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-   -   Help - is my anchor chain 'big' enough? (http://www.trawlerforum.com/forums/s42/help-my-anchor-chain-big-enough-27428.html)

AlaskaDreaming 07-31-2016 09:16 PM

Help - is my anchor chain 'big' enough?
 
Hi All,

I am new to owning a trawler, having just purchased a 1982 42' KadeyKrogen. She is a big boat, that does take a lot of windage with a very high bow and lots of area to get blown around. Upon purchasing I noticed that the chain was pretty rusty - up to about 110' (looks very solid after that and it is 5/16" 3B chain). I assume rust up to that point is due to it being pretty old and likely of the 320', this is the part that got the most use. I was trying to decide whether to swap the chain end of end, putting the rusty end where it is unlikely to come out of the chain locker - or was considering getting a chain connector and just cutting off the 110' of rusty chain and replacing. While taking the chain out to get a better look - lots of folks offered opinions. One person said that for a boat that size I needed minimum 3/4"chain, and that 3B was not good enough grade - also that I needed a minimum of 300'.

Thoughts? Opinions? I was always under the thought that 3:1 scope on chain was sufficient and 5:1 in a blow ... this person said that for a boat this size 5:1 is minimum and 7:1 in a blow ... any thoughts on that??

Appreciate opinions :confused: :banghead:

dhays 07-31-2016 10:23 PM

I have a similar sized boat and it has 5/16 chain. I think it is sufficient, but who knows?

I have 300' of chain which would give me 7 to 1 scope in 40' and 5 to 1 in 60'. I think it is sufficient, but wouldn't want less given where I boat. I am not used to all chain rode so I like 5 to 1 scope. That is overkill for most situation I think.

Congrats on the KK. Nice boats.

drb1025 07-31-2016 11:17 PM

I have a 46 DeFever with 300' of 3/8 BBB chain that seems to work well. I think your size chain is good for your boat.

Xsbank 08-01-2016 12:28 AM

I have a 52' with 100' of 3/8" and 300' of 3/4" rope. I've only been anchored in 30 knots so far but it was fine.

Bay Pelican 08-01-2016 02:58 AM

If you were starting over or replacing the chain and / or windlass for other reasons I would suggest 3/8" BBB or 5/16" high test.

Bay Pelican, an identical Krogen 42 to your boat, has had 300 feet of 3/8" BBB for 20 years. Can't say whether or not 5/16" BBB would have been sufficient over the years. We have anchored in 54 knot winds and frequently in 40 knot winds. The windage on the boat is high.

With the amount of rust you have on the first 100 feet, and the location you are in, the PNW, you will be doing a lot of deep anchoring. Likely you will be replacing the chain in five or so years. If so then look at the cost of a new gypsy for the windlass and 3/8" chain.

By the way, I have substantially reduced rust by washing the chain and letting it dry whenever we haul out. The chain locker on a Krogen 42 would allow you to use a fresh water hose every several months while you are still in the water.

O C Diver 08-01-2016 05:25 AM

I can't answer whether 5/16 is adequate, for my boat (45' 40,000 lbs.) 3/8 was what it came with and feel very secure with it in high winds. Before making a decision, I would pull the chain out and examine the whole length. When doing that to mine, I found that the worst section was at the bottom of the chain pile where the chain sat in salt water drippings. Ended up loosing about 50' of chain because nobody ever flushed the chain locker with fresh water.

Ted

Steve Bedford 08-01-2016 08:11 AM

There are a number of factors that should enter into your decision (no particular order):
1. Working Load Limit (WLL) of chain:
HT chain: 5/16": 3900 lbs and 3/8": 5400 lbs
BBB chain: 5/16": 1900 lbs and 3/8": 2650 lbs
2. Size of the windlass gypsy. What chain will fit in the current windlass? Is a new gypsy a consideration?
3. Matching the WLL of the other components of the ground tackle (anchor, shackles). You do not want to create a weak link.
4. Quality nylon anchor rode can exceed the WLL of chain. Decide how much chain you really need. Chain should be used to minimize or prevent chaifing on seabed material. As long as the remaining chain is of sufficient length to be all that contacts the seabed and not nylon rode, removing the the rusty chain should not be a problem.

Steve Bedford

bayview 08-01-2016 08:30 AM

Do some research on chain links and gypsy. I think you will find that short link BBB was deigned to not kink and jam in the locker as the longer links may do.

djmarchand 08-01-2016 09:11 AM

As Steve just noted above, your 5/16" BBB chain had a wll of 1,900 lbs when new. Who knows what it is now, maybe 1,000 lbs. You can easily put 1,000 lbs of force on it in a blow with that boat.


