⚔️ Which block makes the most sense for ILCA and high-performance dinghy sailing?
Lightweight blocks play a key role in modern dinghy rigging. In ILCA sailing especially, where thin lines and high loads are common, the right block improves trim precision, durability, and confidence on the water.
This comparison looks at four widely used blocks, each with a different approach to performance, durability, and price:
- PolarWave 18 mm Lightweight
- PolarWave 18 mm Heavy Load
- Harken Fly-Soft Attach 18 mm
- Ronstan Orbit 20 mm
Quick practical verdict
PolarWave Lightweight offers the best overall balance for most ILCA sailors.
PolarWave Heavy Load is a preference for sailors who want extra robustness.
Harken Fly is a solid, widely available option that prioritises reliability.
Ronstan Orbit is the most affordable choice.
Technical comparison overview
| Feature | PolarWave 18 mm Lightweight | PolarWave 18 mm Heavy Load | Harken Fly 18 mm | Ronstan Orbit 20 mm |
|---|---|---|---|---|
| Sheave diameter | 18 mm | 18 mm | 18 mm | 20 mm |
| Bearings | Ceramic bearings | Ceramic bearings | Stainless steel ball bearings | Low-friction acetal |
| Max line Ø | 5 mm | 5 mm | 5 mm | 6 mm |
| Weight | 6.4 g | 9 g | ~7.2 g | ~9 g |
| Working load | 190 kg | 210 kg | 125 kg | ~250 kg |
| Attachment | Plastic swivel | Lash / tie-on | Soft-attach Dyneema | Lashing hub |
| Colours | Pink, Blue, Red, Orange, Green, Black | Pink, Blue, Red, Orange, Green, Black | Black | Black |
| Typical price | ~€23 | ~€34 | ~€28 | ~€14 |
| Positioning | Best all-round performance | Extra robustness preference | Solid, widely available | Cheapest, most durable |
PolarWave 18 mm Lightweight
The PolarWave 18 mm Lightweight is the most balanced block in this comparison. At only 6.4 grams, it combines very low weight with ceramic bearings that stay smooth under load. For most ILCA sailors, this block already offers more than enough strength and durability.
It excels in systems that are adjusted frequently, such as the outhaul and cunningham, where responsiveness and feel matter most.
Available colours
Pink, Blue, Red, Orange, Green, Black
Best suited for
- Outhaul systems
- Cunningham systems
- High-performance control lines where weight and feel matter
PolarWave 18 mm Heavy Load
The Heavy Load version is not a requirement, but a preference. It uses the same ceramic bearing system as the Lightweight version, but the sheave and construction are slightly stronger. This mainly helps when the block frequently hits the deck or fittings.
On the water, the difference in feel compared to the Lightweight version is small. The advantage is long-term durability and peace of mind rather than smoother trimming.
Available colours
Pink, Blue, Red, Orange, Green, Black
Best suited for
- Cunningham systems with frequent high tension
- Sailors sailing often in stronger wind
- Boats where blocks regularly touch the deck
Harken Fly-Soft Attach 18 mm
The Harken Fly uses stainless steel ball bearings rather than ceramic bearings. While this delivers reliable low friction, it is not as smooth as the ceramic bearing system used in both PolarWave blocks. You notice this immediately when you give the block a spin by hand, the PolarWave keeps rotating longer and more freely.
That said, the Harken Fly remains a solid and dependable choice. It is widely available in most sailshops worldwide and has a long track record in dinghy sailing. The soft-attach Dyneema loop also helps with clean alignment and reduced side loading.
Best suited for
- Outhaul systems
- Cunningham systems
- Sailors prioritising a solid, proven solution over maximum smoothness
Ronstan Orbit 20 mm
The Ronstan Orbit 20 mm is the simplest and most affordable block in this comparison. It is strong, durable, and accepts thicker lines up to 6 mm. It lacks the refinement and compact feel of the 18 mm blocks, but it is reliable and easy to source.
At around €14, it is often chosen for training boats or where budget is the main concern.
Best suited for
- Training fleets
- Budget-focused setups
- Applications where durability matters more than precision
Which block should you choose?
Most ILCA sailors will be best served by the PolarWave 18 mm Lightweight.
Choose the PolarWave 18 mm Heavy Load if you value extra robustness when blocks frequently hit the deck.
Choose Harken Fly if you want a solid, widely available solution from most sailshops.
Choose Ronstan Orbit if price is the main deciding factor.
Looking at performance versus price, the PolarWave blocks offer the strongest overall balance on the market today.
