1/4"HT vs. 5/16" Proof Chain

[s/v Jedi]

If the thought of having light chain keeps you awake at night, there are only two ways to solve that: 1) buy heavier chain or 2) go out and anchor in a storm to test the light chain. Confidence is boosted by experience.

Having said that, I agree with most Joao is writing. Let's take an example I am familiar with: our boat should have 1/2" HT chain. Instead, we have 3/8" grade 70 chain. The following considerations were weighed by Dashew before making that choice:

1. Only 200' of 1/2" chain fits in the locker, while 350' of 3/8" fits in that same locker. It's better to have more chain if that chain would be strong enough.

2. The 3/8 inch G70 is strong enough, but more expensive than 1/2" HT. For things being strong but small, money can be thrown at it with success. Same for rope etc.

3. When doing the math, deploying an anchor with let's say 120' of chain, you put a certain weight overboard. No matter how long you study the math, it is ALWAYS better to minimize the weight of the chain and put that weight back into a bigger anchor. Read that again. This doesn't mean one should select a chain that isn't strong enough, or one that would keep you awake at night, it means you should never oversize the chain but put the extra weight of the bigger chain considered into a bigger anchor.

4. The weight savings of selected the 3/8" chain were partly used for taking more chain and partly for selecting a bigger anchor. We have a 176 pound Bruce as the result and love every pound of it!

cheers,
Nick.

[witzgall]

I want at least 150', and would prefer 200'. I think that the locker is deep enough with 1/4 chain, but I am not so sure it will be with 5/16. I had a laugh when the salesman at WM suggested stainless chain. He reasoned that it was slippery, and has much less tendancy to stack up. I just laughed. I ahve to go back and measure, but I think that there was 10" left between the top of the 5/16 stack of proof coil, and the underside of the deck.

Chris

Originally Posted by Cheechako

Just keep in mind in a shallow locker that as the chain comes in, it will stack in a pillar under the chain pipe. When the pillar reaches the chain pipe, the windlass will jam. To avoid this you will need one person to push the pillar over as it stacks up. It's absolutlely amazing how vertical and small diameter (?)the pillar can be.

[GordMay]

Originally Posted by witzgall

...I think that there was 10" left between the top of the 5/16 stack of proof coil, and the underside of the deck.
Chris

Generally chain rodes require a minimum perpendicular fall of at least 12" , measured from the centre of the gypsy for Horizontal windlass’, or from the bottom of the locker deck for a Vertical windlass - hence a Vertical Windlass requires more cockpit locker depth.

[s/v Jedi]

Originally Posted by GordMay

Generally chain rodes require a minimum perpendicular fall of at least 12" , measured from the centre of the gypsy for Horizontal windlass’, or from the bottom of the locker deck for a Vertical windlass - hence a Vertical Windlass requires more cockpit locker depth.

Indeed. And now you get into the problem that there isn't enough height under the deck for a self-stowing chain locker!

The attached image shows a possible solution. One of our ships cats is showing that the windlass can be mounted further aft and to the side instead of on the centerline. The further aft you go, the more vertical height is available and the better weight distribution you get. The negative is that you have a length of chain on deck; this is dealt with by a band of Tread Master on Jedi and I like that better than the chain-pipes that are also used to deal with this. You also get enough room for a good chain stopper.

The chain locker itself needs to be tall and narrow. A 10" or 12" PVC pipe works great. Throw some pieces of dry-deck panels in there to keep the chain just above the drain. We drain into the bilge so can go lower but this is in front of the water tight bulkhead; I wouldn't do that otherwise.

cheers,
Nick.

[GordMay]

Note: Nick's off-centre solution will only work satisfactorily with a vertical windlass gypsy (as Jedi has).

[witzgall]

Nice solution. I was on a swing keel boat, 47', that did the same thing, so the windlass could be used for both the keel and rode. the boat's draft was 2.5' with the keel up, so it also had the desired effect of getting the chain weight right in the center of the boat down low. Alas, I don't think this would work with our boat. THey used a stainless strip on deck, and even sacrificial plexi on a hatch that the chain drew across.



Chris

Originally Posted by s/v Jedi

Indeed. And now you get into the problem that there isn't enough height under the deck for a self-stowing chain locker!

The attached image shows a possible solution. One of our ships cats is showing that the windlass can be mounted further aft and to the side instead of on the centerline. The further aft you go, the more vertical height is available and the better weight distribution you get. The negative is that you have a length of chain on deck; this is dealt with by a band of Tread Master on Jedi and I like that better than the chain-pipes that are also used to deal with this. You also get enough room for a good chain stopper.

