[TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder

[TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Printable Version

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[TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Horacio Battistini - 05-26-18 06:49 AM

Dear Friends,

I have a Vetus hydraulic steering system in my 41 footer steel sailing boat, with a 255 cm3 cylinder (model MTC 125). A friend offered me a Raymarine autopilot combo in a very good price including ACU 400, EV1, P70Rs and a Type 3 hydraulic pump. The recommended pump for my system is the Type 2. In spite of that, is it possible to use the type 3 pump with my cylinder of 255 cm3? What would happen? Damage to the cylinder? Excessive power consumption? Or it would work fine except for the super dimensioning?

Thanks in advance

Horacio Battistini / SV Viralata

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Tom - Raymarine - Moderator - 05-29-18 06:47 PM

Hello Horacio,

It is important that you match the pump to the capacity of the steering system. If you use a Type3 pump with a 255cc steering cylinder then the steering will be too fast (the pump will pump fluid too quickly) and the pilot will probably continually active, 'hunting' trying to settle on the correct rudder position and always over-shooting. The results will be at least some of the following:
- excessive current consumption
- early wear of the pump
- poor steering performance
- uncomfortable rocking motion as the pilot continually makes small left-right rudder movements

I would recommend selling the T3 pump and buying a T2 instead. You can use the T2 with the ACU400 and the rest of the pilot system of course.

Regards,
Tom

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Horacio Battistini - 05-30-18 05:14 AM

Thank you Tom for your response.

One last doubt. Except for the pump, the other components are ok for a sailing boat? Does the P70Rs have all the sailing functions P70 and P70s have (specifically steer by wind vane and tack)?

Thanks in advance.

Regards

Horacio

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Tom - Raymarine - Moderator - 05-30-18 09:01 PM

Hello Horacio,

A good point that I hadn't picked up on from your first post.
p70R/p70RS can do Vane mode (as long as the boat-type is set to Sail), but not auto-tack. A p70S would be better.

Regards,
Tom

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Horacio Battistini - 05-31-18 06:04 PM

Hi Tom,

Regarding the current consumption you mentioned in your first reply, what is a normal expected consumption for the Type 2 pump? I havenÂ´t found this information in the pump specifications.

Thanks in advance

Regards

Horacio

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Tom - Raymarine - Moderator - 05-31-18 11:20 PM

It's difficult to give a realistic idea of average consumption because there are so many variables:

Factors which affect the load on the drive:
- boat weight
- rudder size
- internal steering resistance and losses
- sail trim
- sea-state and wind-speed
- point of sail
Factors which affect how frequently the pilot has to drive:
- sail trim
- sea-state and wind-speed
- point of sail
- pilot response level and calibration
- ...

We don't attempt to take all of these into account in order to come up with an average consumption over time. As a very rough guesstimate, though, I'd say that if your drive is averaging anything more than 10-15% of the peak current over time, you have something badly wrong in your setup or sail-trim.

Regards,
Tom

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Horacio Battistini - 06-08-18 08:11 AM

Hi Tom,

I understand your point of view, and agree that it is very difficult to determine previously the drive power consumption, but what IÂ´d like to see is the same estimation presented for the linear and rotatory drives (see attached PDF). For the hydraulic drive I havenÂ´t found these numbers.

Thanks in advance

Regards

Horacio

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Tom - Raymarine - Moderator - 06-12-18 07:03 PM

Hello Horacio,

Those estimates are essentially based on vessel displacement rather than drive size (it takes roughly the same energy to push the rudder on a 11,00kg vessel whatever suitable drive type you do it with.)

We can't give estimates based on vessel displacement when it comes to hydraulic pilots though because the pump is specified on the basis of cylinder size, not vessel weight.

If you look at your attached table and compare the vessel displacements for the Linear drives to your own boat, that will give you a reasonable idea of the consumption to expect from your hydraulic system.

Regards,
Tom

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Horacio Battistini - 06-21-18 10:00 AM

Hi Tom,

Thank you very much for all your considerations.

Still in the pump selection, can I use the HyPro + 1.5 pump with this autopilot? Is it homologated by Raymarine? I found this model in Brazil and the specification indicates this one for cylinders from 250 to 350 cc (mine has 253 cc). Although itÂ´s manufactured by a third part company, does this HyPro pump work fine with Raymarine EV-400?

Thanks in advance

Regards,

Horacio

RE: [TG11] Use Type 3 Hydraulic Pump With a 255 cm3 Cylinder - Tom - Raymarine - Moderator - 06-27-18 02:13 AM

Sorry for the delay replying, I've been out of the office a bit recently.

You can use any hydraulic pump, as long as its peak current consumption is within the range of the ACU's current output (and of course as long as the flow rate is correct, as it sounds like this one is.

Regards,
Tom