Backing Down / Testing Reverse Thrust

[Maine Sail]

Well I finally got to test out my new toy, a digital strain gauge. For my first little experiment I wanted to see just how much load my motor could place on my mooring/ insert anchor here.

I inserted the load cell just outside my bow chock then put the boat in reverse and throttled her up to 2400 RPM which is 80% of max rated RPM. The elasticity of a rode or weight of my very, very heavy mooring chain creates a very un-steady reading but still it is quite clear that backing down at 80% is and should not compromise any anchor for a 36 footer.


I specifically ordered this unit with internal rechargeable battery and 30 feet of cable so I can use it on the boat. I also plan to measure varying wind loads. It will be fun to put the theories into a real world test which to my knowledge has not been done. Now I just need to waid for some good 20, 30 & 40+ knot blows to measure. I also plan to measure the loads it takes to straighten a rode with a kellet/sentinel and compare that to wind loads on the boat. There are many experiments I want to undertake but don't hold your breath during the sumer as I am generally too busy actually sailing..

Aside from few spikes up into the 600-800 pound range, likely from my USCG bottom chain moving on the bottom and spiking the load cell, it seems the average loads were under 500 pounds.

Considering my anchor has been tested to hold 5000 pounds, by more than one publication, I am comfortable that backing down at 80% throttle provides nothing more than a good set.

The engine is a 44HP Four cylinder Westerbeke turning a 16X9 Campbell Sailor three blade fixed prop.


Reverse Thrust Video (LINK)

 

[Bob Mack]

Great information. I have a swivel on my 5/16 chain at the anchor that is rated at 1400 LBS and I have been wondering what the real world safety factor is when I back it down, or am anchored in a fair blow. (373 Beneteau, 40HP Yanmar, 18", 3 blade Max Prop Classic, 20 deg pitch.)

 

[Roger Long]

While you are playing:

Next time there is a strong, steady wind, please put your load cell between the boat and the mooring and record wind speed. She's fairly typical and I would love to have a data point for windage loads to check some of the inconsistent estimates I've seen over the years.

If she sails at the mooring, there would probably be peaks as she sheers off and then a number when she is head to wind. That would be great data.

 

[Maine Sail]

While you are playing:

Next time there is a strong, steady wind, please put your load cell between the boat and the mooring and record wind speed. She's fairly typical and I would love to have a data point for windage loads to check some of the inconsistent estimates I've seen over the years.

If she sails at the mooring, there would probably be peaks as she sheers off and then a number when she is head to wind. That would be great data.

Already part of the plan...

 

[Stu Jackson]

Anchor Swivels

Great information. I have a swivel on my 5/16 chain at the anchor that is rated at 1400 LBS and I have been wondering what the real world safety factor is when I back it down, or am anchored in a fair blow. (373 Beneteau, 40HP Yanmar, 18", 3 blade Max Prop Classic, 20 deg pitch.)

Bob, we've had discussions ad nauseum over on our C34 Message Board about swivels. I think they are a disaster waiting to happen and suggest you seriously consider removing it. It is surely your weakest link in the chain. One of our members has been sailing for a lot longer than I have, and he doesn't recall his chain ever getting wrapped enough to ever require a swivel. Do you? What are the rest of your components rated at?

 

[jibes138]

But Summer's Almost Over

My grandfather used to say on the fourth of July that summer was almost over up in Massachusetts, so in Maine I'd assume it is pretty much over by the fourth, the days are getting shorter, the nights colder. So we'll give you until mid-July to get some data out to us, unless by then your excuse will be you are packing everything up getting ready to haul out for winter storage.
This will also be a good test for how much it takes to haul in your anchor without a windlass (like me) in certain wind conditions and why we need Hermitt Scott to invent a windlass made from a trailer winch that can be cranked by hand and which is removable so the bow doesn't look like an old rusty trailer. I am convinced sales of such an item would be quite brisk. The winch typically has about 20 feet of nylon webbing with a very large pulling capacity that should be good for pulling the anchor out of the mud when the rode (chain) is vertical. I'll assume motoring up to the anchor will at least get you that far. Just need some king of mounting bracket and a plate to attach to the deck to get the crank high enough so you don't crack your nuckles.

