Mainsail Systems

The subject of mainsail rig and furling systems is an important one, and the question of “What is best?” invariably comes up early on when reviewing sailboats with clients.

First, some history…. Up through the mid 1970s, sailors had little choice in mainsail handling systems other than traditional slab reefing with lazy jacks and multiple reefing lines. Then, in 1975, the first in-mast furling system, the Hood “Stoway,” was introduced, followed years later by Selden and other notable brands still active today. Later, inspired by the Hood “Stoboom” and Schaefer Marine in-boom furler systems first introduced in the 1980s, others developed in-boom systems, with LeisureFurl now the most widely used in-boom system on boats under 80’.

One will find in-mast and in-boom systems offered with either manual or electric/hydraulic drive furling options. Of course, equipment manufacturers have worked hard to improve the ease of handling of a non-furling mainsail. Electric halyard winches, full-length battens with roller cars, single reef lines and built-in zip sail covers all make life easier when it comes to raising, lowering, securing and covering the sail.

The question of “What is best?” really depends on a multitude of factors. One basic factor we discuss with clients is how much they want to emphasize performance — i.e. will formal racing be a major part of their plans? Or are ease of handling and short-handed capabilities more important? A slab reef, full-batten mainsail will definitely offer the best sail shape and maximum roach on the leech for maximum performance, while in-boom systems are similar in area, but are often cut with a flatter shape forward in order to roll into the boom more smoothly, with outhaul controls that are limited. In-mast systems can offer some positive roach with vertical battens, but require a slightly heavier mast section with added weight aloft of the furler rod (approx. 1.5 lb./ft.). They are also cut flatter to roll in smoother, although the outhaul can more easily adjust draft in lighter winds.

Another important factor is the design of the boat. An aft cockpit configuration typically provides a lower boom that is mostly forward of the dodger and is relatively easy to reach from the cabin top to flake, secure and cover the mainsail. In contrast, a mid-cockpit design requires the boom to be higher off the cabin top and will often feature a semi-permanent bimini that makes it very difficult to flake, tie down and cover the sail aft of the dodger. For that reason, the percentage of mid-cockpit designs with some kind of mainsail furling system is much higher.

Cost is another important issue. In-mast systems are the most expensive option when either building a new boat or retro-fitting an existing non-furling rig, since the latter requires a completely new mast section and standing rigging. When retrofitting an existing slab reefing rig, one can usually modify the mast to accept an in-boom system and only need to replace the boom and mainsail itself.

Lastly, ease-of-use is a key issue for almost any prospective owner to consider. A non-furling mainsail has its limitations and improvements as noted above. What is most common today is the debate between in-boom versus in-mast systems. In-boom systems are relatively easier to deploy, as one simply raises the main halyard with some light tension on the furling line or with synchronized power unfurling to closely match halyard speed (hopefully electric!). In-mast systems require a little more attention when deploying initially, as one needs to keep tension on the outhaul when rolling out the first 10-20% of the sail, in order to avoid bunching up within the mast cavity — a situation that can easily be rectified by reversing the process.

However, an in-mast system has a significant advantage when reefing in or rolling away, as one simply needs to keep light tension on the outhaul line without needing to be directly head to wind. In contrast, an in-boom system requires a precise angle of the boom to avoid the sail creeping forward or back when furling; halyard tension must be monitored closely, and the sail must be furled or reefed with no wind in the sail whatsoever.

In summary, the question of “What is best?” is not so easily answered and depends in part on a balance of performance, ease of handling, cost and function, as well as cockpit design and layout.

One thought to leave you with: How often do you see a boat owner enjoying a beautiful day on the water sailing under genoa alone with the mainsail still flaked and covered on the boom?

Perhaps “performance” should be redefined to include not just speed, but also ease of handling.

We hope this note helps to highlight the many considerations involved in choosing a mainsail handling system. Give us a call anytime to discuss your sailing needs.