Parasailor or just a hole in a spinnaker?

[dgadee]

Was watching something advising downwind sails for the ARC (no intention of participating!) and the parasailor seems to be advised as the most stable because it lets air escape from the sail rather than spill over one edge and then the other. Why not just put a hole in the centre of an everyday spinnaker? Would that give enough advantage to make it more user friendly?

The other advantage specified for the parasailor was that the hole pushed air down and thus lifted the bow of the boat. A simple hole wouldn't do that, of course.

 

[sarabande]

Those of us who are long in the tooth and who sailed in the 60's will remember with fondness such a spinnaker, invented by a froggy designer caller M Herbulot. It had dozens of holes with little flaps on to direct the wind downwards.


It was marvellous at lifting the spinnaker up into the air, but as for translating that energy into forward motion, we quickly stuffed it into the storage locker ashore.


Shirley, lifting the bow will depress the stern, causing more drag ?

 

[JumbleDuck]

Shirley, lifting the bow will depress the stern, causing more drag ?

The forward force from the sail, being applied up in the air, will be trying to push the mast forward and the bows down so I imagine that the idea is to counteract that.

 

[Stemar]

I've no personal experience of a Parasailor, but a friend had one on his Starlight and thought it was great.

 

[duncan99210]

The “hole” is actually a slot across the majority of the width of the sail. It has a ”wing” just under the slot which is inflated by the airflow and keeps the sail open: think of a rectangular steerable parachute which has an airfoil shape when inflated by the wind What you have in the Parasailor is a modified version of that, which gives shape to the sail and means you don’t need a pole to fly it.

 

[dgadee]

The “hole” is actually a slot across the majority of the width of the sail. It has a ”wing” just under the slot which is inflated by the airflow and keeps the sail open: think of a rectangular steerable parachute which has an airfoil shape when inflated by the wind What you have in the Parasailor is a modified version of that, which gives shape to the sail and means you don’t need a pole to fly it.

But if you accepted you needed a pole, would hole in the middle of a spinnaker stop it from being unstable?

 

[RichardS]

There used to be two different sails, Parasailor and Parasail. I was never sure what the difference was but perhaps the latter has been dropped.

Richard

 

[duncan99210]

But if you accepted you needed a pole, would hole in the middle of a spinnaker stop it from being unstable?

The point is that it’s not a hole but a slot supporting by a ram air wing: the slot is there to produce a flow of air to the wing which in turn provides an almost rigid structure that maintains the shape of the sail without a pole. Simply putting a hole in a conventional spinnaker will do little or nothing to improve its stability: it’s the pole and associated lines that control the sail.

 

[dgadee]

The point is that it’s not a hole but a slot supporting by a ram air wing: the slot is there to produce a flow of air to the wing which in turn provides an almost rigid structure that maintains the shape of the sail without a pole. Simply putting a hole in a conventional spinnaker will do little or nothing to improve its stability: it’s the pole and associated lines that control the sail.

Ah, I get it. But I'm still not sure whether a pole and a hole wouldn't be just as effective.

 

[Yngmar]

There used to be two different sails, Parasailor and Parasail. I was never sure what the difference was but perhaps the latter has been dropped.

Richard

The Parasail by the same company that makes the Parasailor (ISTEC) is still around: Parasail - ISTEC - The Downwind Company

There's also the very similar looking Wingaker by the competition: wingaker.com - Entwicklung

 

[Seven Spades]

I wanted one of these but I was advised that they are very bulky and heavy to store. One year I was advised that they are the best thing since sliced bread and hardly need trimming and the following year I was told that a number had "exploded" on the previous Atlantic crossing. This conflicting advice was passed on by the same person. I was attracted by the idea that the Parasailor does not induce roll whereas wing and wing induces it.

I am sure that the truth lies somewhere between all this.

 

[Sandy]

I liked the idea of a Parasailor until I got the quote!

 

[RichardS]

I liked the idea of a Parasailor until I got the quote!

Same here. I was think along the lines of a few thousand quid. Think again!

Richard

 

[laika]

The Parasail by the same company that makes the Parasailor (ISTEC) is still around: Parasail - ISTEC - The Downwind Company

There's also the very similar looking Wingaker by the competition: wingaker.com - Entwicklung

There's now also equivalents of the parasail and parasailor from oxley:
SAILS-OVERVIEW – OXLEY Sails

Apparently the patent on the parasailor expired recently. Oxley supposedly have one of the original parasailor designers on board and their "bora" is very similar to last year's ISTEC parasailor. At Boot this year ISTEC were saying Pah! their product is like our old one! Our new one is much more betterer! but it was the old one they were quite happily telling me was wonderful at Southampton last September.

I was somewhat put off dealing with ISTEC's UK distributor by them failing to honour a deal a friend struck with them at Southampton last year which is a shame because I'm pretty interested in something like this, despite the cost.

 

[capnsensible]

I wanted one of these but I was advised that they are very bulky and heavy to store. One year I was advised that they are the best thing since sliced bread and hardly need trimming and the following year I was told that a number had "exploded" on the previous Atlantic crossing. This conflicting advice was passed on by the same person. I was attracted by the idea that the Parasailor does not induce roll whereas wing and wing induces it.

I am sure that the truth lies somewhere between all this.

A couple of years ago I used one for several days on a passage trip from the Azores to Biscay France. Hardly needed any trimming, dogs dooh dahs and didn't explode! ?

 

[JumbleDuck]

Same here. I was think along the lines of a few thousand quid. Think again!

Go on then ... how much? Everyone says they are expensive, but I don't think I have ever seen a figure.

 

[Yngmar]

Bit over 6k for the 105 square meter Parasailor they recommended for our 40 footer. That includes the snuffer and bag, but not the extra deck fittings and running rigging you need. Would've liked one but simply can't afford!

 

[RichardS]

Go on then ... how much? Everyone says they are expensive, but I don't think I have ever seen a figure.

£10k.

Richard

 

[TernVI]

A couple of years ago I used one for several days on a passage trip from the Azores to Biscay France. Hardly needed any trimming, dogs dooh dahs and didn't explode! ?

That seems to be the only kind of passage people enthuse about them for.
A lot of cash to be blown dead down wind a couple of knots faster in a favourable wind is one description.
If some patent has expired, we might see some development.
If you look at kites for boards and paragliders, there is a lot of potential.

But how long do these things last?
An old spinnaker will still work. Complicated slot wing structures might not when the material has done a few thousand miles?

 

[JumbleDuck]

£10k.

Richard

Gordon Bennett.