 

[Don12364]

Its called "ANCHORWATCH"

Well done Main - great video.
Yes it has been done but I guess nobody told America.

A few years ago John Knox (Professor), also a sailing instructor, from Edinburgh, adapted a Load Cell and did a series of tests on his anchor rode under a range of conditions.
He went on to manufacture and market the unit shown in the link(s) below.
It can be used for every anchoring and can even alarm if you drag.
I agonized over buying one (£199 ~ $300) to do exactly as you are now doing but miserliness got the better of my good intentions.

The whole was written up in two of our sailing magazines, both of which I still have, so I will try to locate the item and post it here (if the author agrees).

http://www.anchorwatch.co.uk/

This is covered in more detail in two articles by J H Knox (1) Anchoring by Numbers, Yachting Monthly, August 1997 (2) Snatching at Anchors, Practical BoatOwner, February 1999. The main conclusions are summarised below.

BTW:-
You might try using the Peak Load setting as it is this which the rode and hull fittings must contain and which causes breakages. It looks as if your unit has this feature.

 

[Hermit Scott]

My grandfather used to say on the fourth of July that summer was almost over up in Massachusetts, so in Maine I'd assume it is pretty much over by the fourth, the days are getting shorter, the nights colder. So we'll give you until mid-July to get some data out to us, unless by then your excuse will be you are packing everything up getting ready to haul out for winter storage.
This will also be a good test for how much it takes to haul in your anchor without a windlass (like me) in certain wind conditions and why we need Hermitt Scott to invent a windlass made from a trailer winch that can be cranked by hand and which is removable so the bow doesn't look like an old rusty trailer. I am convinced sales of such an item would be quite brisk. The winch typically has about 20 feet of nylon webbing with a very large pulling capacity that should be good for pulling the anchor out of the mud when the rode (chain) is vertical. I'll assume motoring up to the anchor will at least get you that far. Just need some king of mounting bracket and a plate to attach to the deck to get the crank high enough so you don't crack your nuckles.

When I first started trying to anchor I had all kinds of ideas to make it easier. I just bought a chain hook for when I am by myself to make it easier. It's almost comical but almost every invention I think of has a one-way device in it. I seem to always be using a ratchet and pawl or a clutch bearing. For my 30' boat I wouldn't even take the time to install a windless if someone gave it to me. The only thing that I think would make retrieving the anchor easier is to use something like a chain stopper. It IS a one-way device but I think it can be improved upon, at least how I retrieve the anchor I think it could be. I think a cam cleat device made for chain with a fair lead that flips over it would be better than a chain stopper, because it's too much trouble to get the chain into it. It should be as easy as using a cam cleat.
I just discovered load cells about 9 months ago. I use them now to determine the force on a brake pad on spin bikes/run rocket to determine what "level" some one is exercising at, something I believe has never been done.
I wish there was as easy way to hook a strain gauge up to the shrouds. I would really like to know how much force there is on an upper shroud while the rail is in the water.
Jibes-I build a bow roller with the intention of having a chain stopper or a cam cleat-made -for-chain installed on the back by where it goes into the anchor locker. Yeah I know my boat is ugly, I'm working on it.

 

[jibes138]

It's pulling up the anchor that's the tough part

Scott,
Not sure I'm following your cam cleat thoughts. My issue is wityh trying to lift a 35 pound CQR, about 20 feet of chain, and a big glob of mud all the way up from the ocean floor. I figure a minimum of 60 pounds getting hauled up from say 13 to 20 feet. A $1500.00 windlass is a wonderful solution but I'm too cheap to spend that on a device used so infrequently and then all the electrical cabling and power drain and maintenance to deal with. So my idea is take a trailer winch used to haul these big old power boats on their trailers (pulling force say 1000 pounds) and rig a mount up near the bow to haul up the anchor once the rode is vertical. It would be simple to mount as a removable unit for when needed. You could even powder coat them or dye colored anodize the mount if you felt you must. Bottom line is you wouldn't want the sail chafing and getting caught during tacks but standing up cranking in the anchor with a cheap (30 to 40 bucks) simple winch would be the cats meow.

 

[Ross]

Re: It's pulling up the anchor that's the tough part

You can use a halyard winch or a sheet winch to haul an anchor. You just need to splice a grab hook to a length of line.

