On small tin boats with a round/oval gunnel, I've cut a small access hole (w/ grommet) to feed power forward to the bow Nav lights, but this would not carry large amp draw wiring typically.
I've also used gray electrical PVC, or golf shaft storage tubes for short runs, even that spiral wrap stuff for some large battery cables, to prevent chafing.
A tube could be suspended inside the boat immediately under the tunnel that carried wiring where needed. Under floor routing can use PVC tubes ... just be sure to LEAVE a long piece of mono or such in there (coil extra loop on one end when not in use) for routing NEW runs, haha!
Had the occasion once where we could just NOT snake a wire fish in through that tube, so I got creative and tied a light piece of cotton ball onto the end of 4# mono, put that in one end of the chase and stuck a high-powered shop vacuum on the other end ... pulled it right through slick as can be! And I dayum sure left a new routing feed 'pull thru' in place, haha!
