Manson Supreme in Weed

[Kettlewell]

Dang, that's a big blow. Are you on the hook?

[JonJo]

Originally Posted by noelex 77

I would describe this as a 30k wind, but others would describe it as higher.

But someone anchored near you in a 30' yacht with a shorter mast is possibly only reading 40 knots with an average of 25knots. I'm probably wrong but wind speed is normally quoted at 10m above sea level. Here we would quote averages with gusts around 40% stronger, so your 50knot gust would equate to an av of 35 knots. But gusts in anchorages would not follow predicitions and could be higher or lower than 40%+ it depends on the anchorage.

Work we did showed that peak loads on anchors followed gusts. We spent days measuring wind speed and loads, but only upto 35 knots. Though the average 'caused' the gusts (to get a 50 knot gust you need an average of 35 knots). However because anchorages can funnell and gusts can be much stronger than 40%+ its the gust that is important as its the gust producung the peak load and presumably the peak loads (in the absence of seas) cause anchors to drag. Some gusts do not cause peak loads but peak loads only occured during gusts (or a few secondas later). On this basis quoting the average is not relevant - its the gusts that are.

Must be a very exposed anchorage.

But I agrre with you summation - people do tend to exaggerate and quote the peaks.

Good Luck, stay safe

[noelex 77]

Originally Posted by Kettlewell

Dang, that's a big blow. Are you on the hook?

Thanks for you concern.
Yep safely anchored. For this region at this time of year these conditions are seen every few weeks. The forces increase as the square of the windspeed.

A genuine average 50k is a very different beast. We see this on average only once a year. It's scary.


The reality the management of these once a year genuine 50 k conditions, is at odds with what I read on CF. If you need to attend to your anchor you crawl along the deck with waves crashing over the bow. There is no communication with the helm (it always happens at 3am)
In short techniques that are fine in 30knots are hopelessly inadequate in 50k of wind.
Deploy a second anchor. How?
Lift an anchor into position?. The waves will crush your fingers.

If you are are cruising boat, get an anchor that will hold you in these conditions. It may cost an extra couple of hundred dollars. It may add another 30lb.

It will be worth it.

[noelex 77]

Originally Posted by JonJo

But someone anchored near you in a 30' yacht with a shorter mast is possibly only reading 40 knots with an average of 25knots

Its certainly a valid point that, like most other sailors, I can only measure and therefore quote the wind speeds at masthead level.
I would expect wind speeds at deck level to be lower.

In practice In most anchorages the gusts accelerate down the hills with some vertical component, so I am not sure the differences recorded at lower levels would be as pronounced as you postulate, but there will some difference.

This compounds the problem when talking about wind strength and anchor holding in general.

It will be interesting to see my anchor tomorrow. This wind is enough that it should have set my anchor deeper than I can achieve with motor alone.

[klem]

JonJo,

You mention taking lots of anchor load data. Is this something that could be made available publicly? I understand if you are not willing or allowed to post it. Something that has always bothered me in both anchoring and mooring debates is a complete lack of data on the actual loads present. Obviously, these loads depend on the exact boat, exact weather conditions and exact ground tackle setup but if someone were able to see enough plots of different conditions, they could get a reasonable idea of what to expect. I have never seen a >1Hz sample rate on anchor load data which bothers me as the rates I have seen it at completely miss the dyanmics that are going on. The other version that I have seen quotes the maximum load which could be a peak far exceeding everything else and may be meaningless if you have a good anchor which drags an inch and stays set or it may be a huge deal if your anchor pulls free. At a minimum, I think that anchor load data when discussed should be quoted as an average load and a standard deviation, peak load would be nice as well.

Since I don't have anything better to go by, I have always use the ABYC numbers which some agree with and other don't. I have spent an awful lot of time standing on the bow (after crawling up there as noelex describes) feeling the rode in nor'easters, named storms and t-storms as well but I can't claim to be well enough calibrated to put a number to it and I am too cheap to buy a load cell.

noelex, I always get a kick when you post your current conditions, good luck in the latest one. Luckily, we don't see those wind speeds as often as you.

[noelex 77]

Originally Posted by klem

noelex, I always get a kick when you post your current conditions, good luck in the latest one. Luckily, we don't see those wind speeds as often as you.

Thanks.
Note the average wind is not that strong. But it's very much up and down.
Today was the blessing of the sea ceremony where the priest throws a cross in the water and the brave young men dive in too rescue it.
Hopefully the blessing will keep the winter gales away

[hpeer]

Originally Posted by noelex 77

Thanks for you concern.
Yep safely anchored. For this region at this time of year these conditions are seen every few weeks. The forces increase as the square of the windspeed.

