Why is it spinning?

[cmedsailor]

When a sailing boat sails upwind it is common if it is hit by a gust to point more upwind and the necessary correction is needed by turning the wheel slightly downwind. However I came across a boat that on every gust it was pointing too much upwind, the boat was not responding almost at all when turning the wheel and in fact it turned 180 degrees without been able to control it. The same “pirouette” on this particular boat was experienced by a couple of other much more experienced skippers than myself so we cannot be all wrong. I mean it is possibly not a matter of reefing.

Could anybody suggest what is wrong with this boat? Could it be a technical problem (wheel, autopilot….???). Just to let you know that the boat is Beneteau Oceanis 361 (1.50 draft) has an in mast roller main sail and a genoa both 5 years old.

 

[ex-Gladys]

Without seeing it in detail it's difficult to know. How much wheel was on to keep it straight before the gust hit? Maybe it had so much weather helm, it was on th verge of stalling out the rudder, and the extra angle did that. Also. on an AWB the rudder is potentially being lifted out because the max beam is continud to the stern and the boat will "heel" slightly forward as well as sideways acentuating the lift.


It amazs me to see some people sailing boats the hard way when a few years in dinghes/small cats would have taught them. I see boats trying to bear away withut easing the main first... On some cats you'd carry straight on if you did that

 

[Lakesailor]

I see Oceanis(s) doing it all the time on Windermere. I don't know why.
I was following one through Bowness Bay in my Foxcub. The wind was easterly which means you'll get violent gusts at at least two points in the bay. Each time it rounded up, whereas my little 18ft boat just kept ploughing on, with a bit more heel for a few seconds. They do seem tender and I would think what Botheras says about their rudders stalling is probably the case.

 

[Mudplugger]

Normally in the situation you describe, the first action would be to ease the Mainsail, not necessarily reefing, unless the wind continued at the level of the gust!, It may well be that the preportion of sail aft of the turning centre (centre of lateral resistance) , is greater than than that forward, so that the centre of effort is behind the CLR, which would have the effect of making the vessel round-up. Can also be caused by having the mast raked aft...., weight distribution biased towards the stern, all in my very humble oppinion, and with a willingness to be corrected!

 

[William_H]

This is a very common response by sailing boats a gust.

When the boat heels the drive from the sails moves outboard away from the drag of the keel. This seems to be the main reason for the savage weather helm that causes the boat to turn into the wind.

As the boat heels the angle of the rudder changes so that at 45 degrees of heel the rudder in trying to correct the weather helm is in fact producing as much force trying to lift the stern as pull the stern windward. So half rudder power is lost which means more rudder angle needed until the rudder stalls. Then you hhave very little steering power.
In our little local sailing area where the wind is typically 20 knots of summers afternoon it is common to see boats lose control through over power. Dumping the main sheet is the first option. To try to turn the boat down wind often results in collisions and the helmsman has to accept that he has now ability to turn dow wind and a tack is the best way to avoid danger. This is very applicable when meeting another boat on the wind on starboard tack. Don't try to veer behind the stern but rather tack.
The other frequent ocurrence I find is on a shy spinacker run when
a gust hits. You must dump the main sheet and turn the boat down wind while you can (before it rounds up) as in this case easing the spin sheet does not help. It becomes a constant worry when racing. Keep the boat under the spin is the cry....

So some boats are worse than others. A big powerful rudder can help but reducing mainsail pressure is the answer.

good luck olewill just 2 weeks to start of season can't wait.

 

[jimi]

I would get the rudder checked if its happening with a reasonable sail plan for the conditions, I had a similar problem and the issue was that the rudder stock and rudder had started moving independently of each other. Once I got a new rudder the problem disappeared. Of course in any large gust the boat will head up to wind but 180 degree roundings up seem unreasonable.

