440: Back-up Auto Pilot for Lagoon 440

[a64pilot]

Originally Posted by Paul L

We are talking a backup. But a backup for crossing oceans, so the passages are fairly long an dthe days are still 24 hours. The L440 is a over 2 of your boats. I would think the CPT would work pretty well on the IP 38.

Paul what has boat size got to do with it? If it takes ten lbs of force to turn the
wheel on big boat, but 20 on a little boat, then the little boat will work the
autopilot harder, if it's a wheel pilot. I know autopilots are sized by boat size, but that is for ones that turn the
rudder directly.
Using my IP for example it has an almost overbalanced spade rudder, reason is
due to the rack and pinion steering only a small wheel would fit and steering effort
with the small wheel was desired to be light.
A much smaller boat than mine with a skeg hung rudder has I'm sure much greater
steering effort and probably a much larger wheel for leverage and would work a
wheel pilot much harder. I feel sure due to the small wheel and light effort a Raymarine
wheel pilot would actually work fine on my boat.

[a64pilot]

Now in this case on the big Lagoon, I'm with you a CPT is not the best option in my mind, I believe a duplicate pilot of what he has, but mounted in the other hull is the best bet, but Cats are different, if a mono had two rudders and some do, maybe a duplicate autopilot mounted to that second rudder is the best bet.

I think Atoll brought up the idea of a second/ redundant pilot, it wan't my idea, but I see the logic in it.

[Paul L]

A64pilot
Just remember what the costs of an AP failing to deal with an extreme when the L440 is screaming down the face of wave with a rag of sail up. Big boats have big forces. There's an L440 on the mooring directly next to me now. You drive from the 3rd deck flybridge. It has a center console dinghy with a 30 HP outboard hanging on the davits and it doesn't look out of place on the boat. The boom must be 20 ft off the water. Mast height is something like 70 ft. Sail area is 1260 sq ft. Its just a big boat.

[a64pilot]

I got that it's big, but unless wheel forces go up in proportion to boat size a CPT will helm it,
I've never heard that only powerful men can helm a Lagoon, I thought even the average middle aged Woman can, can't she?

[Paul L]

Originally Posted by a64pilot

I got that it's big, but unless wheel forces go up in proportion to boat size a CPT will helm it,
I've never heard that only powerful men can helm a Lagoon, I thought even the average middle aged Woman can, can't she?

I've been on boats in gales where competent women crew said they did not have the strength to drive reliably. The average forces are certainly not that high. But when the sh*t hits the fan, the response time and force needed to keep the boat safe is significant. And the cost of not doing it can be catastrophic. Let's not

[robert sailor]

Boats do steer differently but up until our ride down to the Canaries we had not had much more than 20 knots to test our back up CPT. The last 2 days to the Canaries we had a day in the high 160's and the next day in the mid 170's which is about all our Moody 42 is good for. Winds were pretty steady in the 25-35 knot range with the odd gust to 40. This was a good time to compare the CPT to our RM below decks elec/hyd pilot. They certainly were not exactly the same but I can say that the CPT handled the boat without any difficulty whatsoever.

[colemj]

Originally Posted by robert sailor

The last 2 days to the Canaries we had a day in the high 160's and the next day in the mid 170's which is about all our Moody 42 is good for.

I know I must be having a brain-fart, but I cannot understand the meaning of this sentence. It can't be wind speed or temperature or wave heights…

Mark

[robert sailor]

Sorry, it was miles per 24 hour run or per day.

[colemj]

Originally Posted by a64pilot

I got that it's big, but unless wheel forces go up in proportion to boat size a CPT will helm it,
I've never heard that only powerful men can helm a Lagoon, I thought even the average middle aged Woman can, can't she?

With this logic, there is no difference in steering and forces between a Catalina 22 and a Formosa 51, and both should be able to use a tiller pilot.

The Lagoon 440 has miles of cables and sheaves connecting a flybridge helm down and aft to two quadrants on separate rudders (at least I don't think they use hydraulic systems). They use a very large diameter wheel to gain enough mechanical advantage.

Our boat has a 42" wheel and the pressure on it can be quite high if things get caught a bit sideways. I know a sistership where the owners replaced this with a 36" wheel to have more space and quickly went back to the 42" because they said they could not control the boat at times.

I assume the CPT does not have different diameter belt wheels? If not, then the forces will be great on a boat like the Lagoon 440. I'm not saying that the CPT can't handle them (I have no idea) - just that that there are different forces on different boats.

Mark

[colemj]

Originally Posted by robert sailor

Sorry, it was miles per 24 hour run or per day.

AH! Yes, it was a brain-fart indeed.

Mark

[2Wind]

Originally Posted by colemj

The Lagoon 440 has miles of cables and sheaves connecting a flybridge helm down and aft to two quadrants on separate rudders (at least I don't think they use hydraulic systems). They use a very large diameter wheel to gain enough mechanical advantage.

Personally, I find the effort, especially to deviate to windward, when over 9-10kts, to be quite high. At times, I've wondered if I had mistakenly left the AP on and was trying to steer against it. On occasion I've even checked to see if a sheave had failed or was out of alignment in the cable run (which I might add is difficult to inspect). It certainly would make any long period of hand steering an onerous task, IMHO. Fortunately my AP has only packed it in due to voltage drop in the middle of a night run when the batteries were on the way out. Having to run an engine overnight just to have the AP functional was a pain, but the best option.

[robert sailor]

I believe the CPT has 2 different drive wheel sizes on the wheel steering depending on the torque required to helm the boat.

[a64pilot]

Originally Posted by robert sailor

I believe the CPT has 2 different drive wheel sizes on the wheel steering depending on the torque required to helm the boat.

It does, 12" and 14" I think.
Now I freely admit to not being real experienced, but if the Wx is that bad, I don't plan on Otto steering, and if it gets to the point that the average Woman hasn't the upper body strength, but the auto pilot does well,
Maybe Sailorboy is onto something with autopilots possibly contributing to rudder failures.

I have a hard time understanding how a modern design could make it into manufacturing that requires more upper body strength than the average middle aged Woman has. (I'm not trying to be sexist here, just assuming on average Women have less upper body strength than Men do).

[a64pilot]

Originally Posted by colemj

With this logic, there is no difference in steering and forces between a Catalina 22 and a Formosa 51, and both should be able to use a tiller pilot.

Mark

That is pretty much apples and oranges and we aren't talking about driving the rudder directly, but by using the mechanical advantage the manufacturer designed into the steering system.

I've not helmed many sailboats, and no big ones, but are the steering forces required to helm a 60+' sailboat,significantly larger than it 30 ish ft cousins?
Modern designs that is.

I'm at least a little surprised that at least these bigger Cats aren't steered hydraulically.

[Paul L]

Originally Posted by a64pilot

.....
Now I freely admit to not being real experienced, but if the Wx is that bad, I don't plan on Otto steering,......

So who do you plan on steering? You and maybe your partner for 36 hours in crap conditions? Do you think you'll be alert and a top-notch helmsmen part the way through this? Generally the APs stay more alert and steer better than a tired Mom & Pop crew.

As far as

a modern design could make it into manufacturing that requires more upper body strength than the average middle aged Woman has.

On average they don't, in most conditions it is fine. But get yourself in tough conditions, confused seas, up a little sideways and it can take a lot of effort to correct.