Spinnaker Size - How Critical?

[Slowboat35]

I've just bought a used spinny that is half a metre longer in the luff than the recommended size - its a big one so maybe it'll work out OK (I haven't sourced all the rigging yet).
Manufacturer's recommended size is 12.9 x 8.8m, the one I have is 13.4 x 7.4.

At the head fitting inside the plastic collar that supports the snuffer there is a wire strop about 20cm long that could be removed allowing the head of the sail to be connected direct to the haliyard but I'l loathe to do this as the maker clearly put it there for a purpose. Any idea how important it is? Could I lose it without damage/upset to the sail and rig? Spinny halyard is external.

 

[davidmh]

The luff is only 0.5M too long but it is 1.2 M narrower. There should not be problem down wind you may find that when reaching the you cannot get the luff down tight enough. You may have problems with the pole length.

David MH

 

[TernVI]

Can you move the inner end of the pole down the track?
How long is the pole?
How does the straight line length frm the halyard sheave to the end of the pole compare with the luff length? The luff should be a curve so it's OK for it to be a bit longer, maybe 10%, but it will limit reaching ultmiately.
You could normally lengthen the pole to allow a longer luff, but that's going to be odd with a short foot, but not necessarily out of bounds. IT would tilt the kite meaning the sheets wanted to be further forwards perhaps.

 

[Slowboat35]

Pole =J. 4.8m
Track is from below rail height to 2.5m above deck.
At full hoist (in the snuffer) the clews are perhaps 20cm above deck level at the forestay. (appreciably below the pulpit rail)

Maybe this doesn't matter as I have a cruising chute for reaching and really only wanted a spinny for deeper downwnd where poling out is beneficial. I'm very much cruising not racing in a heavy long-keeler. It is not a high-aspect rig hence the rather tubby shape of the 'official' sized spinny.

 

[William_H]

The luff is only 0.5M too long but it is 1.2 M narrower. There should not be problem down wind you may find that when reaching the you cannot get the luff down tight enough. You may have problems with the pole length.

David MH

This is an interesting statement because I have found with my spin (in fact 2 spins one smaller) that when reaching I need to ease the luff tension. The theory is that if you have a lot of luff tension the camber will go forward providing a hook near the luff. The spin will tend to luff sooner when shy.
Is this a function of different spin cuts? Or do a lot of people get it wrong?
Re OP question. The strop at the top I presume is to stop spin going right up so fouling the snuffer. If I understand correctly. It may be essential therefor if you use the snuffer. Other wise it is desirable to get the spin top in tight close to the mast to stop it swinging sideways. So if you don't need a snuffer. I have never used one. Then spin will be closer to correct size. More narrow spin will be a good thing in more wind. ol'will

 

[TernVI]

This is an interesting statement because I have found with my spin (in fact 2 spins one smaller) that when reaching I need to ease the luff tension. The theory is that if you have a lot of luff tension the camber will go forward providing a hook near the luff. The spin will tend to luff sooner when shy.
Is this a function of different spin cuts? Or do a lot of people get it wrong?
....

The pole height/luff straightness on a shy reach will need to be what it needs to be.
I suspect how people set the kite on broader reachs will vary and may be higher or lower pole.
Kite cuts vary a lot! How it interacts with the maon varies a lot.

 

[TernVI]

The other thing is, depending on the cut of the kite, it may be easy for a sailmaker to take a slice out of the middle.

 

[flaming]

I've just bought a used spinny that is half a metre longer in the luff than the recommended size - its a big one so maybe it'll work out OK (I haven't sourced all the rigging yet).
Manufacturer's recommended size is 12.9 x 8.8m, the one I have is 13.4 x 7.4.

At the head fitting inside the plastic collar that supports the snuffer there is a wire strop about 20cm long that could be removed allowing the head of the sail to be connected direct to the haliyard but I'l loathe to do this as the maker clearly put it there for a purpose. Any idea how important it is? Could I lose it without damage/upset to the sail and rig? Spinny halyard is external.

You would likely not notice the difference in luff length, and I very much doubt that the manufacturer would have specified the largest that would possibly work on the rig. I would leave the short strop, 20cm will mean nothing in the scheme of things when you're talking about a kite for cruising purposes.

Get out and sail with it, take pictures and then we'll be better placed to advise how to get the most of it.

 

[flaming]

This is an interesting statement because I have found with my spin (in fact 2 spins one smaller) that when reaching I need to ease the luff tension. The theory is that if you have a lot of luff tension the camber will go forward providing a hook near the luff. The spin will tend to luff sooner when shy.
Is this a function of different spin cuts? Or do a lot of people get it wrong?

There's a difference between getting the kite to set, which as you say is easier done when you ease the luff a bit, and that set actually producing the best drive forward. When you have the luff too lose on a reach you get a lot of sideways pull, but less forward thrust than when you have the luff straighter.
If you think about it, when you are easing the luff tension you are in effect rotating the body of the kite more to leeward. At the extreme there will then come a point where the kite is filling perfectly but actually dragging the boat backwards...

 

[Slowboat35]

Good advice everyone, much appreciated.