My preference would be 3/8" HT chain and enough of it to have 5:1 scope in 95% of the anchorages, plus 150' of 3/4" nylon behind it. That of course will require a new gypsy and possibly a new windless.


Also what anchor are you using?


David

dhays 08-01-2016 09:41 AM

In looking at the working load of the chain, keep in mind that a chain hook will reduce the strength of the chain and thereby the WWL.

jleonard 08-01-2016 09:42 AM

Quote:

Thoughts? Opinions? I was always under the thought that 3:1 scope on chain was sufficient and 5:1 in a blow ... this person said that for a boat this size 5:1 is minimum and 7:1 in a blow ... any thoughts on that??
I usually go about 7:1 even if its calm. I have 5/16 BBB chain, the high strength 5/16 wouldn't feed thru the windlass.
FWIW I use a 35# Danforth high tensile as my main hook in L I Sound which is mostly heavy mud bottom.

Larry M 08-01-2016 09:52 AM

We have 300' of 3/8" G-4, HT and have never worried about the SWL. Enjoy the boat. :)

tinped 08-01-2016 10:31 AM

Dhays,dont forget the scope is measured from your bow pulpit,not the waterline,so your scopes are a bit off.

tinped 08-01-2016 10:39 AM

http://idealwindlass.com/ALL%20CHAIN%20.htm
here is a link to help out calculating you scope

koliver 08-01-2016 10:45 AM

AD:

You also need to consider the likelihood of high loading on the whole anchoring gear As your cruising waters are probably restricted by other factors to the protected waters of the south coast of BC, with the dreamed of trip to SE Alaska some sunny summer, you will not be exposed to 50 knot winds combined with a big surge. Without those risks, your choices will likely be more along the lines of what the boat came with. For example, mine came with a Lofrans Tigres windlass, hauling 5/16 chain, 200' long, backed by another 200' of 3/4" nylon. All of this has been sufficient for at least 2 trips from Vancouver to SE AK and 36 summers anchoring up and down the south coast.

Bay Pelican 08-01-2016 11:25 AM

Quote:

Originally Posted by dhays (Post 465428)
In looking at the working load of the chain, keep in mind that a chain hook will reduce the strength of the chain and thereby the WWL.

Dave

I am confused what do you mean by a chain hook and when is it used? I have seen chain hooks normally used as part of a shock absorbing system to keep te pressure off of the windlass.

psneeld 08-01-2016 12:33 PM

West Marine catalog.....


DescriptionWM Model #MFG Part #AvailabilityPriceQuantity*5/16" BBB Chain, Inside Link Length: 1.00", MWL: 1900lb., Breaking Strength: 7600lb., Weight: 1.1lb./ft.

Breaking strength....wayyyyy past my anchors best tested holding strength....

If ever in a hurricane....I will replace the chain...otherwise 1900 pounds working load will cover 99.9999% of my anchoring needs....even weakened 25% to 30%.....

If compromised past surface rust...I would replace or repair with a good connector link....guessing at that 25 to 30% while no beyond comprehension, isn't my cup of tea.

dhays 08-01-2016 12:43 PM

Quote:

Originally Posted by tinped (Post 465449)
Dhays,dont forget the scope is measured from your bow pulpit,not the waterline,so your scopes are a bit off.


Yup, you are right. I was just ignoring that in the post. I have my depth sounder give me the amount of water under my keel (rounded down by 6"). So I end up adding 10' to my depth sounder depth when figuring scope. This ends up being a conservative number.

dhays 08-01-2016 12:48 PM

Quote:

Originally Posted by Bay Pelican (Post 465464)
Dave



I am confused what do you mean by a chain hook and when is it used? I have seen chain hooks normally used as part of a shock absorbing system to keep te pressure off of the windlass.


Exactly. However tests have shown that the use of a chain hook reduces the working load limit of the chain that it is used on. Another way to look at it is that a chain hook reduces the strength of a chain much like a knot reduces the strength of a line.

Hawgwash 08-01-2016 01:55 PM

Quote:

Originally Posted by Xsbank (Post 465361)
I have a 52' with 100' of 3/8" and 300' of 3/4" rope. I've only been anchored in 30 knots so far but it was fine.

Quote:

Originally Posted by koliver;
Without those risks, your choices will likely be more along the lines of what the boat came with. For example, mine came with a Lofrans Tigres windlass, hauling 5/16 chain, 200' long, backed by another 200' of 3/4" nylon. All of this has been sufficient for at least 2 trips from Vancouver to SE AK and 36 summers anchoring up and down the south coast.

Were you two born with full on logic or do you work at it every day?

:thumb::thumb:


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