Anchor riding sail for catamarans?

[Paul Howard]

My 38ft catamaran lies to the wind quite well with a bridle off the bows, sometimes I have to change the length.
A friend with a 40ft. cat said his lay quieter by attaching the anchor rode off one bow. He was well set up for it, cleat well forward, chafing strip, short nylon line attached to chain to quiet rumble transmission, etc. He claimed that by having the boat cocked to one side the wind steadied the boat and the longer diagonal across from one bow to the opposite stern slowed the movement in a rolly anchorage.

[jim King]

Just got back from 10 days in the Exumas in a Leopard 45. I found some anchorages a lot better than others. Had a sleepless night on the windward side of Rose Cay doing exactly as you mentioned. Should have gone to the leeward side. Like others have mentioned playing out more line on the bridals helped keep things in line with the wind. Some anchorages can be effected by the tidal changes and because most of the islands are not over 10 meters in protective elevation, the winds coming at you can shift a lot while at anchor. It could have been one specific anchorage that you experienced this and also the 28 knots of wind. It's probably too late to move to a more protected anchorage and you will have to hold position and try the aforementioned adjustments to the bridal. Also not a great time to start playing with a sail anchor in such a blow. If you aren't dragging I'd certainly hold tight where you are. a drogue off the back might also stabilize things a bit.
Be safe, be well

[meirriba]

Originally Posted by Mr B

I anchor off the centre cleat on my Cat, My Cat goes around in circles all night long,
Basically the same as a bridle off both bow cleats,
Occasionally it accelerates forwards till the anchor stops it, Clunk again,
I tried a stern anchor but it gets caught on the rudders, So I stopped using it,
Tied to a pier, Its racing backwards and forwards all night,
It slowly moves away from the pier, Then accelerates till the rear mooring ropes stop it dead in its tracks, With a bang,
I have tried various positions with the rudders, But that does nothing,
The one that really gets me, Is my stern likes to point into the wind,

Anchoring off the central cleat is not similar to an use of bridle....
It is an invitation for sailing in circles😁

[meirriba]

Originally Posted by Dave_S

Sorry for the dumb question, what is an anchor riding sail ?

and why do I feel like I'm going to regret the question ��

Nothing to be ashamed of...
A riding sail is a sail raised as near as possible to the stern of a boat, e.g. on the backstay of a single mast monohull or on the boom of the mizzen mast on a yawl rigged vessel.
As this sail pulls the stern downwind, it helps to keep the bow into the wind.

The OP asked how to rig something to that purpose on a cat - problem being lack of a backstay.

[parachute]

Riding sails are not used on anchors they are used on a backtay. I assume a cataraman has two if the riding sail is offset then it won't work.

[NevilleCat]

Originally Posted by parachute

Riding sails are not used on anchors they are used on a backtay. I assume a cataraman has two if the riding sail is offset then it won't work.

** sigh **

[Moontide]

Usually the longer the bridle the less swinging.



However, when a puff hits the boat will go aft lifting the chain off the bottom and when the puff ends the boat will surge forward as the chain drops back down. With lighter boats this can be very significant movement.


If the rudders are not straight the bow will go one way when moving backwards and the opposite when the boat surges forward.



On some moorings where you cannot really use a long bridle I just hang the mooring line off of one bow instead of tying to both bows.

[Djarraluda]

Originally Posted by meirriba

Nothing to be ashamed of...
A riding sail is a sail raised as near as possible to the stern of a boat, e.g. on the backstay of a single mast monohull or on the boom of the mizzen mast on a yawl rigged vessel.
As this sail pulls the stern downwind, it helps to keep the bow into the wind.

The OP asked how to rig something to that purpose on a cat - problem being lack of a backstay.

Use main halyard as a back stay, but problem is lack of a boom or something to attach clew outhaul to

[Jim Cate]

That’s only 14 knots, which is not that much. In steady winds with a decent V bridle from either bow you shouldn’t have any swinging troubles.

