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A great sail!

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Steve Milby
Past Commodore

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USA
5902 Posts

Initially Posted - 08/12/2008 : 09:54:52

Yesterday morning I left Annapolis Harbor and sailed about 30 miles south to my marina. Wind was from the west at 10-15 knots, gusting to 20. That made it a beam reach all the way. Small craft warnings were out, but, because I was sailing fairly close along the western shore, the waves were relatively small for that much wind. As a result, the sailing conditions were absolutely perfect, and the boat was making unbelievable speeds. Her hull speed is 6.93 kts., but she was sustaining over 8 knots for considerable periods of time, and topped out at 8.7 kts.

It was a good opportunity to observe how the bow wave behaves when the boat exceeds hull speed. I noticed that, as the boat speed increases, the bow wave on the windward side gradually moves aft, until it streams almost from the transom. At that time, you know the boat has driven over it's own bow wave. I always thought most sailboats couldn't exceed hull speed without the help of a big wave, pushing them along, but I think that's wrong. At 35 ft lol and over 13,000 lbs, my boat is certainly no ultra-light racer, but it repeatedly over-ran it's bow wave and began to surf solely on the strength of wind gusts, without the aid of a big wave. The engine could not have pushed the boat to anywhere near such speeds. That means the sailing rig must generate far more power than the engine. That fact alone doesn't surprise me, but I am a little surprised to see how much more power the sails produce.

Once I got the boat on course and trimmed, I turned on the autopilot, made a sandwich, drank a Coke and read a book, while the boat carried me home. What a great day!

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/12/2008 : 11:40:07

Sounds like the ultimate ride--a strong beam reach in an offshore breeze! Loved hearing about it! Yup, there's a lot of power up there!

I don't know if it would surprise anyone, but my little $+!nkp*+ at cruising speed on Long Island Sound or the ocean is a lot more work to pilot than most sailboats. I have to have one hand on the wheel and the other on the throttle full-time, constantly changing speed and course for seas and wakes (and lobster pots). I don't think an autopilot is feasible at 20+ knots--I just need to rely on getting there quicker so I can rest! In a few weeks, I'll be doing 4+ hours of that, and will be very tired when I arrive! (I've only done about two hours straight at speed so far.)

Like they say, "...on a sailboat, you're already there."

Edited by - Dave Bristle on 08/12/2008 11:58:08

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 08/12/2008 : 14:42:54

Steve,
Based on a 35' length on the water, shouldn't your theoretical hull speed be closer to 8kn? I did the calculation (1.34 x #8730;35) = 7.93, is that correct?

At any rate, it sounds like you had a blast.

Edit:
Hmmm... that was supposed to show up as 1.34 times the square root of 35 in the formula above, not sure how to get it to show up properly.

Edited by - delliottg on 08/12/2008 14:44:26

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/12/2008 : 15:17:30

His LWL is 26.75'.

Edited by - on

Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 08/13/2008 : 08:28:42

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by delliottg
 Steve,
Based on a 35' length on the water, shouldn't your theoretical hull speed be closer to 8kn? I did the calculation (1.34 x #8730;35) = 7.93, is that correct?<hr height="1" noshade id="quote"></blockquote id="quote">I mis-typed "lol" instead of "loa". My boat is 35' length over all. The hull speed is calculated on the basis of length at the waterline. Dave is correct that the waterline length is 26.75'. I didn't trust my math skills, so I plugged the numbers into an on-line calculator and let the computer do the brain work. Hull speed came out to be 6.93 kts.

Edited by - on

Oscar
Master Marine Consultant

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USA
2030 Posts

Response Posted - 08/20/2008 : 20:25:04

I know exactly where you were and can picture the ride.......neat!

According to Mr. Tides, high tide in Annapolis was about 07.30 which would give a down Bay flow from about 10 to 16.00 This would account for the extra knot or so.

Edited by - on

Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 08/21/2008 : 09:25:53

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Oscar
 I know exactly where you were and can picture the ride.......neat!

According to Mr. Tides, high tide in Annapolis was about 07.30 which would give a down Bay flow from about 10 to 16.00 This would account for the extra knot or so.<hr height="1" noshade id="quote"></blockquote id="quote">
Welcome back to the forum, Oscar!

The tidal current tables show a maximum current of about .5 to .6 kt, but most of those measurements are taken in deep water, nearer to the commercial shipping channel, where the tidal current is much stronger than where I was sailing. I was sailing closer along the western shore, where the maximum currents were more likely in the range of .2 to .4 kts. Moreover, those measurements are at max flow, and are less at other times. My knotlog showed speeds that averaged about 1/3 to 1/2 kt less than the gps speed, which is fairly consistent with the tidal currents.

Last weekend, I skippered a friend's boat on a diamond-shaped course from Thomas Point Light southeast to a buoy, then to another buoy near Poplar Island, then northwest to another buoy, and then back to the starting line. The race was a navigational race, and we were allowed to choose whether to sail around the course clockwise, or counterclockwise. We rounded it clockwise, sailing into the strong flow of the deep water of the commercial channel early, which carried us south with about 1/2 kt boost from the current. Then, after we rounded the southernmost buoy and headed north again, the wind turned very light, but the current began to change, and we had either no current, or a little current flowing with us, which increased as the day wore on. We were scored in both our one-design class, as well as in a phrf class, and finished first in both classes.

There are places where the current is around 1 kt, but that's not the norm across the main body of the Bay. Usually about 1/2 kt. is closer to what we find at maximum flow, even in the deeper water, with a weaker current along the western side.

Edited by - Steve Milby on 08/21/2008 09:31:39

Ray Seitz
Captain

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USA
416 Posts

Response Posted - 08/21/2008 : 13:12:27

Hi guys, nice discussion & good reading. Thanks for the post Steve et al.

Edited by - on

Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 08/23/2008 : 18:01:37

Thanks Ray. It's always nice to hear from folks from Brookville Lake. It looks like you've moved up to the big lake!

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/24/2008 : 11:24:56

The Race, the infamous gap between Fisher's Island and Plum Island, NY, where tides flow between the Atlantic and Long Island Sound, produces currents over 5 knots at full flow... Sailors here definitely plan their itineraries around the tides! You can double your speed or go backwards--take your pick! You could say I gave up--don't worry too much about it any more.

But the 200' underwater cliffs with that tide running over them can still make things exciting, especially when the tide is opposing the seas--sorta like a giant washing machine! You can avoid the worst of that by going through Fisher's Island Sound, past Mystic--Oscar and his dad picked that route in his dad's new $+!nkp*+ last year.

Edited by - on

Ray Seitz
Captain

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USA
416 Posts

Response Posted - 08/25/2008 : 12:41:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">It looks like you've moved up to the big lake!<hr height="1" noshade id="quote"></blockquote id="quote">

The family likes it better, attractions, destinations, less sail handling etc. Probably will mean less time sailing as the commute got a lot longer. It is different lots of time between tacks & long spaces between destinations.

BTW remember when we entered a few races on Brookville in Sea Major and were having trouble with rounding up. Well Arlyn, Oscar and many others were 100% right about the rudder. I really pushed the powers to be at Catalina and got them to sell me a beaching rudder. It is like a different boat it actually sails well now (I still don't but that's another matter

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