Calculate Windlass power requirement

[StefanSG]

Hi
I have 37 meters of 10mm chain at 2.2kg/meter and a 16kg Delta anchor. What is the minimum power in watts of windlass I need, as I seem to recall the rule of thumb is somehow 5 x the combined dead weight in kg so 97 x 5= 500w ? The reason I ask, I just bought a Simpson Lawrence Sprint 1000 which i mistakenly assumed was 1000W but it has a maximum load of 1000lb and a wattage of 400W

 

[Tranona]

1000W would be fine - although 10mm chain is really not necessary for a 16kg anchor. If buying a new windlass would suggest getting new 8mm calibrated chain.

 

[Neeves]

1000W would be fine - although 10mm chain is really not necessary for a 16kg anchor. If buying a new windlass would suggest getting new 8mm calibrated chain.

10mm chain on a 16kg Delta anchor is OTT. As Tranona says 8mm is fine and maybe you could use 6mm (you don't mention your yacht characteristics). The big issue is you already have the chain and the windlass has a 10mm gypsy and gypsies are expensive. You might find an old smaller gypsy on an old retired windlass - if you are very lucky. The chain in your bow locker weighs well over 70kg, the weight of a fit man, which is sitting in 'just where you don't want it' for sailing performance. That 10mm chain also takes up a lot of room (which might be better employed) and needs a better battery reserve as its heavier to retrieve.

37m of chain is really not very much - at a 5:1 scope your water depth, guessing at tide, is going to be a bit restrictive. If you decide to add some chain note that 10mm chain has 2 size specification and they do NOT overlap. The chain specification is embossed on the gypsy (you may need to take the gypsy apart to find it). You can join chain - use a Crosby 'C' link (check Vyv Cox's website for details).

If you decide to make ANY changes - post here first as many have been in your position, oversized chain is common place, people ignore the 2 different 10mm chain sizes (at much expense) and you will receive more focussed advise.

Jonathan

 

[NormanS]

You guys are fantastic. You don't know the size of the OP's boat, or where he sails, or the type of anchoring that he does, but you're already jumping in telling that he's got it all wrong, and that he should scrap his existing chain and buy lavvy chain. Amazing.

 

[Plum]

Hi
I have 37 meters of 10mm chain at 2.2kg/meter and a 16kg Delta anchor. What is the minimum power in watts of windlass I need, as I seem to recall the rule of thumb is somehow 5 x the combined dead weight in kg so 97 x 5= 500w ? The reason I ask, I just bought a Simpson Lawrence Sprint 1000 which i mistakenly assumed was 1000W but it has a maximum load of 1000lb and a wattage of 400W

If it is still unused and in it's box I would ask the seller if you can part-exchange it for a 1000W model

 

[Tranona]

You guys are fantastic. You don't know the size of the OP's boat, or where he sails, or the type of anchoring that he does, but you're already jumping in telling that he's got it all wrong, and that he should scrap his existing chain and buy lavvy chain. Amazing.

Not difficult to work out what sort of boat he has from the size of the anchor and thr fact that he has an SL 1000 windlass. 8mm is more than adequate and where he anchors or where he sails is totally irrelevant. 8mm is more than strong enough for any load that a 16kg can exert on the chain. Look up any reputable anchor and chain sizing guide and it will tell you that 8mm is the correct size for a 16kg anchor.

What is amazing is the ignorance you display in these matters. We know you believe "more weight" is better for anchoring. Regrettably you have never presented any evidence other than your own prejudice to support this.

 

[Tranona]

If it is still unused and in it's box I would ask the seller if you can part-exchange it for a 1000W model

Doubt it. The SL Sprint is long out of production so it it probably secondhand. The gypsy may well not be 10mm as 8mm or Imperial sizes were far mor common.

 

[StefanSG]

If it is still unused and in it's box I would ask the seller if you can part-exchange it for a 1000W model

Unfortunately it’s an eBay purchase, no returns. And it comes with an 8mm gypsy, the 10mm gypsy seems very rare.. probably because it doesn’t suit the power output of the windlass. The seller does have some 8mm chain for sale but he’s in Scotland W Coast and I’m on S Coast England.

 

[PaulRainbow]

Not difficult to work out what sort of boat he has from the size of the anchor and thr fact that he has an SL 1000 windlass.

We don't know if he has the correct anchor and it's almost certain he has the wrong windlass.

8mm is more than adequate and where he anchors or where he sails is totally irrelevant. 8mm is more than strong enough for any load that a 16kg can exert on the chain. Look up any reputable anchor and chain sizing guide and it will tell you that 8mm is the correct size for a 16kg anchor.

What is amazing is the ignorance you display in these matters. We know you believe "more weight" is better for anchoring. Regrettably you have never presented any evidence other than your own prejudice to support this.

 

[NormanS]

Not difficult to work out what sort of boat he has from the size of the anchor and thr fact that he has an SL 1000 windlass. 8mm is more than adequate and where he anchors or where he sails is totally irrelevant. 8mm is more than strong enough for any load that a 16kg can exert on the chain. Look up any reputable anchor and chain sizing guide and it will tell you that 8mm is the correct size for a 16kg anchor.

What is amazing is the ignorance you display in these matters. We know you believe "more weight" is better for anchoring. Regrettably you have never presented any evidence other than your own prejudice to support this.

Ha ha. So you can determine the size of someone's boat by the size of his anchor? Yes, that's pretty amazing. Anyway, the OP is asking about the wattage.
Any comments that I make about anchoring are based on a lifetime's experience in the real world.

 

[Tranona]

Ha ha. So you can determine the size of someone's boat by the size of his anchor? Yes, that's pretty amazing. Anyway, the OP is asking about the wattage.
Any comments that I make about anchoring are based on a lifetime's experience in the real world.

So your comments are completely unrelated to the OP as it is only based on your experience - and ignore any basic physics. Your "experience" seems to be doing the same thing over and over again rather than having explored alternatives so is only really relevant to you.

Yes it is a reasonable assumption that the size of anchor has some relationship with the size of boat - but as anybody has studied the subject knows that the size of chain is unrelated to the size of boat but to the size of anchor which determines the maximum load that can be applied - and the loads 8mm can withstand way exceed the holding power of even the very best 16kg anchor.

 

[MontyMariner]

So you can determine the size of someone's boat by the size of his anchor? Yes, that's pretty amazing.

There are guidelines from Delta for 16kg anchor