These clever hydrofoils, made right here in New Zealand, attach directly to your outboard’s cavitation plate and work to keep your boat flatter, faster, and more stable. The result? Improved steering, quicker planing, reduced bow lift, and a smoother overall ride.
In this guide, we’ll show you exactly how to fit a Permatrim to your outboard, step by step, using three different methods - including the True Kit team’s preferred no-drill Sikaflex technique.
What Is a Permatrim and Why It Improves Performance
A Permatrim (sometimes called a hydrofoil, foil, or performance plate) is a specially designed wing that mounts to your outboard’s cavitation plate - the flat fin-like surface above your propeller.
When installed, it increases lift at the stern by changing the hydrodynamic pressure field, lifting the transom and keeping the bow lower in the water. That balance not only improves your boat’s planing speed but also makes it more efficient at every throttle level.
Key benefits of fitting a Permatrim include:
- Improved steering response and control.
- Better planing and acceleration.
- Reduced ventilation and drag.
- Smoother take-off in choppy conditions.
- Greater fuel efficiency.
True Kit recommends Permatrim hydrofoils for all models — from the Discovery and Navigator to the Tactician — because they perfectly complement the lightweight, low-drag design of our inflatable catamarans.
What’s in the Box
Each Permatrim kit comes with:
- The hydrofoil plate
- Fitting instructions
- A small hardware pack containing nuts, bolts, and washers
It’s a complete package designed for straightforward DIY installation, compatible with a wide range of small to mid-size outboards.
Three Ways to Fit a Permatrim Foil
There are three main methods for attaching a Permatrim to your outboard. Each has its advantages, depending on your motor size, confidence, and whether you prefer a permanent or removable setup.
1. The Bolted Method
This is the traditional approach and ideal for all outboards.
How to do it:
- Position the foil on the cavitation plate and mark the holes.
- Drill through both the plate and the foil.
- Secure using stainless steel bolts, nuts, and washers.
- Apply a marine sealant (such as Sikaflex) between the surfaces to prevent corrosion.
Advantages:
- Strong and permanent.
Considerations:
- Requires drilling holes in your outboard.
- Can create minor turbulence around bolt heads in the water.
2. The 3M VHB Tape Method
For those who’d prefer a no-drill option, 3M’s VHB (Very High Bond) tape offers a surprisingly strong alternative, which is common in the DIY world.
How to do it:
- Clean both the cavitation plate and foil thoroughly with a solvent such as acetone or MEK.
- Apply the 1.1 mm VHB tape evenly.
- Clamp the foil firmly in place and leave it for 24 hours to cure.
Advantages:
- No drilling required.
- Quick, clean installation.
- Easy to remove later if needed.
Considerations:
- Works best on smaller outboards or light-use setups.
- Must be applied on clean, dry, oil-free surfaces for full strength.
- Not the best installation method as it has the highest failure likelihood.
3. The Sikaflex Marine 291i Method (True Kit’s Preferred Option)
This is the True Kit-recommended method — clean, strong, and completely drill-free. It produces an incredibly durable bond with no visible hardware, preserving your outboard’s sleek, hydrodynamic look.
How to do it:
- Mark and mask the fitting area with a pencil and tape.
- Clean both surfaces using a solvent such as toluene, MEK, or acetone.
- Apply a thick, even layer of Sikaflex Marine 291 sealant.
- Clamp and weigh the foil securely to ensure full contact.
- After about 20 minutes, remove the masking tape once the Sikaflex has skinned over.
- Clean any excess with methylated spirits.
- Allow 48 hours for a full cure before use.
Why we love this method:
- No drilling required — protects your outboard’s integrity.
- Clean, professional finish with minimal drag.
- Removable if you ever sell your motor.
After curing, you’ll have a permanent, waterproof, and streamlined bond — built to last through countless adventures.
Tools and Materials You’ll Need
To make the job easier, prepare the following:
- Pencil or fine marker
- Masking tape
- Cleaning solvent (acetone, MEK, or toluene)
- Clean rags
- Clamps or small weights
- Methylated spirits for final cleanup
These tools help ensure your Permatrim installation looks neat, aligns perfectly, and bonds securely.
Tips for a Clean, Professional Finish
- Always mask around the cavitation plate before applying Sikaflex to prevent mess.
- Apply even clamping pressure from front to back — this avoids gaps or air pockets.
- Remove tape after 20 minutes and wipe away residue while the sealant is still soft.
- Use methylated spirits, not harsh solvents, to avoid damaging paintwork.
- Let the Sikaflex cure for 48 hours before launching your boat.
Following these simple steps guarantees a strong, smooth, and hydrodynamic finish. Always remember to avoid have unessasry load on the transom. Do not lift it or step on it.
Performance Benefits You’ll Notice
Once fitted, you’ll notice the difference immediately.
Here’s what a Permatrim does for your True Kit:
- Reduces bow lift: Keeps your boat flatter when accelerating.
- Improves planing: Gets on the plane faster, even under load.
- Enhances control: Smoother, sharper steering at all speeds.
- Minimises ventilation: Keeps propeller grip consistent in choppy conditions.
- Improves fuel efficiency: Less drag means better range per charge or tank.
It’s a small, smart upgrade that transforms how your boat performs — particularly when carrying passengers, gear, or using smaller outboards.
Installing a Permatrim Performance Foil on Your Outboard
Installing a Permatrim Performance Foil is one of the easiest and most effective ways to enhance your True Kit inflatable catamaran. Whether you choose the classic bolted method or the Sikaflex approach, the result is the same — better handling, smoother take-offs, and improved efficiency.
It’s an upgrade that pairs perfectly with True Kit’s lightweight, low-drag design philosophy, helping you get the most out of your outboard motor and every moment on the water.
Explore our range of True Kit accessories to find the right setup for your next adventure — or learn more about performance optimisation in our latest guides:
