Rock and Roll

Discussions on the characteristics of the EC12. Yes, it handles different than most R/C Sailboats

Moderators: Capt. Flak, bigfoot55, Chuck Luscomb

Rock and Roll

Postby nquinn » Sun Jan 22, 2006 10:12 am

Crossing the "T" after beating to two upwind marks, the turn to the downwind marks is 90 degrees and directly downwind....

Wind speed was very near the "A" rig maximum and all was tightened up.

Can anyone suggest the best technique to minimize the tendency of the yacht to rock and roll?
nquinn
 
Posts: 8
Joined: Mon Nov 01, 2004 1:38 pm
Location:

Postby Doug Wotring » Sun Jan 22, 2006 11:44 am

not claiming to be an expert and not knowing anyting about your boat 95std or pre 95?, sail maker and or condition, etc.)

My Experience has shown that too much sail twist is a large contributing factor.

My First boat ( Dumas Hull) was also prone to rolling even with sails trimmed correctly in Heavy winds, more so if water was choppy
Doug Wotring
 
Posts: 462
Joined: Thu Sep 18, 2003 8:46 pm
Location:

Postby nquinn » Sun Jan 22, 2006 11:50 am

Doug,

Pre 95, Hickman #367, New "A" rig by Zellanack with his Carr sails design. I think the boat is now a wee light, weighed it after having the interior reworked by ROn Brown, came in at 22.5 pounds.

Thanks on the Twist, taking in the Vang will reduce that right?

Nick
USA 1334
nquinn
 
Posts: 8
Joined: Mon Nov 01, 2004 1:38 pm
Location:

Postby Doug Wotring » Sun Jan 22, 2006 12:08 pm

Shouldn't be the Hull as I have not seen this tendency in Othe r Hickman Pre 95'''s.

Without going to look I think 22.5 is minimum waterline.....and thus wouldn't be the best option for heavy wind.

Most I think shoot or the middle of the Window on the waterline.

I myself am to the long side.

But Shortening the vang should help dramitically. I might also check that you are sheeting out to the maximum too as I think a Main not sheeted out all the way will add some wobblies
Doug Wotring
 
Posts: 462
Joined: Thu Sep 18, 2003 8:46 pm
Location:

Postby PaulP » Sun Jan 22, 2006 12:26 pm

Nick
I've learned the Rock/n/Roll characteristic is directly influenced by the amount of twist. Tightening up on the vang will reduce the twist. Less twist, less rolling action.

But in certain conditions, you need to compromise.

I think I first read about this in the EC12 manual but not 100% sure.

Paul P
User avatar
PaulP
 
Posts: 1225
Joined: Tue Sep 09, 2003 10:46 pm
Location: Manchester, MO

Postby Rick West » Sun Jan 22, 2006 1:12 pm

Nick,
The comments about the twist is excellent. Under those condition sail sail tuning should move to tightening up everything and increasing the back stay pressure. When I look at the top batten of the main on shore when setting the twist, I will tighten the vang to set a little curl in the batten to windward. This is opposite of lighter air. Then I will push on the batten to note the tension, thereby simulating wind pressure, as I do not want it to move to the lee too easily.

The other thing is balance. This is easily adjusted by moving the mast forward on the step. Trim the jib all the way out to dump some air and a wing on wing set is manditory.

In this configuration going to weather, sheet out till the boat will not round up easily. This is part of balance. In doing so you will drive harder through the seas with power. When the main boom at the clew starts touching the water it is time for a sail and rig change.

In all conditions: you do not want to manhandle an EC12. She must run free and with as much momentum as conditions and sail will permit.

Hope this helps with the concepts.

...94 [8D]
User avatar
Rick West
 
Posts: 3204
Joined: Sun Sep 14, 2003 8:53 pm
Location: San Francisco, CA

Postby Mike Zellanack » Mon Jan 23, 2006 6:57 am

Nick
Mike Zellanack
 

Postby Mike Zellanack » Mon Jan 23, 2006 7:12 am

Nick

Ooops. Pushed the wrong key on my last. Tightening the vang will definitely help. However, you need to make sure your lower-lowers are adjusted correctly. They help reduce the lateral movement of the mast in heavy air conditions. When pressure builds up in the main, the sail wants to lift the boom. The vang won't let that happen. Instead, the increased pressure causes the mast to move to leeward. You can simulate this condition by sheeting your main all the way out and lifting the end of the boom with you finger. Watch what happens to the mast at the gooseneck as you lift the boom. When the mast moves in this manner it allows the boom to lift causing the main to develop more twist which contributes to the "rock and roll" problem.
One other trick you may want to try is to briefly sheet in the sails until the boat stabilizes and then sheet out again. This will help the boat straighten up. You may need to do this more than once on a downwind leg depending on the strength of the wind.

