Rocna Vulcan anchor size for Grand Banks 42?

[diver dave]

S

Secondly, if you are worried about total weight, why carry an all chain rode? I've always had a chain/nylon rode. Even the Spade anchor website advises against using an all chain rode. They recommend something in the 75 ft range. Others recommend about a boat length of chain and the rest nylon. It's less weight in your bow (where you don't want it) and improves anchor holding in most situations. It's also less weight for your windlass. Before I'd switch to a smaller anchor because of weight issues, I'd rather lose some of the chain.

That worked well for me on my last boat. It had a combo wildcat, and it made the steel to nylon transition painless. Sometimes had to hand manage the rope as it stacked in the locker. Current boat is all chain, and certainly now brainless to manage the chain only; but always use a V bridle now. So that's the choice; nylon thru the windlass somehow, or the extra step of installing the snubber.

 

[rslifkin]

Trying to better understand the chafe concern. I get that you don't want rope rubbing against a rough bottom, but if you have a chain-nylon rode, wouldn't you normally have chain against the bottom anyway? If you are in a dead calm anchorage, I could see that some nylon could rest on the bottom, but in that case is chafe really a concern? And if it really was that calm, you could likely shorten scope till it's only chain resting on the bottom. I'm probably missing something. I don't buy into the all-chain increasing holding power. As the Spade website points out, an all chain rode in rough conditions could actually do more harm by dislodging the anchor if the chain becomes bar tight, as well as putting higher loads on your boat. If you are concerned about holding, you could get a bigger anchor and still carry less weight by getting rid of a couple hundred feet of chain.

If you're in an area with any big rocks down there or coral heads, etc. you run the risk of the rode catching or wrapping on something when the wind dies down and the rope reaches the bottom. Then when the wind picks back up, the now snagged rode chafes itself to bits and fails.



In many bottoms, it's not an issue (and some areas have no bottoms with significant chafe concerns). But to stay on the safe side, my rule of thumb is that if you've got a mixed rode, the maximum usable rode in a chafe-prone bottom is the length of chain plus 1 water depth (not including freeboard) of rope (that way the rope can never quite reach the bottom, even if it's all hanging straight down).

 

[Hippocampus]

Agree with rs. If you can much prefer all chain. Beyond coral heads (Caribbean)and rocks(Maine) there’s other concerns in the New England area. Most harbors have been in use for several hundred years. There’s a major collection of junk down there. A lot of it with sharp edges or very abrasive. Even in Newport it’s a concern. So between that and the catenary effect prefer chain. Also think it’s safer. Never want anyone near the windlass while it’s working. We do put line after the first 250’but can count on fingers/toes times it was used.

 

[rslifkin]

Also think it’s safer. Never want anyone near the windlass while it’s working. We do put line after the first 250’but can count on fingers/toes times it was used.

For that part, in my mind, if you've got a mixed rode where you'll be using the rope portion more than very rarely, it should be spliced rather than shackled and handled on a windlass that can pull rope with the gypsy. That way there's no manual fussing to transition between the rope and chain portions.

 

[Hippocampus]

Agreed. Have found line doesn’t always feed into the locker as flawlessly as chain.the weight of the chain makes the feeding a non issue.

 

[ranger58sb]

Even the Spade anchor website advises against using an all chain rode. They recommend something in the 75 ft range. Others recommend about a boat length of chain and the rest nylon. It's less weight in your bow (where you don't want it) and improves anchor holding in most situations. It's also less weight for your windlass. Before I'd switch to a smaller anchor because of weight issues, I'd rather lose some of the chain.

I suspect SPADE is marketing to sailors with that recommendation, where extra weight in the bow can be a big deal.

And I suspect those "boat length" (and similar) recommendations are sometimes meant as minimums.

We routinely use a mixed rode but... we haven't been anchoring in Maine or the Caribbean etc. We had 8-plait with a 25' chain leader on our last, and that worked well through the windlass and also laid in the locker nicely.

-Chris

 

[NEtrawler58]

My setup is 8-plait nylon spliced to 50' of chain. The nylon feeds and stores very well and my windlass can handle both. I sometimes have to encourage the splice to go though by hand when retrieving, but otherwise it's fine. It's fairly new and I think the splice will become a little more flexible with time. The rode it replaced never had a problem.

 

[GBNI]

Vulcan 33 fitted

Thought I would post photo for info.

 

[Slowmo]

I'll throw my 2cents in here. I've had both mixed rode (chain + nylon) and all chain. My former boat had a Maxwell winch with about 25' of 3/8 chain and then nylon rode. It worked well though you had to be careful when the splice went through. My current boat is all chain with an older (slower) winch. Since we cruise in the PNW we don't have to worry about chafing of the rode. Between the two setups I found the mixed chain/nylon setup to have be preferable. First up it is significantly lighter in the bow. I see many trawlers sitting 'bow down' likely because of all that chain in the bow. Second, if the winch were to fail (and they do), pulling the anchor in by hand is much easier. However, if you want a total 'remote control' then all chain is probably better since I found you really did have to pay attention to that splice going through since 10% of the time you'd have to reverse briefly.

