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UK Sailmakers Ireland: Top Tips for Headsail Trim

26th February 2019
When you are maneuvering during the pre-start make sure your inhaulers are fully off. Inhaulers are a great tool for improved trim, but only when sailing fully upwind. Read down for more tips on headsail trim When you are maneuvering during the pre-start make sure your inhaulers are fully off. Inhaulers are a great tool for improved trim, but only when sailing fully upwind. Read down for more tips on headsail trim

The headsail trimmer is a crucial member of a boat’s “speed loop” along with the mainsheet trimmer and the helm. But often headsail trim is overlooked and is reduced to “pull it in and hike” mentality. Without good headsail trim, you will be going very slow, or simply not as fast as you could be. In this article, Graham Curran of UK Sailmakers Ireland takes us through his top 5 tips for headsail trimmers.

For this top tips article, we are going to focus on the headsail trimmer on a keelboat with a non-overlapping jib setup.

I recently had the chance to back over the footage of Fools Gold’s IRC European Championship and IRC/ORC World Championship campaign during the 2018 season, skippered by Robert McConnell of WHSC. My primary role aboard the boat was primary trimmer (T1 / Trim 1) – headsail trim upwind and spinnaker trim downwind. Pressure events like European and World Championships are all about the small details – good hoists and flawless tacks were not racecourse gains in these fleets, they are the minimum requirement to be on the pace.

I’ve trawled through our footage to find examples of the crucial big picture and little tweaks needed to be an effective trim one. We won’t go too deep into the technicalities of sail setup for different conditions, rig tune, car positions, or twist control. We’re looking for the simple things that lead to big gains. To help you do your part to improve the overall performance of the boat. This article is by no means exhaustive – see below my top five tips for headsail trimmers.


When you are manoeuvring during the pre-start make sure your inhaulers are fully off. Inhaulers are a great tool for improved trim, but only when sailing fully upwind. When reaching or bearing away during pre-start it is important to keep the boat at maximum power and speed (when needed). If you inhaulers are on your jib will twist open when the sheet is eased, but the inhauler will hold the clew inboard, leaving the bottom of the sail over trimmed. Leave those inhaulers off and increase the reaching power of your headsail. Pull them back on to your marked upwind setting on your final approach to the line.


... but not the ones you may think. The headsail luff tell tails are a great indication of where the sail is in terms of power and car position, but the leech tell tails are absolutely crucial as they show how close you are to max trim when sailing upwind. Unlike the mainsail, where some stall is good, we want as little stall as possible on the leech of the jib, but we want to be right on the edge, as close to stalling as possible. Our leech tell tails are the best indicator of this.

Generally, your top leech tell tail will stall first. Trim the sail in using your sheet until the top tell tail starts to fall in behind the leeward side of the sail. It is actually being sucked into the leech by the air separating off the leeward side of the sail. Once you have this stall ease the sheet a touch to get the tell tail flowing again. 95% flying with a 5% stall is a good indicator that the jib is fully trimmed in average conditions.

If the conditions allow it, stay to leeward and check this constantly. If the breeze drops the sail will stall and the sheet will need an ease. If a puff hits the sail may become under trimmed and will need a squeeze on the sheet, always looking for that little bit of stall.


In light airs tacking is expensive. Reducing the pain as much as possible is key. This is why we roll the boat and try to use as little rudder as possible. Do your part by holding the headsail on the windward wise for 2-3 seconds after the boat has passed through the wind. The sail will fill on the windward side and help the bow come around. Release quickly and snap it in on the new side. This will give instant power to the helm coming out on the new tack.

It is important to discuss this with the helm and be consistent. The helm will become used to having the small back of the jib to help him, he will use less rudder to turn the boat as he knows the jib will help, and the boat will lose less speed as a result. If you suddenly decide to not back the jib he will then overcompensate with more rudder – and likely give you an earful.

It is also helpful to count into your release for your second trimmer, so they can quickly snap in the jib on the new side. Entering a tack is usually say “small back” or “big back” and count “2 … 1 …” as the jib fills on the weather side.


