WATERSPORT HATS

When the temperature drops, sailing doesn’t have to stop. With the right layers and smart kit choices, winter sailing can be just as rewarding as summer — sometimes even more so. For junior sailors, learning how to stay warm and dry on the water is a key part of growing in the sport. At Rooster, we’ve spent years developing kit that works as hard as the sailors wearing it — gear that keeps young sailors confident, comfortable, and ready to face the chill head-on. Why the Right Winter Kit Matters Cold conditions can make or break a training session. It’s hard to focus on racing tactics or boat handling when you’re distracted by numb fingers or shivering. Proper layering helps young sailors stay safe and comfortable — and most importantly, enjoy every moment on the water. Rooster Rider Amelie Ballantyne puts it best: “Once you’re warm and dry, everything changes. You can focus on sailing — not surviving. My top tip is to block the wind BEFORE you get wet. Wind chill is your number one enemy and it’s hard to warm up if you’re already cold and wet. I always wear my Pro Aquafleece Top to keep warm"   What Our Riders Recommend We asked our Rooster Riders to share their top layering tips for winter sailing — the things they wish they’d known before their first cold session. Their advice all points to the same truth: getting layering right means you’ll stay on the water longer, sail better, and have more fun. The Junior Winter Kit System Here’s a simple layering setup our Riders swear by: 1. Base Layer – Polypro or ‘Hot’ Top & Leggings  A warm, stretchy yet thin foundation that regulates body temperature without restricting movement. 2. Mid Layer (Wetsuit layer) – Supertherm 4mm Longjohn and Top The powerhouse of your winter kit. Neoprene creates a dynamic thermal barrier by trapping a thin layer of water and maintaining your core temperature, all while offering stretch and freedom of movement for active sailing. 3. Outer Layer –  Aquafleece Spray Top Your essential weather shield, perfect for throwing on over your base. Protects against spray, rain, and wind chill — keeping core warmth in and water out. 4. Accessories – Gloves, Boots, and Hats Often underestimated but crucial. Warm extremities = happy sailor. Shop Junior Winter Kit Layer up, Sail on… Great kit doesn’t just keep you warm — it builds confidence. When juniors can focus on their technique rather than the temperature, they develop faster, stay positive, and actually look forward to those early winter starts. That’s what we love to see at Rooster — young sailors who are comfortable, capable, and ready to take on any conditions. Explore our Rider-approved winter essentials for junior sailors and help your sailor stay warm, dry, and ready for every challenge this season. Read more about the right layers for you on our Layering Guide

Winter sailing can be some of the most rewarding time on the water — crisp mornings, steady breezes, quieter waters. But with colder conditions comes one big challenge: staying warm. Your wetsuit is your first line of defence, and choosing the right thickness is critical. Here’s why upgrading to a Supertherm 4mm wetsuit can transform your cold-weather sailing experience. Quick Look: 1. How Neoprene Keeps You Warm Neoprene works by trapping a thin layer of water between your body and the suit. Your body heats this water, creating an insulating barrier. The thicker the neoprene, the more insulation it provides — making it much harder for heat to escape. 2. Why Thickness Matters 1.5mm neoprene (like our Thermaflex) offers flexibility and comfort for mild to warm conditions. 4mm neoprene (like the Supertherm) adds serious insulation for cold-weather training, helping you retain heat for longer sessions. Think of it like the difference between a light jacket and a winter coat — both have their place, but when the cold bites, you’ll want the thicker layer. 3. Advanced Linings for Extra Warmth The Supertherm 4mm range isn’t just thicker — it’s smarter. Enhanced linings wick moisture away from your skin, add thermal comfort, and dry faster between sessions. That means less of the “chill factor” when you put your wetsuit back on for the afternoon race. 4. The Role of Stitching: Flatlock vs GBS Not all seams are created equal. Flatlock stitching (used in thinner suits like Thermaflex) is breathable but allows small amounts of water through — fine for warmer sailing. GBS (Glued and Blind Stitched) seams, used in all our Supertherm range, are sealed to minimise water entry. This keeps the insulating layer of water more stable and your body much warmer. 5. Designed for Winter Performance Sailors often assume thicker neoprene means restricted movement — not with Supertherm. Our panels are engineered for stretch and flexibility where you need it most, so you stay agile and comfortable while still benefiting from maximum warmth. 6. Pairing with Other Layers The Supertherm range is built to be part of your complete winter system. Layer it up with: ·       Thermal base layers like our Polypro or Hot tops & leggings — not only do they help manage moisture, but they also add an extra insulating layer, trapping air and boosting warmth. ·       Spray protection such as the Aquafleece® or SB1 Inshore Dry Smock — your outer defence against wind and water. Together, these layers create a system that locks in heat, keeps you dry, and stands up to whatever winter sailing throws at you. Read more about layering by visiting our Layering Guide. Don’t let the cold hold you back. With the right wetsuit, winter sailing can be just as enjoyable — if not more — than the summer season. Our Supertherm 4mm range is designed to give you the warmth, comfort, and performance you need to sail on through the colder months.

