Autopilot Selection for Catamarans

[svcattales]

Hi, I have been shopping for autopilots for our Privilege 37 and I don't know how to apply the manufacturers guidelines to a cat. Cat Tales displaces about 18K lbs loaded. Although there are two rudders to move (about 3ft/sq, ea), the boat doesn't seem to generate WX helm. Will I need more or less power than a monohull of the same displacement? I found a good deal on a leftover Raymarine ST 5000+ for 2,200 bucks. It is rated for 20K lbs. Would that work OK, or do I need more power??

[Jentine]

With very little effort,I have found the Raynav 6001 on the net for a couple of hundred dollars more than the outdated unit you are looking at. $2200 for that unit is not a good deal.


The 6001 is rated at 22,000 lbs. and should serve you well.

[Strygaldwir]

Greg;

Just came up from Florida to North Carolina. I'll have to hook up with you when we come back down. But, in anycase, we used our Raymarine autopilot about 95% of the trip. It worked very well. We have a new ST6001 control head, but the drive mechanism is from an older ST5000 system. Since there were very few issues with it, I think any drive unit rated for 17k and above is going to be okay. If I were replacing my system I'd go with the newer units. They have significantly upgraded the electroncs, interfaces and software in the newer versions. The cost differential is not enough to warrent the headaches you'll have with the out of warrenty equipment. I got my control head from Dahhanes, they had the best price at the time.

Good luck.

Keith

[svcattales]

Thanks for the advice Jim & Keith. I'll see if I can find a deal on an ST 6001. I just talked to a friend that has a 6001 on his Lagoon 37 and he is also happy with it. Keith, let me know when you return to Fl. Greg

[Talbot]

You would be much better buying a new S2 system from Raymarine. Especially if you buy the S2G. This has accelerometers built into the system that enable the steering to anticipate movements and apply the appropriate amount of helm. I understand that according to the long distance racing people, this enables the autohelm to be 3% better than the best human helm even in very bad conditions

Cost will very much depend on which model you buy, but if you have hydraulic steering, even the S2G is not going to be a lot more than the out dated overpriced 5000 you were offered.

[svcattales]

Talbot, Thanks for the help. I have been doing some internet shopping and found a new 6001 with S1 corepack for $2,179 (USD), but it goes up to $2,927 with the plain S2. (Based on the 12 V linear drive). Trying to decide how much I want to pay for extra capability.

[GordMay]

Autopilot Manufacturers:

Alpha Marine Systems, Mercer Island, WA
"Alpha" "Spectra"
Web: www.alphamarinesystems.com

B&G/Brookes & Gatehouse, Clearwater, FL
"Network," "H1000," "Hydra" & "Hercules" "Pilot" linear drives & hydraulic pumpsets
Web: www.bngusa.com

Benmar Marine Electronics, Santa Ana, CA
"Compu-Course," "Course Setter" underdeck
Web: www.benmarmarine.com

ComNav Marine, Richmond, BC Canada
Autopilot systems, electro-hydraulic linear & pumpset/ram drive units
Web: www.comnavmarine.com

Euro Marine Trading, Newport, RI
"NKE" "Gyropilot," hydraulic linear drives & reversing pumps, wireless remote
Web: www.euromarinetrading.com

Furuno U.S.A., Camas, WA
"NavPilot"
Web: www.furuno.com

Lewmar/Whitlock, Guilford, CT
Rotary sprokcet & drag link underdeck electric drive units
Web: www.whitlocksteering.com

Navman USA, Nashua, NH
"G-Pilot" compass/rate gyro
Web: www.navman.com

Octopus Precision Products (Canada Metal), Delta, BC Canada
Hydraulic pumpsets, cylinders & linear drive units
Web: www.octopusmarine.ca

Raymarine, Nashua, NH
"Autohelm Series" "ST" "SeaTalk"
Web: www.raymarine.com

Simrad, Lynnwood, WA
"AP" electric & hydraulic linear drive and pumpset
Web: www.simrad.com

Si-Tex, St. Petersburg, FL
"SP" hydraulic pumpset
Web: www.si-tex.com

Tecnautic (Electronics), West Hills, CA
Autopilot electronics package for use with other companies' drive units
Web: www.tecnautic.com

W-H Autopilots, Bainbridge, WA
"AP" & "P" series hydraulic
Web: www.whautopilots.com

[Talbot]

svcattales once whispered in the wind:
S1 corepack for $2,179 (USD), but it goes up to $2,927 with the plain S2. (Based on the 12 V linear drive). Trying to decide how much I want to pay for extra capability. :

The biggest difference between S1 and S2 is the power of the linnear drive. I assume that you must have cable/chain steering connection from wheel to rudder quadrant. The system that mates with a hydraulic connection is a lot cheaper!

The Si and S2 both have more expensive versions S1G and S2G that incorporate the accelerometers. The standard S1 and S2 can both be upgraded later (but that will cost more), and I understand that the accelerometers do make a big difference in bad weather.

[svcattales]

Thanks for the links, Gord May. Talbot, I do have mechanical steering so I need the expensive drive. I agree about the rate gyro option, "G" version. It is probably worth the money to have a better heavy weather AP. Sent an e-mail to RayMarine to see what they recommend. Will let you know what they have to say.

[Bill Balme]

Do wind vanes (like the monitor) work on cats - or only on leaning boats?

[Talbot]

some people do claim that you can use them, and in a heavily laden cruising boat it may be OK. The problem is that a cat especially a modern lightweight version has a very fast rate of acceleration. The other problem is that in a gust of wind in a cat you do not luff up into wind, because the increased wind pressure alone will increase the stress on the rig, and decrease stability, the action of luffing up into the wind increases the apparent wind speed thus further increasing the stresses etc, and the very act of turning into the windwill add a further vector in the same direction. If you are running under the control of a wind vane, the acceleration on a big gust could actually put the boat into danger. - much better to have the autopilot steer a specific course.

BTW, the biggest danger for a large cat is not a capsize, it is a pitchpole, caused by running too fast. Therefore an essential safety item is some means of slowing the boat such as a series drogue.

[svcattales]

After lots of research, I was ready to order the Raymarine ST6001 with the rate gyro and 12V linear drive. Before ordering, I downloaded the install manual and discovered that linear drive is too long for the only place it can go. Forced to start over, I looked at several other APs. When I checked out the details of Navman's G-pilot, I thought gee that drive unit looks familiar. Next, I found the Octupus web site which makes the hydraulic drive for Navman and got the specs on it. Lo and behold, it is the same drive that is already installed in my boat as part of the old Navico 8000 system. Since the drive works and its not a Navico product, the Navman G-Pilot could be a good solution and will save me about 2 grand. Anyone have any experience with Navman G-pilot? It has all the features of ST6001 plus steers to apparent wind with an wind input. What do you think?