autohelm on a broad reach

[scott]

hi all,

i was sailing on saturday on jervis bay with a plan to have a nice relaxing cruise across to some public moorings, a nice beach and a quiet night on the mooring....but 25 odd knots of n/ne put an end to all that!

anyway, heading across, i was on a broad reach with about 15-20kts and choppy seas of about a metre or so and running with the main only. the autohelm wasn't able to keep me on a course, unable to stop the boat from roundign up. my feeling is this was due to a combination of a few things. one being the wind and it's position on the rear quarter, the waves wanting to push the boat around and perhaps also that i was only under the main.

so i'm wondering if i could have done this any better so the autohelm could have kept a better course and been able to stop the boat from wanting to have a mini broach at times. if i had a headsail up as well, or only a headsail, would that have helped? any other tips?

as for the quite night, i had to can that, turns out that mooring is not as protected as i'd believed...so back to my mooring i went. the wind had picked up a little and the waves a little bigger for the return run, but this time the autohelm held the course with no problems.

thanks for any views / help,
scott.

[karl010203]

Hey Scott

For me my autohelm doesn't like running with the wind and seas astern. The motion is enough to make it unhappy at times. A flat day is fine but the combination, esp. if there is any tendancy for corkscrewing with the swells makes it pack the sads.

I think you have answered your own question though, with the tendency for it to want to round up all the time indicates that the rig balance was not right, and a headsail would have counteracted this. The beauty of our yachts it that being long keeled and well mannered that they can be balanced properly and sailed without exertion.

If you are having to use muscle to keep her on track there is no way your autohelm will.

With 15 - 20 knots you would have had 10 - 15 apparent which is great sailing and with a headsail on you would have been having a ball. You could have had only the headsail up but then would have faced lee helm... the secret was in the balance.

Sailing back were you close hauled with a headsail up?

[scott]

hi karl,

thanks for your advice. the tiller was certainly very heavy when trying to counteract the weather helm and your right, i doubt there'd be many tiller pilots that could correct that. actually, that night sitting out in the cockpit and enjoying a cold beer, i felt a little like i do after kayaking for 10k or so! it was fun, but tiring...

from this experience and one other situation in similar conditions, i'll definitely set the headsail next time and perhaps put a couple of reefs in the main. one thing i've been wondering is how the headsail will go reefed, ie only 'unfurled' half way or so. will it start to unfurl itself from the top? i was tempted to try it on saturday, but didn't fancy fixing that problem being short handed.

coming back i was close hauled. rather inconveniently, the wind was pretty much coming right off the direction of my mooring. i didn't have either the main or headsail set properly and could have, or should have had them set closer in, allowing to point a little higher, but i chose to leave it was it was and sail a little off the wind. but the tiller pilot worked perfectly on the return and allowed me to enjoy the ride a little more than the way out.

in short, it was a really crap day sailing! but thinking about it now, there are plenty of lessons learnt from it, which in the end made it a worthwhile day out.

i'd be interested to hear if anyone has any advice of the headsail unfurling itself when only partly unfurled with the intention of reefing it too. i feel a larger headsail may do this, but perhaps a smaller one wouldn't?

thanks,
scott.

[karl010203]

Yeah certainly hard work if you are fighting the boat.

I have reefed the headsail on furler before no problem- although I have heard it is not good for your sails, not sure if someone else can elaborate more on that. I know some furlers are also designed for reefing and others not - I don't know enough about the that one... I am sure others more experienced on the board can provide guidance.

Hey, the crappiest days are the learning days, and we all have plenty of those and survive to be a little wiser.
Still beats the hell out of work!

[Tales]

Scott,
I have raced on my mates Mottle 33 many times when he has part furled the headsail as the wind got up and it did not unfurl.

A couple of things to think about though.

1. Very important to adjust your jib sheet cars to match the angle of pull to the 'new' sail size.

2. The fabric is chosen for the wind strengths appropriate to the original size of sail ie a smaller sail would be made from stronger cloth. The danger is that it might stretch in the stronger wind.