28 mph =~24 knots... still not all that much, but quite different from 14!

Jim

[boatman61]

Use a storm jib.. one clew at rear of boom, one on mainsheet to haul it up tight and the third with a line to tension/flatten it leading to a mast winch.

[owly]

The problem is the windage is on the same end as the anchor.... A riding sail brings the windage aft so a boat will lay to anchor without hunting constantly. I've read a number of accounts of people who swear by anchoring off the stern. At least one case where the owner attributes the survival of his boat in a storm to having been laying to a stern rather than a bow anchor....... It does make some sense.

[boatman61]

Originally Posted by owly

The problem is the windage is on the same end as the anchor.... A riding sail brings the windage aft so a boat will lay to anchor without hunting constantly. I've read a number of accounts of people who swear by anchoring off the stern. At least one case where the owner attributes the survival of his boat in a storm to having been laying to a stern rather than a bow anchor....... It does make some sense.

Huh..!!!!

[Chotu]

Ah HA!!!!

That’s why mine was basically winning the upwind leg of a regatta any time at anchor!!!

It would tear back and forth at high speed. It ripped port at a few knots, until it ran out of scope, then the rode would pull the bow around and it would tear across the anchorage in the opposite direction.

I had my boards up and rudders down.

I have a lot to learn about real catamarans. My old one was a lot like a monohull.

Originally Posted by thinwater

A bridle is nearly always all the solution that is required. A riding sail can help, but most cats already have a big hard top with a lot of windage aft. But there are lost more answers:

• Two anchors in a 100-130 degree V. No fore aft, but wide enough that they don't reset in a reversal. To avoid tangling, terminate the secondary rode to the main rode forward of the bridle apex (or at the apex--I made a special plate for this).
• Drogue from the apex. Slows yawing and surging. Just enough rope to keep it in the water.
• If you can raise the rudders (Gemini) raise them. Keep the boards down. If you raise the boards and keep the rudders down you ARE going to sail at anchor. No help for you.
• Hammer lock. Lower a second anchor or kellet until it just scrapes on the bottom (1.5:1 scope). Very effective, but do not use if there is sea grass or coral.
• Riding sail. If you must. The simplest AND most effective is a diamond of cloth rigged over aft 2/3 of the boom and sheeted outboard in a wide V, and then the boom is raised. 3-5 feet. Very strong, very effective. Single luff (traditional) riding sails don't work on multies.

Good luck.

[fxykty]

Originally Posted by Chotu

Ah HA!!!!

That’s why mine was basically winning the upwind leg of a regatta any time at anchor!!!

It would tear back and forth at high speed. It ripped port at a few knots, until it ran out of scope, then the rode would pull the bow around and it would tear across the anchorage in the opposite direction.

I had my boards up and rudders down.

I have a lot to learn about real catamarans. My old one was a lot like a monohull.

In order:

How long are your bridle legs? Increase to at least width of your beam (at the bows) per bridle leg. If you’re in a shallow anchorage and are worried about bottom drag of your bridle, you can use a small float to keep the bridle connection about a metre off the bottom.

Keep a deep loop of chain between anchor roller and bridle attachment point. This is one place where heavier lower grade chain is preferable to lighter higher grade chain. We currently have G40 and were thinking of upgrading to G70, but are rethinking that.

Lower your daggerboards - start with half way down.

Try one bridle leg shorter by 2+ metres. Though that might just keep you on a tack?

If you have a topping lift on your boom, or could use your main halyard, try a storm jib rigged with clew forward (sheet to your mast near your boom gooseneck) and tacked to the back end of your boom (if it’s on the centreline), otherwise to the bimini or rear beam on a strop.

[thinwater]

Drogues go on the bow, not the stern. I don't know how that meme started, but if you want to slow yawing you add underwater resistance FORWARD not aft. It will slow it aft, but it will work better forward. Try it.


[But honestly, if a drogue helps, you are already yawing way too much]