anchor rope ratings??

bobbo268

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Can someone tell me how to chose the correct anchor rope strength. So if a rope says it has a 380 lb strength, how big of a boat and how windy of a day will that handle, how about 500 lb rope, 700 lb, etc.... The reason I ask is because if you get "anchor rope" it costs you a fortune, but nylon rope, with some pretty high strength ratings, is usually more than half price. And the boats not hanging from the rope, so I guess i'm not sure how much force is actually being applied.

My specific application will be for a 17ft pontoon boat. It weighs 875 from the factory, add the motor, gear and 5 normal people, maybe 15 - 1800 total weight.

Thanks for any info.
 

Bifflefan

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Re: anchor rope ratings??

While I can not tell you any formula, any 3/8 rope of medium quality should do fine. Don't spend a fortune on it, go the TSC or a horse/tack sales place and get it by the foot.
I bought 200 ft at a horse shop (cant think of a better name for it) for 50 bucks, and it floats too. A chunk of chain on the anchor end and it works great.
Just remember the 10 to 1 rule. You need 10 feet of length for every foot of depth to get the very best hold. Now, does anyone live by that rule???? I think no.
 
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Chris1956

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Re: anchor rope ratings??

Floating anchor line is likely polypropylene, which will not stand up to sunlight. Normally you would want twisted nylon anchor line, as it has some stretch. 3/8" line is a good size, however, you are not buying anchor line only for strength. You want something you can handle comfortably, so thicker is better, even though the strength of the thinner line is adequate.
 

thumpar

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Re: anchor rope ratings??

How deep do you need to go? We use an elastic anchor line called an anchor buddy. It keeps the waves on the boat from pulling the anchor from the bottom. I think is stretches from 14' to 50'.
 

tpenfield

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Re: anchor rope ratings??

Anchor rode . . .

380 lb test versus an 1800 lb boat sounds OK . . . rode should be rated higher than the holding power of the anchor.
 

bobbo268

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Re: anchor rope ratings??

On the lake we go to max depth is 35 ft. What's the best knot to tie the anchor on with?
 

tpenfield

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Re: anchor rope ratings??

On the lake we go to max depth is 35 ft. What's the best knot to tie the anchor on with?

An "anchor bowline" of course :D . . . but you really want chain and a spice as stated instead of a knot.
 

Thalasso

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Re: anchor rope ratings??

Maybe this is getting to technical but gives you an idea

Nylon drops by 15 to 20% when it is wet, as compared to the catalog breaking strengths (which are dry rated). Second, when nylon is repeatedly cycled at a high percentage of its breaking strength, typically above 50%, it generates substantial amounts of internal heat. This internal heat degrades the structural performance of the nylon, by as much as half, and is thought to be a common cause of failure at high loads. This internal heating process is worse when the rope is wet. Third, when you consider the stretchiness of nylon it has much less chafe
chafe resistance than other materials such as polyester (Dacron).
There are no scientific rules for sizing anchor rodes. Everyone goes by experience.
Nylon's small advantage over polyester expands significantly when the stress is not steady, but applied in pulses. For shock jobs, nylon is significantly stronger.
The load is determined by the scope of the rode

Get yourself some nylon and go boating. 18 ft pontoon isn't going in nasty waters.
Remember the smaller dia of the line makes it tough on the hands when you pull it in
 
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bobbo268

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Re: anchor rope ratings??

Can I just tie directly to this type or should there be a chain?
river-anchor.jpg
 

oldman570

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Re: anchor rope ratings??

It is best to have a chain repair link and 3'of chain on the anchor, as rocks and other stuff on the bottom can cut the rope when it is spliced directly to the anchor. It also is flexible and adds weight to the rope and helps keep the anchor from pulling lose after it has set. The chain will help get the anchor lose if the anchor gets hung up in a submerged tree also.
JMO
Oldman570
 

dingbat

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Re: anchor rope ratings??

I've have witnessed #250 poly line break under the tension (shock) of a planer board, more than once.
 

Scott Danforth

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Re: anchor rope ratings??

if you're anchoring in 35' of water on a pontoon, your river anchor shown will probably not work well. your anchor rode should be a minimum of 5:1, preference of 7-10:1 in length. so you should have 250-350' of anchor rode. you do want a section of chain between the line and the anchor

if you are attempting to anchor in a high wind, a pontoon boat is a great sail, and wind load can be quite high.

I would recommend 3/8" rope at the minimum.
 

agallant80

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Re: anchor rope ratings??

Just remember the 10 to 1 rule. You need 10 feet of length for every foot of depth to get the very best hold. Now, does anyone live by that rule???? I think no.

I do. I want to be able to sleep through the night without worrying so I have an anchor that is rated for a 40 foot boat (my boat is 25). I always let out my 60 feet of chain them some additional line. I always shoot for at least 8:1 if not more.

My advice for anchoring is to get an anchor that is over sized for your boat, have at least 10 foot of chain and learn how to set it, throwing it over the side is not setting the anchor.
 

bobbo268

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Re: anchor rope ratings??

Thanks for all the info! I have a Danforth that I use off the front when swimming and that River anchor I use off the back along with the Danforth in front when I'm near the sand bar to keep my boat from spinning.
 

dingbat

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Re: anchor rope ratings??

My advice for anchoring is to get an anchor that is over sized for your boat, have at least 10 foot of chain and learn how to set it, throwing it over the side is not setting the anchor.
+1...
 

H20Rat

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Re: anchor rope ratings??

I do. I want to be able to sleep through the night without worrying so I have an anchor that is rated for a 40 foot boat (my boat is 25). I always let out my 60 feet of chain them some additional line. I always shoot for at least 8:1 if not more.

My advice for anchoring is to get an anchor that is over sized for your boat, have at least 10 foot of chain and learn how to set it, throwing it over the side is not setting the anchor.


Depends on your situation. If you are overnighting on a decent sized boat in water that can get a little squirrely, absolutely! Someone with a 17' pontoon most likely not anchoring in those conditions. I've anchored a larger pontoon with a rock tied to the end of a rope, with almost no scope. Worked perfectly for what it needed to at that time.
 
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