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Anchor choice
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| robb huff |
Posted on 08/29/19 - 8:43 AM
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Looking for direction -
2004 conquest 305
dual 250 Yams
I boat in San Diego. so ocean floor is mostly sand and mud. The anchor issued with the Conquest (plow style) tends to drag frequently enough that we lost confidence in it.
Changed it out with the 'transom' anchor I purchased which is a danforth and works much better, but I'm guessing it's a bit small/light for use as a main anchor.
Is there a 'weight' minimum for a main anchor for this boat? And if I went with a larger/heavier main anchor (Danforth) what should that weight be (allowing for 25' of 3/8" chain.
Finally, I've hear 'bruce' mentioned, but can't see any discernible difference between a Bruce and the 'Plow' that came with the Conquest.
Robb
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| biggiefl |
Posted on 08/29/19 - 11:05 AM
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I would look t an aluminum Fortress. You can usually find one on craigslist or E-Bay used. Their website will tell what size you need and how much chain.
24 Whalers so far.... |
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| JRP |
Posted on 08/29/19 - 11:40 AM
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The danforth design (including Fortress versions) makes for a good primary anchor on smaller boats, or a secondary/stern anchor for larger boats. But the design is based on maximizing surface area to create holding power, so it gets awkwardly large and cumbersome when sized appropriately for a bigger boat like yours.
For a boat your size, there are other anchor designs which use mass (not just surface area) to create holding power. Your plow is one such.
I have a fortress (danforth) on my little 19 outrage. It works well for a boat this size. But on lareger boats I’ve owned, I’ve used both plow and bruce designs extensively. The plow (e.g. CQR, Delta) has its place, but the Bruce design (aka Lewmar Claw) is a much better all-around anchor. It would do very well in the sandy/muddy bottoms where you boat - - far better than a plow style.
I recommend going up one size from the standard recommendation, and having an appropriate length of chain as well (a VERY rough rule of thumb would be use chain equal to the length of your boat.)
Another important factor in good holding is your anchoring technique. It doesn’t matter what anchor is used if you aren’t familiar with the procedure for properly deploying it. It’s my experience that many motorboaters never learn how to properly set an anchor. Hopefully you’ve got that part down.
19 Outrage II (1992) |
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| robb huff |
Posted on 09/16/19 - 8:26 AM
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very much appreciate this info. I will look into the Bruce design, retaining the danforth for a stern / back up. and probably sell the low that came with the boat....
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| wrangler |
Posted on 09/17/19 - 3:33 AM
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Everyone mentions type of anchor. How Long of a scope or amount of line are you using?
The scope average is 7 to 1. Or 7 times the depth of the water from the bow of the boat to the bottom. 10' of water at scope 7 = 70' plus the distance from the water to bow of boat.
If you put out less or even 7, it may drag.
Soft bottom, wind, current all effect this.
You may have to go to 10 to 1, to stop dragging.
Mark off the line at 10 ft intervals and measure how much you put in.
Also, what size chain are you using? The bigger the chain, the better the anchor will perform.
A boat I came across was having trouble anchoring. He put out 50' of line in 25' of water. No way would it hold.
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| sailor dude |
Posted on 09/17/19 - 11:03 AM
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If you need 7:1 scope in anything but a gale you are using the wrong anchor.
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| svsonora |
Posted on 09/17/19 - 3:48 PM
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uh, 7:1 scope is a very good conservative scope ratio. Any real serious cruiser will run close to that. I can't count how many times I've been at a crowded anchorage and winds pick up and everyone else except for a few sailboats start dragging.
I'm almost never below 5:1, and on my big boat I have a huge oversized anchor too.
If you've been getting away with something a lot less than 7:1 then you either have really good holding power in your locality and you never really leave it, you have a really big anchor, or you have only been fair weather boating.
Edited by svsonora on 09/17/19 - 3:49 PM |
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| butchdavis |
Posted on 09/18/19 - 7:16 AM
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On a larger cruiser for which rules of thumb demand a chain length of over thirty feet the anchoring tackle/rode can become very cumbersome and difficult to handle without the appropriate power windlass.
The length of chain can be significantly reduced with the use of a catenary or weight installed on the chain.
Butch |
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| svsonora |
Posted on 10/01/19 - 1:01 PM
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butchdavis wrote:
On a larger cruiser for which rules of thumb demand a chain length of over thirty feet the anchoring tackle/rode can become very cumbersome and difficult to handle without the appropriate power windlass.
The length of chain can be significantly reduced with the use of a catenary or weight installed on the chain.
Nothing is free though. you lose abrasion resistance of chain, and the weight itself probably causes some issues too. Nice option to have though.
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| butchdavis |
Posted on 10/02/19 - 7:06 AM
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Agree, almost any benefit has a drawback or two.
The US Navy is known to use catenary devices when installing permanent four point anchored mooring buoys. The four point system has the advantage of maintaining the buoy on-station during sea state and tidal changes. This can be critically important in harbors and around other moorings.
Butch |
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