RE: [PSUBS-MAILIST] Rudder Indicator using 3 Reed Relays

Frank, What diameter is the shaft on these actuators and what is their rated load and speed. If they don’t have a tail rod sticking out the other end then they are going to lose some actuating force. I.e. if they are say 5/8” diameter and you rate them for say 300 ft (approx 150 psi) then the force on them will be 46 lbs approx. This is likely to slow down the actuator in the out-stroking. I am not trying to kill the idea but making sure you are aware of the compensation required and therefore the sizing of them. I would like to see it work so we can adopt them. Regards, Hugh

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of vbra676539@aol.com
Sent: Saturday, 27 March 2010 8:16 p.m.
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Rudder Indicator using 3 Reed Relays

Frank,

Cool. Is there any reason these things would operate with oil compensation? It would be dirt simple to do.

Vance

-----Original Message-----
From: ShellyDalg@aol.com
To: personal_submersibles@psubs.org
Sent: Fri, Mar 26, 2010 11:01 pm
Subject: Re: [PSUBS-MAILIST] Rudder Indicator using 3 Reed Relays

In a message dated 3/26/2010 6:54:30 P.M. Pacific Daylight Time, vbra676539@aol.com writes:

I still like the electric linear operator for this. The ones I've seen look like hydraulic cylinders with a rod coming out one end through a seal. Have you seen those? Inside is an electric motor and a worm gear. Extension/retraction has some sort of indicator, too (as an option). I wonder what those puppies cost?

Vance

Hi Vance. Yes that's what I'm using. These electric linear actuators look and operate much like a hydraulic or pneumatic cylinder. Basically a rod that goes in and out. The more expensive ones can have a position sensor potentiometer built right in. The Minnkota and Lenco trim tabs use this type. The Minnkota ones have a 2 inch stroke, are sealed to IP68 rating, and have a built-in sensor. They cost $259 each plus the rocker switch/LED thing showing if it's up or down. ( $89 each )

I went with electric actuators because of the simplicity of the thru-hull ( epoxy and wires ) and controls which is just a 12 volt rocker switch at $8 each. Here's a small picture of the actuator for the dive planes. It's got a 6 inch stroke, 40 pounds push/pull, and is 2 inches square by 14 inches long. The rubber boot is from a power steering unit on a car. These actuators are $129 each but don't have the built-in position sensor.

The IP68 rating means they can be submerged a little but not made for under water. I'll be covering the actuator with a thick layer of fiberglass and the rubber boot clamps onto the shaft and body. The 2 wires will pass through a PVC threaded fitting bonded into the fiberglass cover. Frank D.

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