Anchor chain length and Tacho question

[SimonBryan]

Two questions - should that be two threads?
1. Need to replace my abchor chain, totally rusted out in places as we never use it and I neglected it. . Curenttly around 40m chain and 20m rope make up the rode. The rope section is fine. Looking at rated chain but unsure if I really need 40m? If we do anchor it is normally in around 4m - 5m depth. Thinking of 25 to 30 max of chain?

2. Flybridge Tacho died, cover was cracked and locking ring missing so have replaced witha Wema but no response. Trying to trace back to the Alternator but unsure how to tell which wire(s) on the alternator is the connection. Have a photo of the back but not sure how to uploade here - it is a Motorola

 

[ScottC]

Hi SimonBryan,


My 2 cents on your anchor chain question:


1) If your normal cruising area is not especially deep and without a sharp rocky bottom, then what you are considering, may well work fine.



2) I said "cruising area" above (as opposed to "anchorage area") because there can be the possibility you will need to anchor unexpectedly, in bad weather, near shore due to engine failure. If the area is rocky, I would rather have 40m of chain.


3) The longer chain will actually serve as a shock absorber, of sorts (because of the weight). Though you will still probably want to have a snubber.


4) I have 40m of chain on my 33' boat, and would gladly have more, if it weren't for the weight. This is because I boat in some, rocky areas, which, in some cases, can be deep right up to the shore.



5) I have galvanized chain, because it came with the boat. When the day comes to replace it, I will seriously consider stainless steel chain.

 

[SimonBryan]

Anchor Chain

Yeah had similar thoughts. Where we are is generally a sandy bottom. Have me motivated to check the charts but pretty confident that 30m would hit the bottom off most the shore.

 

[O C Diver]

While I prefer all chain, whether you go with a combination of all chain, I would never want to be short in a bad weather situation. If shortening the chain, you might want to think about adding more rope.

Ted

 

[SimonBryan]

OC Diver all crusing is in pretty much enclosed waters. Our longest cruise is generally about 90 minutes from home mooring to our upriver mooring. We are too timid to go offshore on our own and one engine. Not so much worried about bad weather as there are l plenty of places to run to but more engine failure

 

[ScottC]

pretty confident that 30m would hit the bottom off most the shore.

At risk of stating something you probably already know, have total chain/rode length of 3x anchorage depth (including hull height above waterline) for fine weather and minimum 5-7x anchorage depth for bad weather.

 

[O C Diver]

OC Diver all crusing is in pretty much enclosed waters. Our longest cruise is generally about 90 minutes from home mooring to our upriver mooring. We are too timid to go offshore on our own and one engine. Not so much worried about bad weather as there are l plenty of places to run to but more engine failure

I would want 10 times the deepest water you can find to maybe 10 meters. Not all the scope is in the water and having some extra just incase somebody gets too close, is never a bad thing. Rope weighs nothing and costs very little in the overall cost of boating.

Ted

 

[DavidM]

Anchor holding strength goes up with scope and levels out at about 6:1 including the bow height above the water line. You say you anchor "normally in 4-5 m" but what about abnormally?

Take your maximum water depth, add the bow distance above the water line and multiply by 6. That will give your required anchor rode length. I too would prefer all chain, but do use a snubber on the chain.

David

 

[SimonBryan]

Yep have always worked on rode of 4 times the depth over the side on a sandy bottom.

 

[SimonBryan]

Thanks all - plnty of food for thought. So at te moment we have 40mChain 20m Rope - total 60M rode - about 2m for the attachement to hull and drop to water. Apart from a few holes the maximum depth is around 10m so am comfortable with that length. WIll consider if I shorten the chain and extend the rope - but would then have to replace the existing rope so cost advantage ay actually be negative!!

 

[Ski in NC]

I am on the far end of the scale. Probably 3m of 3/8" chain, the rest 5/8" nylon. Still works fine. Fortress #23. Boat about 14k lb.

 

[sbman]

On your alternator/tach issue, the tach should be the P, S, W or T terminal. I believe on the Motorola, it's the P terminal (Pulse), Ford alternators usually are marked with S (Stator). Others used W (Waveform) or T (Tach)

If only the Flybridge tach quit working, then it is likely daisy chained from the interior helm, so a wire from interior tach to flybridge tach.

With the engine running you should be able to measure 2-3 volts (AC) to ground on that wire. Be sure you use the AC setting on your meter and measure from ground to the Tach wire and you should get 2+ volts even at idle, although this may vary based on the quality of your meter. A true RMS meter will give a more reliable reading.