a Vessel Assist tow boat. Swing keels have some disadvantages which I won't go into here, as there are hundreds of postings on this forum that cover swing keel maintenance issues. Having owned both, I am happier with my Wing, and appreciate not having to worry about the various keel cable "WCS" events (worst-case-scenarios). I just have to be a little more careful about getting close to shore or shoals. Thankfully, I don't have to worry about running aground on an ebb tide, or being pushed onto a shoal by a rip current, since Folsom Lake has neither tides nor currents; we just have 4 months of summertime kamikaze powerboaters and waterskiers, whizzing around at Warp 10 through narrow channels and passing you on both sides, close enough to reach out and touch them with a boat hook sometimes. BTW, looks like this coming weekend will be "first splashdown" for 2006. I plan to spend Friday getting the boat cleaned up, sails rigged, and launch in the afternoon. If the weather is decent, will probably spend Friday night on the boat, and maybe Saturday night too. I am still about 5 years out on the waiting list for an in-water slip, so it will be dry storage for at least that much longer. The dry storage is getting to be kind of a pain with these high gas prices; since I have to ramp launch the boat every time, I have to drive my heavy-duty tow vehicle (15 mpg), and this costs me about $25 fuel for every trip to the lake on top of the marina fee. If I had an in-water slip, I could drive a 40 mpg economy car out to the lake instead of the guzzler, plus I could be out sailing for the hour-plus it takes to launch, retrieve and move the boat from dry storage to the ramp.

Edited by - on

Brooke Willson
Admiral

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USA
983 Posts

Response Posted - 03/29/2006 : 03:35:39

Larry, that's a wonderful analysis of C25 keel types and their advantages. You've distilled years of forum blather into an elegant statement. As a Chesapeake swinger, I couldn't agree more. Thanks.

Brooke

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raulpou
Navigator

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144 Posts

Response Posted - 03/29/2006 : 07:54:46

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by djn
 If you take that thinking a little further. Get the the boat going fast enough with the weight in the back and you could call it a hydrofoil. Cheers.
<hr height="1" noshade id="quote"></blockquote id="quote">

There's always one in the group! :)

Edited by - on

Steve Milby
Past Commodore

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USA
5913 Posts

Response Posted - 03/29/2006 : 08:55:47

The C25 is an excellent downwind boat, even with white sails. With a poled-out 150 and about 12-15 kt winds, the C25 can hang with or beat most similarly sized boats, and can often beat them regardless of whether they are flying a spinnaker. The difference usually comes down to the skill of the crew on the other boat. If they're a little slow getting the spinnaker up or down, or if they occasionally let it collapse or get out of control (i.e., the "average' crew), that's enough to keep the non-spinn. boat competitive. I have occasionally passed spinnaker boats downwind in about 15-18 kt winds with a poled out 110. In order for it to be that fast, the bottom and keel have to be smooth and fast, and the jib has to be poled out.

You can't give other boats the advantage of flying a 150, when you're only flying a 110 on a light air day, and expect the boat to keep up with the fleet. That doesn't mean the boat design is slow downwind. The sail is our "motor," and all the other boats had bigger motors than the C25 on that day.

With regard to the original question, I don't think the boat usually changes its pitch that much downwind to make a significant difference in the angle of attack of the wing. If the winds are strong, and if you're flying a spinnaker, the boat will pitch forward more than in light air with white sails. In that case, the wing will probably generate more drag than when the boat is at its normal pitch. So, in those two instances, the wing will be a little slower downwind, but I think the difference will be extremely slight, and any difference in racing performance is equalized by the handicap allowance.

If you overload the stern while running downwind, the pitch of the wing is the least of your concerns. Normally, when running downwind, you want to move your crew forward and to the leeward side, at about the shrouds, because when you tip the boat forward and to one side, it raises the stern of the boat (the fat end) partially out of the water, and it reduces the amount of wetted surface. Reducing the wetted surface reduces drag, and makes the boat faster. The amount of drag that is eliminated by pitching the boat forward far surpasses the slight increase in drag that is caused by changing the pitch of the wing.

If you move your crew aft, so that the stern squats down, you increase the amount of wetted surface, and you change the angle of the wing, and it's like putting on the brakes.

Edited by - Steve Milby on 03/29/2006 10:35:09

raulpou
Navigator

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144 Posts

Response Posted - 03/29/2006 : 21:08:12

Thanks for the comments, they are excellent!

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Gloss
Master Marine Consultant

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USA
1916 Posts

Response Posted - 03/30/2006 : 17:23:53

Having used my 89 wing as a hydrofoil, I'll have to say it handles remarkably well, all things considered.

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 03/30/2006 : 18:59:00

I did very well in a 40 mile downwind Mug race 2 yrs ago. We only had the cruising chute and came in 6th in Spinnaker class. We were the only one without a pole(17 other) boats. I would say the wing scoots downwind. I ran for 25 miles between a morgan 27 and a melges? 24.

If my boat was sailed better or we had less....provisions.....on board, we would have been near the top.

Tom.

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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
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