Neo wrote:Ok there's been a couple of mentions of throwing two anchors out. Under what conditions would you need to do that?....
# Two off the port/starboard bow's?
# One off the bow and one off the stern?
How would you set these up if the tide was 2ft .... or if the tide was 6ft?
I'd never use a bow/stern setup if there are going to be heavy winds, especially if there will be a shift in wind direction. If you get the wind shift to where it is coming in off the beam then you can get tremendous loads on the rodes. I was tied up like that at Lake Powell to opposing rock shores when a front went through with 50+ mph winds and the winds shifted as the front passed and the stern line (a new rode) just exploded. Luckily I had two bow lines going to opposite rocks and the boat didn't swing into the shore as it would of if I would of just had one line.
I now take all lines to the bow. More than one line to the bow if the anchors are close to 180 degrees from each other will keep the boat in a very tight location. Good if you are near shore and expect a wind change or near other boats and want to decrease your swing but there you have to be careful as if they swing on a wind change and you don't then they might of expected that you would of and they might possibly swing into you. The negative about having the two down 180 apart in a big blow is that you can get the wind coming in at 90 degrees to the two anchors and now you have the load on the rodes pulling from a direction that is 90 degrees from how the anchors were set and not pulling so as to have the wind, the anchor, and the boat all in a straight line.
If I'm expecting winds over 25 I usually put down two bow anchors in a "V" shaped configuration. This is easy if there are two of you. Set one anchor and drift back and set it with the outboard. Have the person at the helm motor ahead in a direction that will put you off to the side of the first anchor. The person on the bow can bring in the first rode as you are doing this to make sure it doesn't end up in the prop. Drop the second anchor and drift back and set it with the outboard with slack in the first rode. Then adjust both rodes to the point you feel they are taking pretty equal loads. If one were to drag a little then the second would have more pull on it and the loads should equalize. I've sat out some big blows (over 40) and never drug with this configuration but also have about 30 feet of chain on each anchor and one is a 22 lb. bruce and the other a 25 lb. Manson Supreme.
On anchor weights, I don't think the difference in weight from say a 16 lb. bruce to a 22 lb. makes that much difference. What I feel does make a difference is how much surface area there is on the anchor that can dig into the bottom and hold the boat. The heavier anchor has more surface area and the new generations like the Manson have even more surface area for the same weight as older style anchors.
I'm a firm believer in more is better when it comes to ground tackle. If you never go out for more than 3-4 days you can be pretty certain of what the weather will be over that time period. More than that and you don't know what might happen. I don't want to be up all night worried about what could happen. I figure that if one anchors a few nights vs. going to a marina they could put that money to very good use in the way of anchors and rodes.
The only difference in anchoring with a 2 foot tide vs. a 6 foot one is that the boat can now be 4 feet higher than the anchor with the higher tide. If you use the 7:1 scope formula you would put out 28 more feet of rode. Figure your scope using the height from the deck to the water and the water depth where the anchor is at high tide. In Florida and the Bahamas where you don't get the tides of say the NE or NW I take the water depth at high tide and multiply that by 7 to 9 depending on what I think the weather is going to be and then let out my anchor not counting the 30 feet of chain but start counting my distance with the marks on the line. The 30 feet of chain takes care of the height from the water to the deck,
Sumner
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