 

[Brisyboy]

Thinking about when is big too big - the windlass really only has to pull the weight of chain going from the bottom to the bow roller BUT the big issue comes getting that great hunk of steel and lead off the bottom ( now INCLUDING the chain) and up to and over the bow roller - thats where the winch earns its keep and sometimes fails, esp the last hurdle - getting the end of the anchor over the roller and the shaft past its point of balance

 

[Simi 60]

Thinking about when is big too big - the windlass really only has to pull the weight of chain going from the bottom to the bow roller BUT the big issue comes getting that great hunk of steel and lead off the bottom ( now INCLUDING the chain) and up to and over the bow roller - thats where the winch earns its keep and sometimes fails, esp the last hurdle - getting the end of the anchor over the roller and the shaft past its point of balance

Well in that case, the windlass is clearly to small

I have NEVER heard anyone complain about having too much windlass or too much anchor when it all turns to custard.

 

[Simi 60]

Usual "wisdom" is, if your boat falls between anchor sizes go up, not down, which you tried. Some even say to go up a size on the recommended size. In your case you had to take the smaller version, it`s "still huge", and will hopefully serve you well for many anchorings.

Why limit yourself to only one size up based on a generic chart?

For most of the new gen anchors, charts says 80lb
1 size up is 100lb for us.

We went the other way
Sent Manson NZ pics of boat, provided weight, usual cruising grounds and told them to size us for 2am world turns to sh1te.

150lb Manson supreme, never let us down, held us in 80+ knots and deformed the chain.

 

[Brisyboy]

Well in that case, the windlass is clearly to small

I have NEVER heard anyone complain about having too much windlass or too much anchor when it all turns to custard.

Correct - and thats what I was saying - hauling up the chain is easy peasy - the windlass needs the grunt for the final part- thats why bigger is better, in winches (and anchors)

 

[rslifkin]

I figure the windlass should be sized to lift the worst case scenario of letting all of the anchor/chain/rope out in infinitely deep water and being able to pull it back in. That leaves plenty of margin beyond normal use (which is good if you end up with something heavy snagged on the anchor that may end up coming up with it before you can get it un-fouled).

 

[bowball]

Why limit yourself to only one size up based on a generic chart?

For most of the new gen anchors, charts says 80lb
1 size up is 100lb for us.

We went the other way
Sent Manson NZ pics of boat, provided weight, usual cruising grounds and told them to size us for 2am world turns to sh1te.

150lb Manson supreme, never let us down, held us in 80+ knots and deformed the chain.

And I thought my 100 pound Ultra was a lot of anchor for a 55’ s/d trawler!

 

[guy with a boat]

Why limit yourself to only one size up based on a generic chart?

150lb Manson supreme, never let us down, held us in 80+ knots and deformed the chain.

You present a good argument as to why oversizing an anchor isn’t always positive. Your chain deformed, which means it was close to the failure point. I think most of us would rather have an anchor drag at 2am than break a chain. The first one you have time to deal with, the second one puts you on the rocks before you get all the way out of bed.

Not saying big anchors are bad, just suggesting that the anchor shouldn’t be dramatically oversized compared to the chain and windlass. Upsize all of it and you are good, or keep the anchor size within the strength range of the chain. The “weakest link” in this system shouldn’t be your chain.

 

[Simi 60]

You present a good argument as to why oversizing an anchor isn’t always positive. Your chain deformed, which means it was close to the failure point. I think most of us would rather have an anchor drag at 2am than break a chain. The first one you have time to deal with, the second one puts you on the rocks before you get all the way out of bed.

.

It was a 180 degree wind shift and it put everyone on a lee shore
Boats did end up on the beach

Close to failure?
I doubt that


The chain only very slightly deformed
It couldn't be measured with micrometre and it still went through the chainwheel ok
But had a weird twist to it, so was replaced soon after.

It's also worth noting that it was soon after purchasing the vessel and at that stage she had a short 25mm silver rope snubber, so no real stretch if any on that size rope.

Now we have a 20mm nylon snubber and a roll of 20mm nylon aboard to make replacements every 2 years.
We see it stretch several inches during a blow.

Not saying big anchors are bad, just suggesting that the anchor shouldn’t be dramatically oversized compared to the chain and windlass. Upsize all of it and you are good, or keep the anchor size within the strength range of the chain. The “weakest link” in this system shouldn’t be your chain

In the perfect world I would do that.
Upsize the chain will be about $30,000 exersise
New windlass
New fabrication of large S/S mounting plate - 3 guys needed to move it
Plus 16mm chain, may as well up the anchor as well.

 

[rslifkin]

You present a good argument as to why oversizing an anchor isn’t always positive. Your chain deformed, which means it was close to the failure point. I think most of us would rather have an anchor drag at 2am than break a chain. The first one you have time to deal with, the second one puts you on the rocks before you get all the way out of bed.

Not saying big anchors are bad, just suggesting that the anchor shouldn’t be dramatically oversized compared to the chain and windlass. Upsize all of it and you are good, or keep the anchor size within the strength range of the chain. The “weakest link” in this system shouldn’t be your chain.

In my mind, you size the chain to the loads for the worst case conditions you want to plan for. You size the anchor to hold that at somewhat restricted scope in a crap bottom. Which means in any decent bottom at longer scope, the anchor is going to be significantly oversized.


Deforming the chain means the chain is undersized. All it says about the anchor is that it's at least big enough. It doesn't in any way mean it's too big.