 

[wotayottie]

The boat heels a lot because it is tender. The hull has a broad beam and stern so as it heels the centre of the waterplane moves out downwind and the shape of the waterplane becomes asymetrical. Then in just the same way you can steer a dinghy by heeling it, the Oceanis alters course to windward. The rudder isnt big enough to stop this happening, stalls and loses grip.

Another way to look at it is to imagine the underwater shape of the boat as a big chubby wing. As the boat heels this wing alters shape drastically, and it is this which causes the boat to head up into the wind. Bad sail adjustment can make it worse.

Basically it is a floating caravan and needs to be kept upright to stay in control even more than most modern boats. My impression is that recent Bennies are rather better than the 1990 ones

 

[jimi]

[ QUOTE ]
The boat heels a lot because it is tender. The hull has a broad beam and stern so as it heels the centre of the waterplane moves out downwind and the shape of the waterplane becomes asymetrical. Then in just the same way you can steer a dinghy by heeling it, the Oceanis alters course to windward. The rudder isnt big enough to stop this happening, stalls and loses grip.

Another way to look at it is to imagine the underwater shape of the boat as a big chubby wing. As the boat heels this wing alters shape drastically, and it is this which causes the boat to head up into the wind. Bad sail adjustment can make it worse.

Basically it is a floating caravan and needs to be kept upright to stay in control even more than most modern boats. My impression is that recent Bennies are rather better than the 1990 ones

[/ QUOTE ]


Thanks for that, I've owned an Oceanis for 6 years and was passing on my personal experience. And your comment "Basically it is a floating caravan and needs to be kept upright to stay in control even more than most modern boats" demonstrates a lack of knowledge of the craft. I'm holding onto a full sail plan under full control when many other boats are reefed.

 

[jimbaerselman]

[ QUOTE ]
The boat heels a lot because it is tender. The hull has a broad beam and stern so as it heels the centre of the waterplane moves out downwind and the shape of the waterplane becomes asymetrical. Then in just the same way you can steer a dinghy by heeling it, the Oceanis alters course to windward

[/ QUOTE ] Exactly right. On beamy boats (bar cats!) the yawing moment due to heeling is high compared to the yawing moment due to sail distribution (relative to CLR).

And if you can't hold the boat straight when it heels (assuming your reactions are OK!), there's something wrong with the rudder - too small, lifting out of the water, loose mountings, whatever. Dumping the main is a means of partially overcoming rudder power deficiencies.

 

[jimi]

The point I was making was that on my Oceanis, the rudder deficiency was a rudder fault, if the rudder stock was held firm then the rudder moved by 60 degrees. The original poster asked the question because he and several other skippers thought the boat was behaving unusually. The rudder bearing would not cause the problem because the bearing is a small sleeve in the stern tube. If their is a problem also experienced under power (partic in reverse!!!!) when the prop wash will deflect the rudder then definitely get it checked.

 

[Phoenix of Hamble]

[ QUOTE ]

Thanks for that, I've owned an Oceanis for 6 years and was passing on my personal experience. And your comment "Basically it is a floating caravan and needs to be kept upright to stay in control even more than most modern boats" demonstrates a lack of knowledge of the craft. I'm holding onto a full sail plan under full control when many other boats are reefed.

[/ QUOTE ]I'll second that..... I don't fundamentally disagree with Wotayottie's comments about the mechanics of the round up.... but his observations ref the Oceanis are rubbish... when set up properly, they sail beautifully... calling them floating caravans is just a little bit insulting.... maybe we should refer to our friends in heavier displacement boats, as sailing floating tractors, or maybe floating lorrys (an oxymoron if i've ever heard one!), or possibly even a floating steam roller.....

 

[jimbaerselman]

[ QUOTE ]
if the rudder stock was held firm then the rudder moved by 60 degrees.

[/ QUOTE ] Some backlash! Yes, I was trying to make a general point about rudder deficiencies. And your point is that some lesser degree of this problem should be checked.

A general Oceanis design fault to be looked out for?