Many boats sailing inshore with non-overlapping headsail setup regularly use up to three headsails. It is vital that you have go-to settings for each sail. I assign a colour to each sail, green for J1, blue for J2, red for J3. I then whip a mark on my jib car adjustment line in each colour, on both sides, so I have a good starting point for each sail. This is particularly helpful if you have been reaching and the car went forward, or if the wrong rope was uncleated at the windward mark, you have a quick reference point in the cockpit go to.

This can also be done with the jib halyard jib by having a scale on the deck in front of the halyard clutch. Put a white whipping on the halyard at the middle of the scale when the sail is hoisted hand tight. Set the sail to good halyard tension (looking at the draft position of the sail) and mark the scale with the sail’s corresponding colour. The sails luff lengths, particularly the J3, could be different so keep this in mind when laying out your scale.

These will give you a solid and consistent baseline to work from for each sail, which can be tweaked for the conditions of the day. Update each of these as your find good settings and as your sails, halyards, ropes change.

This will also make your skipper very happy as the day you cannot make it for sailing doesn’t mean that the headsail trim falls apart. Anyone can step in and use our basic settings as an immediate guide for good trim.


Your last job at the top mark before switch to spinnaker trim is to ease the jib for the bear away. This is extremely important and has roll on consequences for the entire crew.

Do not over ease the jib sheet. The sail needs to be eased just enough for the top to twist open and depower the boat so the helm can bear away. Usually 8/9 inches of sheet is enough. If too much is eased there will be a large space between the leech of the jib and the back of the main. The wind will blow through this gap and suck the spinnaker, now being hoisted, into it, filling it prematurely. This will make your mast man and pit person very angry.

By having the jib trimmed in a little it also sucks the spinnaker onto the back of the sail, allowing it to go up the back of the jib and not fill prematurely. Once you get used to this smaller ease you will be able to move straight to your spinnaker sheet and be ready for the fill once the jib is on deck. It also has the added advantage of making life on the point end a little easier as the jib will be less likely to go over the leeward rail.

If on a spreader leg or in bigger breeze it is ok to ease the jib to allow the boat to bear away and be at max speed for the leg (don’t forget to ease those inhaulers) but trim is back in a bit before the hoist to close the gap. Remember you are in no rush to get to your spinnaker sheet, it isn’t going to fill until the halyard is up fully and the jib is coming down, provided you’ve done your job right!


Doing the simple stuff right makes a big difference across the race course. Take these tip aboard and put them into practice next time you are on the water.

uksails topper

About the Loft

UK Sailmakers Ireland brings modern professional sailmaking to Irish Sailing.​ Formerly known as McWilliam Sailmakers; the company was started 47 years ago to bring the latest technology to Irish sailors - we continue this mission today.

Under new leadership in 2018; our loft is dedicated to fulfilling the needs of all Irish sailors. ​As sailmakers, we do not just design sails for boats. We design and build sails for your boat. Our extensive and versatile product line allows us to produce sails to suit your requirements and expectations.   

​As a core loft within the UK Sailmakers Group, we are uniquely placed to draw from a worldwide pool of knowledge and experience - these ties have been recently strengthened with the return of Barry Hayes and Claire Morgan from Hong Kong. ​Barry held a key role in our primary production facility on Hong Kong Island for the past fifteen years. With their return comes a renewed focus on technology R&D on Irish waters.  

​With a wide variety of sailing conditions and an impressive pool of talent, the Irish cruiser racing fleet is the ideal testbed for new technologies.​ 

​As with all things in sailing; the secrets will be closely guarded - but for the first time in decades Irish sailors will be at the forefront of sail technology development.​

Although much has changed; some constants remain. The same great sail and customer service we have provided in the past will continue, as does our commitment and passion for growing the sport of sailing all over the country. 


Barry Hayes [email protected]

Claire Morgan [email protected]

Andrew Steenson [email protected] 

Contact Information:

UK Sailmakers Ireland

Hoddersfield Mill


County Cork

P43 EY26

Republic of Ireland

Tel: +353 21 4831505

Fax: +353 21 4831700

Email: [email protected]

Graham Curran

About The Author

Graham Curran

Email The Author

Graham Curran is a sailmaker and director of UK Sails Ireland

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