Cal 2-27 speed

[Family Time]

I own a 1976 Cal 2-27, does anybody know the top speed for that boat? I can only seem to get up to 6 1/2 Nots. I'm hoping that the new bottom job will increase it to about 8 1/2 knots, but I should be able to get at least 10 down wind due to the flat bottom. I can't seem to find any useful info online.

[svHyLyte]

Originally Posted by Family Time

I own a 1976 Cal 2-27, does anybody know the top speed for that boat? I can only seem to get up to 6 1/2 Nots. I'm hoping that the new bottom job will increase it to about 8 1/2 knots, but I should be able to get at least 10 down wind due to the flat bottom. I can't seem to find any useful info online.

With a 22.08' WL, your theoretical top speed is about 6.3 knots (1.34 x the square root of the water-line length). Unless the boat's heavily loaded, you can, to some extent, exceed that by surfing her down/off the wind but you'll need at least 4 foot waves for that. We had a similar Cal 2-29 for 26 years and often managed to surf her along down wind at 9-10 knots or more for a few minutes at a time or more. We often made the run from Bird Rock, Catalina Island, to the jetty a Alamitos Bay in Long Beach, Ca. in less than 3 hours, or an average of just over 9 knots on a broad reach. Ten knots on the 2-27? Not likely...

[Family Time]

We got the boat put in the water last weekend just in time for a race in 25 knot wind we hit 8.2 knots up wind and near 12 knots down wind, I has zero response in steering.

We took it out today in 9 knots of air, upwind we did 7.3 knots and downwind we hit 8.8 knots. Still some tuning to do but we are getting there.

[Jim Cate]

Originally Posted by Family Time

We got the boat put in the water last weekend just in time for a race in 25 knot wind we hit 8.2 knots up wind and near 12 knots down wind, I has zero response in steering.

We took it out today in 9 knots of air, upwind we did 7.3 knots and downwind we hit 8.8 knots. Still some tuning to do but we are getting there.

Might want to check the calibration of your knotmeter, for those speeds seem quite unlikely, especially equaling windspeed downwind.

Jim

[Family Time]

It's a GPS used on every race. It's calibration is done every time we go out. If I could figure out how to upload videos I would. Not trying to brag as I still want another 3+ knots. But believe it or not I know that the reading was correct.

[Family Time]

Another thing we are on a lake not open sea.

[Jim Cate]

Whatever you say, mate, but exceeding hull speed to windward in a 2-27 is quite a feat.

You should be winning every race you enter with boatspeed like that...

Jim

[Family Time]

We actually did win.. first place in Pro Am regatta. Our next race is April 23 2016. How do you post pictures?

[four winds]

How do you calibrate a gps?

Waterline is ~27' on my Pearson, hull speed is 7.03 knots.

Stumbled upon the "numbers" on my Garmin earlier today, never reset in six years cause I didn't know they were there.

Max historical speed, 8.4 knots. Probably a following sea in the Gulf of Mexico. Always wait on good conditions, always sail, offshore winds 12-20, seas less than 4'. Prefer apparent wind just ahead of the beam, but a few DW runs poled out wing on wing. Don't like quartering seas.

Before the bottom job would average 5.3-5.5 overnight. After average is 6.2-6.4 overnight. These are fair water mark to fair water averages.

All seems reasonable for my boat with old sails.

I smiled when I noted the odometer showed 8522 nm. My estimate was less. Wondering when I can shed the self imposed newbie label. Not yet I suppose.

[Family Time]

Look guy's I really don't care if anyone believe that we went as fast as we did. I saw and felt it. However I do have another question. Why does the back end of the boat sink down in the water so much when going this fast.

[Stumble]

I suspect you are reading in km not kn. Frankly those speeds are not just difficult to believe but impossible. Just as an example, the light air speeds you are reporting would have you beating a TP-52 boat for boat around a race course.

I appreciate that you are reporting what you believe, but it simply isn't possible for a Cal-27 to reach those speeds. In survival situations I could envision a C-27 hitting maybe 10kn dropping off of huge waves. But at these speeds theboat would be massively out of control.

Below is a copy of the TP-52 polars to give you an example of what a million dollar race boat with a dozen high paid crew would expect.

[Stumble]

Originally Posted by Family Time

Look guy's I really don't care if anyone believe that we went as fast as we did. I saw and felt it. However I do have another question. Why does the back end of the boat sink down in the water so much when going this fast.

It's called stern squat in shallow water like some lakes. https://en.m.wikipedia.org/wiki/Squat_effect

Otherwise what you are describing is just wave making resistance. Basically it's a symptom of the water being displaced. http://www.cncphotoalbum.com/technic.../hullspeed.htm

[four winds]

Family Time, how do you calibrate a gps? Never heard of that.

[Jim Cate]

Originally Posted by Stumble

It's called stern squat in shallow water like some lakes. https://en.m.wikipedia.org/wiki/Squat_effect

Otherwise what you are describing is just wave making resistance. Basically it's a symptom of the water being displaced. Javascript: a little window

And while we are at it, the squat indicates that you are at or just below hull speed. IF you were really going 12 knots, you would absolutely need to be planing, and when planing, the stern squat disappears.

I don't imagine that we will convince you that what you report isn't likely, but physics are hard to mess with...

Jim

[amiller]

Originally Posted by svHyLyte

With a 22.08' WL, your theoretical top speed is about 6.3 knots (1.34 x the square root of the water-line length).

This simple equation is new to me; probably because math was never my strong suit....

How does the equation change when calculating for a catamaran? I hear a lot of "fast" speeds quoted for cats on a broad reach, numbers that would seem to exceed this equation.

So is the equation valid for cats? Or do you multiple x2, or divide by 2, or....