Winter doesn’t mean your sailing or training has to stop – it just means you need to prepare your kit properly. The right layering system will keep you warm, dry, and able to focus on performance instead of the cold. At Rooster, we’ve refined our layering philosophy so every piece works together, giving you flexibility whether you’re racing, coaching, or training ashore. You can check out our full layering guide for tips throughout the year, but for Autumn/Winter specific keep reading below:   The Golden Rule: Layer Like an Onion Layering is about trapping warm air close to your body while managing moisture and protecting against wind and spray. Each layer has a job to do, and when combined, they deliver comfort and performance in even the harshest conditions.      Think of this as your second skin. Its job is to regulate body temperature and wick moisture away, keeping you dry even when you’re working hard. Technical base layers: Soft, quick-drying fabrics prevent chills caused by sweat. Close-fitting design: Ensures no cold gaps and allows easy layering on top.   Rooster Pick: Hot Top & Leggings – the winter sailor’s secret weapon. Top tip: Skip rash vests or Lycra layers as insulation – they won’t add warmth and can actually make you feel cooler. When it comes to layering, sometimes less really is more.   This is where you add warmth. Choose pieces that are flexible, breathable, and easy to peel off when conditions change. Flexible layering: Adjust your neoprene thickness to match the forecast. When the temperature drops below 15°C, reach for your Supertherm® 4mm Top and Longjohn for maximum warmth. In milder conditions, your Thermaflex® 1.5mm layers may be all you need – and if you’re someone who feels the cold, add extra base layers for comfort. When it is really really cold, you could double up on neoprene!   Check out our blog on what the forecast says vs the actual temperatures.   Your shell is the barrier against wind, spray, and rain. Look for waterproofing, breathability, and freedom of movement. Aquafleece Spray tops or SB1 Inshore Smock: Great for dinghy sailing. SB1 Jacket or Pro Rigging Jacket: Added protection when conditions are rougher.   Your hands, feet, and head lose heat fastest, so finishing your system with quality accessories is vital. Neoprene gloves & mitts for grip and warmth. Neoprene socks layered under boots for warm, dry feet. Hats, beanies, neck gaiters & balaclavas to prevent heat loss from your head and neck.   💡 Did you know? Research published in the British Medical Journal found that if your head is the only part of your body uncovered, you can lose around 7–10% of your body heat through it. A simple hat or hood can make a huge difference to your comfort and endurance on the water.   Customer Favourite Pick for Autumn/Winter Training: AquaPro Gloves, Hot Socks, Supertherm Beanie & Aquafleece Neck Gaiters.   One of the toughest parts of winter training is when the day is split into two sessions with downtime in between. That mid-day break can be when the cold really creeps in, leaving you feeling flat, sluggish, and unmotivated for round two. The good news? With a few smart habits, you can stay warm, recover properly, and head back out ready to perform.   Top tips for staying warm between sessions:  Layer up quickly: Throw on a warm, windproof outer layer such as our Pro Aquafleece® Rigging Coat or Aquafleece® Robe to trap heat and stop the chill setting in. Swap your kit: Take a spare pair of socks and gloves to change into during the break – dry, warm hands and feet make a huge difference. Don’t forget your head: A simple beanie helps keep body heat in and makes you feel instantly warmer. Refuel smartly: Pack proper food and a hot drink to top up energy levels and keep your core temperature steady. Keep moving: Light activity between sessions helps circulation and stops you from cooling down too much.     Avoid rash/lycra layers – they hold water and makes you cold. Stay flexible – pack an extra mid-layer, socks and gloves in your kit bag so you can adapt. Check your fit – layers should sit comfortably without restricting movement. Look after your gear – rinse saltwater off regularly and let items dry fully.   Final Thought: Winter sailing and training are all about preparation. Get your layering right, and you’ll be warm, comfortable, and ready to perform – whatever the weather throws at you.   Our full layering guide and more information on layering for different conditions can be found here.

