Re: Adding brakes?
Championtrailers.com has a good tutorial about brakes.
First, I hope your tow vehicle is capable of handling the load. In other words, don't try to pull a 7,000 pound load with a front wheel drive mini-van. Hopefully you're pulling with a full size V8 powered truck or SUV.
Second question is how heavy is the boat AND trailer? 3K to 4K is one thing if you're just pulling a short distance to the lake. But if you're grossing over that, brakes are really needed.
If you need to put brakes on the trailer, you should consider 4 wheel disc surge style brakes. Surge brakes just do better on boats than electric actuated drum brakes. They're not hard to install for a backyard mechanic, and readily available at many websites at good prices.
I can't believe anyone built a 23' aluminum tandem axle boat trailer without full brakes.