




HD RDM Aluminium Mast Extension (U-Pin) 30
Bulletproof Rigging: The HD RDM Aluminium Mast Extension That Won't Quit When You Need It Most
Experience uncompromising durability with the HD RDM Aluminium Mast Extension (U-Pin) 30 – the heavy-duty extension built to withstand whatever Mother Nature throws at you. When other extensions fail, this powerhouse keeps performing, giving you the confidence to push your limits in the gnarliest conditions.
Rigging becomes effortless and intuitive with the intelligently oriented pulley/cleat system. The 2-roll pulleys provide smooth downhaul adjustment while the strategic design ensures you spend less time setting up and more time crushing waves. Just connect, adjust, and hit the water – it's that simple.
Crafted with premium materials throughout – from the hardened T6 aluminium main tube to the fiber-reinforced nylon base. The revolutionary connection between these components is fortified with a stainless steel insert, creating an ultra-rigid construction that handles higher loads than standard extensions. Perfect for high-performance racers and wave riders who demand gear that matches their intensity.
Join the windsurfers who refuse to compromise.
The HD RDM Aluminium Mast Extension delivers peace of mind when you're focused on your next big move – because the last thing you should worry about is your equipment failing.
Upgrade your rig today and experience what true durability feels like.
Also available in 30cm
Care & Maintenance
- Rinse thoroughly after each use to remove salt and sand.
- Keep sliding components clean and sand-free to prevent wear.
- Replace your downhaul line at least once per season.
- Apply silicone lubricant to cleats for better grip.
- Inspect for cracks, corrosion, or worn components before each session.
- Store completely dry, away from UV exposure.
- Never leave extension inside the mast during storage.
Warranty
At Unifiber, we stand behind everything we make.
- First year: Your product is completely covered.
- Second year: Continued support against manufacturing defects.
- Keep your proof of purchase handy when you need us.

Learn More
Choosing the right windsurf mast extension can make a big difference in your rigging experience and overall performance on the water.
From pulley systems to downhaul ratios, every detail plays a role in ease of use and durability.
In this FAQ, we’ll answer the most common questions to help you find the perfect extension for your setup.
1. What type of rope should I use for a boom or mast base extension?
- It’s best to use Dyneema or Spectra rope, as they are highly durable and have low stretch. A diameter of 4–5 mm is ideal to minimize friction while ensuring a good grip.
2. What do I need to know about mast extension insertion length?
- Because of the tapered shape of an SDM mast, there's a limit to how far one can insert the mast extension. This value relates to the total length of your extension tube, not to confuse with the range settings.
- A maximum 45 cm insertion length means that most 32cm mast extensions can be fully inserted into the mast. A maximum 60 cm insertion length means that most 46cm mast extension can be fully inserted.
- In case a non Unifiber brand extension does not fit, as an alternative solution the mast extension end cap can be removed without problem.
3. What is the downhaul ratio?
- The downhaul ratio refers to the mechanical advantage provided by the pulley system.
- For example, a 3:1 system means that for every unit of force applied, the tension on the sail is multiplied by three. Modern extensions often have 4:1 or even 6:1 systems, making downhauling easier with less effort.
4. Why is the pulley angle important?
The pulley alignment affects how easy it is to downhaul the sail. Proper alignment between the extension’s pulleys and the sail’s pulleys reduces friction and makes rigging easier. If the pulleys are misaligned, the rope can wear out faster, and downhauling becomes more difficult.
Explore our extensions.

Essentials RDM V2 Aluminium 30
RDM - 30 cm - Aluminium, U-Pin
From 64.95 EUR























