auto pilot

[warby1212]

Hi,

I am contemplating a longish trip (600 miles, by far my longest ever) and am not looking forward to steering the whole way. My boat is a steel 14 ton 38 foot beast and a proper autopilot is way beyond my means. I was wondering if it would be feasable to build a seperate rudder of the back like the type used for wind vanes and mount a small tiller autopilot on that. If it worked it would be sufficient for good weather?
Also, would the steel hull be a problem?

Thanks Stephen

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[snowleopard]

with large tiller-steered boats it is an accepted method to fit a trim tab to the trailing edge of the rudder and drive that with the autohelm. it will take a bit of experimenting to get it to work but should result in reasonable performance.

the trim tab will need to be 10-20% of the rudder area and you'll need to make up the linkage to reverse the effect of the autopilot as the trim tab moves the opposite way to the rudder.

modern autopilots contain software to allow for the deviation of a steel hull, you tell it to callibrate then steam round in slow circles while it works out the deviation table, thereafter you can set magnetic courses accurately.

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[warby1212]

Hi,

Thanks for the reply. Yes, I've heard of the trimtab approach but I have wheel steering and the rudder is not accessable. Do you think it would work with extra small rudder mounted on the transom?

Cheers Stephen


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[snowleopard]

in short, no.

in favourable weather with the helm well-balanced then lashed, an auxiliary rudder would cope so you could make coffee or have a doze. in heavier conditions and downwind i doubt a tiller pilot could cope with a rudder that was big enough to be any use.

wheel steering is a b****r for rigging self-steering, the old standby of attaching sheets and bungy to the tiller are no use to you. wind-actuated systems are all v. expensive and electronic ones powerful to be any use are also expensive.

probably your least expensive option is one attached to the wheel but whichever way you go won't be cheap.

my personal view is that the freedom an autopilot gives you on a passage is worth every penny. bite the bullet and go for a 'proper' system.

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[warby1212]

Yes,

I pretty sure I must have it otherwise I'll go crazy. The prevailing winds for my journey will be on the nose so I'll probably be motoring 90% of the way on fairly flat water. Power therefore won't be a problem then also. I might l look into rigging the emergency tiller semi permanently (disconnecting the outside wheel) and using a tiller pilot on that.

hanks fro your advice

cheers
Stephen

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[paulrossall]

Is not the easiest solution to get someone to do the trip with you? If you are not carefull you will spend loads of time and some money trying to lash up something to work, which is probably not going to be very succesful. Also another body means you can get your head down for an hour. Where are you sailing from/to?

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[qsiv]

Hold on - arent we talking of a servo pendulum, rather than an auxiliary rudder?

theres no particular reason it cant work, providing a) the drive lines can be got to the tiller and b) the tiller can drive the wheel (i.e not a worm driven mechanism). With those two provisios I see no reason why it shouldnt work.

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[warby1212]

I'm sailing from Airlie Beach (Whitsundays Australia) to Brisbane, about 600 miles.
Because of the wind here it would be on the nose and probably motoring most of the way. Pretty boring steering i would think but my longest stint so far is about 3 hours.

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[markdj]

I think you need to recalculate how long the trip will take accounting for tacking against wind and tide. 600 nm could mean 2 weeks at sea. R you going continuosly or are there ports/anchorages to stop all the way.(I don't know area).

If 3 hours is the longest you've been out then I think you should get the boat shipped their on a lorry or container ship. This trip sounds quite lengthy and you would really need some experienced help with you.

If you're looking for an autopilot, bite the bullet and get it professionally installed and then go out and test it to get familiar with the setup before doing the trip. I hope you have all your safety equipment up to scratch with flares, lifejackets/raft, VHF, possible satellite phone, EPIRB, chart plotter or up-to-date charts and GPS, laminated paper charts? maybe.

Concerned mariner

MarkDJ

<hr width=100% size=1>Mobile UK Weather
<A target="_blank" HREF=http://www.stronge.org.uk>http://www.stronge.org.uk</A>

 

[warby1212]

Thanks for your reply. I'm concerned too.

The trip would not be for at least ten months. We are moving and the boat has to get there too. I'm starting preparation now because of my lack of experience in distance cruising. We have had the boat for 6 years, cruising around the islands and know her well. I would be allowing at least a month for the journey as I don't want to be under pressure to go on when the weather is bad or I am tired. I've actually done a cruise of similar distance before but only as crew. That was non-stop. The number of stops I can make along the way will be the final decision maker in whether to go or not. Whenever possible the legs will be short and that is what I am mainly looking into now, just how short and how near will safe harbour be at various points.

The auto pilot issue is probably (as far as I can see) what will make or break the journey in terms of being an endurence test or a holiday.That's where my knowkledge stops, what makes a good long trip.

Cheers
Stephen

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[DeeGee]

As you have a reasonable time in hand - although moving probably means busy - you might consider doing it properly and making your own s/s servo-pendulum system. Try this site: http://www.mindspring.com/~waltmur/Self-Steering/ or http://www.cruisenews.net/cgi-bin/windvane/windvane.pl

I haven't done this myself, having a Monitor, but I have met peeps who have. I wish I had.


<hr width=100% size=1>Black Sugar - the sweetest of all

 

[warby1212]

Thanks for that. I'll have a good look at them.

Cheers
Stephen

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