anchor

[cunuck]

I'm changing my anchor to a bruce claw type for my 2400scr and I think 16lbs would work but others say 25 lbs would be better also I have 50 feet of 5/16 chain .I will be boating in vancouver bc and around.I think I will get the lewmar 1000 to lift it.any advice thanks

[seapuppy]

you might be doing a bit of overkill....get the lewmar 700......I've owned 2 and they are really nice windlass's....25ft of chain is more than plenty...usually for your size boat most people only use about 6-10 ft of chain....then 250 ft of rode...
as for anchor...18lbs is plenty if your using the claw type..the key to good holding is the chain.....so..with that said...the 25ft of chain would provide plenty of bottom holding by keeping the claw type of anchor pointed downward...

just my thoughts...

SP

[shrew]

I'm a fan of a slightly larger anchor, slightly larger guage and length of chain and a slightly larger anchor line. I like to look at the recommended size charts and go up one size above the size of my boat. Here is a chart on recommended anchor size and rode based on boat size/weight. (Note the boat size and weight on the chart. I would go by the weight of the boat, not necessarily the size. In the chart it shows a 25-30 ft. boat with a weight of 5,000lbs. My 28 ft. weighs 8,000lbs and that is not counting the gear and people. In this chart, I use the weight of the boat instead of length):

Anchor Weight Guide:

BOAT SIZE ANCHOR WEIGHT
Length(ft) Weight(lbs) Bruce(lbs) Danforth*(lbs) Fortress(lbs) Plow(lbs) Yachtsman(lbs)

20-25 2,500 4.4 8-S, 5-H** 4 10 15
26-30 5,000 11 13-S, 12-H 7 15 25
31-35 10,000 11/16.5 22-S, 12-H 7/10 20 35-40
36-40 15,000 16.5 22-S, 20-H 10 25 50
41-45 20,000 22 40-S, 20-H 15 35 65
46-50 30,000 22/44 65-S, 35-H 21 45 75
51-60 50,000 44 85-S, 60-H 32 60 100

Anchor Rode Guide

BOAT SIZE ANCHOR RODE
Length (ft) Weight (lbs) Chain (dia.-inch) Nylon (dia.-inch) Length (ft)

20-25 2,500 3/16 7/16 90
26-30 5,000 1/4 7/16 135
31-35 10,000 5/16 1/2 190
36-40 15,000 3/8 9/16 225
41-45 20,000 7/16 5/8 240
46-50 30,000 1/2 11/16 315
51-60 50,000 9/16 3/4 360

*Danforth is a registered trademark. Similar-style anchors may differ significantly in
performance. **S indicates standard anchor; B indicates high-tensile anchor


Alternate Recommendations for calculating Chain rode:

Light Medium Heavy 3-Strand Nylon Chain
26´-30´ 23´-27´ 21´-24´ 3/8" 3/16" PC
31´-35´ 28´-32´ 25´-28´ 7/16" 1/4" PC
36´-40´ 32´-36´ 29´-32´ 1/2" 1/4" PC
41´-45´ 37´-40´ 33´-36´ 9/16" 5/16" PC/BBB or 1/4" HT
46´-50´ 41´-45´ 37´-40´ 5/8" 5/16" PC/BBB/HT
51´-60´ 46´-54´ 41´-48´ 3/4" 3 /8" PC/BBB or 5/16" HT
61´-70´ 55´-63´ 49´-56´ 7/8" 1/2" PC or 3/8" HT
71´-80´ 64´-72´ 57´-64´ 1" 5/8" PC or 1/2" HT



There are two basic 'schools' on measuring length of chain:

Chapmans: Boat LOA/2 = length of chain
-> Using this calculation a 24 ft. boat would use approx. 12 ft. of chain. I still go a bit higher. My 28ft. boat has 20
ft. of chain, while this method would only warrent I use 14ft. of chain.

Earl Hinz Method: Weight of anchor + weight of ground tackle (shackles, line, etc) = Length of chain
-> This method requires that you calculate the weight of the chain per foot. For example: If you have a 7-lb.
Fortress aluminum anchor with a 1/2” twisted three-strand nylon rode, you would need to use at least 11.2 lbs.
of 5/16” proof coil chain, which weighs 1.15 lbs. per foot. Therefore, you will need at least 9’8” of chain.


