Bridle Triangle Angles

[thinwater]

Originally Posted by promax

I guess I am showing my lack of knowlege here but....... what is a bridle actually do?

With a proper bridle, they are steady as a rock.

[Dudeman]

As a climber this is pretty basic knowledge when anchoring to two fixed points or in this case twin catamaran bows. These figures are from Mountaineering the Freedom of the Hills. Reducing the load and stress on each fitting is an advantage of using a bridle but if it's too short you're actually putting more load on each fitting.
Angle In Degrees/Force on each bridle strand or bow
0 50%
60 60%
90 70%
120 100%
150 190%
170 580%
Also having a bridle allows two points attached to the boat so if one chaffes through you still have another that will hold which leads to my number one rule when anchoring. If you don't get a warm fuzzy fealing when you drop the hook fix it until you do.

[sv_makai]

Originally Posted by thinwater

With a proper bridle, they are steady as a rock.

you can also shorten one side of the bridal to help offset any unusal winds water movement. Several times i found that it help steady the boat if the tidal movement was at odds with the wind.

Result. Steady as a rock!

[thinwater]

Originally Posted by markpj23

The bridle plate is a great idea, but isn't the weak point the caribiner? The specs on all of those I've seen are far less than a similarly sized galvanized shackle.....

...it does not need to be the same size. The hole can be drilled any size. The shackle and biner in the example are not the same size; they are sized to both have the same SWL, about that of the chain. Yes, the strain is lowered by the angle, but if waves are hitting from odd angles or if one side fails, the whole load falls on a single leg.

I thought perhaps I was not clear on this.

Simply my choises, my reasoning, and my experience. What I have presented was not my first aproach - it required a few trials. One size never fits all. The "correct" answers for my last cat were different. There are many factors to consider.

[thinwater]

Originally Posted by SettingSail2009

Last week my old bridle disintegrated and I need to make a new one. I've read through a lot of the bridle posts here, but I haven\t found exactly what I was looking for.

I have a beam of 7.42, but between the points where I will fix the bridle permanently I have about 7 meters. To give some quick specifications: I have a 43 feet catamaran weighing around 10 tons, a Rocna 33 anchor and all chain rode. I'm heading into the Pacific, so that's where I'll be doing all my anchoring soon.

I plan to make a bridle along these lines (which I found in another post on bridles):



The big difference will be that I have stainless steel thimbles where the bridle connects to my boat. They will be permanently attached there with a shackle on each pontoon.

Now on to my questions:

1. I hear a lot of different things about the length of the bridle on a catamaran. Some say it should be a 90 - 45 - 45 triangle, others say 60 - 60 - 60, some say the legs should be so short that the bridle doesn't hit the water, while others again say it should be as long as you can.
So now I reach out to all of you, which do you prefer ... and why?

2. How thick and which kind of nylon rope would you use for the bridle?

3. Would you make the bridle out of one long rope (like in the picture above), or out of 2 ropes that get shackled together right before the chain hook?

I appreciate any help.

111111

[Laidback]

Originally Posted by promax

what is a bridle actually do?

Simply put, the bridle when attached to the chain becomes a shock absorber between the boat and the anchor.
Another benefit is that it assists in preventing the anchor being dislodged when the chain is fully extended in a blow.
Yet another benefit when having the bridle in line stops the transmission of sound when the anchorage is made up of rock or other hard material - (allowing the person/s in the 'V' berth a decent nights sleep)
In boats that 'hunt' when anchored, the bridle may slow down that activity.

[Penelope]

Hi I dont have a Catamaran but I use a briddle on my Hans Christian I made this Chain grabber out of 316 stainless steel plate 3/8ths thick the keeper is also 316 stainless 1/8th thick Iwill never loose the chain no matter how crummy it gets.

[Dan Morton]

Hi cruisers,

I read the above post on bridles and was also interested if anyone has a catamaran on a swing mooring and what bridle shape do they use. I have a 38fit lightwave, the main problem being when the wind dies and a current pushes the boat over the bridle, with potential for ropes under hulls with fin keels, rudders and legs! So I am favouring short, but how short?

Thanks, Dan.

[fxykty]

Originally Posted by Dan Morton

Hi cruisers,



I read the above post on bridles and was also interested if anyone has a catamaran on a swing mooring and what bridle shape do they use. I have a 38fit lightwave, the main problem being when the wind dies and a current pushes the boat over the bridle, with potential for ropes under hulls with fin keels, rudders and legs! So I am favouring short, but how short?



Thanks, Dan.

Generally, just short enough so that the mooring ball cannot touch the other hull even at full extension 90* to the side. That should surely keep the ball (and lines) away from your hulls, rudders and props.

[thinwater]

Originally Posted by fxykty

Generally, just short enough so that the mooring ball cannot touch the other hull even at full extension 90* to the side. That should surely keep the ball (and lines) away from your hulls, rudders and props.

My feeling is that one size does not fit all. When on a mooring (rarely) I would shorten up as described above, and when anchored the bridle is longer. The short bridle does not control yawing as well or absorb wave impacts as well.