My favourite training routine for small to medium sized groups is a ‘Follow-On’.

Autumn is a season of change — cooler mornings, shorter days, and crisp conditions on and off the water. It’s also the time when the right layers and reliable kit make all the difference. For the Autumn 2025, we’ve launched a brand-new line-up designed to keep you ready for whatever the season throws your way: the 50L Semi-Dry Duffel Bag, the Shoreline Jacket, the Polartec® Fleece, and Polarised Sunglasses. Whether you’re heading to training, commuting, or escaping to the coast, these new arrivals are built to perform across every part of your lifestyle. NEW IN: When it comes to transporting kit, durability and reliability are key. The new 50L Semi-Dry Duffel Bag has been designed to handle the demands of everyday use and weekend adventures. 50-litre capacity: spacious enough for sailing kit, gym gear, or a weekend away. Semi-dry construction: water-resistant materials keep contents protected from spray and showers. Built to last: rugged fabrics and reinforced details ensure long-term reliability. It’s the ideal bag for the sailor, coach, or anyone who wants one solution for their kit, wherever they’re headed. 👉 [Shop the Duffel] The Shoreline Jacket brings together performance and versatility. Designed to bridge the gap between watersports protection and everyday practicality, it’s a lightweight, breathable jacket you can wear almost anywhere. Water-resistant and breathable for comfort in unpredictable conditions. Lightweight design makes it easy to wear on its own or over a fleece. Everyday style that looks just as good on a coastal walk as it does on the daily commute. It’s the kind of jacket you’ll keep by the door, ready for whatever the day brings. 👉 [Shop the Shoreline Jacket] A dependable fleece is a year-round essential, but it really comes into its own in autumn. Our new Polartec® Fleece delivers premium warmth without bulk, making it perfect as a standalone piece or a layering option under waterproofs. Made with Polartec® fabric for trusted quality and performance. Warm yet lightweight, so you stay comfortable without overheating. Versatile fit that works on the water, at the club, or in everyday use. It’s practical, comfortable, and built to last — everything you need from a mid-layer. 👉 [Shop the Polartec Fleece] Autumn brings low sun and dazzling glare, especially around the water. Our Polarised Sunglasses are designed to protect your eyes and improve visibility in these conditions. Polarised lenses cut through glare and sharpen detail. Lightweight and durable frames for all-day comfort. Essential protection for training, coaching, or time outdoors. They’re a small piece of kit that makes a big difference to comfort and performance. 👉 [Shop Sunglasses] Ready for Autumn Adventures From the tough new duffel bag to versatile layers and glare-cutting sunglasses, this 2025 collection has been designed with durability, comfort, and practicality at its core. Whether you’re preparing for time on the water, long coaching days, or simply making the most of crisp autumn weekends, this kit is built to move with you. 👉 [Explore all New 2025 Collection]  

This summer, I was lucky enough to win the Tera Sport World Championships, surprisingly making me the first person to be a double World Champion in both a Topper and a Tera.

