Over Bond Flange (OBF) Rear Sponsons

(2 customer reviews)


Over-the-bond-flange rear sponsons for any standup watercraft. This kit does not come with hardware to save on cost. We require installing these sponsons using our proven silicone adhesive.



OFB (Over Bond Flange) sponsons offer amazing stability right where the rider stand and leans, which adds confidence for a new rider and also offers an edge to the experienced rider. More turning grip is also an advantage with these OBF (Over Bond Flange) sponsons. This is the best bang for the buck to improve the ride of your stand up watercraft.

This Sponson kit is designed to improve the riders confidence when riding their recreational stand up watercraft. We want to make a cost-effective product to allow those with a tighter budget to experience the benefit of additional grip. These Universal Rear Sponsons offer improved turning grip, better stability in a straight line and when leaning over in a turn. The difference between us and the other options on the market is grip and high speed turning the ski is easier to lean which makes the ride smoother through the complete turn. The HFC sponson bolts to the top of the bond flange.

ProWatercraft Hybrid Flex Composite (HFC) material is designed to flex supporting your riding style. HFC blows all the other rigid products out of the water with many improved features. These sponsons hold up better than the industry standard and limits bouncing, reduces subbing, even MORE stability, and better grip.

This product does NOT come with hardware.

What You Need to Know:

  • For the warranty, you need to install this product with our approved silicone. Apply silicone to all the edges and wipe off any excess from the surface of the product after installation. Smooth out any excess silicone along the edges as well. Allow the silicone 24 hours to cure.
  • If you have a 650SX and still have stock bumpers, you will need to remove or modify the bumpers to mount this sponson kit.


Fitment: Kawasaki 440 / 550, Kawasaki 650SX, Kawasaki 750, and more!
Installation time: 20-30 minutes

These sponsons have no install instructions. They are designed to be mounted at the back of the tray, flush with the deck edge. If you have corner bumpers or HIN tags, you can mount them a little more forward without any issues.


  • Is there a recommended place to mount these?
    These Over-the-Bond-Flange (OBF) sponsons were made to be placed and mounted how you like. We can help point you in the right direction but installing is up to you.
  • What is included?
    Everything you see above is what is included: Left and Right side of the sponsons. We want to make a cost-effective product to allow those with a tighter budget to experience the benefit of additional grip.
  • Is this part legal to race with?
    You will need to check the rules from your racing organization to verify if this part is legal for competition. ProWatercraft takes no responsibility if you are disqualified from this part breaking any racing organization rules.

Additional information

Weight 2 lbs
Dimensions 12 × 7 × 3 in

2 reviews for Over Bond Flange (OBF) Rear Sponsons

  1. Kevin (verified owner)

    Mounted these on the back of my 550, noticed an improvement in stability and predictability in turns. Great low cost handing mod and easy to install. Be sure to pickup some stainless steel hardware so you can mount them when you get them!

  2. Ryan McIntyre

    This part alone transforms the JS hull into a modern ride. Corners are consistent, smooth, and predictable. Confidence in any water condition is improved immensely. If you only wanted one product to make the best improvement in handling, this is it.

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