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Old 19-11-2015, 01:15   #1
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Sailtrim for autopilot

Now going thru North TRIM book to improve my sail trimming skills. Enjoy it a lot especially with practical sessions.

Good trimming requires permanent attention. For me it is fun 2 hours but then not any more and autopilot takes over and my attention goes in enjoyment of other aspects of sailing and travelling.

Any hints or guidelines for sail trim under autopilot ?

I have difficulties going upwind under autopilot under 43 deg apparent. Although boat can do 30 deg manually steered.

I am also reluctant going deep downwind because of gybe. 140 app is the most I can dare to set autopilot. Yeah, i know parasailor is answer, but is there anything better ?
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Old 19-11-2015, 01:41   #2
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Re: Sailtrim for autopilot

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Originally Posted by arsenelupiga View Post
I am also reluctant going deep downwind because of gybe. 140 app is the most I can dare to set autopilot. Yeah, i know parasailor is answer, but is there anything better ?
For the lazy sailor, like me, twin genoas wing and wing. I used that across several oceans leaving them to look after themselves for days on end. I didn't use any poles but would have liked one for when we were around 140 app as the windward side would sometimes collapse when we got that far away from dead downwind.
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Old 19-11-2015, 01:47   #3
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Re: Sailtrim for autopilot

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For the lazy sailor, like me, twin genoas wing and wing. I used that across several oceans leaving them to look after themselves for days on end. I didn't use any poles but would have liked one for when we were around 140 app as the windward side would sometimes collapse when we got that far away from dead downwind.
how do you do 2 genoas ?

gennaker & furler genoa ? My gennaker is 75m2 and genoa 28m2.
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Old 19-11-2015, 11:46   #4
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Re: Sailtrim for autopilot

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Originally Posted by arsenelupiga View Post
Any hints or guidelines for sail trim under autopilot ?
Balance. Get the boat balanced as much as you can to limit the work the AP is doing.

Quote:
I have difficulties going upwind under autopilot under 43 deg apparent. Although boat can do 30 deg manually steered.
I think this is pretty typical, especially if you're good at sailing upwind. Some boat and AP combinations are probably better than others. The AP cannot anticipate nor react as well to the wind speed and direction changes and doesn't have the multiple inputs a good helmsman can use. Also, the highest app wind angle you can steer doesn't necessarily get you the best VMG.

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I am also reluctant going deep downwind because of gybe. 140 app is the most I can dare to set autopilot. Yeah, i know parasailor is answer, but is there anything better ?
Don't use your mainsail deep downwind. And a traditional symmetric spinnaker is probably far cheaper than a parasailor.

It sounds like you set your AP to steer to an apparent wind angle. I have found that this is hardly ever better than setting it to a heading or to a waypoint. But this probably varies a lot with differing wind instruments and APs and boats.

Dave
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Old 19-11-2015, 11:59   #5
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Re: Sailtrim for autopilot

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Originally Posted by arsenelupiga View Post
how do you do 2 genoas ?

gennaker & furler genoa ? My gennaker is 75m2 and genoa 28m2.
My new genoa and an older genoa, one in each slot on the furler, both hoisted on the same halyard. Rolled away together if reefing needed. There will be some photos in my wife's blog (link below) but it may take you a while to find them. I think we first used this setup from the Galapagos to the Marquesas in around March 2010. I'll see if I can find some photos elsewhere as well.
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Old 19-11-2015, 13:04   #6
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Re: Sailtrim for autopilot

WHat brand autopilot? My Simrad has anti-stall and anti-gybe features.


Any higher than an angle you set as a minimum for upwind it will automatically switch to a higher rate and avoid going into irons. (You set the rates too)


Downwind it automatically switches to true wind at around 130'. And switches to high rate at about 150 or so.


It's very good, we sail wing on wing near DDW a lot of the time at say 175', with a gybe preventer set, and it works well.
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Old 19-11-2015, 17:39   #7
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Re: Sailtrim for autopilot

I too wouldnt bother with the main below 140 apparent (unless I think I might want it later to douse the spinnaker in higher winds - then I might leave it up with a reef in). Fact is most cats dont do too well deep down wind under main alone anyway.

Twin headys or a spinny the auto will be just fine even at DDW then.

Upwind sail balance is the key. I usually have a bit of a hand steer and feel how hard the rudder is working or not but I dont have hydraulics getting in the way of the rudder feel. Without mechanical steering maybe lock the helm and trim till any tendency to round up or down is gone then turn on the AP.

If the AP is struggling at lower AWA's it seems you have weather helm and its working pretty hard against the main. Makes sense with the small genny you have.
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Old 22-11-2015, 18:30   #8
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Re: Sailtrim for autopilot

Fine if you have a spinnaker. We've just got 2 sails, main and jib.
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Old 22-11-2015, 20:18   #9
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Sailtrim for autopilot

We both have L400s so I guess our experiences should be similar if you have raymarine AP. Upwind depending on the sea state we usually sail in wind vane mode with the vane set around 32-40 degrees depending on wind and waves. The vane steers better than me most of the time unless it's pretty choppy and an eye on the waves helps keep things moving. Downwind we reach to around 150 degrees, usually not in wind vane mode. Past that we wing in wing in wind vane mode with the AP set at 165-175 degrees. Never had an accidental gybe under AP but I managed one the other day hand steering 🙈 Longer DW passages we break out the parasailor.

Edit...when we wing in wing we lead the lazy sheet around the centre mooring cleat to hold the jib out wide with a bit of tension on both sheets. Also on a reach we often sail in vane mode as well. Vane mode = less sail trimming but obviously more attention to the course and obstructions if the wind is variable..
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Old 22-11-2015, 20:29   #10
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Re: Sailtrim for autopilot

Quote:
Originally Posted by arsenelupiga View Post
how do you do 2 genoas ?

gennaker & furler genoa ? My gennaker is 75m2 and genoa 28m2.
The guys that set up for this have two identical hanked-on jibs so they lay on top of each other until they are needed wing & wing. You can also add a sail if your furler has two tracks & spare halyard. Most often, use two poles. There are books written on this. The total sail area is about the same as a kite but the center is very low and stable.


I have found our autopilot really better than I can steer most of the time. It goes to weather much closer than I can average unless the sea is rough. If yours is not stable, over steers; under steers, check your manual to see if you can adjust the gain. One thing that is very important is that you balance the rig so that there is little weather helm. This is usually faster anyway. "When in doubt, let it out"
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Old 23-11-2015, 01:37   #11
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Re: Sailtrim for autopilot

thanks for ideas

I will first validate weather helm. I think that is issue no 1.

I take if Monte with his L 400 can do 32 deg with autopilot, my best 43 deg is definitely something not right. Maybe raymarine autopilot playing up as well.

Like idea of 2 jibs, but need to check if that is an option on my furler. I suspect it is not.

2 genoas in one seem a bit too much, except if one makes this as separate sail. Then probably there are better options available.

It is such a waste to leave main down when downwind, so will try couple of ideas. Attractive one is: SPI one side max to windward hull and try to make mainsail teltales flow backwards without poles.

if I find any good setting, will post.
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Old 23-11-2015, 05:59   #12
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Re: Sailtrim for autopilot

Our raymarine plotter was factory set with 15 degree offset from true north for some reason. This effected the wind data output. (Plotter showed variation to displays) Change it to zero and it may work better in vane mode. Also play around with VMG data on the displays when sailing upwind. It can give some useful info for the fastest upwind angle to sail.
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