Blog written by Kirsten Pollock, SKUD18 Sailor   Hansa are the largest manufacturer in the world of sail boats used by people with disabilities. The boats are designed to a Universal principle, with weighted keels, that allows anyone, whether young, old, able or with a disability to sail easily and safely, making sailing a very equal and inclusive sport. Every two years the five Hansa Classes come together for an International and World Championships. The boats are named by metric size, the smallest is the 2.3, then 303 divided into one and two-person fleets, the larger Liberty and finally the fast and powerful Paralympic SKUD18. The 2025 Hansa Worlds took place at Pittwater, near Sydney, Australia. Sixteen nations, with competitors from Australia, Chile, France, Germany, Great Britain, Hong Kong, Italy, Japan, Netherlands, New Zealand, Poland, Portugal, Singapore, South Korea, Spain and USA took part and, representing Great Britain in the SKUD Class, was me, crewed with top local sailor Brett Pearce who was Australian Reserve Crew for the 2016 Paralympics in Rio. Other illustrious names in the fleet were Dan Fitzgibbon, three times Paralympic Medallist, plus Asia Pacific SKUD Champion Neil Rowsthorne. The Rooster clothing was brilliant, especially the long sleeved UV top, UV neck sleeve and cap helped protect me and my crew from the sun. I have fair skin and burn very easily so having the right clothing especially in strong UV conditions makes all the difference. I could focus on sailing rather than having to contend with sunburn etc. After the regatta I went travelling and Rooster were with me every step or wheel of the way. I spent a few days in central Sydney. I then went to Uluru, from there I went to Port Douglas and went to the Barrier Reef, I wore Rooster kit in the water to protect me from the UV rays. I then went to Melbourne. My Rooster kit proved to be the ultimate travel companion — keeping me protected, comfortable, and ready for whatever came next. Whether I was sailing in high-performance conditions or exploring some of Australia’s most iconic landscapes, having reliable gear made all the difference. I genuinely wouldn’t travel — or sail — without it.

11th August 2025   We’re proud to announce our new partnership with the Royal Nova Scotia Yacht Squadron (RNSYS)—the oldest yacht club in the Americas—marking the start of an exciting new chapter for Rooster in Canada. After beginning our support earlier this season, we’re now officially the Squadron’s technical clothing provider for 2025 and beyond, supplying high-performance apparel for sailors, staff, and major events both on and off the water.   Kicking Off with a Major Youth Sailing Event   Our first supported event under this partnership will be the Canadian Optimist Nationals, hosted at RNSYS from August 16–22, 2025. This premier youth sailing event will welcome some of the most promising young sailors from across Canada, and we’re looking forward to providing technical gear designed to keep them comfortable and performing at their best.   Looking Ahead – Foiling and High-Performance Sailing   Following the Opti Nationals, our partnership continues in October with the CANFOIL Cup—a key event on the Canadian foiling calendar. The regatta also incorporates the WASZP Nationals and Foiling Provincials, showcasing some of the most exciting and progressive aspects of modern sailing.   A Shared Vision for the Future   "We’re thrilled to be partnering with the Royal Nova Scotia Yacht Squadron—a club with deep heritage and a bold vision for the future of sailing in Canada," says Kate Morrison, Head of Marketing & Product at Rooster. "This is more than just a sponsorship; it’s a shared commitment to supporting all levels of sailing and foiling, from youth development to cutting-edge performance."   This partnership marks Rooster’s first major club collaboration in Canada, reinforcing our growing presence in North America and our dedication to supporting sailors at every level. Together with RNSYS, we look forward to building a strong future for the sport in 2025 and beyond.     Next up: Canadian Optimist Nationals – August 16–22, 2025Where: Royal Nova Scotia Yacht Squadron, Halifax, NS   Follow the action and event updates on our social @RoosterKit.

