catamaran gust question - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 15 Old 04-10-2010 Thread Starter
Senior Member
 
2Gringos's Avatar
 
Join Date: Jan 2008
Location: SW Devil's Triangle
Posts: 858
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 8
 
catamaran gust question

I was reading another thread on ASA certification, and it jogged a question I had that I still am not sure I understand. This cropped up in my own ASA marathon back in december in the BVI.

We were sailing a 42 ft. R&C catamaran in the Christmas Winds and decided to sail outside Jost van Dyke and to circumnavigate the island. I venture to say we were the only two student sailors out there that day, with sustained winds in the high 20's and gusts to over 32 a few times. We were sailing on the second reef, just us two noobies and our instructor ( we chartered the whole boat). I was at the helm, getting a real first hand feel for how a catamaran that size feels in solid 28 kts of wind and a following 8-10 ft. sea on the stbd. quarter. As we were heading out into it around the east end of Little JVD, my tendency was to head up into the gusts, as most of my sailing has been in monohulls in the past, and that's always what I did. Especially in my small 16 ft. AMF daysailor. BUT our ASA man told me that in a catamaran, you bear off in the gusts. As we came around headed more to the west and practiced white-knuckle jibes for the next few minutes...I meant to get a better explanation for why not head up into a gust on a multihull.....but my limited attention span was quickly overwhelmed and I forgot about it. And I just remembered, today, that I am not sure I understand this 100%. Since we are bound and determined to buy a catamaran of our own before the year is out, I thought I better ask.

Can someone explain why we steer downwind in a gust in a multihull, instead of heading up into the gust? I imagine it has something to do with the rigging, transferring load into hull speed instead of spilling it or heeling? I dunno. But I figure someone here will.

Two Americans move to the TCI.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
2Gringos is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 15 Old 04-10-2010
ASA and PSIA Instructor
 
Join Date: Apr 2000
Posts: 3,555
Thanks: 7
Thanked 24 Times in 24 Posts
Rep Power: 16
 
For two reasons you bear off in a multihull.

First any boat is typically longer than it is wider, so it is more difficult to sommersalt if forward stern-over-bow than to capsize it laterally.

Secondly when you bear off, you reduce the apparent wind, whereas when you head up, you increase the apparent wind

The same forces are true for a mono-hull, its just that there's little penalty for heading up and luffing, as the keel will resist the boat rolling over, whereas with a multihull, the price and can be extreme.

Certified...in several regards...
sailingfool is online now  
Quote Quick Reply Share with Facebook
post #3 of 15 Old 04-10-2010 Thread Starter
Senior Member
 
2Gringos's Avatar
 
Join Date: Jan 2008
Location: SW Devil's Triangle
Posts: 858
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 8
 
Well, thanks, and that sounds a lot like the explanations I think I was getting, but I am still not 100% sure I understand it. Pointing any boat directly into the wind always seems to me like the best thing to do in a strong gust, whereas turning a cat more broadside to the gust seems counter intuitive...

(hey I had similar issues when I went from flying Cessnas to flying weight shift ultralights....that landing flare can be a booger when you forget to push the bar forward to flare instead of pulling the yoke back...as you are used to.)

Two Americans move to the TCI.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
2Gringos is offline  
Quote Quick Reply Share with Facebook
post #4 of 15 Old 04-10-2010
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 2,517
Thanks: 1
Thanked 49 Times in 49 Posts
Rep Power: 7
 
Also, bearing off causes...

Quote:
Originally Posted by 2Gringos View Post
Well, thanks, and that sounds a lot like the explanations I think I was getting, but I am still not 100% sure I understand it. Pointing any boat directly into the wind always seems to me like the best thing to do in a strong gust, whereas turning a cat more broadside to the gust seems counter intuitive...

(hey I had similar issues when I went from flying Cessnas to flying weight shift ultralights....that landing flare can be a booger when you forget to push the bar forward to flare instead of pulling the yoke back...as you are used to.)
...

* the sails to stall, reducing drive
* the jib is blanketed by the main

However, in really strong gusts (micro-bursts) even on a large boat of any sort, that may not be enough. Then, the key is to get into the wind BEFORE the force becomes too great.

Your instructor was correct for the conditions. Thunderstorms are a different animal.

You can't really learn this on a large boat. Talk becomes theoretical. Go out on a Hobie cat in gusty weather - really, it is the only way to really understand when each method works.

(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pdqaltair is offline  
Quote Quick Reply Share with Facebook
post #5 of 15 Old 04-10-2010
Telstar 28
 
sailingdog's Avatar
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 14 Times in 12 Posts
Rep Power: 14
         
2Gringos—

The problem is that while pointing a boat directly into the wind sounds like a good idea... getting a boat to that point can be very dangerous on a multihull. Also, windage issues on a multihull, like high freeboard of the hulls, can make the boat not point into the wind well.

