My catamaran defies the laws of physics

[davewtsnape]

Not unusual at all, even in mono-hulls. If it's wind over tide the wind can angle the hull or keels or rudder to the tide or vice versa. Boat then 'foils' upwind or uptide. Had it on my 37ft mono. Stranger things happen at sea.

[Old Swampy]

With little tide and moderate wind I've had good luck deploying a light anchor perpendicular to the main anchor/mooring rode. There needs to be a little tension on the rode to the small anchor. The scope doesn't have to be great.

[Cadence]

My dumb ass guess would be wind and a slack tide. A mono may bump a mooring ball or have the rode pass down the hull. A cat is going to eat them. An anchor Sally might help?

[Bulawayo]

A long bridle is preferred NOT a short one. Another often overlooked aspect is that you are anchored primarily with rode. You dont mention the type? Is it stretching and then springing back - and you witness the bounce back? Try more chain & 150-200% beam bridle (as someone else stated). Also what size of chain are you reliant on? We generally use 150% but our bridle can be lengthened to 200% of beam under adverse conditions. Despite our using all chain (with nylon bridle) we have experienced a few 'unusual' movements but can usually attribute the cause. Would be great to hear the outcome.
Best wishes.

Originally Posted by jvolpehoo

I have a Prout Quest 31 that often behaves in a baffling way. Has anyone had this experience:

1. At anchor, every other boat drifts back away from their anchor with the wind and tide. Mine goes inexplicably toward the anchor or drifts differently from the other boats. I'm using about 15 ft of appropriately sized chain spliced to a nylon anchor line.

2. At anchor, after pulling back and setting the anchor I later find that the bridal and anchor line are running taught under the foredeck directly under and behind the boat. Why would it take this attitude toward its anchor?

3. At a mooring ball I tried 25 of line with a bridal and wound up with the mooring ball banging into my hull. I started the motor twice to back away from the ball but the boat insists on returning to it repeatedly and stays there defying the tide and wind. I then tried using 2 - 15 ft bow lines, one to each forward cleat and for some reason the mooring ball again winds up banging into my hull...

must be a marine poltergeist!

[thinwater]

Why do people misquote just so they can correct? Everything I said related to the OP, which is the point most threads. If we broaden the topic to anchoring, we'll get lost for sure.

Longer bridles are better re. yawing. They will not make you yaw more unless you have a terrible balance problem you need to resolve and are on very short scope. In that case, they can give more slack to get yawinf started. This can happen on moorings, but using a long bridle on a mooring is simply a mistake. However, I did not say that I don't use a shorter bridle. In fact, I use 1:1 most of the time, and een less when on a mooring to avoid hitting the ball.

Sailing up because of yawing is a different, obvious case. If a cat is anchored by the beam it will dart all over the place, proving nothing, other than that mistakes were made.

Yes, wind against tide can be weird. I've ended up backwards, which is pretty comical. Normally, I'm just glad I'm on all-chain so I can't tangle.

Rode does not mean rope in any dictionary I have ever seen. Rode is the line, which may be either chain or fiber. Substituting "rode" for rope is sloppy nomenclature.

Definition of rode (Websters)

1. : a line (as of rope or chain) used to attach an anchor to a boat

[Cadence]

[QUOTE=thinwater;2277169]Why do people misquote just so they can correct? Everything I said related to the OP, which is the point most threads. If we broaden the topic to anchoring, we'll get lost for sure.

Longer bridles are better re. yawing. They will not make you yaw more unless you have a terrible balance problem you need to resolve and are on very short scope. In that case, they can give more slack to get yawinf started. This can happen on moorings, but using a long bridle on a mooring is simply a mistake. However, I did not say that I don't use a shorter bridle. In fact, I use 1:1 most of the time, and een less when on a mooring to avoid hitting the ball.

Sailing up because of yawing is a different, obvious case. If a cat is anchored by the beam it will dart all over the place, proving nothing, other than that mistakes were made.

Yes, wind against tide can be weird. I've ended up backwards, which is pretty comical. Normally, I'm just glad I'm on all-chain so I can't tangle.

Rode does not mean rope in any dictionary I have ever seen. Rode is the line, which may be either chain or fiber. Substituting "rode" for rope is sloppy nomenclature.

Definition of rode (Websters)

1. : a line (as of rope or chain) used to attach an anchor to a boat

I was going to jump in on rope, it is on the spool. Is it worth the worrying about?

[Cheechako]

Does your cat have more windage forward than aft? Maybe that would make it turn 180 on the rode...?

