Proper conservative chain length for 39’ catamaran

[Brassmonkeys]

The catamaran is 39’ and between 8,800 and 10,000 displacement, 18 beam

I am thinking 150 feet of 7/16 chain and 250’ of a good quality nylon attached to a 45lb anchor.

I am inheriting a 33lb anchor with about 50’ of what I assume is 3/8 chain.

Would love to have a good quality anchor setup for piece of mind at night knowing I already have a decent backup anchor. Do you think this set up is okay?

[s/v Thea]

7/16 is heavy chain, 5/16 HT would be conservative.

[rslifkin]

5/16 G43 is plenty strong for that boat. How much chain length you need will depend on where you intend to travel. For many places, your planned 150 ft of chain + 250 of nylon will work nicely. Some areas may favor more chain.



I'd probably go bigger than 45 lbs with most anchor designs due to windage on a boat like that. Maybe something in the 55 lb range.

[Tomodore]

Where your cruising grounds are makes a difference. Tropical with coral heads and exposed anchorages or sticky mud with protected anchorage as much of Pacific Northwest. It's tempting to get something that works for multiple areas and depending on your timeline that may make sense. We sail a 34' monohull and went from 50' 5/16 chain and 200' 5/8 nylon with 33#Bruce to 250' 5/16 chain and 100' nylon and 55# Rockna when we traded Pacific Northwest for Mexico.

[chris mac]

Our 42' cat, 16,000lbs has 300 feet of g4 5/16 chain. I've never used more than 150 feet, but so far only in the shallow banks of bahamas. Previous owners circumnavigated with bbb 5/16
7/16 seems overkill to me, and alot of extra weight

[StuM]

Originally Posted by Brassmonkeys

The catamaran is 39’ and between 8,800 and 10,000 displacement, 18 beam
I

First question: pounds or kilograms (or firkins )?

[sailorboy1]

Originally Posted by Brassmonkeys

The catamaran is 39’ and between 8,800 and 10,000 displacement, 18 beam

I am thinking 150 feet of 7/16 chain and 250’ of a good quality nylon attached to a 45lb anchor.

I am inheriting a 33lb anchor with about 50’ of what I assume is 3/8 chain.

Would love to have a good quality anchor setup for piece of mind at night knowing I already have a decent backup anchor. Do you think this set up is okay?

I understand the question and think that is a good conservative setup, but would upsize the anchor.

[TrentePieds]

And make sure to specify whether it's a "beer firkin" or a "wine firkin" as the wine firkin is nearly 8 times the volume of a beer firkin :-)!

TP

[AJ_n_Audrey]

As others have noted, 5/16 G43 is plenty for your boat. I have been doing calculations in anticipation of replacing my windlass, and I confirmed that via my own research and from the boatyard owner's confirmation.

[kas_1611]

40ft mono with 60m 8mm G70 spliced to 40m 16mm Octoplait and a 33kg anchor. The anchor is oversized but the 16kg one we had before was undersized so 20-25kg would be a good range unless.

Length of rode is determined by where you might be anchoring. 100m of rode at 5:1 for the mixed rode I have allows me to anchor safely in 18.5m of water (1.5m WL to bow roller) but also to ride out a storm in 8.5m at 10:1. And to stern to moor into a town wall with plenty of scope out (I've had 85m of it out in 3m of water in one harbour at the request of the harbour master).

[joelhemington]

Originally Posted by Brassmonkeys

The catamaran is 39’ and between 8,800 and 10,000 displacement, 18 beam

I am thinking 150 feet of 7/16 chain and 250’ of a good quality nylon attached to a 45lb anchor.

I am inheriting a 33lb anchor with about 50’ of what I assume is 3/8 chain.

Would love to have a good quality anchor setup for piece of mind at night knowing I already have a decent backup anchor. Do you think this set up is okay?

Where do you plan to sail - this will make a big difference in how much scope you need. If you go upping the chain size, you may find yourself replacing the gypsy on your windlass - maybe even the haws pipe.

[Tupaia]

Good discussion here in the Multihull section.
https://www.cruisersforum.com/forums...at-247492.html

[BillKny]

Your anchor is-by far-the weak link your set up.

Stick with the 5/16 HT chain as has been recommended, you will save enough weight that you could go to a 55 lb anchor, have less total weight on the boat, and actually stay put in a serious squall.

That would give me a setup I could sleep with on that boat when the T-storm rolled through with 60 knots gusts at 2AM.

[jim King]

33 lb seems light for a 39' cat. or did you mean kg? I have never looked at my anchor in a blow and said, "oh, that's too heavy" Your cat also has much more windage than a mono hull and will require a heavier anchor. As for length of chain and rope, I think your suggestion should cover most anchorages.

[Sailorman Ed]

Your anchor is-by far-the weak link your set up.

Stick with the 5/16 HT chain as has been recommended, you will save enough weight that you could go to a 55 lb anchor, have less total weight on the boat, and actually stay put in a serious squall.

We have a 39 ft cat, 12,000 lbs, 165 ft 5/16", 180 ft 8 plait and 55 lb Rocna. Works great for us.