How do you all manage all the excess wiring from the transducer to the fish finder? I'm running a scupper mount setup for the transducer and the Lowrance is off a center rail right next to the scupper hole. I didn't want to attempt to splice the wiring because I didn't know if that was feasible.

velcro

Never ever cut a transducer cable. You ruin it if you do. 1) the signal voltage is only a tiny tiny fraction of a volt that will be wrecked by a splice. 2) A splice causes an impedance discontinuity, resulting in signal reflection that becomes "noise" to the system.

When you bundle the cable, try to do it in fewer long loops instead of a lot of short ones. The cable is shielded but it is still better to not push the limit by creating a high signal noise environment from wadding a lot of cable up in a tight bundle.

I have fished a long slender cable bundle into a section of inexpensive flex bilge hose ( 1 1/8 or 1 1/4 inch, looks similar to vacuum cleaner hose).

I have my cable looped and then velcro'd. I have tie down bungee cord that came on the kayak in the very front. I use that to strap the looped cable down and it keeps it from going all over the place.

Looped and out of the way in the bow.

I used a Yak Attack CelBlock to mount mine and wrapped the cord around the built in wire holders and then ty-wrapped them to keep them tight.

The fish finder folks need to make shorter transducer cables for Yak fishers as we don't need 30' of cord!