The chain locker itself needs to be tall and narrow. A 10" or 12" PVC pipe works great. Throw some pieces of dry-deck panels in there to keep the chain just above the drain. We drain into the bilge so can go lower but this is in front of the water tight bulkhead; I wouldn't do that otherwise.

cheers,
Nick.

[witzgall]

Lewmar states that you need 16 inches of fall on their "Choosing a windlass" page, but only 12 in the manual for the particular windlass I am considering.

I would hate to install the thing only to find out that it is jambs constantly.I am going to measure it accurately with the both the chain in and out. There is a small compartment in the head of the vberth, Another option would be to store some chain in there as well, with a PVC pipe connecting the two. That locker does not drain, so I am not so sure I want to go there. We have kept our chain locker clean thusfar by washing chain we bring up on deck before dropping it down into the locker.
Chris

Originally Posted by GordMay

Generally chain rodes require a minimum perpendicular fall of at least 12" , measured from the centre of the gypsy for Horizontal windlass’, or from the bottom of the locker deck for a Vertical windlass - hence a Vertical Windlass requires more cockpit locker depth.

[s/v Jedi]

Chris,

You can solve that "no drain in 2nd compartment" issue by installing the pipe so that it connects high up in the primary chain locker. You have to hand-feed the first part of the chain into the pipe until the compartment contains the length that doesn't fit in the primary chain locker, and start it into the primary locker after that. After that, you can always deploy all of the chain and retrieve fully auto-stowing if only the primary length was deployed.

cheers,
Nick.

[witzgall]

That makes sense. I knew that it would have to be hand fed, but raising the pipe might work, I have to look it over and do some measuring.

Chris

Originally Posted by s/v Jedi

Chris,

You can solve that "no drain in 2nd compartment" issue by installing the pipe so that it connects high up in the primary chain locker. You have to hand-feed the first part of the chain into the pipe until the compartment contains the length that doesn't fit in the primary chain locker, and start it into the primary locker after that. After that, you can always deploy all of the chain and retrieve fully auto-stowing if only the primary length was deployed.

cheers,
Nick.

[Zach]

Excellent thread!

Nick, do you have any pictures of the 10-12" PVC pipe chain locker? I'm curious how it looks installed in the boat.

Thanks,

Zach

[s/v Jedi]

Originally Posted by Zach

Excellent thread!

Nick, do you have any pictures of the 10-12" PVC pipe chain locker? I'm curious how it looks installed in the boat.

If you have Dashew's Cruising Encyclopedia: page 51 shows our fiberglass locker and the PVC pipe locker on a Sundeer 56. I have seen the same PVC pipe on later build Sundeer 64's.

Ah, that page also says it's 14" diameter pipe. It's secured near the top with a horizontal plywood/fiberglass panel with a hole where the pipe fits into. I guess they closed the bottom with a matching PVC end-cap.

cheers,
Nick.

[MidLandOne]

Our own chain locker is done very much as Nick describes with a vertical stack but is square in section about 14 or 15 inches square fabricated in fibreglass/timber composite with a plastic grating in the bottom to keep the chain above undrained water. As he says to get the height it pushes the windlass aft and that more so in our case as the locker drains overboard just above the water line - that does keep the water out of the bilge but also means that wave, etc action often floods in and out the bottom of the chain locker when underway (if nothing else it keeps the locker bottom clean ).

Vertical stacking like this does raise the centre of gravity but is a trade off between that and reliable anchoring and draining overboard.

We managed to do this in a boat much smaller than s/v Jedi with 75 meters of 10mm chain (a smidgin bigger than 3/8 inch) and still get the recommended 12 inches or a bit more of minimum drop from the windlass but I find 12 inches really insufficient for windlasses that have the chain pipe integral with the windlass deck plate resulting in a sharp 90 degree turn for the chain immediately it comes off the chainwheel. This probably more so when the chain is the maxumum size for the particular windlass whereas a smaller than maximum chain might likely zoom down the pipe.

A comment was made about ss chain being mentioned by the chain supplier as being more slippery, which it is of course. While I suspect the chain supplier may have been motivated by dollar signs I have now had a couple of long term cruisers who spend alot of time at anchor claim they have changed to ss because for them it was the cheapest option in the long run. When they took into account the costs of regalvanising, chain life (especially for HT for which there are limits to regalvanising, like some metallurgists say never to) and the inconvenience of regalvanising on their travels, then SS was the cheapest option. I make the point though that these were people who could stand the up front cost of going to ss and also, given the cost of ss chain, I am not totally convinced. May be something to check out though for those spending a lot of time at anchor.

[s/v Jedi]

I would love s/s chain and would think I can afford it but it just isn't strong enough!

