Raymarine ST30 Speed transducer replacement

[Dino]

Hi, I’m looking to replace some electronics on my boat. The old ST30 Speed transducer is missing a blade and the head unit is badly sun damaged. The previous owner had already replaced the ST30 Depth unit with a i40.
will an i40 depth transducer fit into the skin fitting for an ST30?

 

[KompetentKrew]

I decided against replying yesterday because I don't know how much help I'll be, but I might as well since no-one wiser has yet replied.

The transducers themselves are usually made by Airmar, whose support are helpful.

The transducers themselves have a part number of their own, separate from the products's ST30 / i40 /whatever designation. You might find Raymarine's part number in the ST30 manual, or it may be printed on the transducer itself. Airmar will have their own part number for the exact same thing, but the two companies may recognise each other's part numbers if you're asking for help.

You don't say whether your speed transducer is the kind that can be removed from the skin fitting for cleaning - these are referred to as "retractible". I guess it probably is, and only depth transducers are non-retractible?

There are at least two sizes of retractible transducer in Airmar's current model range - I sought their help with the UST and UDST models and both have a 2½" skin fitting, but the transducers themselves are different sizes and the skin fittings are different. One of them is backwards compatible with some other older skin fittings, so you can just slot the transducer straight in to the old skin fitting, but the other is not and the skin fitting must be replaced. IMO you need to find out exactly what you have.

Did you make a typo in your last line? I thought the PO had already replaced the depth unit.

 

[Dino]

Thanks KK,
You are correct, I did mean the speed transducer. It is indeed the retractable type. I have the dummy plug unit so I will measure it and see what works. I did see an ST800 that looks very similar.
Thank you for your reply. I’ll get the vernier callipers out and take some measurements

 

[KompetentKrew]

A part number may also be cast into the plastic, if not printed.

Take pics and contact Raymarine and Airmar support.