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-   -   Seamanship fail (Or how things add up) (http://www.sailnet.com/forums/seamanship-navigation/84320-seamanship-fail-how-things-add-up.html)

davidpm 02-25-2012 02:03 PM

Seamanship fail (Or how things add up)
 
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We have a lot of new members so I thought a through analysis of my beginners mistake last Thurs would be instructional. It's not like I don't know better. I've done this run dozens of times and since I happen to have so much good data and it is fresh in my mind it may help someone else.

Below is a picture of my track composed of 5 legs.
1. From Duck south past "W" about 2 miles to (SH P) (2:30 to 3:30 PM)
2. From my South most point to just past "8A" bearing about NE (3:30 to 4:30PM)
3. From past "8A" bearing W about 3/4 miles (4:30 to 4:55)
4. From end of leg 3 over the shoal bearing N (4:55 to 5:30)
5. From end of leg 4 bearing NW back to Duck (5:30 to 6:30)
Max ebb current was at 2:17PM about 2Knots 90 degrees ebb at 6:00 PM
Wind was 15 to 23 with seas from 2 to 3 feet.
Almost no moon, temp 45 degrees plus

The idea was to leave about 2:30 and get back in by dark or a little later.

Leg one was Jib only only half out, course 180M, and only took an hour.
I was thinking that I had a west wind so I could just beam reach out and turn around and reach back in.
Lots of things were wrong with that plan. First the wind was probably closer to 290 than to 270, second my course of 180 was magnetic so my true course was probably closer to 165. So the end result was I was really on a broad reach almost a run and the current and waves were not affecting my course as much as they will on leg 2.

Leg 2 I'm thinking I need to steer about 330 magnetic (Which apparently was still not enough). I could only steer 30 magnetic but I was having such a blast going 7 to 8 knots I figured I would worry about where I was later.

Leg 3 I'm trying to go back but can only do about 260, also the wind has moved about 20 degrees more north by this time probably 270.

It's going to get dark so I figure I will motor sail with leg 4. I could barely make any way against the waves with the outboard popping out.
I'm still going the wrong way almost 360

It gets dark and the seas calm down and I just motor directly back.

This is just a very good lesson that a lot of things can add up to make it very difficult to get where you want to go.
I was a little off on my estimate of the wind direction.
The wind clocked the wrong way about 20 degrees.
The seas make forward progress difficult.
I had to stay under canvased because of the wind.
The current was especially strong.

stormrider27 02-25-2012 02:43 PM

Thanks for the anaylisis. Its good to see that everyone can always learn.

Storm

SlowButSteady 02-25-2012 03:26 PM

For a little daysail like that I always try to plan things so that I go upwind on the way out, particularly if I have guests on board. That way, I should always be able to fetch the mouth of my home port sailing more or less downwind w/o tacking or gybing. Granted, where I sail this is probably a bit easier since the prevailing winds blow onshore. But, my aim is to do all the "hard" sailing on the outbound leg(s) and have a relaxing broad reach back home.

Excuse the arm-chair quarterbacking (or is that quarterdecking?), but if you had sailed a starboard tack, close-hauled or maybe a bit free (more or less to the southwest) on your outbound leg, and kept adjusting your course as the wind veered more to the north, your return leg would have still been a reach coming home. You also would have avoided crossing that shoal (which I'm guessing was getting pretty choppy as the wind piped up). If the wind had veer more to the south, rather than the north, you would have had an even easier time getting home.

davidpm 02-25-2012 04:06 PM

Quote:

Originally Posted by SlowButSteady (Post 836692)
For a little daysail like that I always try to plan things so that I go upwind on the way out,

me too that's what I usually do. In this case I was having too much fun going fast and knew I was going to have to pay.
Was just surprised how much though.

SlowButSteady 02-25-2012 06:05 PM

Quote:

Originally Posted by davidpm (Post 836708)
me too that's what I usually do. In this case I was having too much fun going fast and knew I was going to have to pay.
Was just surprised how much though.

Fair enough....don't get me wrong, I didn't want to sound preachy. I've been caught in similar situations, particularly when enjoying a weak or moderate Santa Ana wind (our version of offshore wind).

davidpm 02-26-2012 06:46 PM

Anyway after looking at my track again I think I see a leaning opportunity.

