Closed Thread
 
Thread Tools Display Modes
 
Old 12-31-2014, 06:20 PM   #201
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
Be careful of using the USCG as an example using Fortress or any other anchor...unless you can post the documents showing the reason.

How many times do you see a USCG vessel anchored overnight in a reversing current situation? Or overnight without a live watch?

I was in for some of the discussions on selecting the anchor for the smaller vessels...about the only facts used that I ever heard were all from the US Navy's tests....virtually hat and the fact they were lightweight, didn't need painting and cost wasn't really an issue.
__________________
Advertisement

psneeld is offline  
Old 12-31-2014, 06:44 PM   #202
Senior Member
 
Join Date: Apr 2011
Posts: 211
Quote:
Originally Posted by psneeld View Post
Be careful of using the USCG as an example using Fortress or any other anchor...unless you can post the documents showing the reason.

How many times do you see a USCG vessel anchored overnight in a reversing current situation? Or overnight without a live watch?

I was in for some of the discussions on selecting the anchor for the smaller vessels...about the only facts used that I ever heard were all from the US Navy's tests....virtually hat and the fact they were lightweight, didn't need painting and cost wasn't really an issue.

My understanding is that the USCG, the vessels that use the Fortress, are geared for 'long' missions, around a week and that they do anchor, overnight.

Accepting they do have a live watch it is difficult to believe they would use an anchor that demanded the vessel to lift its anchor and then re-set every time there was a wind shift or change of tide.

A point I tried to make was that concave roll bar anchors have a weakness, and a weakness that is being increasingly reported (and denied by the proponents). If they clog and there is a wind shift or tide change that upsets the anchor then they will not re-set until that clogging is washed clear. No anchor is perfect.

As an aside, windlass makers here, Maxwell and Muir, love concave roll bar anchors. Lifting an anchor full of mud introduces an extra load on the windlass and the motors burn out (the fact that the windlass might be underspecified is another issue - and nothing to do with the windlass makers). Lots of new motors and windlasses being sold. Amazingly some actually say they like to see their anchor arriving at the bow roller fully clogged as it shows it was well set (now that's a scientific measure we could introduce for excellence in an anchor) - little do they realise its a sign it might drag in a wind shift.

Anchors must be one of the few marine items where you can make a virtue out of a negative.

As Eric asked - how often does a Fortress 'capsize' in a wind or tide change. (Possibly quite often given they have sold 500,000 units) - but how often as a percentage of the whole. We are only hearing of roll bar concave anchors dragging now because it is only now we have sufficient numbers out there to provide reports.

in a post above Fortress stated quite clearly seabeds in which a Fortress anchor might struggle - hands up if you have ever seen another anchor maker (or their marketing arms) raise his hand and say their anchors struggle in X, Y or Z? They are full of criticism, some valid some invalid of the opposition - but being transparent of their own designs - no way.


Happy New Year to you all, may 2015 be one of good health, fair winds, blue skies and sandy bottoms.
__________________

Djbangi is offline  
Old 12-31-2014, 06:50 PM   #203
Veteran Member
 
City: Wherever the boat is
Country: Europe
Vessel Model: 48 foot sailing Yacht
Join Date: Jul 2014
Posts: 92
Quote:
Originally Posted by manyboats View Post
Noelex how often do you think a Fortress would be likely to fail?

In most cases an anchor that develops a high list like the Danforth/Fortress when changing direction will reset in the new direction without any problems. However, it is very disconcerting to see an anchor with very little grip on the bottom as it rotates. A gust at the wrong time, when the anchor is rotating, will see the anchor sliding backwards.

Underwater, I see Fortress/Danforth anchors develop this high list with minimal grip of the flukes quite frequently. In most cases the anchor will reset without the skipper realising there is a problem. Occasionally a gust at the wrong time will see the anchor dragging. Once moving an anchor is unlikely to grip again. This is a much greater problem in strong wind.

In practice, the dragging problems with a change of direction of pull are only infrequent, but observing underwater, the difficulty of these anchors rotating are very common and obvious. They are much worse than most anchors when changing direction.

If there is risk of a significant change in the direction of pull, I don't consider the Danforth/Fortress anchor a good option. This must be weighed against the extraordinary holding power of the Danforth/Fortress in medium/soft substrates when the direction of pull is constant.

The idea is to maximise the attributes of the anchor.

As a secondary anchor the direction of pull tends to be constant. The very high holding power of the Fortress anchor for the weight make it the best secondary anchor available, hence its popularity in this role.

As a primary anchor I think there are better alternatives.

Happy new year everyone.
Attached Images
 
Noelex is offline  
Old 12-31-2014, 06:57 PM   #204
Master and Commander
 
markpierce's Avatar
 
City: Vallejo CA
Country: USA
Vessel Name: Carquinez Coot
Vessel Model: 2011 Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 10,254
I agree the Danforth/Fortress is a good secondary anchor. I've got one, but have a claw as primary with which I'm satisfied as it hasn't failed yet despite 180-degree current changes. (Is there no anchor that has never failed that was properly set?)
__________________
Kar-KEEN-ez Koot
markpierce is offline  
Old 12-31-2014, 07:42 PM   #205
Senior Member
 
Join Date: Apr 2011
Posts: 211
Noelex,

We spent last European summer in Europe on the Med, 3 months. What was noticeable was that we saw only one Fortress and no Danforths. We saw lots of wannabes, Brittanys and copy danforths. We visited chandlers in most centres, Venice, Pireaus, Monaco, Barcelona, Naples, Trieste, Istanbul etc and we saw no original Danforths. (In fact the only offshore location I have ever seen Danforths for sale was in Japan - so I've never seen originals in either the UK nor Oz). Fortress in many chandlers. Consequently your suggestion that you have seen many Fortress/Danforths being actually used looks very suspect.

I am sure you have seen danforth copies, if a Brittany is a copy and if the many nefarious products are copies, I am sure you have seen them being used - but 'many'? and 'many Danforths, very sceptical. You claim to have taken an image of every anchor you have seen being used, I do not recall 'many' danforth copies but I am sure you will post a confirmed original Danforth within the hour

There is another aspect - anchor usage seems to follow very nationalistic lines, so you see French designs in the western med, Brittanys, Spades and Brakes and more Ultras and 'copy' (usually rusty) Bugels as you move east - buying 'American' would be very out of character - when there are cheap copies available.

To damn a design on the basis of a few copies looks questionable - but come up with those original images of he 'many' you have seen.
Djbangi is offline  
Old 12-31-2014, 08:51 PM   #206
Senior Member


 
City: Fort Lauderdale
Country: United States
Join Date: Apr 2013
Posts: 156
Noelex,

I guess based upon your expertise, we should fold our tent and inform the 500k customers that we have earned since 1987 that they should stop, or never consider, using their Fortress as a primary anchor. Ridiculous.

Additionally, your math is flawed because one single 40-ft boat will encounter loads of 300 lbs in 15 knots of wind, as per ABYC tables.

Happy New Year!

Brian
Anchor Brian is offline  
Old 12-31-2014, 08:59 PM   #207
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
Quote:
Originally Posted by Fortress Anchors View Post
Noelex,

I guess based upon your expertise, we should fold our tent and inform the 500k customers that we have earned since 1987 that they should stop, or never consider, using their Fortress as a primary anchor. Ridiculous.

Additionally, your math is flawed because one single 40-ft boat will encounter loads of 300 lbs in 15 knots of wind, as per A7BYC tables.

Happy New Year!

Brian
Not to be a total wanker...but those ABYC numbers are complete BS.

I can pull my boat against a 15 knot wind without exerting anywhere near 300 pounds of pull...so where do those numbers come from?

Maybe from surges from waves..but the wind data only is way flawed.
psneeld is offline  
Old 12-31-2014, 09:09 PM   #208
Senior Member


 
City: Fort Lauderdale
Country: United States
Join Date: Apr 2013
Posts: 156
Bob Taylor's comments on the ABYC tables:

"I checked on the basis of the ABYC table. It includes a factor of safety of 3 to account for waves and for current so the numbers are probably realistic.

What this means is that the loads specified are high if all I have to deal with is wind but as soon as current and wind enter into the equation a boat may assume an orientation that results in a larger projected wind and current drag areas.

Wind and current can come from different directions so the boat will assume an equilibrium position that resolves all the forces.

If I presume that this load is realistic then I need to select an anchor that will safely hold this load so I need to provide a factor of safety to the anchor selection.


If I do a full up dynamic analysis to determine loads then most regulatory agencies suggest sizing an anchor with a factory of safety of 1.5.

So, let's assume that the loads in the table reflect that of a dynamic analysis because they presume that wind, waves and current are considered. At a minimum an anchor should hold 50% more than that in the table (my suggestion).


If I were being really safe I would suggest a factory of safety of 2 because of the uncertainties in bottom condition."
Anchor Brian is offline  
Old 12-31-2014, 09:13 PM   #209
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
Quote:
Originally Posted by Fortress Anchors View Post
Bob Taylor's comments on the ABYC tables:

"I checked on the basis of the ABYC table. It includes a factor of safety of 3 to account for waves and for current so the numbers are probably realistic.

What this means is that the loads specified are high if all I have to deal with is wind but as soon as current and wind enter into the equation a boat may assume an orientation that results in a larger projected wind and current drag areas.

Wind and current can come from different directions so the boat will assume an equilibrium position that resolves all the forces.

If I presume that this load is realistic then I need to select an anchor that will safely hold this load so I need to provide a factor of safety to the anchor selection.


If I do a full up dynamic analysis to determine loads then most regulatory agencies suggest sizing an anchor with a factory of safety of 1.5.

So, let's assume that the loads in the table reflect that of a dynamic analysis because they presume that wind, waves and current are considered. At a minimum an anchor should hold 50% more than that in the table (my suggestion).


If I were being really safe I would suggest a factory of safety of 2 because of the uncertainties in bottom condition."
all that I will buy...but that needs to be in the discussion.....

saying in a tiny tidal creek my anchor will need to hold 300 pounds is nuts as the chain isn't even moved much in 15 knot winds.

that is why many of these anchor discussions are lost in space.

I love Fortress anchors.....as one in an inventory for a serious cruiser...where it spends it's life is only personal preference.
psneeld is offline  
Old 12-31-2014, 09:33 PM   #210
Senior Member
 
Join Date: Apr 2011
Posts: 211
psneeld,

I had always assumed that the ABYC were 'worst case', so your example of the tensions developed in a tidal creek are completely correct, but that same anchor will be required for that 'worst case' in an open roadstead with 15knts with a bit of surge, wind over tide and some veering. At 15 knots the tension is not even enough to lift all the chain, say 100', off the seabed.

I always assume anchors are chosen for worst case (and may we all be restricted to 15knots of wind in 2015!) but actually have anchors for 50 knots
Djbangi is offline  
Old 12-31-2014, 09:36 PM   #211
Veteran Member
 
City: Wherever the boat is
Country: Europe
Vessel Model: 48 foot sailing Yacht
Join Date: Jul 2014
Posts: 92
Quote:
Originally Posted by Djbangi View Post
Consequently your suggestion that you have seen many Fortress/Danforths being actually used looks very suspect.
I am not sure what is "suspect". Ignoring my previous sailing experience I have been full time cruising, staying at anchor for over 300 days a year for the last 8 years. I have owned a Fortress anchor for all of this time.
Noelex is offline  
Old 12-31-2014, 09:42 PM   #212
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,868
Quote:
Originally Posted by Djbangi View Post
psneeld,

I had always assumed that the ABYC were 'worst case', so your example of the tensions developed in a tidal creek are completely correct, but that same anchor will be required for that 'worst case' in an open roadstead with 15knts with a bit of surge, wind over tide and some veering. At 15 knots the tension is not even enough to lift all the chain, say 100', off the seabed.

I always assume anchors are chosen for worst case (and may we all be restricted to 15knots of wind in 2015!) but actually have anchors for 50 knots
just another case of believing or using data that is out to lunch at least 50% of the time....

I'm with Marin sorting through personal experience is no more full of landmines than technical or "test" data and has gotten quite a few experienced boaters where they want to be with anchors. Especially when my own personal experiences reinforce what others say and is in opposition to what I read from "testing".
psneeld is offline  
Old 12-31-2014, 10:05 PM   #213
Senior Member
 
Join Date: Apr 2011
Posts: 211
Quote:
Originally Posted by Noelex View Post

Underwater, I see Fortress/Danforth anchors develop this high list with minimal grip of the flukes quite frequently. In most cases the anchor will reset without the skipper realising there is a problem. Occasionally a gust at the wrong time will see the anchor dragging. Once moving an anchor is unlikely to grip again. This is a much greater problem in strong wind.

.
Noelex,

I quote what you said - you imply anchor(s) plural, you also imply Danforth (which you do not own and thus must be on other vessels). You now suggest you have been using your own Fortress in changes of tide - etc - why when you know, or say you know, it is so dangerous do you ever use your Fortress - except for a guaranteed straight line pull?

The gist of your post (and the implication to me) was that you had broadly viewed many Fortress and many Danforths, specifically these brands You now suggest its only your Fortress? and maybe no Danforths. Without more evidence you seem to be trolling.

I'm guessing you are struggling to find any images of a Fortress or genuine Danforth as not seen much in the Med or even Asia (as Japanese cruisers are notable by their absence). Its that jingoistic buying pattern. However Brittany anchors are very common in the Med - and you almost never mention them at all. So anchors that are common you ignore and anchors that are like hens teeth you make a point of mentioning.
Djbangi is offline  
Old 12-31-2014, 10:21 PM   #214
Grand Vizier
 
Delfin's Avatar
 
Join Date: Jan 2010
Posts: 2,487
Quote:
Originally Posted by Djbangi View Post
Noelex,

I quote what you said - you imply anchor(s) plural, you also imply Danforth (which you do not own and thus must be on other vessels). You now suggest you have been using your own Fortress in changes of tide - etc - why when you know, or say you know, it is so dangerous do you ever use your Fortress - except for a guaranteed straight line pull?

The gist of your post (and the implication to me) was that you had broadly viewed many Fortress and many Danforths, specifically these brands You now suggest its only your Fortress? and maybe no Danforths. Without more evidence you seem to be trolling.

I'm guessing you are struggling to find any images of a Fortress or genuine Danforth as not seen much in the Med or even Asia (as Japanese cruisers are notable by their absence). Its that jingoistic buying pattern. However Brittany anchors are very common in the Med - and you almost never mention them at all. So anchors that are common you ignore and anchors that are like hens teeth you make a point of mentioning.
+1. Thank you for noticing.
__________________
Delfin
"Dad always thought laughter was the best medicine, which I guess is why several of us died of tuberculosis." - Jack Handy
Delfin is offline  
Old 12-31-2014, 10:25 PM   #215
Veteran Member
 
City: Wherever the boat is
Country: Europe
Vessel Model: 48 foot sailing Yacht
Join Date: Jul 2014
Posts: 92
Quote:
Originally Posted by Fortress Anchors View Post
Noelex,

I guess based upon your expertise, we should fold our tent and inform the 500k customers that we have earned since 1987 that they should stop, or never consider, using their Fortress as a primary anchor. Ridiculous.

Additionally, your math is flawed because one single 40-ft boat will encounter loads of 300 lbs in 15 knots of wind, as per ABYC tables.

Happy New Year!

Brian
Brian I know we disagree about the about the ability of the Fortress anchor to reliably cope with significant change in direction of pull. On this subject I think we are better to agree to disagree, and perhaps open another bottle of champagne to celebrate the new year .

As to the maths I don't see anything wrong with your calculations:

"one single 40-ft boat will encounter loads of 300 lbs in 15 knots of wind, as per ABYC tables"

My tables give 288 Lbs which is close enough.

I don't see how that disagrees with my figures:

Quote:
Originally Posted by Noelex View Post
4x38 foot boats @ 15mph=792 lbs according to ABYC calculations. This equates to a single 38 foot boat in an average wind speed of 30 mph (26 knots ).

Re-reading River Cruisers post he probably is referring to 5 not 4 boats (his boat plus four others) rafted up together in which case it would be equivalent to 29 not 26 knots. The total drag would not necessarily be the sum of the drag on 5 individual boats, but it would be close.

Perhaps you could explain how my maths is flawed? I am happy to learn if there is a mistake.
Noelex is offline  
Old 12-31-2014, 11:17 PM   #216
Veteran Member
 
City: Wherever the boat is
Country: Europe
Vessel Model: 48 foot sailing Yacht
Join Date: Jul 2014
Posts: 92
Quote:
Originally Posted by Djbangi View Post
Without more evidence you seem to be trolling.
Jonathan, I find it surprising, and perhaps strangely reassuring that anyone would suggest that I have not spent enough time studying anchors, particularly over the last 8 years.

In the last week I have posted 14 photos of the performance of a Guardian anchor. (a slightly simplified Fortress made by the same company)
Noelex is offline  
Old 01-01-2015, 01:33 AM   #217
Senior Member


 
City: Fort Lauderdale
Country: United States
Join Date: Apr 2013
Posts: 156
Noelex, do you think that 5 boats tied together, each of separate displacement and windage, will have the same load in 15 knots of wind as does one single boat of a comparable length in 30 knots of wind?


Djbangi, I saw the images that Noelex posted on the Cruisers Forum of the tiny 2.5 lb / 1 kg Guardian G-5 for boats up to 16-ft, and I am wondering if he will use this anchor for his basis of evidence regarding the performance of our product.....and compare it to the over-sized 125 lb / 55 kg Mantus, which he glowingly posts images of in that thread.

This anchor also has a shank that bent under a minimal load while in use aboard his 45+ (?) boat.
Anchor Brian is offline  
Old 01-01-2015, 03:17 AM   #218
Senior Member
 
Join Date: Apr 2011
Posts: 211
[QUOTE=Noelex;295237]Jonathan, I find it surprising, and perhaps strangely reassuring that anyone would suggest that I have not spent enough time studying anchors, particularly over the last 8 years.

In the last week I have posted 14 photos of the performance of a Guardian anchor. (a slightly simplified Fortress made by the same company)[/QUOTE

I cannot think you are serious:

If your posts of your 'tests' of a Guardian anchor are meant to lift your credibility I suspect you will be most disappointing. There will be some sycophants around but most will simply find your evidence a joke - but maybe that was the intention and the humorous punch line will come later.

You have made a public statement saying you have observed Fortress/Danforth anchors in use- I am still waiting for you to substantiate that statement as you have used that statement as the basis of a derogatory comment of both Danforth and Fortress. I think either you show statistically sound evidence on which you base your accusations or simply apologise.

If I want to pass comment on the negative performance of a product I would be very, very careful and have some form of corroboratory information - otherwise its trolling.
Djbangi is offline  
Old 01-01-2015, 03:51 AM   #219
Senior Member
 
Join Date: Apr 2011
Posts: 211
Noelex,

You establish yourself as an expert in anchor performance, your previous post, and with that you also take on a mantle of responsibility which in your case is further also underpinned by being a Moderator on Cruisers Forum.

Given the foregoing I think you, and CF, appear to be walking on very thin ice as there is no evidence you have to support your contention that you have observed a Fortress or Danforth 'performing' in a way that is dangerous. You 'underpin' some of your comments by a childish series of images of a 1.5kg Guardian being 'tested' in 1m of water. You have also, on CF, made unsubstantiated negative comments of other anchors, in particular convex anchors (some of which you have never seen in use nor used yourself).

Your criticisms of Fortress, Danforth and convex anchors has been sustained and repetitive and until you mentioned you actually had seen this 'poor' performance of both genuine Danforth and Fortress your comments could have been anecdotal (and not that of an expert). Now as an expert of 8 years, who states publicly to have seen this poor performance, you need to be able to substantiate your comments. Over 8 years you would need to be able to document the number of times you have seen this and define for each example where, which vessels, depth, scope, wind speed etc etc. These are serious accusation it needs serious documentation.

In the absence of proof I would have thought that the possibility of legal action starts to loom, for you personally and CF.
Djbangi is offline  
Old 01-01-2015, 06:39 AM   #220
Veteran Member
 
City: Wherever the boat is
Country: Europe
Vessel Model: 48 foot sailing Yacht
Join Date: Jul 2014
Posts: 92
Quote:
Originally Posted by Fortress Anchors View Post
Noelex, do you think that 5 boats tied together, each of separate displacement and windage, will have the same load in 15 knots of wind as does one single boat of a comparable length in 30 knots of wind?
River Cruiser referred to 15mph not 15 knots. 15mph = 13 knots

ABYC figures for the force on the anchor rode of a single 38 foot boat are:

13 knots= 198 lb
30 knots = 1,056 lb

An alternative formula has been proposed by Professor Knox for calculating anchor forces. His formula gives lower numbers, but the ratio with increasing windspeed is the same. The following results for a single 38 foot boat:

13 knots= 45 Kgf
30 knots = 241 Kgf

It cannot be assumed that 5 boats tied together will experience 5x the load of a single boat, but as an approximation it will be reasonably close. 5x198 lb = 990 lb. this is the force produced by a single 38 foot boat at 29 knots. Professor Knox's formula gives exactly the same windspeed.

As the force rises dramatically with windspeed, errors in this assumption are not great in any case. For example if we assume 5 boats tied together will experience 7x the load of single boat then the equivalent windspeed only rises slightly to 34 knots.

Anchor forces rise roughly as the square of the windspeed so the force rises much more dramatically with an increase in windspeed than might be imagined.
__________________

Noelex is offline  
Closed Thread

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 10:52 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012