Problem sailing DDW

[gpdno]

I don't have a spinnaker so when I sail down wind, I sail Wing and Wing. The problem is my boat seems to roll back and forth quite a lot which is uncomfortable and a bit unnerving. It also seem that I have to use a lot of steering input to keep course, in fact the autohelm struggle to work and usually bails after a time.

Am I doing something wrong or do I just need to get used to this rolling back and forth?

FYI - Boat is a 27' Watkins, 7500 lbs displacement, 3500 lbs lead encapsulated keel with a 3'8" draft.

Thanks

 

[Ross]

The best I can suggest is shift to about 10 degrees off dead down wind

 

[thinwater]

The best I can suggest is shift to about 10 degrees off dead down wind

Yup. And rig a preventer; it may be smother by-the-lee.

Also, play with the trim; sometimes tighter or looser is the trick. Play with the vang. Play with the jib lead.

 

[JoeWhite]

The rolling is normal. What happens is when you are surfing down the wave you are moving at the same speed as the water. If there is not water going passed the rudder then you loose control. This is the same as drifting. So you can not change the direction of the boat. You can actually sail faster if you are at about 20 degrees off the wind and at about the same with the waves. Since you are sailing faster you will not loose control.

 

[gpdno]

Thanks for the advise. If it stops raining I may be able to get out tomorrow and try the suggestions. The "sunshine state" is a bit of a misnomer

 

[Don12364]

The Death Roll?

In the UK we call it the 'Death Roll'. Obviously an over dramatic title.

It is caused when running DDW and the upper parts of the mainsail sag away ahead of the mast. The wind then generates 'lift' driving the mast to weather when the rest of the rig is trying to drive it to leeward.
These opposing forces don't cancel out and a roll develops which only seems to get worse the more the helmsman tries to correct for it.
Laser and Finn dinghies also suffer from this.

A way of minimising it is to harden down on the vang to minimise twist in the sail and also to not square off the boom to dead abeam. The intention being to stop the top of the main going beyond 90° to the boat's centreline.

Of course Hunters with swept spreaders don't rarely into this situation.

 

[Bill Roosa]

Hey JoeWhite
The waves don't move the water sideways, just up and down. You are still moving through the water when surfing down a wave. Check your stern next time you surf, positive there will be a wake disturbance. Unlike when drifting and you get no wake disturbance.
I suspect the boat is close to pitch-polling. The sails are unbalanced (wing in wing but one or the other is not powered up for some reason, perhaps the main is shielding the jib), this causes a rounding up effect that is very pronounced, heels the boat over making the rudder ineffective as it is no longer vertical plane. If taken to extreme the rudder will cavitate the boat will spin on its keel, the wind will produce extreme heel and the next wave will cause a lot of problems.
The best thing to do in this situation (besides not sailing DDW, sometimes DDW is the only option) is to reduce sail or tow drag lines or a drogue to slow the boat

 

[bffatcat]

dead down wind sailing

In simple terms Sailing dead down wind sailing leaves the breeze directly from astern With no breeze on either port or starboard to prevent it the natural tendency of the boat is to roll.
The prudent sailor sails a few degrees off the breeze to prevent rolling and accidental jibing

 

[Stu Jackson]

Many folks sail with their mains out too far when going w-o-w. And if it's breezy and waves have built up the tendency of the boat to roll is caused by the waves not the sails. If you sail a little bit by the lee going w-o-w you'll get more drive. The waves usually cause the autopilots lots of grief unless you have a stronger below decks AP.

http://www.c34.org/faq-pages/faq-autohelmwacky.html

 

[Johnb]

Further to what Donalex said, when sailing dead down wind in a dinghy I always raise the center board. Without that "pivot" in the water the boat has much less of a tendency to veer off one way or another.

By the way death roll is not too bad a description for dinghys as I have experienced it - the more you jump about and steer the worse it gets until finaly you are swimming.

This feeds into the whole issue of full keels vs fins and "sea kindlyness".

I hardly ever sail dead down wind because if you are anywhere down wind from land the swirls and wind shifts just make it a PITA.

 

[Ross]

Some of the most difficult sailing I do is down wind into an opposing tide flow.

 

[Joe]

Try dropping the main, or centering it, and sailing with head sail only.

 

[Benny17441]

No need to get used to the rolling motion, just change course and avoid sailing DDW.

 

[Tree]

wondering....

Great advice here.... I too love to learn from others that have more experience.

So, if you steer 10 degrees off dead down wind, is there a preferable direction as to sail configuration..... main vs jib when wing on wing. It would seem that it would be better to have the main to lee and the jib would be slightly to weather..... but, maybe it's the other way around?