A genuine average 50k is a very different beast. We see this on average only once a year. It's scary.


The reality the management of these once a year genuine 50 k conditions, is at odds with what I read on CF. If you need to attend to your anchor you crawl along the deck with waves crashing over the bow. There is no communication with the helm (it always happens at 3am)
In short techniques that are fine in 30knots are hopelessly inadequate in 50k of wind.
Deploy a second anchor. How?
Lift an anchor into position?. The waves will crush your fingers.

If you are are cruising boat, get an anchor that will hold you in these conditions. It may cost an extra couple of hundred dollars. It may add another 30lb.

It will be worth it.

Ahmen!

[JonJo]

Originally Posted by klem

JonJo,

You mention taking lots of anchor load data. Is this something that could be made available publicly? I understand if you are not willing or allowed to post it. Something that has always bothered me in both anchoring and mooring debates is a complete lack of data on the actual loads present. Obviously, these loads depend on the exact boat, exact weather conditions and exact ground tackle setup but if someone were able to see enough plots of different conditions, they could get a reasonable idea of what to expect.

klem,

Sorry been out on the water - its summer here. Tomorrow summer is really here and we will be cowering from 43 degrees and the threat of fires.

For a quick answer, for me, try

http://www.cruisersforum.com/forums/...-92960-11.html

post 163.

I cannot vouch for all the links!

[JonJo]

Noelex,

You have mentioned that if you see someone upwind of you with a USL Code sized (or undersized) anchor - you would move. If I find you in an anchorage I will move! Your anchorages are too windy.

Excluding Cyclones it is our southern shores (and Tasmania) that are subject Storms. They do occur, and are forecast, and when we hear of them we go to places with shelter - so as to reduce the opportunity to enjoy averages of 50 knots in the anchorage. For us to enjoy averages of 50 knots we would need, as soon as we hear a storm is forecast, to get out and find the least exposed place possible - and anchor. Our northern coasts are currently subject to cyclones, they are few and far between (compared with other places, say Hong Kong, Phillipines). During cyclone, or typhoon season most yachtsmen leave the area completely - and go somewhere else. In Oz some yacht insurance policies exclude being in a cyclone prone area for the period of the cyclone season.

I admire your tenacity but I'd be looking for more sheltered anchorages.

But you mention having fingers chopped off, water over the bow, etc. As far as I can make out you have a fairly large yacht and to have the water over the bow implies the development of big seas - whereas I understand bullets causing 50knot gusts, you must be quite far offshore to have seas breaking over the bow - even with 50 knots. Also having a large yacht, you have large anchors and I can understand you would not want to be humping them about (twin bow rollers seems an option?). A 9 year old (female) can carry an FX 23 - not suggesting I'd expect her to deploy one in anger! An FX 3 for a 35' cat is huge but its not difficult to deploy from one bow or the other (even at 2am - been there done that - why always 2am in the southern hemisphere and 3 in the northern?)

take good care.

Jonathan

[klem]

JonJo,

Thank you for the link. I took a look through the PS article and it had much better data than most that I have seen. I take it that the data reported in the graphs was the maximum for a given windspeed? Were you guys data logging throughout? Simply seeing a plot with time on the independent axis and load and windspeed on the dependent axes would be great for a few minutes worth of data, I just don't know if it exists. Being an R&D guy, I spend a lot of my time analyzing high speed data and I would love to put a real DAQ system on a bunch of boats in a mooring field in the path of a big storm but I think that I am probably dreaming on that ever happening.

I am glad to hear that you are out there sailing while some of us are huddled inside with our heat on.

[Bash]

Originally Posted by JonJo

Your Kedge and Storm anchors are huge, surface area!!! I'm not knocking your choice, we carry an FX 37 but yours, combined, are real monsters. Do you carry them assembled or as a kit?

The G-37 stays assembled in the chain locker, and can be deployed in about 30 seconds on a second bow roller. The FX-55 is disassembled down below. I doubt it would fit in the chain locker unless the rodes were removed to make room.

The storm anchor resides disassembled in a locker with two other pieces of gear I hope never to use--the emergency rudder and the galerider drogue.

[Kettlewell]

I can deploy a second anchor in a few minutes if I am completely unprepared, but usually if any sort of blow is suspected I have the second anchor either ready or already deployed. Yes, your primary should always hold in whatever normal weather you are expecting, but a secondary anchor should be ready to go.