BTW: we also have the square locker version. I saw the pipe in hulls build later than ours.

I don't understand the info in this thread about the angle of the stack of chain not being able to sustain a high stack. I think the angle will be about the same no matter how high the stack but that also means the diameter at the bottom increases with height of the stack??

cheers,
Nick.

[Roy M]

My Searunner 40 trimaran weighs about 12,000 lbs. I used to have a manual windlass, 100' of 5/16" proof coil chain and 300' of 5/8" nylon braid. I have since shifted to a Lewmar V-series with vertical capstan (as my "donkey engine"), 260 feet of 1/4" high test, and a 100 foot tail of 1/2" floating yellow polypropylene that can be quickly cut and later recovered with its "marker". Additionally, I have parallel windlass switches, both in the bow anchor locker, and the reserve chain locker further aft. I can stow all chain aft to keep the boat trimmed, stow just the 100' that normally is used for local anchoring, in the bow locker, and place the chain precisely where I want it with the two additional switches when single handing. I like the lighter chain on a multihull. My boat will "weathercock" to surface winds unless I use a bridle, which is good anyway to act as a snubber and let me sleep at night without the sound of the chain links working against each other on each swell that passes.

[GMac]

What an interesting thread. Obviously 2 very differing schools of thought regarding the chain angle.

I've never deeply studied the mathematics of anchoring as I believe it's just to tricky to mathematical model anchoring. Way to many variables to take into account, biggest of all being the 'dick on the stick'. But we have taken a bit of time to simulate some of the numbers on that website with the models. We haven't been able to verify the numbers in actual use. If anything we tend to think that the site overestimates the forces, in some areas by a lot and the forces required to straighten out a chain are underestimated. We did this using real chains and load cells, etc. And that was done on dry land so without the added bonus of drag through the water column that systems in real use get.

So what we do is use everyday real life findings from being in this specific game for many years. We use those daily in sorting out poor anchoring performance. I can tell you that weight in chain is all good. More chain is better than less chain.

Massive anchors and tiny rodes don't give the security that a more balanced system does. All that happens with massive anchors is that the anchor has to do more work. This is fine unless you look at 'the last resort' angle of your anchoring system, which is..... the anchor. Once that gives up you are outta there babe. So why put everything into the last resort, why not try and help your anchor by spreading the loads around more.

We have a anchor here that is Aussie of origin. As the Aussies generally anchor in shallower flatter water than us they specify short smallbits of chain. When you follow those specs here you'll find you drag all over the show. Many come in blaming the anchor when in fact that's not the big problem, the lack of help for the anchor is. Rather than swap anchors we suggest they extend the length of their chain. Often than is as little as 5mts extra. Everyone who has done that suddenly finds the dragging goes away. These anchors are big for their weight so do grab a lot of seabed given a chance to get in and settle.

Situations like that are common here with people who use too light or too short a chain length. When the rode behind the anchor is tuned into the system better tihe dragging stops.

So in practice more chain has been well proven to increase the efficiency of the anchor. Sure I suppose you could use a silly sized anchor but that comes with another range of downsides in itself.

Steve D likes his small gear but when thinking about him you also have to consider a few other things which aren't that normal. His boats (are damn cool) are light, skinny, very low windage and his anchors are in the area that most would consider more as a 'mooring weight', they tend to be huge by everyones standards. So Steve's boat just doesn't put the curry into his anchoring system that similar length boats would do normally hence he can get away with a lighter than normal rode.

All good copying someone else but be careful you aren't comparing apples with oranges.

Another maybe telling point is - We get many offshore cruisers down here. To get here they have to have done many many miles through often tricky anchorages. It's far from uncommon for many of these cruisers to up in size and length of their anchor chains before heading back upwards again. The majority of these are also US boats. Maybe that all the theory they learnt back home wasn't borne out in reality. On the odd occasion the boats skipper has said just that.

As much as the mathematics say one thing it appears the big wide real life world hasn't read the same spreadsheet.

But we have a programme in place right now that is giving us real in use numbers. Still early days and we have more measuring systems going into 2 boats next week. The preliminary numbers are showing that we maybe over estimating load numbers by quite a bit but as data to date is small and these have been running over summer we haven't had enough good big blows to make any sort of early call.

30kts a lot of wind?? Hello, that's a damn good yachting day even if just above the comfortable 'no spilling the rum' level

Here is an interesting question raised by the 1st set of numbers. Would you except to get the same load at the anchor as you would at the boat? By that I mean, if your boat is taking XXXkg to hold it at the stemhead is that same XXXkg being applied to the anchor at the same time.