This is the second iteration of a rigger boat based on this design:
http://www.ne-stuff.net/2011/04/jae-mini-sprint-fe-outrigger.html

The first iteration achieved a max speed of 48MPH on 4S. The second uses a 70mm Powerfun EDF, which runs best on 6S, can be purchased here: https://www.amazon.com/Ducted-Blades-Brushless-Airplane-Balance/dp/B07CVQZGSC

The EDF mount(s) are designed for the EDF listed above, but others could be made in a jiffy depending on what you have available.

The two hull halves can be printed vertically on a printer with about 250mm of height and the two sponsons laid sideways with however much infill and walls you need. Try to keep it as light as possible as the EDF weighs a lot. Make sure you take all possible measure to keep hull watertight too as the rear will be sitting below the waterline.

The sponsors are designed to accept a 6mm diameter carbon fiber rod.

Tip 1: Filler primer is your best friend when spray painting in order to make the hull and sponsons water tight. The two halves were mated using the gray/black Jb Weld and the sponson's rods with 15 minute epoxy.

Tip 2: The hull was designed to accept 2 3S 1300mah batteries in parallel (good for ~ 3 high speed passes). You may be able to use a single 6S pack, but check dimensions first.

Edit 1: Added two old EDF housing designs (labeled 'Simple V1/V2'). While the servo mount looks weak, I have never had it fail on the numerous housings I've printed. Most of the force from the rudder is exerted on the servo itself. If the servo mount fails on the housing, the rudder will still continue to function.

In action:
https://www.youtube.com/watch?v=5U70ThGSDfk