Anchor bridle length

[damianham]

Anyone any thoughts on the optimum length of the each bridle line as a % of boat width ?

[kmacdonald]

Originally Posted by damianham

Anyone any thoughts on the optimum length of the each bridle line as a % of boat width ?

2.5 times the boat width. That's what is recommended for a Jordan Series Drogue bridle.

[SailFastTri]

Originally Posted by kmacdonald

2.5 times the boat width. That's what is recommended for a Jordan Series Drogue bridle.

Of it's a multihull and your bridle is intended for use on a permanent mooring, in a crowded mooring field 2.5x might be too long. In that case each leg should still be long enough so the bow is at least 10 feet back from the mooring buoy. Longer if mooring spacing allows.

[damianham]

Sorry for the lack of specific details. The boat is a 14m wide catamaran and my question is related to anchoring not using a serial drouge.

Many thanks

[kmacdonald]

Originally Posted by damianham

Sorry for the lack of specific details. The boat is a 14m wide catamaran and my question is related to anchoring not using a serial drouge.

Many thanks

It needs to be at least 1.4 times half the beam to use the same size bridle as anchor line and maintain the same strength. Does that clear it up for you?

If it were me, I would use 2.5 times the beam for each leg of the bridle.

[belizesailor]

Originally Posted by kmacdonald

...
If it were me, I would use 2.5 times the beam for each leg of the bridle.

Whats the basis for 2.5?

I can see that for a drogue to absorb shock loads, but for an anchor bridle that would be crazy long. For example, a cat with a 22' beam = 55' ! Ive run a LOT of cats and never encountered a single one rigged like that.

[belizesailor]

Originally Posted by damianham

Sorry for the lack of specific details. The boat is a 14m wide catamaran and my question is related to anchoring not using a serial drouge.

Many thanks

14 meters wide, wow!

[Cheechako]

About 10 meters + tying room for a 45 degree angle to the chain hook. I'd go 15 meters each side of the double bridle.

[StuM]

It's all about trigonometry. If you used the suggested 2.5 x beam for each leg, the angle of the bridle leg would only be 11.5° from dead ahead. The bridle would be 70 meters long and the attachment point to your anchor rode would be over 34 meters forward of your bow. Effectively, it would be no better no bridle at stopping you from sailing around at anchor. And in many (most?) cat anchoring situations, your bridle would be constantly dragging around on the bottom abd being abraded. It wouls also provide two more lines in addition to the anchor rode which could to snag on obstructions. That suggestion is just plain stupid!

I'm with Cheechako. You need a bit less than the beam for each leg if it permanenty attached to strong points. If it is detachable and you need to secure it to cleats, them a bit more that the beam for each leg.

[wrwakefield]

Practical Sailor had a detailed article on this topic (including catamarans) in March-2016.

In case that is of interest.

Cheers! Bill

[kmacdonald]

I benign conditions anything will work. In storm or hurricane conditions 2.5 times the beam is what should be used. From the responses here it comes as no surprise that most people lose their boats (and often their lives) when anchored in hurricane conditions. There really isn't any excuse for it other than stupid.

[kmacdonald]

Originally Posted by wrwakefield

Practical Sailor had a detailed article on this topic (including catamarans) in March-2016.

In case that is of interest.

Cheers! Bill

Looks like they agree with me for the most part.

[StuM]

Originally Posted by kmacdonald

Looks like they agree with me for the most part.

Strange, I didn't see anything in that article on snubbers (as opposed to bridles) that agrees with you in any part.

You suggested a 70 meter total bridle for a 14m beam cat.

The article talked about "long snubbers" being over 20 ft (6 meters) in length and recommended:
"• Double-braid or brait nylon snubber length = 1.3 x boat length. For dynamic climbing rope, snubber length = 1.1 x boat length. These are minimum snubber lengths; longer is better, up to about 60 feet."

Your recommendation would give the OP 4 times that "up to about 60 feet".

[StuM]

Originally Posted by kmacdonald

I benign conditions anything will work. In storm or hurricane conditions 2.5 times the beam is what should be used. From the responses here it comes as no surprise that most people lose their boats (and often their lives) when anchored in hurricane conditions. There really isn't any excuse for it other than stupid.

I see from your profile that you sail a 22ft monohull.

How much experience do you actually have with anchoring a large catamaran using a bridle?

[kmacdonald]

Originally Posted by StuM

Strange, I didn't see anything in that article on snubbers (as opposed to bridles) that agrees with you in any part.

You suggested a 70 meter total bridle for a 14m beam cat.

The article talked about "long snubbers" being over 20 ft (6 meters) in length and recommended:
"• Double-braid or brait nylon snubber length = 1.3 x boat length. For dynamic climbing rope, snubber length = 1.1 x boat length. These are minimum snubber lengths; longer is better, up to about 60 feet."

Your recommendation would give the OP 4 times that "up to about 60 feet".

Where did I suggest 70 metes? I said 2.5 times the beam. I am guessing the 14m beam cat was a typo. If not it's totally out of our league to even make a suggestion for something that large. The rules of thumb would not apply. A bridle or a snubber would need to use the same design parameters for storm or hurricane force winds.