Sailing on a mooring

[billwa]

I have bought a new catamaran after years of a monohull ketch. The damn thing does not like to sit nicely on a swing mooring, but seems to try to sail forward a bit to port, drop back, sail forward to starboard, fall back.

The neighbours complain that my boat is "hunting" on the mooring.

What causes this, and is there a way to stop it?

[vida nueva]

You are running mooring lines out from both bows, right. And you can play with the length of those lines for stabilization.

Unless you have rock steady wind and current some lateral hunting is to be expected on any boat, but a catamaran should generally do better than a monohull if set up as above IMHO.


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[billwa]

Originally Posted by vida nueva

You are running mooring lines out from both bows, right. And you can play with the length of those lines for stabilization.

Unless you have rock steady wind and current some lateral hunting is to be expected on any boat, but a catamaran should generally do better than a monohull if set up as above IMHO.


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Nope - just one line to the centre of the two hulls.

[UNCIVILIZED]

Do you have the vessel moored via a bridle? Boards & rudders, up or down? And how much tide exchange & wind are we talking about?


Odds are, what's causing it is the boat's windage is so great in comparison to it's underwater profile, that the wind's causing it to sail on the mooring.
A bridle should help this, & unless you have big tidal shifts where you are, boards down may help also.
Plus you might consider a small riding sail in light to moderate conditions, & or trailing a small parachute anchor off of the stern.


Though it'll be easier to diagnose when we know the answers to the questions above. In addition to perhaps, the boat's make & model.

[boatman61]

Originally Posted by billwa

Nope - just one line to the centre of the two hulls.

You need a line from each bow.. make up a bridle.. longer the better...

[zeehag]

friend of mine has a 55 ft tri on a mooring--he has a line from each outer ama to the ball and a preventer on th e main hull bow. somehow it works. doesnt have the slam against the ball many boats experience and doesnt yaw on mooring.

[meirriba]

Originally Posted by billwa

Nope - just one line to the centre of the two hulls.

A bridle (two snubbers) from both bows connected to one central line that leads to the mooring will diminish the 'hunting'.
Nothing will eliminate it completely except perhaps a second, stern, bridle with central line connected to a stern buoy.

[MIRELOS]

Two years on a mooring, including a hurricane and not a problem.
You need a bridle!

[StuM]

Bottom line: Never moor or anchor a cat on a single line. Always use a bridle.

[smj]

Originally Posted by StuM

Bottom line: Never moor or anchor a cat on a single line. Always use a bridle.

This doesn't always hold true. Our old Cherokee 35 would sit about 15 degrees of the wind if anchored or moored of one hull and wouldn't hunt. This held true with winds up to 60-70 kts.


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[meirriba]

Originally Posted by smj

This doesn't always hold true. Our old Cherokee 35 would sit about 15 degrees of the wind if anchored or moored of one hull and wouldn't hunt. This held true with winds up to 60-70 kts.

The single line discussed was supposed to be connected to the middle of the boat. While connecting it through a single bow you will certainly reduce the yawing but it is still, in my opinion, not the best choice, which is, again - in my opinion only) - a bridle.
Sitting on one line attached to one bow, introduces an angle between the rode which my be beneficial if the waves come from this direction (where the bow now points), i.e. wind and waves are not aligned.

[smj]

Originally Posted by meirriba

The single line discussed was supposed to be connected to the middle of the boat. While connecting it through a single bow you will certainly reduce the yawing but it is still, in my opinion, not the best choice, which is, again - in my opinion only) - a bridle.
Sitting on one line attached to one bow, introduces an angle between the rode which my be beneficial if the waves come from this direction (where the bow now points), i.e. wind and waves are not aligned.

Totally understandable. With the Cherokee it didn't matter wether she sat on a bridle or anchored of one bow, she didn't yaw either way. You're right, we did use the attachment on the bow to angle the boat into the waves and also to direct the breeze to our stateroom. When on a Bahamian moor we would run both anchors of the same bow. A major advantage to me was if we dragged anchor there was no bridle to contend with.


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[admiralslater]

All the multihull in our club (35) all use bridles, even tris. Not all the bridles are long and none hunt. All boats are on moorings. Look up tmcc on Google