Getting Chain Out of the Bow

[DoubleWhisky]

Originally Posted by Dockhead

I think on this boat the lighter chain plus rope is the only option.

That's what I'm going to do and I'll report on the results.

When switching to the G70 chain it is well worth remember that long (60% LOD of the boat being minimum, as a rule of thumb) and highly effective snubber is essential.
The G70 is not accepting the shock loads and the effects of such loads do accumulate with time. At some point the crystal structure of the chain is affected enough to make it brittle and failure mode is catastrophic one.

It is a reason for me to regard G40 as generally the best compromise for anchor chain.
While Med mooring tied to the wall it is impossible to arrange for effective snubbing of shock loads on chain. On the other hand it is the only real limitation G70 impose on the user.

For Your boat and anchor the G40 11 mm is completely adequate, so really You do have an 70 kg of unnecessary load on Your bow. Somehow I do believe the simple switch from 12 to 11 mm, together with new tender solution (getting rid of davits, weight of tender moved forward, may be lighter tender of different kind) should cure most of Your problems.

Another possibility is to go for 10 mm G50 stainless steel chain.
The WLL will be even higher than for 11 mm G40, You will not have any more problems with regalvanization and no problems with piling up in anchor locker (this problem is not only, and even not mainly due to the size of anchor locker).I know - the initial investment is somewhat prohibitive, but You need to remember the costs of one proper regalvanization of G70 (including "baking" the chain after the dip to remove hydrogen from solution) which is at least 50% of the price of the new chain. If You assume the use of SS chain of 15 - 20 years, the price is not so absurdly high.

You know, I'm now thinking about the same problem...
Similarly sized boat, anchor, chain...
Oh, but I will never get rid of 100 m all chain rode
My real desire is the duplex steel chain, but somehow I didn't found one yet...

Cheers,

Tomasz

[Wotname]

Originally Posted by IdoraKeeper

Interesting that you frequently indentify issues that many of us have. In my case I am already bow down and have 230 ft of the same chain as you currently use. I need at least another 100' of chain for some expeditions I am contemplating. I can't have the extra chain in the bow. I have the additional complications of a manual windlass. Adding rope rode transforms a one man recovery into a three crew operation. One to crank the windlass, one to belay the line on the rope side of the windlass and one below to flake the line into the chain locker to ensure an orderly chain pile. None of this works for me. I will be curious to learn how your solution progresses.

Slight thread drift - sorry Dockhead.

Surely this depends on your gypsy; the gypsy on my vertical manual windlass handles both the chain and the line rode without problem so it remains a one man operation to retrieve the anchor.

Bur perhaps you have a horizontal windlass?

[s/v Jedi]

Here's how Dashew solved it: from 1/2" chain down to 3/8" G7 and bring the windlass and chain locker back.



ciao!
Nick.

[UNCIVILIZED]

s/v Jedi aka Nick,
That pic is exactly what I mentioned earlier on which you can see in the Dashew's video. Thanks for posting it.

And since this thread's gone way past the loony/over thinking things factor... One can always rebuild the bow in order to add more buoyancy & improve pointing.
New Bow for Wobegone Daze Wobegone Daze Bow

That, & I've one question, & I'm not putting it out there to be rude, but... Everyone is talking about; deck/windlass/hawsepipe mods & gear swaps etc.: ALL of them Very high priced items, especially on a 54' Gucci yacht. But has anyone done the math on the cost of say a staysail on a boat that size, particularly when compared against the cost of 100m of chain?
I mean seriously guys. Especially as chain IS a major safety item. One which you'll get a lot more time & use out of than pretty much any other "consumable" onboard a vessel.
And when you start talking about multiplait anchor line, it's price is literally about the same as G40 chain, if you do a bit of looking around (for chain that is). Albeit it's lifespan's a fraction of the chain's.

And just as something to ponder upon. 20 yrs ago, folks in the cruising community were afraid to use G40 chain as it didn't "stretch" as much as PC/BBB. No joke.

[carstenb]

Dockhead,

Actually you can figure all this out mathematically. The formulas are here:

Stability


Set the formula up and plug in your numbers (try it with both less chain and then trying moving your dinghy's approximate weight 2 meters forward (don't forget to include the weight of your divats) (or perhaps you can cheat and say the new construction weight and leverage arm will equal your current leverage arm for the divat construction.) The weight of the dinghy still needs to be moved however.)

Removing 100 kilos from your bow will not change your trim that much. Moving your dinghy off the divats and on board will change your aft/bow trim back again.

[noelex 77]

Originally Posted by s/v Jedi

Here's how Dashew solved it: from 1/2" chain down to 3/8" G7 and bring the windlass and chain locker back.

Thanks Nick.

It is a bit hard to get the perspective from the photo. Approximately how far back is the chain locker from the bow and is the bottom of the chain locker above, or below the waterline?

I am just playing around with possibilities for my fantasy yacht and Dashew's solutions are usually very well thought out and executed.

[barnakiel]

Dashew's comments on chain /weight distribution must be taken in context. Their boats were long narrow with extremely fine entries and not too much buoyancy in the bow.

Now a Moody 54 has vastly more forward buoyancy and will get far less affected by her chain's weight.

Also, look at where they cruised. They did want all chain and plenty of it.

All chain becomes chain and rope every time we anchor. Think about the snubber.

b.

[s/v Jedi]

Originally Posted by noelex 77

Thanks Nick.

