Catamaran Anchor Bridle Design

[JayH]

Originally Posted by Ben

@tomfl For simplicity I just use a fixed bridle, for which Outremer has provided padeyes. I thought most people were fine with this but would like to hear from others who also adjust each bridle leg in response to sea conditions.

Only on very rare occasions have I adjusted for sea conditions, and only in the Bahamas. I haven't seen that kind of requirement anywhere else in the Caribbean. When I did so, it was more than a few inches and I even moved the attachment of a bridle leg to the stern.

I often adjust bridle legs under other conditions, though.

Mooring balls. Some mooring fields have rules about how long your bridles can be. It kind of makes sense because it affects the swing radius. Also when slack, long bridles tend to get hooked under the ball float, which is a real pain. Third, long bridles can allow nasty ball floats to rub on the hulls, or worse, get caught on the outside of one of the hulls.

Chafe. When weather is bad I'll sometimes let out a little bridle length in order to move the chafe point on the chock and cleat. Maybe less of an issue with bowlines.

Emergency. I've never had to do this, but I don't like the idea of having to move the boat forward in order to release myself from my chain. Either because of extreme wind, or a boat dragged across my bows, or anything else that has never happened, I want to be able to cast off my bridles (with the option of tying on backup bridles before I do). I believe you would have to cut yours.

[tomfl]

Originally Posted by JayH

SNIP

Emergency. I've never had to do this, but I don't like the idea of having to move the boat forward in order to release myself from my chain. Either because of extreme wind, or a boat dragged across my bows, or anything else that has never happened, I want to be able to cast off my bridles (with the option of tying on backup bridles before I do). I believe you would have to cut yours.

Never thought about that but I like the idea of being to quickly release the bridle if necessary. While it might be easier to cut the lines with a sharp knife this is how my bridle is attached.

https://www.youtube.com/watch?v=2CLt4BEBMRk

[Perfect Ride]

Hello Ben.
Here are a few comments on what has worked best for me on a 44' cat:
- Use two independent lines from hull to chain with each side of each an eye splice. This removes knots and minimizes wear if knot would otherwise get exposed to coral bottom on shallows.

- luggage tag to the hull at just above water line. Eye is stronger than knot and no hardware against hull and cannot untie. Water line gives addl 42' of scope at 7:1 w 6' freeboard, great for reducing swing in tight areas.

- Two eyes at chain end are coupled with wichard D

- use fire hose or other protection around bridle at chain side to reduce wear on shallow coral or in the case of waterline attachment against anchor when hauled up. I have 1" around leading 6' of line (attached before making eye splaces) and a 4-6" hose around leading 2' of coupled eyes, all attached with stainless wire to bridle.

- attach to chain or rode with combo of dynema soft shackle and dynema loop. Loop is attached to chain or rode w prusik, adjusting number of wraps on conditions. No knots and quick to deploy and easy to make replacements.

- agree on the length though I go just a wee longer in practice.
This arrangement seems to last 1000-1500 days of anchorage between replacements. This in widely differing conditions around the world: bottom types, depths, sea states and winds.

Hope this helps.

[Jon Hacking]

Interesting analysis, Ben. Well done! I wouldn't use a bowline to connect to the pad-eye, as bowlines take 35% of the strength out of the rope. I'm sure you know of better knots.

Some things to think about (like you, I'm not trying to sell anything)

We use a chain hook that I've modified by grinding a bit away just before the tip of the hook. Then I use a tie-wrap (zip-tie) to keep the hook connected to the chain. The ground away bit prevents the tie-wrap from coming off accidentally. There's enough stretch in the tie-wrap to force it over the end of the hook to disconnect/reconnect it easily.

The chain hook is shackled directly to the thimble that forms the loop for my bridle (I use a double-figure-8 knot here). IMHO, you want to minimize the distance from where the bridle comes together to where it connects to the chain, to improve the centering action of the bridle. With knot, thimble, shackle & hook, I'm running about 15cm or 6".

We've recently decided to connect our bridle to the pad-eyes that take our water-stays to our prod (what would be the bottom of a bobstay on a monohull). This increases our effective scope, as the pad-eyes are near the waterline. The pad-eyes aren't quite as strong as our deck-mounted bollards that have always taken the bridle loads, but they're strong enough, with 4 big bolts into a big SS plate inside the hull. Anyone else trying this should check the strength of their pad-eyes. For shallow anchorages, we lift the bridle back up to our deck bollards, as we don't like the hook to drag on the bottom.

We use 1/2" 3-strand nylon. Yes, it's weaker than our 10mm chain, & I need to replace it every 4-5 years or so, but it gives us more stretch, so less snatch on the ground tackle. I have a spare one always ready to go. The bridle that came with Ocelot was 14mm double-braid. One afternoon in a surgy anchorage it parted with a sound like a rifle shot (& scared the kids we had on board at the time). Good stretchy nylon is definitely the way to go.

[Millerslocal]

Hi Jon, do you perhaps have a few pictures of your set up you could share?

[Jon Hacking]

Originally Posted by Millerslocal

Hi Jon, do you perhaps have a few pictures of your set up you could share?

MillersLocal, I don't think so. Problem is, we're always either at anchor or moving, seldom at a dock or mooring. And we only have internet for another few hours, then we're offline for ~2 weeks in the Ninigo Islands of NW PNG. But if you have questions about my explanation above, I'm sure others do as well. Lemme know & I'll try to clear things up...