Anchors are a Drag... Waking Up On a Beach in Our Boat

[goboatingnow]

Originally Posted by belizesailor

Yes, apparently that confuses a lot of people. Documentation issue maybe?

Would be interesting to crack open and iPad and a Samsung tablet and see what's inside. Odds are high that they have the same GPS chipset.

Well its different in different models ,iPhone 5 uses the Qualcom MDM9615, A-GPS and Glonass GPS receiver combined, reportedly a very sensitive and fast to first fix receiver. The GPS is integrated with the cellular modem chip.

whereas the newer Galaxy s5 has a broadcom 47531, with 5 constellation support (GPS, GLONASS, QZSS, SBAS and BeiDou)
the older s4 uses the BCM 47521, which supports A-GPS and GLONASS as well as a hardware based geofencing.


dave

[Terra Nova]

Robert--good post.

[belizesailor]

Originally Posted by goboatingnow

Well its different in different models ,iPhone 5 uses the Qualcom MDM9615, A-GPS and Glonass GPS receiver combined, reportedly a very sensitive and fast to first fix receiver. The GPS is integrated with the cellular modem chip.

whereas the newer Galaxy s5 has a broadcom 47531, with 5 constellation support (GPS, GLONASS, QZSS, SBAS and BeiDou)
the older s4 uses the BCM 47521, which supports A-GPS and GLONASS as well as a hardware based geofencing.


dave

So to relate chipsets back to the subject of the thread, is there any practical difference for the purpose of an anchor alarm?

For example, both my Samsung devices (phone & tab), presumably with some flavor of the Broadcom chipset have worked quite well for my purposes (anchor watch and nav respectively).

[Kenomac]

Does anyone have a suggestion for a good anchor alarm app for my Samsung S4 phone? I'm currently using Inavx on the iPad Air cellular with independent gps. The Samsung will probably get traded in in a few weeks for the samsung mega when I return to the US because I don't like the keypad for typing. While I'm asking, will the samsung droids work with navionics app? The samsung mega is a phone almost as large as a tablet, so with an Italian SIM card in my ipad an phone, my internet and phone service are taken care of. The ipad becomes a hotspot for other on board devices.

We also have a Garmin 521 GPS chart plotter on board that's dedicated for AIS while under way, it also has an anchor alarm. But the only issue, is that I can't figure out how to turn up the volume loud enough to hear it. Nothing in the directions or online tell me how. Does anyone know how to do this on the Garmin 521?

Ken

[Kenomac]

Zee wrote this on a snubber thread yesterday. I thought it was so funny and appropriate for this thread. Same issue we encountered, different anchorage, different country.

Here it is:

"winds picked up a tad in spring, preparing for summer blows, i came in when the winds were at 30 kts, having walked backwards a few feet with each new blow, i decided it was time. ... our holding here sucks, and when i lifted anchor i learned why i was walking back--- there was only 2 inches of anchor set into anything worth setting into . not unusual here. the set did fine to 30 kts then we walk 2 ft... botttom is silt over wtf,and no one eknows what the wtf is..is a river bed and gets righteous in summer with runoff and storms.. every year the bottom is different here, and bad bad bad holding.
it has beeen found that when one backs down on their anchor here, there will be an unsetting of that anchor and that boat will drag. here one needs to lay down more than 150 ft chain to stay put. please remember this when ye come to barra lagoon, as we (all the cruisers here) do save ye, is best when we dont have to.
we did tests after the third boat dragged the second time." Zeehag

"Bottom is silt over WTF".... brilliant!

Ken

[Alan Mighty]

Originally Posted by Kenomac

Does anyone have a suggestion for a good anchor alarm app for my Samsung S4 phone?

Not cheap. But good.

Slim Jim Anchor Alert

[bobsadler]

Can anyone provide an estimate/guestimate of how much pull is being exerted on an anchor with say 150hp engine in reverse at (1) 1000 revs or (2) 2000 revs with a 6inch prop?

I know there are bollard pull formulas but don't have any of the books with me.

