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how fast can a cat 25 swing go

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quilombo
Captain

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USA
301 Posts

Initially Posted - 03/16/2008 : 19:42:38

just wondering , in full combate regalia, how fast can a catalina 25 swing go, with an experienced helmsman at the tiller
with the right wind of course,, any war stories out there,

Edited by - on

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 03/16/2008 : 20:20:24

Hull speed equals:

1.34 x (sq. root of lwl) or 6.31knots

http://home.golden.net/~capone1/wsc/calc.htm

So, in theory, your boat can go no faster than hull speed. That is, the speed that the the displacement hull can move water out of the way and move forward.

Having said all that, somebody here will tell tales of going faster than hull speed.

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 03/16/2008 : 21:52:32

>"tell tales of going faster than hull speed."

Remember that the hull speed equation is an approximation. Bottom line is that your best (only?) shot at exceeding 6.some-odd knots in a C25 is getting a push from a following sea.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 03/16/2008 : 21:57:39

First, theoretical hull speed is just that. Actual hull form can allow some variations, but it applies pretty well to a C-25. That's the speed at which, to go any faster, a boat has to climb up over its bow wave, which generally a sailboat doesn't have enough power to do. The most common time that it does is when gravity is helping--on the front side of a wave ("surfing") before the wind. C-25's have gotten into the 8+ knot area in that situation. You can tell you're exceeding hull-speed when spray starts coming off the hull admidships. You've probably had fun going much faster in a powerboat, but when you get a sailboat surfing, there's hardly any greater rush!

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Derek Crawford
Master Marine Consultant

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USA
3321 Posts

Response Posted - 03/16/2008 : 23:06:51

I've hit 10.4k on a beam reach (verified by another boat alongside (an O'day 28)who had an accurate knotmeter. I've also hit 9.5k going downwind with a poled-out 155%. Both of 'em were quite a rush!...

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Justin
Admiral

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502 Posts

Response Posted - 03/17/2008 : 07:28:32

I've had my GPS show holding mid-high sevens, maxed at 7.8 knots over ground last fall during an awesome sail on the Chesapeake Bay. We were surfing with the waves and it was a blast!

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/17/2008 : 07:51:03

I've done 8.4kts under headsail alone. Keep in mind the LWL increases with heel.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 03/17/2008 : 15:23:25

...a tiny bit... The C-25 doesn't have much overhang.

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JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 03/17/2008 : 15:31:25

I've seen high max speeds like thy've said. You can easily reach 7.5 knots when there are big waves and strong wind - its fun!

On the other hand your trip planning should assume a speed of 5 to 5.5 knots under power and 4.5 knots under sail. Yes you can hit the mid sixes or higher. You won't be averaging that over any distance. You won't want to power up the outboard to push you at 6.3 knots either - it burns a lot of gas. Cruising along at 5 knots is a very comfortable and economical RPM - 12 minutes per mile. I get about 15 to 20 mpg at this speed.

When you are under sail and on a cruise trying to get somewhere and speeds drop below about 3 knots (its different for everyone) time to start motorsailing.

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 03/17/2008 : 15:32:12

oh and thank God for all the questions from Quilombo, without you this board would be dead right now!

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Ben
Master Marine Consultant

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USA
1234 Posts

Response Posted - 03/17/2008 : 15:34:19

I was on a beam reach during a race once and got the boat (according to the GPS) up to 6.7 knots. I sail on a small reservoir, so there was no current or tide to account for this. At the time I posted on this site the phenomenon, because it struck me as incredible, but someone explained it adequately (not that I remember the explanation).

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John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 03/17/2008 : 15:51:13

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Ben
 I was on a beam reach during a race once and got the boat (according to the GPS) up to 6.7 knots. I sail on a small reservoir, so there was no current or tide to account for this. At the time I posted on this site the phenomenon, because it struck me as incredible, but someone explained it adequately (not that I remember the explanation).

<hr height="1" noshade id="quote"></blockquote id="quote">
A. Hull speed is a theoretical, calculated number, your actual milage may vary.

B. The calculation goes up as you heel since, as Don pointed out, the LWL increases with heeling.

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esailor
Navigator

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USA
118 Posts

Response Posted - 03/17/2008 : 16:39:48

Don't know about the c25 but I have water skied behind an Escow.

Pete

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 03/17/2008 : 21:25:31

Planing hulls are another world, especially rockets like scows

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aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 03/19/2008 : 12:46:14

Wind approx 15 knots. Waves approx 3.5 ft. Sails, main and asymetric spinnaker. Speed 11.2 knots. Absolutely the most awesome sailing experience in 19 years of sailing a C25.

Edited by - aeckhart on 03/19/2008 12:50:54

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 03/19/2008 : 13:30:22

At the rate the speeds are going up, we'll be racing Maxi's next week.

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Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 03/19/2008 : 13:43:17

There is always the factor of whether you measure speed on GPS (over ground), or on your instruments (relative to the current) being pushed along at 6 knots by the wind with a 6 knot current helping could get you up to 12 knots on GPS, but only 6 knots on the instruments.

Then there is the difference between speed and velocity made good, which factors in leeway and efficiency in your course.

Seems nothing is simple in sailing...

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2far2drive
1st Mate

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USA
74 Posts

Response Posted - 03/20/2008 : 12:14:15

Ive hit 6.7 on GPS. best avg over 10 minutes was 6.3

Ive been watching a lot of racing lately, what does 20+ feel like>????

anyone seen the video of the French attempt to beat the record for sail driven vessel?

http://youtube.com/watch?v=xFJocBvj-_w

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 03/20/2008 : 12:26:33

Edited by - Dave Bristle on 03/20/2008 12:31:27

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 03/20/2008 : 13:09:01

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by 2far2drive
 Ive hit 6.7 on GPS. best avg over 10 minutes was 6.3

Ive been watching a lot of racing lately, what does 20+ feel like>????

anyone seen the video of the French attempt to beat the record for sail driven vessel?

http://youtube.com/watch?v=xFJocBvj-_w
<hr height="1" noshade id="quote"></blockquote id="quote">

47.6 knots -- pretty slow for an airplane. Wonder why they couldn't rotate and fly? That thing only vaguely resembled a sailboat. Looked more like a poorly designed airplane. If I ever need to go that fast, I'll go for a ride on Bristle's stinkpot.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 03/20/2008 : 14:14:44

Sorry John--I can't quite get to 40... but 47.6 is pretty good for an "airplane" with no engine and not diving!

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stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 03/20/2008 : 16:52:12

Hey Dave, Sarge looks pretty good with those C25 handrails.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 03/20/2008 : 21:05:50

Thanx! There's even a pair under the hardtop--you can't see them in the pic. All done with Cetol Natural Teak. Almost like being a rag-bagger again!

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