This September, Rooster is returning to the Southampton International Boat Show – and we've moved! Our stand is now in a fresh new location with even more space to showcase the latest 2025 gear - including some of this years most exciting launches. You’ll find us right in the heart of the action – check out the map below to plan your visit.   What’s New? We’ve been busy designing, testing, and launching innovative new gear for sailors and watersports lovers. Here's what's new at the stand: Rooster Sunglasses – high-quality lenses, built for performance on and off the water. SB1 Inshore Dry Smock – reliable and breathable outer layer, perfect for inshore conditions. Coastal Hi-Fits – durable protection for coastal cruising without unnecessary bulk.  Waterproof Socks – because dry feet are happy feet.  SB2 Deck Trainers – designed for optimal performance in any environment, with unbeatable grip and comfort.  Microfibre Polartec Fleece – lightweight warmth, ideal for layering.  Upgraded Tech Shorts & New Women’s Tech Shorts – improved fit and function and now in a women's fit. Swing by to try them on, check out the quality up close, and chat with our team – we’re always keen to talk all things kit.     Win Your Way In – 5 pairs of tickets up for grabs! We’re giving 5 lucky Rooster fans a chances to win a pair of tickets to attend the show for free. To enter, simply: Follow us on social media Like the competition post (check it out on Facebook and Instagram) Share it on your story and tag @roosterkit Tag the friend you’d bring along in the comments Winners will be announced via DM from the Rooster official Instagram and Facebook pages – so make sure you’re following us on Instagram and Facebook to stay in the loop and enter your name in the draw.   Save £10 – Tell all your friends! Want a discount on your ticket? Use code ROOSTERSAIL at checkout when booking your tickets to get £10 off via the Southampton International Boat Show Website. Share the code with your Yacht club, Sailing Club and all your friends to spread the word!       Rooster x Rockley Giveaway – Scan to Win This year, we’ve teamed up with Rockley for an exclusive giveaway. Keep an eye out for Rooster x Rockley signs around the lake – Scan the QR code to sign up for your chance to win a £1000 bundle from Rockley and Rooster – the perfect way to stock up on essentials and book that sailing course or activity you’ve been dreaming of! (Terms and conditions apply).     We can’t wait to see you at the show. You'll find our exclusive show-only deals and our much-loved Outlet steals (get there early - they don't last long!)