[noelex 77]

Originally Posted by bobsadler

Can anyone provide an estimate/guestimate of how much pull is being exerted on an anchor with say 150hp engine in reverse at (1) 1000 revs or (2) 2000 revs with a 6inch prop?

Fortress in their "Safe anchoring guide" have a table that lists the expected pull based on shaft horsepower.

Fortress Anchors – The World's Best Anchors! – Safe Anchoring Guide

You can look up your engine specifications which will list the HP relative to the engine revs.

The table is obviously an approximation. It does not take into account the type of prop for example. One of the textbooks covering propulsion may be more the sort of information you are looking for.

The opposite side of the equation looking at the force exerted by various wind strengths is also an approximation, with some believing the ABYC guidelines overestimate the holding requirements by as much as x3.

If it's any use, I have noted that after our anchor set procedure of full reverse for 30 seconds, the anchor does not set deeper until the wind force is around 25-30 knots average (gusts will be higher).

While there are some variations based on prop configuration and the selected engine size, this relationship seems to hold for other yachts reasonably independently of boat and anchor size assuming they set their anchor in a similar way.

[Kenomac]

Originally Posted by Alan Mighty

Not cheap. But good.

Slim Jim Anchor Alert

I just downloaded three anchor alarm apps onto my samsung s4 including slimjim. This one, although it cost $15.99 as compared to $0 for the others... Looks to be the easiest to use with its advanced features. One thing I like over the other apps is the ability to project the anchor location after the set, and also the ability to set an exclusion area. Which will come in handy if some knucklehead comes in late and drops 2:1 scope right next to me.

Thanks for the recommendation

[monte]

One of the features I like with the iPhone or iPad anchor watch his the automatic google earth overlay. It also is easy to position the anchor either by pressing as you drop (my preferred method) , coordinates, or tap the screen where you think it is afterwards.
The earth overlay is very handy when you are anchored close to shore as it will show shoals and rocks in your swing circle.
Using it now off cascais.

Also has functions such as send email or SMS if you swing outside the circle to alert you if not on board.

[Kenomac]

I just purchased the anchor watch for ipad HD app. Wow... So far it's the easiest to use. Only $1.99. Had some trouble with slimjim, couldn't get the alarm to shut off without powering off my cell phone, hopefully, I can sort it out.

I'm so glad I started this thread, so many good suggestions for anchor alarms. I'm testing all of them... Apps for ipad and apps for android.

Ken

[weavis]

Originally Posted by Kenomac

I just purchased the anchor watch for ipad HD app. Wow... So far it's the easiest to use. Only $1.99. Had some trouble with slimjim, couldn't get the alarm to shut off without powering off my cell phone, hopefully, I can sort it out.

I'm so glad I started this thread, so many good suggestions for anchor alarms. I'm testing all of them... Apps for ipad and apps for android.

Ken

I quit purchasing apps. Yes they are cheap but I found I had to get at least 5 variants because I discovered things about them I didnt like or they didnt "quite" work as I hoped........ Not so cheap in the end........

[weavis]

Spandex rules.

[noelex 77]

Ken has suggested I post this photo here.

I hope it illustrates the situation where an anchor can hold a high force from applying full reverse, or withstand a strong wind force without actually holding very well.

The photo isn't great. The tip of the anchor is actually caught under a rock although this is perhaps not as obvious from the photo as it could be.
Note this sort of thing can happen at anytime. Even if the area is devoid of rocks a similar thing can happen with some debris on the bottom.

A small change in wind direction can unjam the anchor and leave the boat lying to a totally unset anchor.

I hope you can forgive the repetition, but this thread shows that there seems to be a belief that if the anchor holds full reverse you have a guarantee of a well set anchor. Testing the anchor with a strong setting force is the best tool we have (other than diving), but it is not foolproof.

[goboatingnow]

Originally Posted by belizesailor

So to relate chipsets back to the subject of the thread, is there any practical difference for the purpose of an anchor alarm?

For example, both my Samsung devices (phone & tab), presumably with some flavor of the Broadcom chipset have worked quite well for my purposes (anchor watch and nav respectively).

No differences between devices, The S4 GPS can do geofencing in hardware, but most apps implement it in software to my knowledge.


dave