The Art Of Anchoring

[rslifkin]

I'd like to do a strain gauge test on my boat, but my gut feel from feeling rode tension is that idle reverse for me on both engines is similar to somewhere around 20-25 kts of wind. That means my usual 1000 rpm test is good for more, probably more like 30 - 40 kts equivalent.

I've anchored for short periods with a little over 70 feet out in 19 feet of water (plus just under 6 feet roller height), so just under 3:1 scope. It held idle reverse no problem with 10 kts blowing at the time. Didn't throttle up beyond idle though. At 3.5:1 in 48 feet of water it'll hold 1000 rpm plus 20 kts with no trouble at all. In that second case, it was rather hard to break out and mud marks indicate the anchor was fully buried (including the whole shank) in the sticky, gooey mud it brought up.

The low settting rpm with a pair of 22 inch props is probably comparable to the force a similar size average sailboat would generate with nearly full throttle.

 

[Nomad Willy]

It has a lot to do w the prop too.

I run an MP Michigan wheel. MP stands for machine pitch. There is supposedly no change in pitch from hub to prop tip. Usually there is less pitch near the tip to accomodate the much higher plade speed. Less efficient? Of course. But it’s only about 3-4%. It’s a smooth prop though.
The big difference is in the thrust in reverse. Most props aren’t capable of anything near fwd thrust in reverse. But the MP prop comes much closer to the fwd thrust. It’s a huge difference when I back down to stop fwd movement. Night and day difference. And when you’ve only got 37hp to stop you’re 8 ton boat the MP prop is golden. Most all fishboats in the PNW had these MP props in the day (40’s, 50’s and probably the 30’s and perhaps before.
Of course tug boats Probably have similar props.

This is the MP prop coated w cold Galvanizing .. rattle can.

 

[Peter B]

Your not the first to say this - my question is why wait? And I mean that as an actual question. Other's have said it's due to Next Gen anchors vs simply waiting for boat to re-orient itself. What material changes are expected?
Peter

Pete, I think the answer is encompassed in my first post on this below...

...however, one thing that did strike me with most of the test runs was that it seemed to be moving a bit faster than ideal, with the flukes sort of rolling or bouncing over the round rocks, and not having time enough to dig in between them - until eventually they did. I realise Steve could not go any slower than idle reverse, however, as Peter (MV Weebles) hinted, it tended to illustrate how the sit and let it drag for a bit before testing a back-down, instead of an immediate reverse thrust, is probably the best way to set virtually any anchor, but especially these next gen ones, and why many of us do exactly that - well, did, in my case.

Cheers,

 

[catalinajack]

Surprised me also. I had to run 45 miles on one engine to Fort Myers on Christmas Eve. Got there is fading light. I was very much annoyed. I no longer have DriveSavers in my drive line.

Really? That's a good tip. I'm surprised.

BTW - my little Willard 36 has a 75hp Perkins 4.236. 1500 may be a bit of an exaggeration. I normally power set at a few hundred RPM over idle, so maybe 1000 RPM.

Peter

 

[Beaverlake]

So I guess I’m a Milquetoast weenie. My “power set” is two or three bumps in reverse after we’ve not too aggressively straightened the chain. It seems like many of the new anchors (ours is a Vulcan 33) continue to dig in after initial set just through normal stretch/relax cycling of the chain/rode. I know we’ve had one or two instances when I thought we were fouled only to finally break free and bring up a huge beach ball sized ball of mud sticking to the anchor.

 

[Slowmo]

Anchoring always gets a lot of comments. In my case I prefer to back up very gently on the anchor and let it set then pull back on it, but fairly gently. Frankly once it's in it just goes deeper. Getting out is typically the harder part.

One thing I've learned is that it is helpful if you can 'feel' what the anchor is doing when you are dropping and setting. This is much easier with a rope/chain set up. My biggest struggle with my current all chain set up is not having the ability to easily feel the line.

 

[Peter B]

Anchoring always gets a lot of comments. In my case I prefer to back up very gently on the anchor and let it set then pull back on it, but fairly gently. Frankly once it's in it just goes deeper. Getting out is typically the harder part...
My biggest struggle with my current all chain set up is not having the ability to easily feel the line.

Slowmo, you can't go far wrong with your technique. Especially the going gentle at the outset - well...maybe go even more gentle. But basically, just keep doin' what you're doin'...

 

[firehoser75]

For you proponents of "power setting", I think the advise some are giving here is very good (even the no power set group ). I believe in, and follow the technique of dropping anchor until I know it is on the bottom, and then we give a "in reverse" and immediately back to neutral (just enough to start a slow reverse motion) while at the same time continuing to let out the rode. We slowly lay out the rode backing very slowly going in and out of gear as needed. Sometimes the wind will lay us back fast enough or maybe even too fast. The idea is to lay out the rode (not pile it on top of the anchor) without putting much force on the anchor. We always set (with power) utilizing good scope (at least 5-1) only after all the desired rode has been laid out. Then the "slack" is taken up very slowly and gently (in and out of gear). Once the rode is tight, we apply continuous power while we carefully check landmarks to ascertain that we are not dragging. When we go back to neutral, the boat will move quickly forward for a bit, further indicating that we are set. If you want a shorter scope, then take up the excess as needed after completing the set.

I think key points are: don't try to power set using short scope; and lay out the rode slowly (no high speed reversing) and take up the slack slowly and gently before applying the power to set the anchor. We have a fairly large engine (330 hp) so I feel comfortable setting using only idle or just above.
We do use a bridle to take the strain off of the windlass.
This method has worked very well for us for over 1000 nights at anchor, having set the anchor at least 300 times. During this time frame, we have dragged anchor only once (circumstances described in an earlier post) and only failed to set "first time" in a handful of locations. I also feel that our method allowed us to find the problems in the "first time" failure locations, whereas I am not so certain I would have known there was potentially a problem using the "let it set itself" methods some others have described.

This is just my opinion, and what gives me comfort when at anchor, and does not in any way purport that anyone else's methods, especially ones that have worked for them for years, are wrong.