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my boat dances on a ball

7K views 48 replies 27 participants last post by  downeast450 
#1 ·
Apparently my 46 Vision from Bavaria has a bad habit. She like to dance around on moorings.Not sure exactly what the deal is but she comes up on the ball. (long story, bought boat, put her in charter, so popular it's hard for me to get time). I'll be one her in two weeks. :D:D:D:D

Apparently running port/starboard line through pennant has been tried. setting helm hard port/starboard has been tried. Currently thinking a drogue , sea anchor.

any thoughts? I know, just run the engine all night and have it in a gentle reverse :cool:
 
#34 ·
My H-260 dances around the anchor like a stripper on a pole. So did my Mac-25 before her. it annoys me to no end but I have no way of stopping it since i have no real backstay to hank on a riding sail. Good news is its anchored in front of my house and therefor not in any danger of hurting itself or another boat.

Brad
 
#37 ·
Brad--

A riding sail does not need to be set on a back-stay. Take a look at Post #2 in this thread. A small Banner Bay Fin-Delta Riding Sail needs only a topping lift or halyard to set and will solve you problems. If you have a Bimini, a small spreader bar made of plastic pipe can be set up between the after guys and chafing gear wrapped around the guys where they might come in contact with the Bimini. On a boat the size of yours, you could likely use an old jib from something like a JY or Lido, picked up at a used sail dealer, set free flying and you'd be in business.

FWIW...
 
#35 · (Edited)
I found that our wind generator (FourWindsII) keeps the boat from sailing at anchor. It's mounted off the transom, far aft.

We sometimes use a riding sail (a.k.a. anchor sail) when the wind generator is secured. It also works perfectly for this.

Tightly furling the headsail doesn't make the problem go away on our boat.

And we often anchor with 2 anchors (Bahama mooring). That stops her from sailing at anchor when the boat is puling on both anchors. If the wind shifts, she starts sailing at anchor again.

I haven't tried it yet, since the riding sail and wind generator work so well, but a large bucket off the bow might work.

IMHO, for a rental, a (quiet!) wind generator would probably be the best option, since renters wouldn't have to deal with it at all. Other than that, maybe get an overly large dodger?

Regards,
Brad
 
#36 ·
Last night, a strong cold front passed over the Florida Keys, temperatures dropped like a stone and the wind suddenly went from nearly calm to 62 MPH, which was recorded at the local airport. I'm sheltered in the canal, and had the added benefit of a 75-foot motor yacht partially blocking the wind. However, a friend that is on a mooring ball in the middle of Boot Key on a 41 Hunter with a fin keel said the wind ripped through the area, his boat swung wildly on the ball, swinging 180 degrees, then whipped back in the opposite direction and heeled over sharply. He experienced a wild 30 minutes while the weather went nuts, followed by torrential rains that put four inches of water in my inflatable dinghy. Ironically, the boats in the harbor with full keels appeared to fairly stable.

Cheers,

Gary :cool:
 
#38 ·
I've attached mine to the topping life a few times, it worked great. Just hauled up the top end using the halyard, anchored the forward clew using a short length of line to one of the cleats on the boom. When everything was stretched tight, the boat immediately stopping swinging on the hook.

Cheers,

Gary :cool:
 
#39 ·
Hallucination – My wife and I are planning to cruise the Med and/or the Caribbean for a few years – a Bavaria Vision 46 is at top of our list at this stage. We have booked and are very much looking forward to a “test it out” cruise on your Hallucination. How, or have you, solved the “dancing on a ball” issue? Thanks very much.
 
#41 · (Edited)
Dancing at anchor or a mooring is a dynamic instability problem that can also be dampened by using a 'stout' bow eye mounted close to the waterline at the bow, or 'bridle' if the boats geometry can apply.
The lower the rode/pennant connection is to the boat waterline, most time will SIGNIFICANTLY dampen or stop the 'dancing'.

My boat is a 'avid dancer'. Since using such a 'bridle system', I no longer need to use an anchor riding sail.

Here's a diagram of what a mooring or anchoring bridle looks like. Note - the bridle has to be pulled 'fairly tight' to under the bow, and may need 'chafe protection'. Sometimes in roaring conditions I'll add a secondary/additional bridle from the midship hawse pipes to the bridle to rode connection under the bow:

 
#42 ·
what the big deal if the boat dances on mooring are you worried about it dancing on the ball when your not on it? i mean it shouldn't be a big deal of it going back and forth. We had a boat in the harbor that the guy left the rudder untied and the boat would go back and forth all day long for the whole summer
 
#46 · (Edited)
I think it's because the attachment point is more forward. By way of an absurd example, if we all had anchor rollers at the end of a 50 foot bowsprit, none of us would dance at anchor. The extra distance lets the tension from the anchor pull the nose into the wind better.

Just a guess. It might be more of an oscillation frequency thing.

Regards,
Brad
 
#44 ·
Smallboatlover, a boat dancing on the ball is a big deal for two reasons. First it is really unpleasant (I have experienced 120 degree swings heeling over 20 degrees on each side). Second, it can greatly contribute to dynamic forces on your mooring or anchoring gear increasing the chances that it will chafe, break, or drag.

billyruffn, I suspect that the answer to your question lies in geometry. Lines (and chain) can only apply a force in line with them. As your bow starts to fall off, some of that force becomes a restoring force to pull the bow back up into the wind and some holds your boat from moving backwards. With a bridle, the proportion of the restoring force is lower at first until the line goes against the bow and then it is equivalent to having the line over the bow roller. The worst is when you have it attached to only one side a few feet aft of the bow. Try this sometime and watch the geometry change as you swing one way and the line goes against the bow and the other and it stands straight out. Ideally, you would have the line attached to a point out in space that is far forward of the bow as that would provide the most restoring force. You should get similar results if you don't have a bowsprit if you pull the bridle up tight as described by RichH as with going over your bow roller. The reason that this is not an issue on cats with their bridles is that the angle is so wide on the bridle that the point where it meets is essentially fixed in space, the geometry never changes. I hope that this makes sense.
 
#45 ·
I'm happy to report that through several tweaks, we got the evil pole dancer off our boat.

1. Kill the dodger, biggest single improvement.

2. Asymmetrically set a bridle

3. set the boom askew, which helped in two dimensions
a. reduced the rigging humm (mast furl)
b. reduced the outhaul slap

4. kick down the Bimini in the last 10%

Now the rowdy little ****** is well behaved in 20+ kts. I'm sure if I really want to kill the prancy dancer, a riding sail would put the issue in the nursing home.
 
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