Hydrodynamics of modular sponsons for my new Jetskis

[lukieshowie]

TL;DR

Looking to hear how jetski sponsons will work when cnc/milled

Hello everybody, I just picked up two 95 Sea-Doo Xp's, one owner, 94 and 98 hours, all service records with it, with a trailer for 1500 bucks, they run fantastic. I am looking to make some custom sponsons, and I am wondering if my idea is feasible.

The idea is that I have a metal bracket on both sides of the fibreglass hull, and there will be a Tapered Dovetail Groove protruding, that the sponson will hook to, and as the water pushes the sponson further back along the tapered groove, it will make more tension and hold it in place, I will also have a back plate, where I will have a 17-4 quick release pin on the endplate, with a 1/16" gap so it can push back more and have a resting place, and then I will also have multiple sponsons shapes and sizes, depending on the conditions and my mood, and then also I can just run no sponsons so I can whip and drift the ski, ik the x4 hull is already pretty tail happy, but I will be out on the big lake (lake Michigan), so I want some options.

the brackets will be out of 7075-T6 Al, and the sponsons out of that as well, or some HDPE. I will cnc everything, and am making it in CAD (SOLIDWORKS) and will run some hydrodynamic simulations, I am just wondering if there are any concerns about this project, is it even realistic to be attempting, and is it possible. bc I want to make it all myself, and want a project this winter before the riding season is here. everything will be 3d printed and simulated before cncing it and installing on the ski.

also am wondering if i should fillet and curve the edges of the sponson, because i want to know if my current setup will have a log and wedge effect with the current setup, due to the fact the i think the edges will have the most stress on them. prolly gonna end up with titanuim bracket and HDPE sponson material. fyi, one of the skis old sponson broke, so I want to upgrade it and figured to make a project out of it. TIA! I will provide a early version of what I am looking to make, as I threw it together in SOLIDWORKS this morning.

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[jrmichler]

Welcome to PF.

Your diagrams only show a slotted object sliding over a T-rail. That's not enough for me to help you. Before I can express any opinion on the value of your ideas, I need more information.

1) Are you attaching to an existing bracket? How is that bracket attached? What are the dimensions of that bracket? How strong is the structure to which the bracket is attached?

2) Show the hull design with and without your sponsons. What do you expect your sponsons to accomplish? Is this based on experience with other PWC's, or just something you want to try?

3) How fast is your PWC? Do you do stunts? Hydrodynamic forces go up with speed.

 

[lukieshowie]

I do not have the hull 3d scanned yet, and I could not find a file for it. The sponons are supposed to be modular so I can have more or less aggressive ones, or take them out completely, my ski tops out at 50 exactly , I will not be doing stunts, just turning and occasional drifting and jumping waves, no like back flips and stuff like that.

the ski is a 1995 Sea-Doo xp, with the x4 hull, I am not attaching to a existing bracket, the sponons will bolted through the fiberglass hull to a back plate on the inside, so the bolts don't rip through the fiberglass. the dimensions of the sponson bracket are 20 long by 1 1/2 tall and 3 1/2 wide, all in inches. the goal of the sponsons is if I want to cruise I can install different shaped one to adapt to my needs. and to also have them be completely removable to drift and change the driving experience.

I am going to be using all titanium for the mounting plate, and 318 stainless steel bolts for it. the sponson will hopefully be made out of HDPE, which is what cutting boards and new sponsons are made out of from factory. its just something I wanted to try, as I am in high school and a tech center with access to SOLIDWORKS and 3d scanners and printers and CNC/milling machines, I figured now's the time to try it out. hope that is helpful, I don't really have a lot more of it planned out so far. Thank You!

 

[jrmichler]

So far, so good. Now I need to see a diagram of the hull with and without your sponsons. Search terms personal watercraft hull design found numerous images. At least one of those should be good enough to show your concept by screenshotting and loading into MS Paint.