Mike
Mike Zellanack
 

Postby Les Ervin » Mon May 14, 2007 12:41 pm

My boat was rocking and rolling yesterday, going downwind in about 13 mph of wind. I was able to get it to stop by briefly coming up slightly, sheeting in the sails slightly and then bearing off again while letting the sails out. This technique stopped the rocking but probably isn't the best strategy when you're trying to get to that downwind mark as fast as possible. The boat is a Dumas with unknown sails.
Les Ervin
 
Posts: 16
Joined: Mon Apr 23, 2007 11:28 pm
Location:

Postby Rick West » Tue May 15, 2007 12:20 pm

Les,
Most Dumas set ups have only about 12 pounds of ballast. That is not enough for 13 mph, which is borderline for most skippers in an A rig.

The assumption is the sails are wing on wing (A must), the leech is tight and the boat is balanced for the conditions (mast position, ballast and sheet postion).

What I hear indicates the boat is over powered in the conditions. Sometimes, for certain boats, this cannot be corrected. There is a point where the skipper needs to move to a B rig.

An EC12 fully sheeted out with a tight rig and the mast forward for the higher wind should not "Rock and Roll." It may fall off the sailing line but not rock. That is a sign of being out of balance.

A boat that is overpowered, having done the right things, will broach. A boat that has all the tuning above correct and has a strong rudder servo and the skipper a steady soft thumb on the helm will broach straight ahead, bury the bow to the mast, come to a dead stop then the bow will rise out of the water and sail on.

Lastly, the skipper has to decide when it is time to change rigs or withdraw. In my opinion, RD's stop an event long before needed and hence many do not get the experience of dealing with the conditions. The safety issue considered should mainly be for the experience level of the fleet and damage comes from out of control boats...the EC12 is capable of sailing in heavier air than many think.

I hope this helps. Practice heavy air sailing and these things will come. In an event a skipper's prime concideration should be the safety of other boats by the actions of yours. Sailing close to others in a high wind is very high risk. The people next to you are your friends.


...94 [8D]
User avatar
Rick West
 
Posts: 3204
Joined: Sun Sep 14, 2003 8:53 pm
Location: San Francisco, CA

Postby Les Ervin » Tue May 15, 2007 7:59 pm

I sailed again yesterday and in the same conditions. I noticed that the rocking and rolling would begin when I turned downwind but would stop as soon as I got the jib to flip over to the side opposite of the main.
Les Ervin
 
Posts: 16
Joined: Mon Apr 23, 2007 11:28 pm
Location:

Postby Rick West » Wed May 16, 2007 10:50 am

Exactly, Les. If a course is close to square, the first order at the helm when rounding the windward mark is to wing and wing the sails. Not only are you presenting the most sail to the wind you are balancing the boat.

In this position of sail set there is a delicate line of sailing to hold the set and to steer the boat so that it will not fall off wind where you will end up in a broad reach tack but the sails will still be in the wing position and you cannot turn back downwing. When this happen either the boat was overpowered or it was helmsman error or the rudder servo was not strong enough to manage the pressure.

When this happens you need to sheet in enough that the main will flip over with the jib so that you are in a broad reach set and having control of the helm. Then try to get downwind again by sheeting all the way out. You need a strong rudder for this.

Practice and learn control in higher winds. Few do. Then at an event you will place high in the fleet if you stay away from others that are having difficulty.

Enjoy...

...94 [8D]
User avatar
Rick West
 
Posts: 3204
Joined: Sun Sep 14, 2003 8:53 pm
Location: San Francisco, CA


Return to Sailing the EC12

Who is online

Users browsing this forum: No registered users and 4 guests

cron