What's Different About the Redesigned Mk2 ILCA 4 Sail

If you sail an ILCA 4, or coach someone who does, you'll know there's a new sail coming. The International Laser Class Association has introduced a redesigned MK2 for the ILCA (formerly known as the Laser) 4, built with heavier 4.93 oz sailcloth and a bi-radial panel layout. It holds its shape better under load, lasts longer through a hard season, and gives sailors more range from their controls.

Here's what's changed and whether you need to make the switch now or later.

Why Is There a New ILCA 4 Sail?

This isn't a case of the class tinkering for the sake of it. The MK1 sail was built around a specific 3.8 oz sailcloth that has effectively stopped being made at scale. Builders were struggling to source consistent material and costs were drifting up, so the long-term availability was becoming uncertain. Considering this affects a youth pathway class that depends on consistent global access to affordable kit, it was necessary for a controlled redesign to be done.

Swapping in a modern equivalent cloth wasn't viable because today's sailcloth behaves differently and a straight substitution would have introduced variability between production runs. So ILCA did a controlled redesign (the same mast, same boom, same one-design principle), but a construction approach suited to materials that are more readily available.

Browse the full ILCA sails collection.

What's Different Between the MK1 and MK2 ILCA 4 Sail?

In case you’re in a rush, here’s the quick list of what’s new with the Mk2 ILCA 4 sail: 

• Heavier, more durable cloth
• Different construction method
• Needs more input from the controls
• MK1 battens won't fit
• Bigger window
  
• Updated reinforcement patches

The change coaches will notice first is more emphasis on active sail trim with the Mk2 sail than with the MK1. Specifically, sailors are going to need more Cunningham to depower properly in a breeze. On the MK1 you could get away with relatively light Cunningham loads and the sail would still behave reasonably. On the MK2, if you're not pulling on enough Cunningham when it pipes up, you'll be fighting the rig rather than using it.

For sailors who've already developed good control habits this is straightforward. For those who haven't touched the Cunningham much, it's worth getting on top of before a big event.

The MK2 uses a bi-radial cut rather than the MK1's cross-cut construction. The panels are arranged so the strongest threads run towards the clew, tack and head, where the loads are highest during a tack or gybe, or when you're fully powered up and trying to hold height upwind. The result is a more stable, consistent shape across a wider wind range. Useful for squads where sailors are spread across the 55 to 65 kg target weight range, and it also brings the ILCA 4 in line with the ILCA 7 MK2, so sailors moving up through the class will find the two rigs feel more familiar.

Arguably the most important practical point is that MK1 battens will not fit the MK2 sail. The batten layout has changed to align with the rest of the MK2 family and there's no workaround. If you're buying the new sail, budget for the ILCA 4 MK2 Tapered Batten Set at the same time.

The transparent panel is bigger on the MK2, which improves downwind visibility. If you've ever had a tricky leeward mark rounding in a packed youth fleet and lost sight of boats to leeward, you'll appreciate it.

High-load areas at the clew, tack and head have updated standardised reinforcement, which is where MK1 sails tend to show wear first after a competitive season.

What Does It Do On the Water?

Overall performance is comparable to the MK1, which is what you want from a one-design update. Sailors who tested it early reported a slightly wider usable range: a touch more power accessible in light airs and a better ability to depower and keep the boat flat as the breeze builds. The target weight range stays at 55 to 65 kg.

The main shift is that the MK2 rewards sailors who are already working their controls actively. If the Cunningham has mostly been decorative, that changes with this sail.

When Does It Become Class Legal?

The MK2 becomes class legal on 1st August 2026, in time for the ILCA 4 World Championship. The MK1 stays fully class legal and there's no forced transition, so your existing sail isn't obsolete overnight.

For anyone targeting major championship racing from August onwards, getting time on the MK2 before the event is the obvious move. For everyone else, the timing of your switch comes down to the condition of your current sail.

Do You Need to Upgrade Now?

If your MK1 is tired and losing shape, this is a sensible point to switch rather than patch up a sail that's heading towards the end of its useful life. If it's still setting well and you're not targeting major events in the second half of 2026, you have time. Coaches running multiple boats or squads may want to start standardising on the MK2 now so sailors aren't getting used to two different rigs going into the championship season.

What You'll Need

The sail comes with a short sail bag. Battens, sail numbers and country letters are all sold separately, so factor those in when budgeting.