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 Post subject: strong winds and smaller sails
PostPosted: Sun Jul 16, 2017 7:51 pm 
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Joined: Fri Feb 18, 2011 10:49 pm
Posts: 36
Just wondering about the Nationals, consistently strong winds, and the fact that not everyone was sailing.

I am an average One Design sailor, but managed to complete almost all the races, mainly using a smaller set of sails after the first day. The main is 6.5m2 and the jib 2m2. These were cut down from an older set of sails, so not ideal, but got me round, still pretty fast upwind, and easier to tack & gybe.

Clearly the top sailors can sail well in these conditions, particularly with the square topped mains and blading off. But I wonder if having a smaller suit of sails would enable some of us more average sailors to compete in very strong winds?

And ensure as a fleet we can race in the same upper wind range as other open water classes?

Hugh
Mustang Sally, 275


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 Post subject: Re: strong winds and smaller sails
PostPosted: Mon Jul 17, 2017 7:34 am 
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Joined: Mon Sep 12, 2005 7:45 pm
Posts: 747
Location: United Kingdom
Hugh's right of course. Finishing races is probably more fun than getting blown off the course and retiring. Its an interesting topic - to me anyway - I've always felt it cannot be right to hoist the same sails in 5 knots and 25 knots when the force on the sails in the latter is 25 times greater.

I explored this a little in the one off singlehander I built in 1999/2000 before I had a Canoe. It had a mast that telescoped down into the mast stump and a zip reef, which was all intended to produce a useful reduction in sail area without compromising mast bend. It wasn't altogether successful, but these are lessons I think I learned.

- on a single sail boat if you can possibly hang on to extra rag upwind and make it to the windward mark then you will want to.
- simply reducing the height of the rig may not work as well as you think.
- even a sub 5 minute change of rig size is enough to discourage you from doing it.

To expand on these:

The first is obvious of course, the gains from the extra power on deep reaches and runs are huge, the losses from the extra rag upwind - if you can stay upright - are more moderate.

The second: with my boat I started with a highish aspect squarish top (90 degrees to luff) main, but when the reef was in and the mast stumped down the resulting rig was distinctly lowish aspect ratio. I never seemed to be going upwind as well as I thought I should with the stumped rig, there was always a slight towing a bucket feeling which wasn't there with the full sized rig. We designed a full sized rig, and then put a reef in it. On reflection both rig positions should have been equally considered in the sail design.

The third. Anyone who's sailed a multiple rig class knows what a hassle it is to get the wrong rig up. When I designed the setup of my boat it was all geared to making it easy to change rig size. It was possible to reduce rig sized even tied up to a jetty. The job was -
- loosen rig tension (highfield on forestay)
- unhook clew and tack.
- release main halyard.
- remove pin that held mast in upper position.
- drop mast down. Pull out fast pins on shrouds and forestay in upper positions, replace in lower positions
- tension rig
- retension main halyard
- roll up main and do up zipper on reef
- rehook clew and rethread tack.
No tools and well under 5 minutes, but it still seemed like enough trouble that I avoided doing it.

So I offer that experience for what its worth. I theorise too about handling factors beyond sail area, but this post is long enough already... Maybe another day.


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 Post subject: Re: strong winds and smaller sails
PostPosted: Wed Jul 19, 2017 11:30 am 
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Joined: Sun Sep 05, 2004 8:49 pm
Posts: 103
Location: Scotland, United Kingdom
jimc wrote:
the gains from the extra power on deep reaches and runs are huge, the losses from the extra rag upwind - if you can stay upright - are more moderate.


The problem is staying upright !!!!

However if sailing AC there isn't the loss downwind as the spi dominates the speed, not the mainsail. I have an old main which no longer fits my boom and am tempted to cut it down to fit and use in strong winds, with my "small" (18.5 sq. m.) spi.

Peter


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 Post subject: Re: strong winds and smaller sails
PostPosted: Mon Jul 24, 2017 8:23 pm 
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Joined: Wed Sep 30, 2015 6:52 pm
Posts: 13
Good Evening All,

It's a good question and I'm going to offer an opinion with help from my own IC experiences but also that of a very different sailing environment. Most of my experience, and 15 years as a sailmaker, are in offshore racing rather than dinghies however there are some parallels here when it comes to drastic de-powering.

I see there being two principle ways to de-power, either reducing sail area or reducing draft/camber (and of course a combination of both when it's really windy).

Firstly it's important to reduce power by reducing draft. We all do this to some degree when the breeze is up principally by heaving on the cunningham and kicking strap and so inducing mast bend etc... We are also fortunate that our rigs have evolved some degree of automatic gust response to make our lives much easier. When sailing offshore, rigs are not quite as adjustable as we're used to in the IC and so we would carry a suit of jibs (often 4) all cut as a different fullness and fabric weight to reflect their intended wind range. Except the heaviest Code 4 jib, the other 3 are broadly the same area.

This reducing fullness or camber to reduce power allows sailing with a full sail plan and so 'designed' rig aspect ratio and balance up to a TWS in the 20s before reefing is considered. Only then in extreme conditions (>25kts TWS) would reducing sail by reefing be necessary offshore. This is a simplistic view as it ignores sea state and yacht design details but that's another story.

This is an approach I also take to IC sailing. I have two suits of sails, both of about 10.6m^2 but of very different sail cuts. I use the flatter cut sails in more than about 12 or 14 knots true. I might consider a reduced sail area but for nuclear strength winds only and bearing in mind that I'm a puny 60kg /9.5 stone only. Being small, I find flat sails work very well, even in the AC that has traditionally favoured a fuller cut.

A reduced sail plan wouldn't be my choice but then that's my opinion. I prefer the efficiency of a full sail plan upwind and the horsepower off the wind but simply taming it with a very limited camber for straight line efficiency and easier corners. Smaller kites when it's blowing are good too, like Peter I also have an 18m^2.

Scott.
Sunshine AC GBR299


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 Post subject: Re: strong winds and smaller sails
PostPosted: Wed Jul 26, 2017 10:18 am 
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Joined: Fri May 30, 2008 9:46 am
Posts: 210
Hi Scott, just a quick mail to enquire are you attending the worlds?
Steve AC 310


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 Post subject: Re: strong winds and smaller sails
PostPosted: Thu Jul 27, 2017 5:24 pm 
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Joined: Wed Sep 30, 2015 6:52 pm
Posts: 13
Hi Steve,
Sadly I can't make it, it's all conspired against me.
Good luck!
Scott
GBR299


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