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tangentair wrote:. . . I am not sure in a marina where you are packed closer than at anchor if Frank's bridle is the best option, but it works at anchor.

Could the mooring dance be slowed by snubbing at the fore-quarter?

I'm not sure what dynamic is moving the boat on a mooring pendant, but I doubt it's the same forces as sailing (i.e., tacking) on the anchor rode. The anchor rode can simulate the swing of a long pendulum. That swinging motion is exacerbated as the wind follows the shape of the hull ... both sides of which resemble a sail.

I believe the boat could be resting motionless at the end of a 100' rode, and a 10 mph wind across either side creates enough "aero-lift" to pull the boat out sideways, until the wind-on-beam began pushes it back to the center .... whereupon, the wind lifts the hull to the opposite side. Rather than decreasing to zero speed, as happens in a gravity pendulum, this wind driven pendulum will continue as long as the wind velocity remains adequate.

• Do you think the hull on a short mooring tether would behave according to those physics???
• Regardless of that answer, if wind is simply pushing the boat from side to side ....
• Would snubbing at the fore-quarter prevent the wind from crossing the bow, catching the other side?
• Would snubbing at the fore-quarter cause that side of the bow to bump against, or ride-on the mooring ball?

I don't think the Mac is a fun place to be when you are moored on a ball with some wind and waves. This happened to me last year in the Vinoy Basin in St Pete and it was a nasty night. The bridle will moderate the swing somewhat, but it doesn't eliminate it. Although I've never tried a stay sail on the backstay like some of suggested, I've found the only way to totally quiet it down is to anchor off the stern as well as being moored to the bow. Of course, in Vinoy, I couldn't get a danforth anchor to set (must be why they provide the balls). If it is a completely waveless anchorage, then the swing is not so bad even if there is some wind, but throw some waves into it and it gets a lot worse fast.

I got duped that night because there was a nice light offshore breeze when i sailed in around sundown. The water was like glass. 3-4 hours later (around midnight), the wind did a 180 and picked up to 15-20 so lots of waves entered the basin, kids were asleep by then and it was too much hassle trying to move before morning.

Is it as simple as the fact that we don't moor our boats with the rudders down so the boat has no fin to stabilize in the current like most other boats?

no fin to stabilize in the current

Actually, we think it is a combination of the high sideboard that causes it to respond to even slight wind pressure changes down the sideboards so it wants to "sail" like any airfoil - and - the direction of waves and current. It happens with the boards down as well as up. All boats do this to some extent when on only one anchor in wind and waves, the extent that the MAC (and others) do it is a concern of some of us who like to eat (and hold it down), drink (and not wear the liquid) and sleep (in one location). I exaggerate but there are occasions when at a crowded anchorage where you can not use a stern anchor or Med mooring to a tree ashore, that it will be more than slightly annoying.

I've just left my Mac on a mooring ball, for the first time. Haven't spent any time on it yet. Had a look at some of the threads on this. Where I sail is heavily tidal, and the tide is usually a stronger force than the wind. Does Frank C's cunning bridle arrangement work when tide is the issue? Or does anyone have any other helpful ideas? REALLY simple explanations or photos greatly appreciated.

When I overnighted at Barnstable (west one that you named the one in the UK after) which is heavily tidal, I noticed no swinging - so my guess is the 'Mac Dance' is more of sail effect.

its dance is mainly tidal,the boat next to mine,a catalina,does the same sway,i tried a bridal but that made it worse

im going to try a bucket or some sort of sea anchor arrangement maybee chains,my problem is that my mooring drys out

We use a fender bridle floating next to the mooring ball--very easy to pick up. We drive past the fender and use the boat hook, unshackle the bow line and cleat the line to the bow cleat. If you are in severe conitions, run the bow line around the mast. The bow line painter is wrapped around a rubber snubber which mitiagtes the pounding.

I do not trust the bow eye.

I intend to get a riding sail the next time I win the lottery

Bob

this here is my mooring...the new dress is my imagination...

This is my answer to the ' problem'

not all that pretty...but pretty effective. The main shaft goes right through with a big backing washer and large nut..and all stainless...got it out of a rubbish bin some time back when a house was being emptied...Its not a commercial product but very well made...Sadly, I had to spend money on the nut and washer. Fitting it was another story.

Do a search on riding sails since I think their effectiveness as reported here was limited.

I throw a mushroom anchor off the back of Catigale at anchor which works well in sand or mud bottoms. I actually put a good cleat on the transom which also serves as a place to cleat off the tender. I put pictures up in the Mod forum IIRC.

Imagine that!! The post was called 'Tender and Mushroom anchor cleat on transom"

The mushroom off the back cleat...

How much line/scope with that?

Thanks,
Jim

I've seen those mushroom anchors in stores and figured they were a cute gimmick. Do they really have enough holding power to stop the swing?

And just out of curiosity...do you really want to stop the swing?

I guess it depends. But if the other boats in your area are swinging then maybe you should swing as well.

Is the purpose of the mushroom to stop the swing completey or to minimize the hunting?

Thanks,
Jim