CPT or not CPT?

[NATBF]

Hello folks-

I am getting some work done on the boat, and it would be the time to install a CPT wheel pilot if I'm going to do it.

I have an EV100 which does not have the robustness to deal with significant waves (even in the bay, but 6' waves outside the gate were definitely too much, as I found out), so I have been thinking of something better. I have a windvane for long distances. I am not enthusiastic about laying out the cash an under-deck autopilot would cost... so looking at CPT.

Any commentary by folks who've used it / know of it would be very much appreciated.

 

[alemon74]

Hello folks-

I am getting some work done on the boat, and it would be the time to install a CPT wheel pilot if I'm going to do it.

I have an EV100 which does not have the robustness to deal with significant waves (even in the bay, but 6' waves outside the gate were definitely too much, as I found out), so I have been thinking of something better. I have a windvane for long distances. I am not enthusiastic about laying out the cash an under-deck autopilot would cost... so looking at CPT.

Any commentary by folks who've used it / know of it would be very much appreciated.

I had installed a CPT autopilot on my cape dory 33 that I recently sold. The upsides as I saw them: It performed very well to windward when the sails were balanced. The unit is much quieter than most other wheel pilots. You really dont hear it at all. It also has minimal power draw. It is substantially stronger than the raymarine autopilot both in overall robustness and torque that it can generate. It's also a very simple and easy install. Totally doable as a DIY project. On the downside, it has no rudder angle sensor. If the boat's course is meandering, especially downwind with any kind of wave action, it doesnt keep up with rapid enough adjustments to stay on course. When trying to get back on course it will attempt to keep turning the helm despite the helm reaching its limit of full starboard/port travel. This results in the belt jumping the gears as the CPT tries to keep turning against the helm that can't turn any further. Additionally, it has the obvious downside of only sailing to a compass heading - ie it has no idea what the wind is doing.

 

[NATBF]

Thanks, @alemon74 -- that is very helpful.

It has been suggested to me that one can level up a CPT performance by using the CPT drive unit with a Pelagic controller. Pelagic says nobody they know of has tried this. In any case, in theory the Pelagic controller would steer better downwind (isn't that what they're known for?), and their controller supports rudder sensors, which would solve the overdriving rudder-limit issue.

CPT turns out not to sell the drive units separately, so I have been thinking of installing the CPT system, then shifting to the Pelagic controller if I was unhappy with the CPT's.

 

[alemon74]

Thanks, @alemon74 -- that is very helpful.

It has been suggested to me that one can level up a CPT performance by using the CPT drive unit with a Pelagic controller. Pelagic says nobody they know of has tried this. In any case, in theory the Pelagic controller would steer better downwind (isn't that what they're known for?), and their controller supports rudder sensors, which would solve the overdriving rudder-limit issue.

CPT turns out not to sell the drive units separately, so I have been thinking of installing the CPT system, then shifting to the Pelagic controller if I was unhappy with the CPT's.

Interesting, I often thought that a smarter cpt would be a cool product.

 

[GBR3068]

I have both CPT as well as a Pelagic that drives my Monitor via the small ram from Brian (with 3 Pelagic control heads, 2 as spares, its that important to me). The CPT and Monitor/Pelagic are complimentary systems to me and I couldn't do without either. The CPT gets me around the Bay when I'm hoisting sails, just need a quick hand etc. The CPT was still good enough to help both to and from Hawaii when I needed it. I found my CPT works a bit better than the Monitor in very low apparent (though on my boat apparent is almost always equal to true) wind. The CPT is very nearly bullet proof and incredibly simple and easy to use. The only thing to watch out for, and maybe the only reason I say the CPT is not completely bullet proof, is the Shear Pins on the CPT. I got hit by a big down draft on the way back from Kauai and the boat wanted to go one way and the CPT another. The Shear Pins lost the battle just as they are designed to do, so that part is bullet proof and a very good design because with the forces involved something serious would have broken if not for those pins. The issue is replacing those pins when they do shear.

Look at the diagram in section 8.4 of https://www.cptautopilot.com/manual/maintenance.html

1. The Shear Pins (10) break as they are supposed to under extreme stress, and it has to be extreme stress.
2. It is possible (and the manual covers this issue in Section 8.4) that the very tip of the ends of the broken Shear Pins might be stuck in one or both of the holes in the Drive Plate (4)
3. If the Drive Plate does need to be removed to get those one or two tiny bits of the Shear Pins out (and they can be wedged in there as was one of mine because of the force required to shear those pins) then you have to remove the Retaining Ring (8). I could find no alternative. You can't get a pick or anything else in there to prod the pieces out. You'll see what I mean if you have one.
4. This operation to remove the Retaining Ring (only if you have bits of one or more pins left) is no big deal when you are at the dock, it is a bigger deal if you are still in conditions that sheared the pins. I had not practiced this on the dock and should have. I think if you just do it once, have the right tools (I now carry Irwin 2078900 for $14 at Lowe's or Amazon, though in a pinch you can use a screwdriver, carefully) and you are cautious about shooting that Retaining Ring around as it wants to do, then it's perfectly do-able at sea. I was lucky, I carry a spare CPT motor unit, so I practiced on the spare in the cabin before performing the real surgery in the squalls outside.

Given that advice to practice changing the Shear Pins, carry spare Shear Pins and a spare Retaining Ring, I can wholeheartedly recommend the CPT. The first time my dock neighbor tried my CPT he immediately went out and bought one for his boat. Really easy to install (and thus really easy to take off, an advantage I hadn't fully realized), and the CPT folks have made it easy with their ordering system. You dont need a yard to install it, it is really easy to DIY. I like the CPT unit as much as my Monitor and my Pelagic. I like the people at CPT (local in Aptos) as much as I like the Scanmar and Pelagic folks (local too). Great people, friendly, knowledgeable and outstanding support.