Also the shape is not right really and the boat won't point as well.

However, most folk I have talked to use them this way instead of doing a sail change so it can't be that bad. Just have to be aware of the limitations.
Cheers,
Tom

[Dolphin]

Gentlemen,
You can use a sail furled on a furler if there is padding in the Luff. Macdiarmid set up my No2 and you can reef it down to a No3. See the attached pic. There are 5 pieces in there. After that the body of the sail is too full and the shape is all wrong. There is too much tension on the leach and the foot. It'd be ok running though.
In 20 kts I often only use the N02 (cause I don't have a no. 1) without the main. That's because the sail plan is unbalanced with a lee helm until you get to stronger winds when the boat heels and the centre of effort in the genoa moves well outboard of the boat and counteracts the lee helm. In short what I'm saying is that in 20 kts with a No 2 Genoa working to windward the boat can be steered to windward with one finger on the wheel.
I once asked a sail maker to put a 3rd reef in the main and he wouldn' do it as the sail cloth is only light compared to a storm main. Sounds reasonable to me.
Further I was racing on a Cole 30 and the genoa started to pull out of the track so we took one wrap on the furler to stop it going any further until we got back to shore.

As "Caveman" from On the Water signs off, " A bad day on the water is better than a good day in the office"
Just keep sailing, Greg.

Felicite sailing.jpg (16.14 KiB) Viewed 2582 times

[scott]

thanks everyone for the comments. i hadn't considered the differing strengths in sail material for larger / smaller sails. makes sense and i'll keep that in mind while playing around with reefing the head sail on the furler.

thanks again.

scott.

[lockie]

Lots of good words about sail balance, all spot on, but let's go back to the auto helm. You can't just whack it on for every set of conditions and expect it to work right with the default settings. I have a Simrad TP22 on my Compass 28, and I've found that it's critical to know how to set it up for different conditions.

It has two settings: "Gain" and "Seastate". I'm not sure how familiar people are with what these mean, so please excuse me if my explanation is a bit egg-sucky from your point of view. And I don't know what terminology Raymarine use, but the principles are the same.

"Gain" defines the amount of tiller movement the autohelm will apply in response to a certain amount of course deviation. If the Gain is set low, the autohelm will only move the helm a small amount for a particular amount of deviation. But if the Gain is set high, it will move the helm a much greater amount for that same deviation.

For following or quartering seas when you need fast response, you need high Gain (I use the max). Conversely for a nice balanced condition (say beam reach in 12 knots) you won't need much Gain at all.

Now to what Simrad calls Seastate: what they actually mean is "Deadband". This is the amount of course deviation tolerated before the autohelm starts to respond. If the deviation stays within the Deadband limits, the autopilot won't move. Obviously if this was set really low, the poor instrument would be constantly working, trying to achieve zero degrees of deviation which is unrealistic. A low Deadband setting will mean the autohelm will start to respond more quickly as your course deviates. A high setting will be a bit slower, by allowing the boat to "wander" a little more before reacting.

So once again, to get that fast response to cope with following seas, you need fast response. So set the Deadband to minimum. For that nice easy beam reach, you could tolerate a higher setting. The Simrad has a "learn" feature for the Seastate/Deadband, but I have found it can be a pain as it takes a few minutes to cogitate, and you don't have that long with following or quartering seas! I find it's all better if I just have a play with it, and by now I can get pretty close to optimum first go.

SO, read the manual and experiment and I'm pretty sure you'll find it will do what you want. I came in thru Port Phillip Heads yesterday with 1.5m following waves and the Simrad did a far better job than I could, not to mention the exhaustion.

The other major benefit of learning all this is that once you get it so the Autohelm is coping, you can gradually increase the Deadband and decrease the Gain so that it doesn't work so hard: you can save a lot of battery power this way, and give instrument an easier life, and reduce that annoying noise.

So, the moral of this long-winded tale is: read the manaul and learn how to make your autohelm sing, and you'll never look back (well maybe to admire how well you're doing despite those towering seas coming up behind).

Hope this helps, Graeme