It is a bit hard to get the perspective from the photo. Approximately how far back is the chain locker from the bow and is the bottom of the chain locker above, or below the waterline?

I am just playing around with possibilities for my fantasy yacht and Dashew's solutions are usually very well thought out and executed.

That hatch is 80cm square so it's about 3m / 10' aft. The bottom of the chain locker is below the waterline and drains in the bilge... but, this is just forward of the watertight bulkhead there so it doesn't run further back.

I have a rectangular plywood+fiberglass chain locker, but one made out of schedule 80 PVC pipe works really well. Like 12" diameter.


ciao!
Nick.

[noelex 77]

Thanks Nick.
Looks like a great boat

[DoubleWhisky]

Originally Posted by noelex 77

Thanks Nick.
Looks like a great boat

Just ideal cruising size...

[Dockhead]

Originally Posted by carstenb

Dockhead,

Actually you can figure all this out mathematically. The formulas are here:

Stability


Set the formula up and plug in your numbers (try it with both less chain and then trying moving your dinghy's approximate weight 2 meters forward (don't forget to include the weight of your divats) (or perhaps you can cheat and say the new construction weight and leverage arm will equal your current leverage arm for the divat construction.) The weight of the dinghy still needs to be moved however.)

Removing 100 kilos from your bow will not change your trim that much. Moving your dinghy off the divats and on board will change your aft/bow trim back again.

By the way, Carsten, it's dAvIt, not dIvAt -- I think you're having a dyslexic moment! Davit - Wikipedia, the free encyclopedia

I don't think the main issue is trim. I think the main issue is the polar moment of inertia around the horizontal athwartships CG. The mass in the very bow inhibits the bow coming up when it meets a wave. My boat's bow is fairly fine, maybe not as fine as a Sundeer's, but not that far off.

Your point about getting rid of the davits is well taken. But removing them will also have the effect of reducing the polar moment of inertia, so will both hurt and help bow rising to meet the seas, at the same time.

As to trim -- indeed, I checked it carefully when I put all that chain on board, and was pleased to see that trim was not detectably changed. But as it turns out, trim is not the whole story . . . . . .

[Dockhead]

Originally Posted by s/v Jedi

Here's how Dashew solved it: from 1/2" chain down to 3/8" G7 and bring the windlass and chain locker back.



ciao!
Nick.

The windlass arrangement is fab, but did anyone notice the other bit of Dashew genius? The mobile padeye for barberhauling absolutely anything in any possible direction, from any possible point on the rail . All I can say is -- wow.

[Dockhead]

Originally Posted by DoubleWhisky

When switching to the G70 chain it is well worth remember that long (60% LOD of the boat being minimum, as a rule of thumb) and highly effective snubber is essential.
The G70 is not accepting the shock loads and the effects of such loads do accumulate with time. At some point the crystal structure of the chain is affected enough to make it brittle and failure mode is catastrophic one.

It is a reason for me to regard G40 as generally the best compromise for anchor chain.
While Med mooring tied to the wall it is impossible to arrange for effective snubbing of shock loads on chain. On the other hand it is the only real limitation G70 impose on the user.

For Your boat and anchor the G40 11 mm is completely adequate, so really You do have an 70 kg of unnecessary load on Your bow. Somehow I do believe the simple switch from 12 to 11 mm, together with new tender solution (getting rid of davits, weight of tender moved forward, may be lighter tender of different kind) should cure most of Your problems.

Another possibility is to go for 10 mm G50 stainless steel chain.
The WLL will be even higher than for 11 mm G40, You will not have any more problems with regalvanization and no problems with piling up in anchor locker (this problem is not only, and even not mainly due to the size of anchor locker).I know - the initial investment is somewhat prohibitive, but You need to remember the costs of one proper regalvanization of G70 (including "baking" the chain after the dip to remove hydrogen from solution) which is at least 50% of the price of the new chain. If You assume the use of SS chain of 15 - 20 years, the price is not so absurdly high.

You know, I'm now thinking about the same problem...
Similarly sized boat, anchor, chain...
Oh, but I will never get rid of 100 m all chain rode
My real desire is the duplex steel chain, but somehow I didn't found one yet...

Cheers,

Tomasz

You assume (like I used to) that G70 chain is more brittle than G40. But is it really so? Are we sure about that? And if it's not, what does that do to our other conclusions?

As to snubbers -- where did this 60% of LOD come from? I've heard it before, but I think that it's pulled out of someone's zhopa. Proper snubber length has nothing to do with LOD -- it has to do with displacement, and the total energy absorbing capacity of a given length of rope of a given diameter. For light weather, it can be thin and relatively short, much less than 60% LOD. For heavy weather, it needs to be thick and long -- longer than 60% of LOD. I have had probably 20 different snubbers on my boat, of all kinds of different weights and lengths. I recommend to others, also, to experiment.

Coincidentally, my favorite snubber is 10 meters and 18mm -- coincidentally, 60% of my LOD :lol:. Pure coincidence!

[zeehag]

Originally Posted by s/v Jedi

Here's how Dashew solved it: from 1/2" chain down to 3/8" G7 and bring the windlass and chain locker back.



ciao!
Nick.

oooohhh!! i LIKE this... uhoh modifications yet again.. sensible arrangement.

[Panope]

What's the big deal about a little water on deck? Dashew doesn't seem to mind.