Nasa clipper log paddle wheel changeability

[jimmyk]

I am updating the boats equipment on a budget which is why I am asking a lot of questions. And getting really good answers I might add

Anyway. I have a nasa clipper log but the transducer is smaller than the old stowe one already fitted. I also have an older seafarer log which is not as clever as the clipper but the transducer does fit the hole. The nasa log has a television type connection to it. Sorry don't know the technical term. The seafarer one has two wires. Both the transducers have two magnets. Is it possible to wire the clipper head unit to the seafarer transducer. Sorry if I have asked simulate questions to this before

 

[[70521]]

Why not ask NASA? I've always found their after sales service brilliant.

 

[Minchsailor]

There are 2 types of log impeller sensor - Hall effect (has 4 wires) and pickup coil (has 2 wire). The NASA (AFAIK) is the coil type.

I would imagine they are pretty much interchangeable the NASA display could be used with other 2 wire sensors which have 2 magnets in the paddle wheel. I doubt if any of the 4 wire types could be interchanged. The 2 wire and 4 wire are incompatible.

The 'television type connector' is a simple co-ax.

 

[jimmyk]

There are 2 types of log impeller sensor - Hall effect (has 4 wires) and pickup coil (has 2 wire). The NASA (AFAIK) is the coil type.

I would imagine they are pretty much interchangeable the NASA display could be used with other 2 wire sensors which have 2 magnets in the paddle wheel. I doubt if any of the 4 wire types could be interchanged. The 2 wire and 4 wire are

The 'television type connector' is a simple co-ax.

Thanks for that. I'll have a play. "Co ax" last night I could not think for the life of me what it was called!

 

[MM5AHO]

There are many different types of coax connector.
Coax (short for coaxial) is really the cable not the connector.
NASA instruments typically use a Belbin coaxial connector, as often seen on TV receivers.
Other coax connectors include TNC, BNC, PL259, N Type, and many more. They're all "coax connectors".

Belbin are perhaps the cheapest and poorest form of coax connector, but usually adequate for this purpose.

Watch out for interchangeability of depth sounders. There are several frequencies is use, and fitting a transducer of one freq. to a display of another doesn't work.

 

[pvb]

Watch out for interchangeability of depth sounders. There are several frequencies is use, and fitting a transducer of one freq. to a display of another doesn't work.

Good advice, but this thread is about log transducers.

 

[pvb]

There are 2 types of log impeller sensor - Hall effect (has 4 wires) and pickup coil (has 2 wire). The NASA (AFAIK) is the coil type.

As I understand it, Hall effect sensors only need 3 wires, usually provided by 2 coloured wires plus the shield. Transducers with 4 wires will usually have a thermistor inside to give a water temperature readout, and the thermistor needs the extra wires.

 

[Rowana]

When I bought Rowana, I had a similar problem. Someone had fitted a NASA through-hull fitting into the original hole in the hull which was too big. The whole thing started leaking. Dried out between tides to effect a temporary repair, which lasted for about 18 months before I took her out of the water for the winter.

The permanent repair was -

1. Remove through hull.

2. Sand back both outside and inside round the hole, and also in the hole itself. This was just to ensure a clean area for the epoxy.

3. Epoxy a ply blank into the hole.

4. Drill the CORRECT size hole in the blank.

5. Paint in a light coat of epoxy into the hole to seal the ply.

6. Install a new NASA through-hull using the correct procedure and sealant as detailed in the NASA manual.


It's been fine these last 7 or 8 years, but I always give it a close inspection when out of the water.

 

[ianj99]

View attachment 49533

There are 2 types of log impeller sensor - Hall effect (has 4 wires) and pickup coil (has 2 wire). The NASA (AFAIK) is the coil type.

I would imagine they are pretty much interchangeable the NASA display could be used with other 2 wire sensors which have 2 magnets in the paddle wheel. I doubt if any of the 4 wire types could be interchanged. The 2 wire and 4 wire are incompatible.

The 'television type connector' is a simple co-ax.

There is a 3rd type, as I found out recently when trying an old Smiths 2wire transducer - see photo. They use a reed switch and series resistor, so the two wires read open circuit, or about 100 ohms as you turn the impellor.

The reed switch type may work in place of either type but will need probably a resistor (try 1k ohms) from one wire to 5v.

 

[MM5AHO]

I've just fitted both speed and depth, and took the hull back to bare fibreglass to be able to fibreglass in the mounting tube for the log (and similar for depth).
The old one was similar diameter, but different fixing mechanism for the inserted transducer.

Many of these different bands of device have sweater temp included, and I had just assumed the 2nd set of wires were this purpose?