Len, actually this is the only boat in my fleet that has fuses.

Lew
Florida ⛱️, USA

Lew, glad to see you use fuses. Len

Three Motors in a boat. (The boat, PT61, is quite heavy for a PT boat, actually an ex-PT boat. My model reflects the mid-war modification to add two 40mm Bofors, and twelve more 50 caliber BMGs, plus armor plating.)

Here how I wired my 47 inch (1/20 scale) PT boat:

The outer motors has its one battery. The outer motors run proportional control through the two ESCs. The center motor is controlled by a servo activated switch which turns the motor off and on from its own battery. No ESC so it is forward high speed only.

❄️Reasoning:
Backing this boat using two motors (or even just one) is sufficient. Don't need the center motor for this.

❄️Operation:
Many model boat operators accelerate their boats too fast. Just push the throttle and the boat (especially the smaller ones) just jump out of the water. Even a PT boat will not go to a high speed in a few boat lengths. So I gradually push the two throttles up (not too slow, but to simulate good acceleration) then when up to speed flip the switch for the center motor to kick in. Same with backing down.

❄️Three batteries?
As I use two standard hobby batteries, two fit better than one large battery and distribute the weight evenly. This way I can keep my run time up by maxing out the battery current (mAh). The 4.8V battery runs the receiver. This battery lasts a while so if one of the other two "motor" batteries runs down the receiver keeps working and I can get back to port using to good battery.

Runs great, "step on board" - here is a video:

Lew
Florida ☀️🚤😊, USA

i have the perkasa 49 inch boat stripped down got the 3 props in 4mm shafts i have three 500 brushed motors and thats it loads toom for batteries iI have a recent not happy experiance with lippos so not going there if that helps

What you could do, is use 2 or 3 ..2s lipos wired in parallel giving out 14.8 or 22.2v then through 3 seperate buck converters down to say 12v then through 3 ESC's (One for each motor)at least that's my thinking.

You can run all three ESC's off one battery.
That said, I would suspect that the type of boat may dictate that you use more than one battery so that you can distribute the weight.
As far as the radio end is concerned, what radio are you planning on using? Do you want/need independent ESC/motor controls? Do you need all three motors to operate at the same time in order for the boat to run properly?
I have a PT boat with three motors, independently controlled. I can use the outer shafts to maneuver at the dock, or to run at moderate speed. I can add the center motor as, and when I like. Each is on a proportional channel. With new computer radios, your options are far greater.
A bit more information from you will help us to help you.