Genoa size

[abbott013]

Can anyone help me, i am replacing the roller reefing on my Mirror Offshore 19 with a Plastimo type unit. i have asked to be supplied with a new genoa, the one they want to supply is 8 metres square, while the genoa size listed for my boat is 5.85 metres square, what i want to know is, will the over size genoa over stress my rig and would it make the boat harder to control.

 

[Pye_End]

You need them to give you the size of wail you want.

The rig should be fine, but you will have to reef earlier and deeper - not a good idea for roller furling. If you find that you could do with a bit more sail just now then the bigger of course will be welcome.

 

[abbott013]

I think what is happening is the original roller reefing only went two thirds up the forestay, while the new unit is cut to almost the full length of the forestay, thats why i am being sold a larger genoa. When i asked about the sail being to big i was told to reef....

 

[BAtoo]

See how big the J measurement is - if the intended sail is 150% of J this can easily & usefully be reduced to 135% and so cut the area without much/any loss of performance, especilly since it will now have an increased luff length.
Do you think you need a bigger sail having sailed the boat with the smaller old sail??

 

[gardenshed]

"the one they want to supply"
Who's the customer?
Buy the roller unit from plastimo and then get your sail from a decent, local sailmaker.
The sailmaker can advise you on the overlap (135%, 150% or whatever), but more importantly, will ensure that the shape of the genoa is better matched to your rig than the off the shelf plastimo white triangle.
Also worth thinking about is a foam filled luff so than when you roll the genoa , the additional volume in the luff has the effect of reducing the draft of the remaing part of the sail.
You have a SAILING boat so buy real SAILS

 

[Phoenix of Hamble]

Absolutely agree... go to a proper sailmaker who will listen to you, give you good advice, and provide the sail you want, not what they have....

PS, second the foam luff..... makes a huge difference on our boat....

 

[VicS]

8 sq.m is not an unreasonable size for a 19 footer, The Seawych genny is 8.37 sq m (95 sq ft) but I think the rig is taller. At some stage the sail area and ballast of the Mirror was increased as they were for the Seawych. It would be a mistake to put the larger sails on a boat with the smaller amount of ballast. The Seawych mast is about 21ft making an "I" measurement of about 22 ft. The J measurement is about 6ft. That makes the genny area about 150% of the foretriangle.

I suggest you do not go above the 150% figure but is your Mirror a mast head rig.

The figures I have for the Mirror are a total sail area of 152 sq ft and 720lb of ballast. I would think those are the increased values but I am not sure. FWIW the Seawych ballast is 720lbs

Apologies for quoting measurements in "old money" but you can convert them as easily as i can.

 

[BAtoo]

Second what Magna Carta says re decent sailmaker & foam luff - tho' if you make the headsail too good then you will need a new main.....................then a spinnaker..................then new sheets 'cos the old ones look tatty on the nice new sails............Oh so is the sail cover not up to protecting your new sails..............etc. etc. etc.
The joys of boat owning!!!!!!!!!