Swinging Or Sailing While On Anchor

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.

kartracer

Guru
Joined
Aug 5, 2014
Messages
529
Location
USA
Vessel Name
M/V LUNASEA
Vessel Make
45ft Bluewater Coastal
Was on anchor last weekend and boat would swing (I think some call it sailing) almost 90 degrees one way then go back the other way 90 degrees. Had a 4-5 mph north wind. What causes this? Is there a way to stop this other than a anchor off the rear.
 
Spring the rode, That means attach a line from a midship cleat to the rode and pull the boat a bit to the side.
 
Agree with bayview. Haven't experience the problem, but we don't anchor frequently. My hypothesis is that a substantial keel reduces continual boat swing.
 
Bayview - got the part about the midship cleat. But could you expand on the rode attachment? In my case (rope rode), when at anchor, the rode is secured to a king post at the bow. Where does the rode attachment occur? Is there a rule of thumb? Or just work with it until the ride settles out?

Would a prusik hitch be suitable to attach the spring line to the rope rode?

Appreciate the help.
 
Haul in 20 to 30 feet of your rode, attach a long line then let the rode back out and use the attached line to bring the rode towards midship. The boat will change angle to the wind/current. When in a good riding position cleat the attached line.

If the wind current is strong you may have to cleat the attached line before you let the rode out, or pull on the attached line as you are letting the rode out.

At times I have had to use the motor give me enough slack to cleat the attached line where I wanted it.

Because of the force of the wind/current, you will likely have to use the horns of your cleat to hold the attached line until it is cleated secure.
 
Thanks, Marty!
 
If there is current running put your rudder hard over. That may help too.
 
"I simply enjoy the constant change of scenery.:thumb:"


The hassle tho is the unending 90 deg pulls as the boat sails then snubs against the anchor.

The watch fob anchor folks may wish they went 50 lbs heavier .
 
Most of our power boats have many times the area above the water then below and that sail area with little keel area (compared to a sail boat) along with the blunt wide bow in relation to the length causes the sailing (swinging, kiteing) at anchor.

Without a stern anchor or a some kind of sail (acting as fins on an arrow) like a mizzen on a sailboat the only thing that can lesson it a bit is an offset anchor line as discussed above. Most steady sails are not mounted far enough astern to help much with this.

In a storm this kiteing can be severe and act to dislodge the anchor with the sharp side to side pulls, two anchors are called for in those conditions in my opinion.

I anchor away from sailboats and enjoy the view for the most part.
 
I have a rather large keel and it dosn't seem to reduce the sailing at all.
 
Many vessels prefer to lie broadside to the wind/wave pattern...both power and sail....

If aerodynamic is such a way that there is enough sail area forward of the point of lateral resistance, the bow will always tend to fall off and get tugged back around.

If there is more sail area aft...like feathers on an arrow or a vessel with a riding sail.....the vessel usually is ore docile at anchor.

Shape and kind of boat is still dependent on the stability issue...not just keel or any given above the waterline shape (to a point). Most all can be helped with a proper riding sail.
 
Yawning at anchor occurs due to a variety of dynamic forces acting on the vessel causing the vessel to fall in and out of balance with these forces. We tend to think of wind forces as homogenous in force and direction but this is never true for a boat whether on the hard, anchored, or in open sea. As psneeld points out, in open water boats will tend to turn broadside to the wind to a point where the center of effort (CE) aligns itself with the center a lateral resistance (CLR) and the boat heaves to and stays there until something upsets this balance. It should come as no surprise then when we anchor, we are in essence moving the CE so far forward the boat can no longer rotate to a naturally balanced position. The whole boat will now react to the varying loads by sailing forward, falling back, falling off and tacking continuously in a harmonic cycle. To better understand these forces, we need to consider the hull shape itself as a sail or wing which will always strive to balance high pressure and low pressure surfaces by creating lift. As wind loads increase, the boat is pushed back and one side will invariably experience higher wind pressure causing the bow to blow off to one side. Next the rode begins to apply a declaration force slowing this downwind drift until it stops and is overcome once again by a asymmetric lift forces driving the boat forward once again. If you want to stop this cycle then you have to either move the CE back to the CLR, or move the CLR forward to the CE, or some combination of the two. Think riding sails aft, or drouges on anchor rode's forward, otherwise enjoy the changing views.


Spell check via iPhone.
 
I have a rather large keel and it dosn't seem to reduce the sailing at all.

When our boat is anchored in a substantial current, I notice little to no "sailing." In slack water with substantial wind, have experienced some sailing of no more than 15 degrees to either side.

Haven't used my main/rear sail to steady the boat while anchored. It is located nearer the center of the boat rather than to the stern. The builder says the sail should be at an angle to the keel.
 
Lots of folks will use a breast anchor , usually to turn the boat from the prevailing breeze into an annoying swell.

At St Barts almost every boat uses the technique.

Perhaps a small anchor that keeps the bow at the far end of a swing would stop the swinging.

Beware in a crowded anchorage some fellow does not come so close aboard as to catch the line for the breast anchor.
 
I have a rather large keel and it dosn't seem to reduce the sailing at all.

Agreed. I watched a smallish (25-30') sailboat at anchor "steaming" back and forth across the anchorage all day. Essentially 180 degree turns at each end. I say steaming because that's what I thought they were doing at first, no sail up but moving at a pretty good clip.

I noticed it had all-nylon rode, not sure if that was a contributing factor. As a sailboat, I assume it had a decent keel, so clearly that didn't help much. There was some minor tidal current and very light breezes at the time. It looked like a pretty light boat. I suspect that contributes.

Mine will yaw at anchor, or on a mooring, in the right conditions. Especially strong currents. Sometimes adjusting the rode or rudder will help, although I haven't gone as far as bringing a line back to a mid cleat.
 
Could you use a sea anchor on the stern ??:hide:

As long as you remember to bring it in :)
 
Last edited:
In certain conditions our boat dances around at anchor, which doesn't bother me.
However - I do try to makes adjustments when the wind and swell are not aligned. I've had limited luck using my mainsail to stay pointed into the swell, as it is too far forward. A bridle arrangement between bow and mid cleat works, but needs frequent adjustment. I find the easiest way is to just use a second anchor off the stern. I rarely anchor with another boat, so there are no concerns about swinging together.
 
Could you use a sea anchor on the stern ??:hide:

As long as you remember to bring it in :)


It would also give you something to do in the morning, you could spend hours of delightful fun getting it out of the running gear. :D
 
Back
Top Bottom