Genoa sheet diameter

mrangry

mrangry

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Looking on my Genoa sheets today I noticed they were badly chaffed and need replaced. They are 18mm which seems a little heavy....or is it. Its a 44ft Beneteau Oceanis and the sheet winches are Lewmar 54s.
 
That does seem a bit on the large size - I suspect 12mm would be more than strong enough but you may prefer 14mm for handling. Look on Jimmy Green Marine for a recommended size.
 
I don't think it has anything to do with strength, even 10mm would be strong enough. Its all about comfort. We cannot decide what would be comfortable for your crew, though with decent winches the crew should not be complain about sheets that are too thin. The smaller the hands the larger the sheets need to be - until you get to 18mm which does seem a bit too meaty.

I'd also have a look at why the sheets are fraying and try to reduce the issue - unless the sheets are very old.

Jonathan
 
I just bought some 14mm Liros from eBay thanks. I was about to make a purchase from a well known UK marine chandler until I realised their varying postal rates for mainland UK, and I am not talking about outlying areas here....con artists.
 
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RichardS said:
Mine were 12mm on a 40ft cat so I replaced them with new 12mm a few years ago and they seem right to me. Maybe the next size up for a bigger boat?

Richard
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Interesting post.

The OPs yacht is longer and heavier - but does that make it bigger?

My guess is the tensions on your headsail sheet could be higher, and probably significantly so, than on the OPs yacht.

If you can handle 12mm sheets - so can he.

Jonathan
 
On a Jeanneau 34 with a 31m sq genny its spec is 14mm for the sheet and I would not want anything smaller.

Have you checked the benateau specs?
 
We have 12mm on a 42 footer with masthead rig and it’s fine because there is no time when a sail can be handled without round a winch and using a handle the moment any slack is removed. So we could go lower without it making a difference to handling but there isn’t an advantage to that.
 
Maybe a step further than you want, but a length of dyneema spliced between the clew and the rest of the sheet works well. Next to no weight, very chafe resistant and use whatever diameter fits the winch best and feels best- youtube has instruction videos.
 
It's really about feel.
If you use the Selden calculators you will find the righting moment for your yacht and the recommended SWL for your deck gear. You can then use the angle of the sheet through the jib car to work out at the SWL for the block what the load on the sheet is. then decide if you want the block to fail before the sheet or vice versa :-)

I did the maths for you and you could use 10mm. I don't recommend 10mm even with nice big winches.

So choose the thinnest which feels comfortable.
 
ctva said:
On a Jeanneau 34 with a 31m sq genny its spec is 14mm for the sheet and I would not want anything smaller.

Have you checked the benateau specs?
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That's interesting. On my 35m2 genoa on a cat I'm using 10mm. It's easy for me to hold, and pull, and plenty strong enough. 14mm is beast size to me. Very heavy, especially when flying around.
 
Mikedefieslife said:
That's interesting. On my 35m2 genoa on a cat I'm using 10mm. It's easy for me to hold, and pull, and plenty strong enough. 14mm is beast size to me. Very heavy, especially when flying around.
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One of our headsails on our cat is 45m^2 and we would never, ever, dream of trying to handle it without a winch - it would be impossible. Its not always possible to handle as it is - so need extra turns. Once you get the number of turns correct 10mm on a self tailer is 'easy' (and I imagine 8mm would be also possible). Our genoa is 35m^2 and we have only 1 sheet winch and cross sheet - again we would not handle the sheets without the winch and they too are 10mm sheets.

All our sheets and halyards are dyneema

Its what fits the winches and as the loads are taken by the winch, on a self tailer, then size is simply what you are comfortable with (and how much money you want to spend).

Jonathan
 
I have 14mm on my Moody 44 running to Lewmar 50 self tailing winches. When I bought the boat it had 16mm sheets and they were just too big and heavy so changed down a size. When these eventually wear out I will replace with 12mm.
As others have said it is all about handling but with ST winches there isn't a lot of that to do anyway. I think 12mm will be perfectly comfortable to handle and remove a little of the bulk from the cockpit
 
Perhaps the OP's sheets are chafed because they are too big for the sheaves in the blocks and are wearing on the edges of the sheaves. This certainly happened to my mainsheet when I realised that my 14mm sheet was running through max 12mm sheaves.
 
44ft boat. We have 12mm genoa sheets for a 700sqft genoa going to Lewmar 58 winches. 12mm sheets are plenty strong enough and feel fine to handle. In light winds the lighter 12mm sheets help the genoa set better than heavier larger diameter sheets
 
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ctva said:
On a Jeanneau 34 with a 31m sq genny its spec is 14mm for the sheet and I would not want anything smaller.

Have you checked the benateau specs?
Click to expand...
The Jeanneau manual for my boat (which is a 1998 45.2) gives 14mm for the halyards and 16mm for genoa sheets. Both are a size bigger than they really need to be for strength, and in fact 14mm halyards are a bit big for the masthead sheaves, so I use 12mm Marlowbraid for the halyards, but use a soft English Braids polyester for the genoa sheets because it is nice to handle. I think Jeanneau were a bit conservative in their specifications, going for strength over lightness, something that is reflected in the rig generally.
 
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