Sizing Chain... Again

[natew]

Hate to ask this but i've spent the last two hours searching and cannot find an answer. Everyone seems to talk about these magical equations and tables for calulating working load based on windage, weight, etc but for the life of me I cannot find them. And it seems from what I read I am stuck deciding between 5/16HT and 3/8HT but am not sure.

I'm going to be buying a new windlass, anchor and chain very very soon so I want to get this right. Currently I believe we have 5/16HT and it has worked great but we don't anchor out very often in rought conditions so who knows?

We currently weigh in at 22,000lbs, are 38ft long and 22ft6" wide.

Any suggestions? My head is spinning from all this. We'll be cruising, hopefully, everywhere but mexico and south is a good starting point. Actually I don't want suggestions, my credit card number is 1234 and my address is over that way please just send me something that'll work! Thanks!

[Paul L]

5/16HT will work fine. Now worry about how long.

[roverhi]

At 22,000# you're at what I'd consider the limit for 5/16" G40 chain. We had about your displacement with 3/8" HT chain and it felt good to have the extra weight on the bottom. Not necessarily good to have the weight in the bow with the anchor up, however.

[sparrowhawk1]

Quote: We currently weigh in at 22,000lbs, are 38ft long and 22ft6" wide.



One of these numbers does not belong. On my 39 foot sailboat I went with three eighths mostly because chain wears. When it comes down to something that is this critical to the safety of my vessel a few hundred dollars is well spent. And I've always kept the weight out of my bow so that I could have heavy ground tackle

[GordMay]

I’d think that 5/16" G40 HT chain, rated ±3900#, should be adequate for your boat’s storm anchor.

Note: Strengths may vary by manufacturer; check with manufacturer regarding actual strengths.

See ABYC “H-40" Tables 1 & AP-1.

here ➥ http://mantusanchors.com/wp-content/...13/11/H-40.pdf

or ➥ Design Loads for Deck Hardware - ABYC Section H-40, table 1 Cruisers & Sailing Photo Gallery

and ➥ WLL for Anchor Rodes - ABYC Section H-40, Table 2 Cruisers & Sailing Photo Gallery

[sailorboy1]

5/16 G40 chain is fine

[barnakiel]

I would use 5/16 but a grade higher than G40. Read Dashews on this.

How long a piece depends only on how much rock and coral you are going to face.

We traveled rtw with a 60' piece spliced with 1/2 dacron rope. No issues ever. Now we are on a 100' piece with 1/2 dacron rope and it feels even better. We also upped our hook from top of the proper size slot to a notch above what was recommended. There is a notable difference.

From my experience with more vs. less I can tell more is more comfort, boat sailing to and fro less and staying closer to where you dropped the hook. But sure on a tri you are limited by weight.

Cheers,
b.

[natew]

Originally Posted by sparrowhawk1

Quote: We currently weigh in at 22,000lbs, are 38ft long and 22ft6" wide.



One of these numbers does not belong.

I've measured beam and length myself. The weight comes from the travel lift the last time it was hauled, I know that they are not the most accurate but I took it to be accurate enough and really the only weight measurement I have for the boat. Of course according to the plans she is supposed to weigh in at 9000lbs but I think that is a measurement just accounting for the hull itself. And with a mini-keel instead of dagger boards i'm wondering if I don't have some small amount of ballast.

[natew]

So.. If I go with 5/16 one grade higher will I have windlass problems? I've read that the link lengths can vary and that typically you want to purchase the windlass type chain as some of the others may not work so well...

On length, i'm going with 300ft I think. Though I'll probably be buying a barrel of 550 for the cheaper per foot price and seeing if I can sell off the other 250ft.

[Terra Nova]

300' of 3/8" chain will bury that tri.

[Cheechako]

Of course it depends on where you plan to go, but I would go with 200 ft and back it up with nylon. 300 ft is going to be a big load for sure. I'm surprised your tri is 22000 lbs... that sounds like a mono!
Everything is a compromise, the higher test chain you go with, the more it is prone to rusting. BBB less prone than G40, G40 less prone than G70 etc. Not that you should decide based on that. Rusting only usually occurs on the ends (for some time anyway) and you can cut a foot off.
If you hadn't mentioned your weight I would have said 5/16 G40... not sure now.

[natew]

Yes.. I was shocked at the weight as well as the design specs say 9000lbs... How much off can a travel lift scale be? Also considering that it was the extra large 150ton travel lift or something. Maybe one of those cases where accuracy is way off when you are on the lighter end? I know my home body weight scale has a hard time accurately measuring anything under like 10lbs. <shrug>

I do question the accuracy of that measurement because if I were to give you my engine HP, prop diameter and pitch and tell you I can do 8 knotts at 2600 RPM you'd call me equally insaine. Either that or I have some magical boat capable of defying the laws of physics.

Is there any easy way to calculate displacement on my own based on the water line?

[sailorboy1]

you are just going to make yourself insane

The 5/16 G40 chanin is enough. You will probably rip out a cleat etc before you would ever break (assuming the chain isn't 15 years old and all rusted up).

[a64pilot]

Originally Posted by natew

Yes.. I was shocked at the weight as well as the design specs say 9000lbs... How much off can a travel lift scale be?

Quite a lot I bet, are those things ever calibrated?

Someone smarter than me could calculate your weight based on waterline, way smarter than me.

Now that I think about it, if your weight was supposed to be 9000 lbs, if you weighed 22,000, I bet your waterline would be so far off, you would have questioned what was going on on launch, is your draft close to spec?

[natew]

Originally Posted by a64pilot

Quite a lot I bet, are those things ever calibrated?

Someone smarter than me could calculate your weight based on waterline, way smarter than me.

Now that I think about it, if your weight was supposed to be 9000 lbs, if you weighed 22,000, I bet your waterline would be so far off, you would have questioned what was going on on launch, is your draft close to spec?

Spec draft is 27" (but does not include the mini-keel), I approximated the draft while it was out of the water including the mini-keel at around 40", I would say the minikeel is probably about 12" so that would put my draft around 28" to compare by posted specs. Give or take an inch or two.