How Much Rode?

[rleslie]

Scenerio: You want to have a 7:1 scope. When you begin dropping the anchor, your sounder reads 10'. As you play out more rode and back, the sounder reads 12' - 16' - 19'. After putting out 70' you are in 20' of water.

The question is: how much rode is needed for a 7:1 scope?

a) 7 x 10' (the depth where the anchor is set)
b) 7 x 20' ( your present depth)
c) 7 x 15' ( your average depth)

[Hud3]

rleslie,

Calculate it based on the depth where the anchor sets, but don't for get to add your boat's freeboard at the anchor roller

[GordMay]

As Hud says, depth = depth at anchor location + freeboard.
7 x (10 + 4?) = 98
In the described scenario, I’d check depths forward of (& all around) this anchor, ensuring adequate keel depth when the wind shifts 180 deg.

[Pblais]

Scope is the angle from the anchor to the bow (see formula above). So long as the water under the boat is not less than the keel depth it really won't matter what the depth is some place else.

Waves and tide may matter more or less. In the tropics where the tide is maybe 1 ft. it's not but in Maine it could. Running aground on the hook is just too embarassing.

[donradcliffe]

If your anchor is dropped in a spot which is shallower than where your boat is, remember to let out a bit more than normal scope--the angle between the anchor and the bottom will be higher than on a flat bottom, and any dragging will put the anchor in deeper water.

The reverse is also true--if you drop in 20 feet and end up in 10 ft, you can probably get by with less rode, as the anchor will have to drag uphill.

[Pblais]

and any dragging will put the anchor in deeper water.

Dragging can put the boat any place.

[Vasco]

All this talk about the right scope. I have all chain and in ten feet or less I always put out 100 ft if there's room. If it's going to blow (over 30 knots) and there's a long fetch, I put out about 120 ft. My chain is marked at 50 ft intervals. No sense in fooling around. Good thing about the Bahamas is that we seldom anchor in over 10 feet. Lots of chain and a good long snubber. That's the secret for a good sleep at night.

[Pblais]

[FONT='Calibri','sans-serif']No sense in fooling around.[/FONT]

Sounds good to me.

[Pelagic]

For a good night’s sleep….. if you can, look at the chart and if there is a bit of an indent or depression on the bottom, drop the pick there. Anchors don’t like to drag uphill!

[Morgan Paul]

For a good night’s sleep….. if you can, look at the chart and if there is a bit of an indent or depression on the bottom, drop the pick there. Anchors don’t like to drag uphill!

Hey I like that idea. I have very little anchoring expierience, but I will keep that idea in the back of my mind and use it.

Thanks, it is truly amazing how many ideas you can gather here.
Paul

[Pelagic]

You’re welcome Paul. Years ago, I used to run a steam yacht and when the boilers were shut down it took up to 8 hours for the engines to be on standby. That trick kept me out of trouble many times in a blow.

[AnchorageGuy]

Originally Posted by Vasco

All this talk about the right scope. I have all chain and in ten feet or less I always put out 100 ft if there's room. If it's going to blow (over 30 knots) and there's a long fetch, I put out about 120 ft. My chain is marked at 50 ft intervals. No sense in fooling around. Good thing about the Bahamas is that we seldom anchor in over 10 feet. Lots of chain and a good long snubber. That's the secret for a good sleep at night.

Yes we know several boats that do this no matter what and it does create problems in crowded anchorages and is inconsiderate. Not to say you would do that. But the point is there are times you can be liberal with your scope and times you need to be conservative, but safety should always be the prime consideration.

[hugosalt]

scope...and other factors

All good points...I find as much as scope, anchor type and size are topics given much discussion as they should....The less discussed subject of mininizing windage and therefore yaw also contribute greatly to a good nights sleep in weather.
(Come to think I never have a good night sleep if it's blowing over 30knots)
I feel it sometimes can make the difference in weather by keeping the windage (especially up foward) to a mininium and using a riding/anchor sail. Keeping the bow
pointing as close the the wind as possible avoiding tremendous loads and shock on the ground tackle when a boat yaws off the wind streching the rode to the max and recycling again and again.
It's my understanding that any windage, stowed sails, dingy, etc. foward (of the
center of effort or is it pivot point) creates lots of yaw.
The riding sail also helps keep the loads down, especially handy when one can't let out as much scope in tight anchorage.

Hugo

[Pblais]

The riding sail also helps keep the loads down, especially handy when one can't let out as much scope in tight anchorage.

Some boats are more prone to it. Our CSY 33 was solid as a rock on the hook no matter the wind no extra anything needed. I think the large bow helped. The Gozzard is good but not that good. Some boats absolutely need a riding sail. Lots of configurations are possible.

[GMac]

I run a rope to chain rode and when the anchor gets chucked it's a simple depth sounder times 5 plus a big handful as a minimum in anything unless it's not a permanent stop. 30kts comes out to 6:1, 40kts + to 7:1.

I do sail like a mongel at anchor, those multis have nothing on my beast, but all that does is set the anchor further. Also helps to keep a few of those big tupperware fizz nasties from dropping their pick close to me. Mind you so does my very big stereo if I see one coming, up she goes and she can go up lots