Also, in choppy conditions, many multihulls don't have the inertia or momentum to push through the chop and bearing off means they don't have to....

Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
sailingdog is offline  
Quote Quick Reply Share with Facebook
post #6 of 15 Old 04-10-2010 Thread Starter
Senior Member
 
2Gringos's Avatar
 
Join Date: Jan 2008
Location: SW Devil's Triangle
Posts: 858
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 8
 
well, dang. I can see I am going to have problems with this. Because until it makes sense to me, it won't make sense. And it doesn't yet.

Two Americans move to the TCI.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
2Gringos is offline  
Quote Quick Reply Share with Facebook
post #7 of 15 Old 04-10-2010
Senior Member
 
P8dawg's Avatar
 
Join Date: Jan 2007
Location: Wichita Ks.
Posts: 156
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
I know what the books say, but i've never pitchpoled by pointing up, and that is as violent as sailing gets. It seems to me when I am worrying about flipping over, the gusts are fairly unpredictable. Granted I'm a lake sailor, but the wind bombs can get pretty powerful. I never have to deal with ocean swells, but I'm with you gringo, I'm gonna keep pointing up.

"cause the fast ones always ride for free." -Mother Love Bone-
P8dawg is offline  
Quote Quick Reply Share with Facebook
post #8 of 15 Old 04-10-2010
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 2,517
Thanks: 1
Thanked 49 Times in 49 Posts
Rep Power: 7
 
Yes, it is complicated.

Quote:
Originally Posted by sailingdog View Post
2Gringos—

The problem is that while pointing a boat directly into the wind sounds like a good idea... getting a boat to that point can be very dangerous on a multihull. Also, windage issues on a multihull, like high freeboard of the hulls, can make the boat not point into the wind well.

Also, in choppy conditions, many multihulls don't have the inertia or momentum to push through the chop and bearing off means they don't have to....

SD is right, of course, about getting straight into the wind or even pointing high. Some light cats - my Stiletto and any beach cat - can literally be blown over backwards by a strong blast, so you learn to fore reach with the traveler down during thunderstorm - actually, each take a different approach - so it is a matter of degree. Pointing high can even be unstable, as the boat tries to stop and fall back. Going into irons in rough weather is bad.

Which is why I suggest sailing a beach cat to learn. You will learn things in moderate and safe conditions that only effect larger cats in wild conditions. And it is a ton of fun. Either bum rides or get a used one and sell it after the summer.

(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pdqaltair is offline  
Quote Quick Reply Share with Facebook
post #9 of 15 Old 04-10-2010
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 2,517
Thanks: 1
Thanked 49 Times in 49 Posts
Rep Power: 7
 
BTW, pointing up with the chute up is a disaster with any boat.

Quote:
Originally Posted by P8dawg View Post
I know what the books say, but i've never pitchpoled by pointing up, and that is as violent as sailing gets. It seems to me when I am worrying about flipping over, the gusts are fairly unpredictable. Granted I'm a lake sailor, but the wind bombs can get pretty powerful. I never have to deal with ocean swells, but I'm with you gringo, I'm gonna keep pointing up.
The boat powers up huge as you make the turn and you will be upside down. The same may go for big reachers. You may think you can come up and let them luff - it doesn't generally work out well - they may become so tangle in the rigging they won't come down.

If over powered seriously with a chute, bear off to dead down wind, get the chute down, and consider your need for further reductions.

(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pdqaltair is offline  
Quote Quick Reply Share with Facebook
post #10 of 15 Old 04-10-2010
Senior Member
 
P8dawg's Avatar
 
Join Date: Jan 2007
Location: Wichita Ks.
Posts: 156
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
It may be that I seldom use anything but the Main and the jib. I know the boat powers up when you point, but it seems to me that it wants to jump right out from underneath me when I fall in a big gust. I feel much more in control of the situation pointing up and barely in control falling down. I have been in gusts that came in from the side and force you down. The impact on the bows is almost instantaneous. The next thing you know, there is an air bubble around your face because the trampoline is against your back, and you have already slammed face-first through a cartwheel.

"cause the fast ones always ride for free." -Mother Love Bone-
P8dawg is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
THE Yacht Builder List T37Chef Boat Review and Purchase Forum 26 07-08-2011 05:51 AM
A Real Cheap Cruise for Real(istic) People on a 62 foot Catamaran February 27th, 2010 notbushwacked Chartering 1 03-07-2010 01:30 PM
Interested in living on a Cat out west. octanetwilight Living Aboard 17 09-26-2009 10:42 PM
Catamaran Questions from a Newbie liveaboarddreamer Introduce Yourself 3 09-21-2009 02:25 PM
38’ Luxury Sailing Catamaran NEEDS CREW from NY to Norfolk 9/16/06 kirkalittle Crew Wanted/Available 0 08-21-2006 12:26 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome