SailNet Community - Reply to Topic

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related) > Mantus Anchors NEWS: anchor sizing tool
 Not a Member? 


Thread: Mantus Anchors NEWS: anchor sizing tool Reply to Thread
Title:
  

By choosing to post the reply below you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:
 

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Topic Review (Newest First)
05-22-2013 10:30 AM
Mantus Anchors
Re: Mantus Anchors NEWS: anchor sizing tool

Quote:
Originally Posted by Minnewaska View Post
A cruising anchor of 105lbs? My gut says that's either pretty conservative or the Mantua doesn't hold well per lb. I suppose bigger is always better, until you have to retrieve it.
The idea is to envelope, hi winds and poor bottom (loose silty low viscosity bottom), we size the gear so to insure safety with a cruising anchor in 40 knots and poor bottom... We believe our to be the single best all purpose anchor on the market (you will have a guarantied set). In areas with silty bottoms you need a bigger blade surface area to achieve the same needed holding power, so we develop the sizing guide to envelope the worst possible situation as described.
05-22-2013 10:21 AM
Mantus Anchors
Re: Mantus Anchors NEWS: anchor sizing tool

This a letter we just received about the Mantus:
A few months ago I purchased a 35lb Mantus anchor for my Endeavour cat 30 sailboat to go with a new windless. I just returned from 2 months cruising the Bahamas. I have sailed for over 30 years and used many brands of anchors.
No anchor I have ever used before has set EVERY TIME, in every type bottom, on the first pull except the Mantus. In the heavy grass I always dive to check the set. The Mantus set perfectly every time with only the "roll bar" showing. Heavy tidal currents and midnight storms all failed to unset it.
Friends I was cruising with would dive their anchors then look at mine and could not believe it. No other anchor even comes close!!!
I also bought one of your chain grabbers. It also worked well with two exceptions:
1) Once in shallow water with little wind, it unhooked itself
2) Once, some how, it grabbed the chain a second time, leaving a loop of chain in the rode. That is hard to believe, but true
A design modification to "close the entry slot" when attached would solve both of the above.
Both items are the absolute best, and I recommend them to all cruisers.

Vaughan Weaver PE,
LCDR USN Ret.
05-22-2013 10:19 AM
Mantus Anchors
Re: Mantus Anchors NEWS: anchor sizing tool

Quote:
Originally Posted by blt2ski View Post
Med,

the article kinda states similar findings issues as you did. In deeper water, the chain wt at shorter scopes could start being an advantage. Shallower water not so much.

Hence the, not sure there is a proper always right way to anchor per say. Just as the weight of the anchor is not always the correct way to look at things too. IE an aluminum fortress when you look at the sq inch of the flukes vs a steel one, the aluminum when set will hold as well as a steel one! Not that I want a fortress style around here........have a heck of a time setting them, vs the other styles. ALong with they do not always reset with tide changes.

I'm also sure a mantus would do great size appropriatly. I do know of one fellow living on ahook in bellingham with a mantus. He complained initially on FB. But with his track record of being ont he hard with a fail anchor system of differenet sorts and reasons........not sure the initial issue he had was the design etc of the anchor! Might be more of a human issue side of things! Not sure what he is hooked up to at the moment.

Marty
Marty can you show me the link regarding the complaint on FB, because we did not have a single customer say nothing but praise. I would want to address this customers issues...
Greg
05-18-2013 12:05 PM
blt2ski
Re: Mantus Anchors NEWS: anchor sizing tool

Med,

the article kinda states similar findings issues as you did. In deeper water, the chain wt at shorter scopes could start being an advantage. Shallower water not so much.

Hence the, not sure there is a proper always right way to anchor per say. Just as the weight of the anchor is not always the correct way to look at things too. IE an aluminum fortress when you look at the sq inch of the flukes vs a steel one, the aluminum when set will hold as well as a steel one! Not that I want a fortress style around here........have a heck of a time setting them, vs the other styles. ALong with they do not always reset with tide changes.

I'm also sure a mantus would do great size appropriatly. I do know of one fellow living on ahook in bellingham with a mantus. He complained initially on FB. But with his track record of being ont he hard with a fail anchor system of differenet sorts and reasons........not sure the initial issue he had was the design etc of the anchor! Might be more of a human issue side of things! Not sure what he is hooked up to at the moment.

Marty
05-18-2013 08:23 AM
Minnewaska
Re: Mantus Anchors NEWS: anchor sizing tool

A cruising anchor of 105lbs? My gut says that's either pretty conservative or the Mantua doesn't hold well per lb. I suppose bigger is always better, until you have to retrieve it.
05-18-2013 12:12 AM
MedSailor
Re: Mantus Anchors NEWS: anchor sizing tool

Quote:
Originally Posted by blt2ski View Post
Med,
...
Not sure if you get or can find the latest "pacific Yachting" out of BC. In it was an article comparing a rope/chain rode to an all chain in lower water depths. Under 30' IIRC. It pointed out a rope/chain with 7-1 will almost ALWAYS do better than an all chain with the recomended 4 or 5-1. As in this example, hurricane force winds. the rope/chain will have a lower pull angle on the anchor, vs the all chain. Mainly due to both options will have almost no rode on the ground, with a direct pull on the anchor itself...

Marty

Ahhh.... now we get into more advanced anchoring theory and practice. I'm not at all surprised that the article showed that chain on shorter scope is no good compared to a longer rope in a hurricane. Guidelines, like "5:1" or "7:1" are good for a start, but there's more to the story.

Lets start with rope, which, in water, we can assume is weightless for our purposes. Therefore, there is no (very little) weight that has to be lifted off the ground and thus there is no caternary effect. Very little wind (or force) is required to pull all the rope off the ground into a straight line making a perfect hypotenuse of a triangle. Thus, the only way to change the angle is with more rope.

Chain, famous for it's weight, has a catenary to it so that when you pull on the boat end, the catenary (or sag in the chain) translates to a lower angle of pull.

All old news right? So far so good.

Now the guidelines for chain start to fall apart when we consider that the deeper we are, the more that 4 or 5:1 actually weighs. Consider chain at 1lb/ft with 10ft depth. At 5:1 that's 50ft of chain, and 50lbs. Compare that with the same 5:1 in 50ft of water, which would be 250ft of chain or 250lbs.

How much more force does it take to stretch out a chain rode that weighs 50 or 250lbs? Not sure, that's getting into more advanced physics than I can easily calculate, but it does take a lot more.

In hurricane force winds, there's enough force to make either the 250ft or 50ft chain straight as a bar. So, the weight is mostly negated. In the magazine example you're really comparing a bar-taut chain to a bar-taut rope. The rope makes a better angle with that triagle because it is longer because it it 7:1. Rope wins in that one, but if the wind was less than a hurricane, the catenary of the chain would still be in effect and they would be equal.

For example if it takes 30kts of wind to make 50lbs of chain bar taut, then 5:1 isn't enough for 30kts in 10ft of depth. That same 5:1 might be plenty of weight to still have a low pull angle if applied to an anchorage that is 50ft deep where you would have 250lbs of chain out. It might be still at a good angle of pull up to 45kts.


The short version of all this is that while I think 5:1 is a good guideline for chain, you can't skimp at all when it's shallow but you can at depth. I've anchored on 3:1 chain in 80ft of water but will use 6 or 7:1 in 20ft. Also, one's errors in calculation for tide height, bow roller height, and depth sounder depth all magnify in the shallower waters, which is another reason why more rode is better the shallower you are.

The other lessons?

1: Avoid hurricanes.

2: Anyone who only uses 4:1 of anything (except depleted uranium chain) in hurricane force winds deserves whatever they get. Another example, I'm afraid, of a magazine anchor test not being particularly applicable to real life.

MedSailor

PS To stay on topic I shall add that I'm sure a Mantus, sized appropriately with the calculator in this thread, would have done great.
05-17-2013 11:06 PM
blt2ski
Re: Mantus Anchors NEWS: anchor sizing tool

Med,

What anchor one uses etc, should and would depend upon the soil under you, type of wind, probably add in some wave and current action......wt and length of chain can also be dependent too.

