HOW TO ... Slab Reef a Mainsail Upwind
An essential guide for handling strong winds safely.
Reefing is a critical skill for an offshore or ocean sailor to master.
Ask any blue-water cruiser: “what sail manoeuvre do you do most?” I bet they will answer ‘reefing’.
And then ask any sailor what sailing manoeuvre they think is most important for staying safe at sea, I bet many say “reefing”.
Reefing is a blue-water sailors’ safety net. If you can reef, you can adapt to strong winds. You can cope with squalls. You have a way to calm the boat down.
Any sailor with a thought-out strategy and well-practised plan for how to cope with strong winds will feel better about leaving the dock. They will be more relaxed, less afraid, and more ambitious with their sailing plans…
… which is what I want for you! I want you to be able to look at the horizon and feel a sense of possibility and opportunity. I want you to dream and feel like it’s within your reach. So, let’s master the art of reefing, overcome the anxiety, and get sailing.
Reefed on the way to Fastnet Rock in 2019
On writing this, in trying to build empathy for anyone new to this, I looked back: how did I learn to reef?
First, I ‘read’ about reefing.
I’d just turned 18 and booked an RYA Day Skipper Course. The school asked if I had completed any other sailing courses. I replied confidently, “well not officially, but I’ve taught myself and I’m up to the required standard.”
It was a stretch - a necessary one as I barely had a thousand pounds to my name and the theory course was £500. I dug out one of my Dad’s ‘How to be a Skipper’ books and started to learn. You know the books – with a white haired, bearded man on the front cover - wearing red trousers, a wool sweater - holding the steering wheel whilst looking out ‘yonder’ – a ‘captain-like’ expression. We didn’t share much resemblance…! But, I scraped through the course.
Then, stage 2 - I ‘did’ reefing.
I went offshore sailing. And, after about a year, I had gained a good understanding of how to reef a mainsail.
Most critically, I had learned how to reef fast. And, learned why fast reefing is critical: to keep the person at the mast less wet.
Finally, stage 3 - I ‘watched’ reefing.
A year into my career, I spent 18 pivotal days at sea on my first ocean crossing. I was the least experienced crew member. As is often the case - and much to my frustration - my permitted rope handling never extended beyond the mainsheet for three weeks. In hindsight, it was a gift.
For three weeks, I stood under the watchful eye of one of the professional skippers right at the back of the boat for every manoeuvre. I had a full stage view of every reefing and un-reefing procedure. So, I could ask any question I liked about what was happening and why. And, in standing back, I really learned how the puzzle fit together. And, how to do it the ‘right’ way.
Since then, I’ve spent a decade refining the ‘hows’ and ‘whys’ of reefing. Now, I want to share it with you.
Definitions & Overview
Slab reefing is the most common way to reduce the sail area in the mainsail.
It’s a way to reduce the ‘active’ area of the mainsail.
By taking a ‘slab’ out of the bottom of the sail and making this pre-defined section redundant, you reduce the sail area that is in use. This reduces the power of the mainsail, lowers the centre of effort, and reduces the heeling force.
In other words – reefing chills the boat out [and the crew].
Generally speaking, a slab reef always begins by depowering the mainsail. Then: you lower the sail down; pin down a new ‘tack’; pull on the head to tighten up the now shortened ‘luff’; pull the new ‘clew’ aft to stretch the new ‘foot’; then re-shape the now shortened leech and power the sail back up to the course you are steering.
In other words, putting a slab reef in is a bit like rolling up a pair of hiking trousers, buttoning them so they don’t un-roll and making them ¾ length!
Ropes
Topping Lift
Lazy Jacks
Tack ‘secure-line’
Mainsheet
Outhaul
Reefing Lines
Vang
Running backstays
Cunningham
Reefing La Vagabonde in 2019
Method
1. Preparation
Go through all the applicable ropes for your boat, and ready them for the procedure.
Topping Lift: Pull it hand tight.
Right now it’s not doing anything as the mainsail is holding the boom up. If you do not have a rod-vang, the boom will fall down to the deck as the sail does. If you do have a rod-vang, this isn’t necessary.