[JonJo]

Originally Posted by klem

JonJo,

I take it that the data reported in the graphs was the maximum for a given windspeed? Were you guys data logging throughout? Simply seeing a plot with time on the independent axis and load and windspeed on the dependent axes would be great for a few minutes worth of data, I just don't know if it exists.

I am glad to hear that you are out there sailing while some of us are huddled inside with our heat on.

It took a lot of fiddling around to ensure the data we collected was correct so we soon found out, when we were still fiddling (trying to get any friction out of the system etc) that the max loads occured with max wind speed. We knew if we had erroneous readings, when we had finished a days work, as the plot needs to cross the load axis on or near the weight of chain at whatever depth we are at with no wind. We had a masthead Raymarine, unit, a deck wind unit and (oddly) a wind gen. We only used the masthead unit as that's what people refer to when they talk about wind. The gusts hit the masthead first, so we could record wind speed in advance of max load. We knew when the gust was getting to the hull, because the hum of the windgen became louder (and an audible indication was better then watching the deck windspeed as we were watching the load as well). We then simply recorded loads and picked out the highest. We got lots of pairings, load and wind and plotted the lot and then simply foucssed on the maximums (we averaged the top loads for a given windspeed). We discarded anything below the maximums - because we were simply interested in the maximums.

We can do time, ie how quickly the snatch/dynamic load develops, and will probably do it in the future. At the time we did not think it important - and you do not know what the results are until you finish and sit down and analyse it all.

Ideally we needed a link between the Raymarine, loadcell and laptop (as we could then sit and drink beer when waiting!) but I cannot afford the programme. It was quite easy to record the data manually. When we do holding capacity tests we do have a recorder but its simply a paper print out of data every 2 seconds - which needs to be manually transferred. Taking wind and load over a 4 hour period as the wind developed you cannot have the paper recorder running continuously - finite paper supply (manpower is cheaper, and we had not thought of the time implications then).

You need to note that the loads are an all chain/dyneema rode - there is no elasticity at all. But we did have a bridle (made up from dyneema) so we tried to make the cat behave as if 'normal' so minimising yawing - though we did still yaw as we would normally. Mind you we see lots of people using all chain and no snubbers - so its relevant. We have another programme planned to correlate different snubbers - so basically the same as in PS but using snubbers - the idea being to define excellence of different snubbers and to show, quantify, the benefit

Your comment about time is quite important. Holding capacity work, the WM/Sail work done in 2005 or 2006 used a big work boat pulling at a specific rate. When we do holding capacity work its done based on the winch speed. If you look at the work of John Knox, in PBO, he pulls 10mm at a time, holds, measures etc. Dynamic loads are not quite but almost instantaneous. So reality, or what we have indentified as reality, and what we can measure are different.

There is the issue of waves and we have only recently worked out how we can measure wave height accurately - so we hope to show what impact waves have (on load).

We have just completed some dynamic testing, instantaneous, loading but we need to refine the process.

Our tests were quite civilised. We could set up, which took time, at low windspeeds and low loads. Once we had finished, say 35 knots, it was quite quick to pack up and we could tidy up in better shelter. To set up in inclement weather needs a lot of planning (as Noelex has pointed out you can chop fingers off) or a lot of foresight.

[JonJo]

Originally Posted by Kettlewell

I can deploy a second anchor in a few minutes if I am completely unprepared, but usually if any sort of blow is suspected I have the second anchor either ready or already deployed. Yes, your primary should always hold in whatever normal weather you are expecting, but a secondary anchor should be ready to go.

Given that I see so few people using snubbers, even short ones that only take the load off the windlass, and how many still persist with CQRs I wonder how many people actually have reasonably sized second anchors. I note people trying to set CQRs and Deltas again and again - maybe 4 times before they get them to set - the fact they never, ever, take out another anchor to use instead of the one that does not set suggests to me that if they have a seond anchor its as useless as the one on the bow roller.

[klem]

JonJo,

Thank you for the information. I understand the troubles with getting a good automated data collection system. At my last two jobs, we have had quite expensive data aquisition systems capable of of really high speeds (>20 kHz) and many channels but they are very finicky. If I could afford a good load cell, anemometer, 3 axes accelerometer, DAQ board, labview for a VI and Matlab for post processing, I would have great data on my own boat at anchor but sadly that is far too much money for me to spend so I rely on others to take the data.

Thanks.