We need to keep in mind that these are averages and will vary based on depths, bottom conditions, wind and current. since the chain is meant to be part of the anchor, not part of the rode. It lays across the bottom inline (hopefully) with the anchor line. When the boat pulls, it is really lifting the weight of the chain, and transferring very little force on the anchor itself. The shorter the rode paid out, the shorter the chain and the deeper the water, the more force will be placed on the anchor. This only really matters when the wind or current kick up. The higher the wind speeds, the more anchor rode and chain you'll need to maintain the same holding.

When you see boats blowing around the anchorage at night, it is most likely because they underestimated how much line needed to be paid out. It is also likely they are using undersized chain, chain that is too short and an undersized anchor.

My 28 ft (8,000lbs) is using a Fortress FX-11 (Danforth), 200ft. 1/2" braided line and 20ft. of 5/16" chain. However, I also keep a spare 150ft. of 1/2" 3-strand twisted in the anchor locker for safety. I also have a second 7lb Danforth with 10ft. of 1/4" chain and 150ft. of 5-16 braided line that I use as a spare anchor and a stern anchor.

[shrew]

I guess the formatting didn't get retained during the post. Sorry about that. Here are some other good links for reference:

http://www.boatus.com/boattech/casey/34.htm

http://www.boatus.com/boattech/anchorin.htm

http://alain.fraysse.free.fr/sail/rode/rode_b.htm

http://www.commanderbob.com/art40.html

http://www.cncphotoalbum.com/technical/anchorguide.htm

[Tommyfmu]

Our experience having a 2400SCR as well, trying out an 8 lb Danforth and 8 lb plow, was that neither would hold, and both let loose many times under mild conditions.

We stepped up to a 16 lb Danforth super Hooker and it's great; holds tight under high winds; problem solved, and well.

[shrew]

Originally Posted by Tommyfmu

Our experience having a 2400SCR as well, trying out an 8 lb Danforth and 8 lb plow, was that neither would hold, and both let loose many times under mild conditions.

We stepped up to a 16 lb Danforth super Hooker and it's great; holds tight under high winds; problem solved, and well.

How much and what size chain are you using? How much scope are you letting out? That Danforth should hold a 24ft. boat regardless of the model. Though technically, I'd probably be putting something slightly larger on myself.

Danforth Traditional (S600): 9lbs will hold a 27 ft. boat in 20kts of wind
Danforth Deepset (TII-1200): 8.5lbs will hold a 35ft boat in 20 kts of wind

I have the Deepset TII-570: 5lb anchor holds 26ft. boat in 20kts of wind. I use as my stern, but I've held my 28ft. alone without issues. I've kedged with it and even held the boat with it as a stern taking 25-30kt winds beam to all night with no issues. It will even hold the stern of a raft with 31,000 lbs of boats on it.

Even my Fortress FX-11 is only a 7lb aluminum anchor and that has never dragged (as long as I have is set to the 'standard' position. The 'deepset' position I've never been lucky with).

I'm not sure how you're setting you anchor, what I would suggest (to anyone) is to slowly drop the anchor and let it drag for a foot or so, then as you're backing, slowly pay out chain and rode. The worst thing you can do is pile chain on the anchor on the bottom, that will rarely grab well. I will pay out more than I need (10:1 or even a bit more) then cleat it off, and back down to 'powerset' the anchor. When I see the bow dip, I know I'm good. I put the boat in neutral and watch to see the bow bounce back and start to drift forward from the recoil. I then pull in the extra line and set it to where I want it. I usually run about a 7:1.
Too little or no chain, too little scope and not properly setting will all potentially cause dragging. (Technically so will grass, weeds, rocks and slime on the bottom, but that's another story).

[Tommyfmu]

Shrew, I've used about 10 ft of what I guess is 3/8" chain (came with the boat), and let out around 3 times my boat's length of chain and rope as I've heard recommended, or at least so the the angle of rope is a lot flatter than 45 deg's. My boat at 25 ft is about 5800 lbs totally loaded etc. I use an 8 lb Danforth to hold the aft when we back into a beach which is fine.

[shrew]

It must be the relative size of the anchor as well as the overall holding of the area. The fortress FX-11 that I use as the main is only 7 lbs because it's aluminum, which is why I went with 20 ft. of a larger chain. However, it's a large in size so there's more area to get a bit. My 2nd stern is a not aluminum and much smaller in size. (I'm thinking like the difference of pulling a up a pole buried 3" in the ground on end, vs. a pole buried 3" in the ground sideways. More area, more hold) I'll also admit that most of the areas I drop the hook are sandy with a high clay content, so I'm sure that may be playing a factor in my success.