 

[Hermit Scott]

Scott,
Not sure I'm following your cam cleat thoughts. My issue is wityh trying to lift a 35 pound CQR, about 20 feet of chain, and a big glob of mud all the way up from the ocean floor. I figure a minimum of 60 pounds getting hauled up from say 13 to 20 feet. A $1500.00 windlass is a wonderful solution but I'm too cheap to spend that on a device used so infrequently and then all the electrical cabling and power drain and maintenance to deal with. So my idea is take a trailer winch used to haul these big old power boats on their trailers (pulling force say 1000 pounds) and rig a mount up near the bow to haul up the anchor once the rode is vertical. It would be simple to mount as a removable unit for when needed. You could even powder coat them or dye colored anodize the mount if you felt you must. Bottom line is you wouldn't want the sail chafing and getting caught during tacks but standing up cranking in the anchor with a cheap (30 to 40 bucks) simple winch would be the cats meow.

AHHHH ok. I thought you were having trouble breaking it free or keeping the rode from getting accidentally paid back out while motoring around trying to pull it in. I have an idea. Let me think on it for a bit and I will let you know.

 

[Hermit Scott]

OK I think I have something. Do you have a picture of your bow area like the one I posted? If you already have one of those $40 winches, you'll need a way to have a platform to mount it on and someway to hook it to the deck.
If all you need if 20' of hauling power, you can sew small hooks into the strap. every few feet. Pull all the strap out. have your anchor with a 1:1 scope. Have the winch sitting ont he deck hooked in(however it will be). Pull out all the strap, use the hook closest to the winch first and start cranking. As that hook gets to the winch, hook the next hook up on the chain. repeat until the anchor is up. I think It would be best to have a chainstopper so you progress will be saved without any chain slipping back out.
If you have a winch on the mast for a halyard, you could use that as well. Make a strap with hooks in it and winch the strap up onto the winch using the same method.
IT would work best with a winch on the mast.
Edit addition:I change my mind. You could have a rope with a one chain hook on the end. Use the winch on the mast to crank the anchor up, the chain stopper saves your progress. Unhook the hook and repeat the process to pull your anchor all the way up. The chain stopper should be mounted near your bow roller. You'll be able to crank up 8' or 10' at a time before repositioning the hook.
http://www.amazon.com/Sea-Dog-3218251-STAINLESS-STOPPER/dp/B002IV8GAK
That's the type of chain stopper I am talking about. That, 15' or 3 strand and a chain hook and you should be able to pull up 100 lb. anchor.
Totally highjacked this thread, sorry MS.

 

[zeehag]

i pull a 35 pound cqr out of water --mud-- when i anchor my ericson 35mII.....i also have 100 ft of 5/16 chain --then rope rode. i pull the anchor line until i have the straight up and down thing going--i let the boat sit for a bit--mebbe a cup or coffee--lol--by the time i am on it again, the anchor comes up clean and smooth.
i am old and i am female. i donot have the strength you young testosterone ridden males have--lol--i also look for used simpson -lawrence windlasses --manual kind, not electric-more reliable--lol----you guys have great over thought ideas and you make me laugh so hard--is awesome fun!! they are practical and ingenious--and do not cost much ----

oh yes--my chain stopper is my bow cleat... i loop the chain around like rope and is all good....

 

[jibes138]

ok zeehag, I'm not really that weak, but I am getting old, I applaud your great strength...perhaps you are casting an anchor spell or two to lighten the load?? I am trying to give Scott a few new product ideas so he can make millions selling them to West Marine, or Phil at SBO. Then he will invite us all for a sail on his brand new Perini Navi . I like the idea of a rope with a hook...this would definitely sell in marine stores...target market....wives as a father's day gift....use the mast winch.... I like it. That way you'd have a run of maybe ten to 15 feet before having to reposition the hook.
I was thinking maybe a trailer winch strap could be attached to the chain rode with the hook at the last link and then tied on twenty feet away. As the rode comes up you connect the strap to the winch and then haul it in the rest of the way. I pull power boats for friends and relatives onto their trailers a lot and these winches would pull an anchor up without breaking a sweat.