I did the vectors on my chart based on wind of 280 and current at 2 knots from the west.
Based on that leg 2 should have been closer to North rather than the 50 degrees I got.

I didn't keep a log, it was just a fun night sail, mybad, but I knew I had only the genny up for leg 1 and furled to 100 percent. Leg two I don't remember. I'm pretty sure I didn't put the main up until leg 3 when I started to try to get back in earnest.

Anyway leg 2 at 50 instead of 0 is a bit of a puzzle.
Maybe the wind was closer to 320
Can I expect to loose a bunch of degrees with only the jib up.
The waves were pushing the bow off I'm sure loosing some more degrees.
Notice the shoal going from 100 feet to 7 feet. I wonder if the current is a little faster on the edge of the shoal?

All in all I was trying to go west and it looks like everything, wind, waves, current, shoal and my own misjudgment was pushing me east.

Like I said I was expecting to be off by a bit but I really wanted to stay on leg 2 for a while as I was making 8 knots over ground for part of it and it was fun.
The surprise was how I lost a whole two miles plus east in only half an hour.

So in summary:
Is it your experience that you loose 10 degrees plus of upwind performance when using the jib only?

If everything is against you, wind, waves, current and you have to reef is a 160 degree tack angle not surprising, IE almost no upwind progress?

Every boat is different of course, this was a Catalina 25

SlowButSteady 02-26-2012 07:32 PM

Quote:

Originally Posted by davidpm (Post 837085)
Is it your experience that you loose 10 degrees plus of upwind performance when using the jib only?

I almost never sail with only a jib. If I sail with only one sail it's the main. However, I would expect to lose at least 10˚ - 15˚ of pointing ability with only a jib; particularly as the wind pipes up.

Quote:

Originally Posted by davidpm (Post 837085)
If everything is against you, wind, waves, current and you have to reef is a 160 degree tack angle not surprising, IE almost no upwind progress?

Every boat is different of course, this was a Catalina 25

A light, little boat like that is going to have a tough time of it to windward in a stiff breeze. Current and waves are going to make it that much tougher. However, with a tightly sheeted working jib and a helmsman who is really paying attention, you should be able to make some progress in anything shy of 25 or 30 kts, or so. The key is to not be too over-canvased (reef early, reef often), and "work" the waves and the puffs as much as possible, scratching out every bit of windward performance you can.

davidpm 02-26-2012 07:47 PM

Quote:

Originally Posted by SlowButSteady (Post 837114)
I almost never sail with only a jib. If I sail with only one sail it's the main. However, I would expect to lose at least 10˚ - 15˚ of pointing ability with only a jib; particularly as the wind pipes up.



A light, little boat like that is going to have a tough time of it to windward in a stiff breeze. Current and waves are going to make it that much tougher. However, with a tightly sheeted working jib and a helmsman who is really paying attention, you should be able to make some progress in anything shy of 25 or 30 kts, or so. The key is to not be too over-canvased (reef early, reef often), and "work" the waves and the puffs as much as possible, scratching out every bit of windward performance you can.

Thanks for that. I had 15 to 23 knots and wasn't paying attention at all until leg 3 and the main is very tired.
Next time I'll try to get better numbers.

SlowButSteady 02-26-2012 07:49 PM

Quote:

Originally Posted by davidpm (Post 837122)
Thanks for that. I had 15 to 23 knots and wasn't paying attention at all until leg 3 and the main is very tired.
Next time I'll try to get better numbers.

A blown-out main, by itself, will kill your windward performance.

CalebD 02-26-2012 10:07 PM

Also, by using only your jib you move the CE (center of effort) of the sailboat forward while the CLR (center of lateral resistance) stays the same. This usually results in a lee helm that always wants to fall off, so in order to make any way going upwind you always have to steer hard up wind, which further slows your forward progress.
If you balance the forces of the sails (CE) by using both the main and jib then the CE is usually slightly behind the CLR which results in either a neutral or weather helm. Even using a heavily reefed main with a jib will move the CE aft and behind the CLR which gives you weather helm. Of course it is best to have them as close to balanced as possible so you use less rudder which acts more like a brake to boat speed.
Most of us instinctively know this (and I know that David certainly does) but here is a link that breaks it down a bit more scientifically then I can: Helm Balance – Center of Effort, Lateral Resistance, Centerboard, Mast Rake - Waves Jordan Yacht Brokerage
Good discussion btw.


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