Not sure if you get or can find the latest "pacific Yachting" out of BC. In it was an article comparing a rope/chain rode to an all chain in lower water depths. Under 30' IIRC. It pointed out a rope/chain with 7-1 will almost ALWAYS do better than an all chain with the recomended 4 or 5-1. As in this example, hurricane force winds. the rope/chain will have a lower pull angle on the anchor, vs the all chain. Mainly due to both options will have almost no rode on the ground, with a direct pull on the anchor itself.

It also pointed out IIRC, that for around here, bruc/plow/spade style anchors seem to work better over danforths.

Lewmar IIRC uses about one anchor size heavier than that bruce chart IIRC. Not sure what the total difference is between a lewmar and a bruce per say. If I do go heavier for a cruise anchor, not sure if I would stick to a bruce/claw style, or maybe go with a fast set or the mantus. The mantus being as it woudl break down, might be a better option, keep my fast stet on the bow for 90% of my sailing needs, and IF and WHEN I find I need to anchor overnight, have the heavier one to pull out of the bildge with its longer chain, heavier rode etc. I've been out as RC a couple of times with the fast set, no issues in a sandy/clay soil holding in upwards of 15 knots. typically 8-12! some current.....

Marty
05-17-2013 11:40 AM
MedSailor
Re: Mantus Anchors NEWS: anchor sizing tool

Marty,

Your post reminds me about the anchor setup on my old boat. It was a 10K 31ft boat and it had a 7.5kg genuine Bruce aboard, but at the bow it had this ridiculous 45lb home made stainless danforth thing.

I found a well-worn, old tattered copy of the original Bruce anchor sizing guide. What a joke! 7.5kg was what was recommended for my boat, and I'm "guessing" that after some bad experiences the owner got some religion had had the monster anchor welded up.

Don't get me wrong, I'm a (genuine, not knock off) Bruce fan, but their sizing chart may be part of why they have always done so poorly in tests and their reputation was so mixed among cruisers. It's a tough call for an anchor manufacturer to decide if they want to look good on paper (ie cheaper, lighter, etc) or if they want to be more conservative and probably build a better reputation over time.

Here is a link to a reproduction of what I believe is the original Bruce anchor chart.
The Bruce sizing guide for Captain Aaron's inflatable tender
25ft boat with a 4lb primary anchor? *Ummm.... No
60ft 50,000lb boat with a 44lb anchor? *Ummm.... No.*

MedSailor
05-17-2013 02:13 AM
blt2ski
Re: Mantus Anchors NEWS: anchor sizing tool

Having the three size options is a good thing IMHO. As for me, I use a lunch/race hook most of the time up front! vs the heavier cruise hook. Probably since I race more than cruise and anchor out........just trying to make the grade with the race rules one has to follow.

For some of you that have not seen at least my local minimum anchor sizing.
(LOA/17)^3..... so for me (30/17)^3 = 1.765x1.765x1.765 = 5.49 ls of min anchor.
Total anchor rode etc is (loa^2)/80.......(30^2)/80 = 900/80= 11.25 lbs of anchor, chain and line. Min length of rode is 150'!
I have a 9lb fastset, 6' of 3/8BBB and 200' of 7/16" 3st.

The other I like in the options. the cruise anchor has a recomended chain size, in both std and hi-test. along with a min rope size. It would also be interesting to see the min option for a lunch/storm potential option too. Or better yet. Lunch is good to say 20knots of wind, cruise to 40, storm to 60, SUPER storm to 80-90 knots!

My recomended sizes were 13, 25 and 35. I have the 9 and a REAL 16.5 bruce! Even says made in belgum! I'd personally feel a bit better with a 10KG/20-25lb anchor and 30-50' of chain vs the 15" of chain I have. 5/16 vs 1/4 that I have. Rope size is plenty at 5/8" for a 30' LOA 7K boat.

Marty
05-16-2013 07:16 PM
swampcreek
Re: Mantus Anchors NEWS: anchor sizing tool

We put a 35# Mantus on our Catalina 320 over the Winter, we haven't used it yet but it fits great and looks sweet!
This thread has more than 10 replies. Click here to review the whole thread.

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


All times are GMT -4. The time now is 11:53 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.