supermax

[patrick]

I just picked up a c38 which came with a 40# supermax anchor and a 40# bruce with 100' of chain and a shackle with stripped threads...we won't go there. Now that I'm down to to a supermax with no chain I was curious as to the reccomended amount of chain to use with this anchor. I've heard it doesn't need much if any -That sounds a little funny to me. If any of you WITH THIS ANCHOR have any input I'd be very grateful. Thanks, By the way, most of my bottoms are hard sand, soupy mud, or something in between! I'll also be using a 15# danforth with 20' of chain (which I'll be using for inshore situations) that has proven to be major overkill for my old 25' Hunter.

 

[txsailor]

My 2 cents.

I have heard as a rule of thumb you should have in chain at least half the length of your vessel. In your case that would be 19 feet. Me being me, I have always thought that if half the length is good, twice that must be better. I have usually used one foot of chain for each foot of boat. I have never had any serious dragging so it must be okay. But, there are others who will tell you that all chain is the only way to go. I'm sure we will hear from everyone on this question, and most will have differing points of view. My advice would be to read everones suggestions and go with what makes most sense to you. If you have problems dragging later, add some more chain until you find a good compremise between how well your anchor holds and how much chain you want to pick-up (and clean) everytime you anchor. Don

 

[Gord May]

Anchor Chain Length

Calculations for the optimum length of chain on a combined nylon chain rode are complex. Chapman’s recommends about one-half foot of chain for each foot of boat length, hence about 19' for your C38.Earl Hinze (“The Complete Book of Anchoring & Mooring”) recommends a WEIGHT of chain equal to the Anchor Weight, hence 40 Pounds of chain for your 40# Anchors (32 Ft. of 5/16" BBB @ 1.25#/Ft., or 27' of 3/8" BBB @ 1.5#/Ft.).William van Dorn ("Oceanography and Seamanship"), presents a graph based on calculations for anchoring oceanographic vessels in storm conditions. It suggests that the optimum chain/nylon combination for anchoring vessels < 50ft. in 30 ft. of water under storm conditions is a 20% chain, 80% nylon rode with an overall scope of 6:1.Chain is used between the anchor and the nylon line for abrasion resistance, and to keep the pull on the anchor shank more parallel to the seabed during the initial set, and under lighter loading. These advantages of chain rapidly diminish as wind loads increase. Once the chain is straightened out (probably at wind speeds of 30 knots or less for many sailboats), it’s off the bottom and providing little catenary or chafe protection. Indeed, a straight chain has no elasticity, so increases shock loading on the boat and hardware, and jerk-out shock on the anchor. With all-chain rodes, it is critical that a rope snubber be employed to provide the stretch that the chain lacks. Snubbers insert a shock absorbing action that protects the deck gear and anchor from sudden overload.So unless you require extraordinary chafe-resistance (rocky or coral bottoms), you may chose to select a minimum length of anchor chain. One of the subjects that seem to dominate cruisers’ cockpit discussions is anchors and anchoring. With the possible exception of the integrity of your vessel’s watertight hull, nothing will impact the comfort, safety, and security of your life afloat more than your ground tackle, and the manner in which you deploy them. The more experience we’ve gained, the more apparent it became to us that there are as many ways to successfully put a cruising boat together, as there are boats and crews out there doing it. I think you’d be safe using anything between 20 to 40 Feet of chain on your 38 footer, anchoring over sand/mud. I don’t think the anchor type (Bruce, Supermax, whatever) is as significant a factor as anchoring depths, bottom types, & etc.FWIW,Gord