ON-OFF-ON relay

[Ric]

I have an on-off-on switch at my helm which can switch between primary and backup autopilots. I would like to fit an under deck on-off-on relay controlled by this switch so that there is less voltage drop to the drives across the wires to the helm (they have to be narrow wires to get through the helm console support tubes). Does anybody know of such a relay? I have tried googling but without success.

 

[jamie N]

If I understand you correctly, you wish to keep the 'helm' switch, but have the 'actual' switching under deck?
Off the top of my head, I reckon that you'd be better off with a pair of relays, each switching in when the relevant switch position at the 'helm' is 'on'. Relays are astonishingly cheap and simple to wire up, so without knowing your actual boat, I'd think that this was easily achievable.
There are people here with greater specific knowledge than me, who will hopefully give a more informed answer to you.

 

[PaulRainbow]

I agree with Jamie, just fit a pair of heavy duty automotive relays, connect the energising wires from the relays to the switch. Actually, you already have a pair of wires from the switch to the AP, so just use those to energise the relays.

Also, don't fit cheap crap relays, plenty of decent ones out there for peanuts, such as Durite 12V 30A Mini Relay - 0-727-12

Others makes/suppliers available

 

[VicS]

A change over relay and an on / off switch at the helm would mean that power is normally on to one autopilot but to the other when the switch is closed. I guess that is not what you want.

Jamie N's suggestion is the way forward. Two relays. One energised by the existing switch in one of its on positions. The other energised in the other on position.

Go to Furneaux Riddall or 12volt planet to find suitable relays.

 

[Alex_Blackwood]

I agree with Jamie, just fit a pair of heavy duty automotive relays, connect the energising wires from the relays to the switch. Actually, you already have a pair of wires from the switch to the AP, so just use those to energise the relays.

Also, don't fit cheap crap relays, plenty of decent ones out there for peanuts, such as Durite 12V 30A Mini Relay - 0-727-12

Others makes/suppliers available

+1 for both replies will have to be two relays.

 

[Ric]

Thanks for the suggestions - yes two relays is the obvious way forward thanks.

 

[Martin_J]

I think it's great that others have all taken time to come up with the solution to the problem and not just an answer to the question.

And so quick as well

The way my mind is working (or isn't working) with this long covid, I would currently have struggled to deviate from thinking solely about the question. [and that's going to be the longest sentence I put together today].