So I'm getting ready to wire up the yard sale fish finder I recently acquired...I confirmed it powered up and now am ready to install.

I have always been puzzled about the different size wireless and how to properly connect them.

There are the very thin wires (red+ black-) and then there's a fuse holder which is significantly thicker.How do I link these wires together? A standard butt connector(blue) won't crimp down on that tiny gauge wire.

Do I just solder them together and lay shrink tubing over the joint that's been soldered?

How does everyone else wire thier fish finders when it comes to the difference in wire size.

Remember this isn't some side/top/3D/microwave/TV/spacestation fish finder like all the new $30&$40k rigs have...I'm working with a 90's era Eagle Magna III on a 12' jon boat...it doesn't have to be pretty, but I sure would appreciate it functioning properly.

Radio Shack carries red butt connectors which are for 18-22ga wire

Whether you solider it or use grip connectors I would us marine shrink wrap to seal the joints. I get mine by the box at Harbor Freight, The are also Marine butt connectors, I get those at Walmart.  The Marine butt connectors have a shrink wrap tube with glue made all in one piece. I still prefer to add another piece of marine shrink wrap over the joint. 

With what you are doing I would just twist the wires together and use Marine Shrink wrap over the twisted wires.

If you want to use butt connectors, you can double up the smaller wires to fit in one end. Strip back double what you need, then double it over and twist it then put it in the butt connector and crimp. Then just crimp the other end like normal then shrink wrap it.

Solder the wires and then use shrink wrap.  No worries about crimp connections and definitely no worries about twisting the wires together.

if you don't have a solder gun you can use butt splice only.

don't double wires over.  get one size larger butt connector than your largest wire.

ie you want to join 18g and 14g wires together: buy a 12g butt connector.  strip both wires 1" and run them parallel (touching side by side) thru the connector.  both wires combined will provide the girth to get a perfect crimp.  slide shrink on wire before crimping

Solder the wires and then use shrink wrap.  No worries about crimp connections and definitely no worries about twisting the wires together.

 

X2, compression connectors have their place in this world (inside and out of the weather) but not in the marine environment.  A solder connection is the best you can get, and will not fail in the future.  Also, only use shrink wrap (the marine grade is best), tape can fail in time.

 

 

Whether you solider it or use grip connectors I would us marine shrink wrap to seal the joints. I get mine by the box at Harbor Freight, The are also Marine butt connectors, I get those at Walmart.  The Marine butt connectors have a shrink wrap tube with glue made all in one piece. I still prefer to add another piece of marine shrink wrap over the joint. 

 

The glue inside the marine grade shrink wrap seals and locks around the wires to keep air and humidity out of the connection so the connection doesn't oxidize, but if you solder oxidation is not a problem and the marine grade shrink wrap is icing on the cake.

whatever you do just DON'T solder AND crimp.  defeats the purpose and will give you a weak connection.

bottom line these are very light wires under very little pressure/weight and you have easy access to them.  the wire will break before a solder connection will.  if you have a solder gun just use it and use shrink wrap. no need to spend a penny.  

i would def recommend butt connectors for heavier gauge wires that may be under constant vibration and are deep inside ur hull (no easy access w/o a major project)

Another vote for solder and shrink wrap.

I learned if you are connecting a small gauge to a larger gauge, use the larger gauge size connector and cut the smaller gauge farther down and fold it over to double it up.  You do not want to trim the larger gauge cause broken wires can lead to hot spots.