[Bulawayo]

Thinwater.....not certain as to whom you referring. Perhaps you are even correct regarding the terminology but Im sure you appreciate what that the term as used (including by myself) is in common use. Just look at: Selecting an Anchor Rode for Boats | West Marine
Language develops - typically look at the word 'gay' and how the use and meaning has evolved over the last 50 years or so.
I believe you shall find that many people when referring to anchor rode are describing what you refer to as 'rope'. Lets not descend into pedantics on this subject as this also is misleading.
As to whether a long bridle is correct or a short one then we are surely talking about average/typical use and not particularly about one aspect.
The US Coastguard have done many trials in this regard - and their findings generally relate to bridle lengths in relation to poor weather. I take my advise from them as I really am not particularly bothered about bridle length under benign conditions. You'll find exactly the same advise about bridle length regarding the use of a JSD.
Fair winds and best wishes to you and yours for the season.

Originally Posted by thinwater

Why do people misquote just so they can correct? Everything I said related to the OP, which is the point most threads. If we broaden the topic to anchoring, we'll get lost for sure.

Longer bridles are better re. yawing. They will not make you yaw more unless you have a terrible balance problem you need to resolve and are on very short scope. In that case, they can give more slack to get yawinf started. This can happen on moorings, but using a long bridle on a mooring is simply a mistake. However, I did not say that I don't use a shorter bridle. In fact, I use 1:1 most of the time, and een less when on a mooring to avoid hitting the ball.

Sailing up because of yawing is a different, obvious case. If a cat is anchored by the beam it will dart all over the place, proving nothing, other than that mistakes were made.

Yes, wind against tide can be weird. I've ended up backwards, which is pretty comical. Normally, I'm just glad I'm on all-chain so I can't tangle.

Rode does not mean rope in any dictionary I have ever seen. Rode is the line, which may be either chain or fiber. Substituting "rode" for rope is sloppy nomenclature.

Definition of rode (Websters)

1. : a line (as of rope or chain) used to attach an anchor to a boat

[44'cruisingcat]

Originally Posted by jvolpehoo

I have a Prout Quest 31 that often behaves in a baffling way. Has anyone had this experience:

1. At anchor, every other boat drifts back away from their anchor with the wind and tide. Mine goes inexplicably toward the anchor or drifts differently from the other boats. I'm using about 15 ft of appropriately sized chain spliced to a nylon anchor line.

2. At anchor, after pulling back and setting the anchor I later find that the bridal and anchor line are running taught under the foredeck directly under and behind the boat. Why would it take this attitude toward its anchor?

3. At a mooring ball I tried 25 of line with a bridal and wound up with the mooring ball banging into my hull. I started the motor twice to back away from the ball but the boat insists on returning to it repeatedly and stays there defying the tide and wind. I then tried using 2 - 15 ft bow lines, one to each forward cleat and for some reason the mooring ball again winds up banging into my hull...

must be a marine poltergeist!

Number 2 is wind against tide. The tide over the keels and rudders holds the boat on a heading and it sails forward on the wind.

Number 3 is pretty commonplace. We've only used public mooring for short stays, and when we do use a mooring we shorten up on it so the mooring float cant hit either bow.

You could try this with your bridle - shorten each leg of it so the float can't hit the opposite hull.

[Moontide]

Having the rode going aft is routine in the anchorage in La Paz Mexico. Strong current opposing wind. Current overpowers the wind so the bow points into the wind but the boat is down current from the anchor.

[Goosebumps]

Cats indeed challenge laws of physics! That is why we sail them! Down to OP's problem. Anchoring is a steep learning curve, less steep if one lives on the hook for most or all of the time. In my case since 2007 I have liveaboard on the hook only in a cruising zone that has all types of coastal anchoring situations. Small cruising cats, like mine of 34ft, have number of different hull types, have different windage depending on their design. I think my Catalac has more windage than most! This results in sailing on the hook. Can be very dangerous if anchor rode goes under hull, in between hulls.... The rode can wrap itself around saildrive, around ketch and rudders with serious consequences. So what to do to prevent this. First learn about your anchor spot choosen, how deep, what type bottom, tides. Consider for example anchoring on sloping bottom, imagine your cat sails at anchor and is likely to hit sloping bottom! There are too many varying anchoring situations to cover them all. It is important to experiment, observe, evaluate the different rode and ground tackle managing possibilities. Only experience, encountering a problem and having to solve it for your specific cat, will improve yoyr seamanship!

[mawtty]

How would your cat respond if you secured the anchor from the stern?

[Goosebumps]

Originally Posted by mawtty

How would your cat respond if you secured the anchor from the stern?

Anchoring from the stern combined with bow anchor in right circumstances can be right. However stern as only anchor point not advisable, the rode will tend to wrap around kedges, rudder, saildrive even prop with consequences thereof. The sailing on a stern anchor can lead to very unpredictable movement of the cat. The response of the cat to tidal movement and windage from stern only anchor won't make for secure anchoring. A cat is designed to be bow anchored using a bridle. I use stern anchoring in close to coast situations where I expect my cat to sit on bottom at low tide. Obviously it is better to keep cat in a controlled position for that, ie amongst fishing dhows in front of local fishing village. A bridle at the stern can be experimented with in conjunction with bow anchor bridle.