Blog submitted by Rooster Rider Amelie Ballantyne, Devon UK As a keen dinghy sailor, there is nothing I like better than getting in my (Rooster) wetsuit and jumping on my boat- it’s the best feeling in the world! However, over the past year, I have started to realise the effects that humans are having on the waters we use and the oceans in general. The statistics around pollution, climate change and habitat destruction are quite shocking, and unfortunately, the evidence of these statistics can be seen rather close to home sometimes- I often see dead wildlife/sea creatures, plastic pollution and sewage where I sail, and it’s not pleasant. As someone who loves using the water, this concerned me, and I wanted to help bring about change. However, I am only a 15-year-old dinghy sailor from Devon, so what can I possibly do to change this global environmental problem? So, to start with, I did my research and created a list of the simple things I could promote at my club (Starcross Yacht Club). Then, earlier this year, I became a Clean Sailors Ambassador and joined a community of international sailors who all want to raise awareness of ocean conversation and sustainable practices in the marine industry. I also joined the US SailGP Climate Action Academy that links students with A-list sustainable experts to learn about global matters. Using social media has been a great platform, and I have organised old sails and wetsuit collections, as well as helping to raise awareness about key issues. Thank you, ITCA Topper community, for your kind sail and wetsuit donations at NS5 Paignton. Who are Clean Sailors and what do they do? Clean Sailors is a non-profit organisation that strives to promote awareness around ocean conservation, amongst other things. Set up in 2020 by Holly Manvell, Clean Sailors share stories, research and campaign for environmental change in the marine industry. One of their big areas of focus is demonstrating what to do with old sails. Currently approx. 97% of sails end up in landfills each year, which is approximately. 2000 tons. This is a shocking statistic! Clean Sailors help direct people to local/global businesses that will take your old sails for recycling and repurposing to keep them out of landfills. Many innovative things can be done with old sails, from clothing and accessories, community shelters for schools and villages, to deckchair covers for the beach; creating a better great circular economy. What can sailors do to help? As sailors, most of us love the seas and rivers we use and would hate to think we are adding to a large-scale environmental problem, but unfortunately, the reality is that there are things that sailors do that have an impact on the environment around them. When it comes to change, even the small steps can make a difference if we ALL start to do them and work together. Think of the times you may have lost a sweet wrapper while doing a race or dropped your sunnies overboard never to be seen again, or that times you used electrical tape and a bit it’s blown away. Well, if every sailor did this, even by accident, the environmental impact would begin to be a big problem for waterways and communities that use them. Here are my top six very easy tips for being a more environmentally conscious sailor: 1. The obvious one – use a reusable drinking bottle and not a single-use plastic bottle. Rooster sells great bottles, and most venues have refill facilities – easy! 2. Recycle your old kit: Don’t dump sails and wetsuits, and buy second-hand where and when you can. 3. Save water. After a sail, you don’t need to shower for hours, have a water fight or spend eternity washing your boat – turn taps off! 4. Use eco-friendly products. There are great boat cleaning products out there, as well as countless products for your body. 5. Take your rubbish home – use the correct bins – maybe have a snack that is not in a fiddly wrapper -Rule 55 guys! The disposable of trash 6. …….use a sunglasses strap/retainer to keep your sunnies on your eyes and not on bottom of the seabed. I am very proud to be a Clean Sailors Ambassador and to be involved in helping with sustainability and change for our future and the longevity of water sports. In my opinion, educating people about the need to be sustainable and the impact each one of us has while doing the sport we love is important; creating new habits and making changes that benefit our whole environment. We all have a role to play; we all live here. It is great to see that even our top sailors in SailGP are getting on board with becoming clean, green sailors and leading the way with sustainability. I am also very proud to be a Rooster Rider, as Rooster is committed to ethical and sustainable business practices, which is important to

- Written by Steve Cockerill    When I started the brand, I was so keen to break down the divide between those who knew how to sail a boat and those who didn’t. I was passionate about sharing knowledge — giving people the confidence to enjoy the sport more. It really all started with me being quietly determined to improve the mainsheet on a Laser (now the ILCA). That was my first goal. I’d tried working with some well-known rope manufacturers, but nothing was quite right. Then I had a brainwave and decided to try it myself. I bought a couple of miles of rope based on that idea… and it worked. People loved it. The breakthrough moment came when I shared it with Robert Scheidt — who was the No. 1 Laser sailor in the world at the time — and he faxed me back saying how much he liked it and asking for more. I’ve still got that fax to this day. That was the spark that made me think, maybe I really could do this. It started in a room upstairs in my house… then a spare room and a shed in the garden… then a double garage and the lounge… then a small unit, then two units, and then a bigger unit. Now, we’ve got a warehouse and office in the UK and a distribution unit in the US — and we’re just about keeping up! I’m still amazed when I look outside and see how many cars are there… and how many great people are working at Rooster, helping it grow. It’s taken a long time — and a lot of passion — to build the brand. Friends of mine used to say, “You’ll need at least a million pounds to turn a vision into a brand.” But I thought, no — you just need to make products people really need. Maybe I was a bit naïve. It’s definitely taken more than just money to get Rooster to where it is today. It’s always been a passion project — and it still is. We’re always checking ourselves, asking if we’re being fair to our customers. And it’s still great fun to represent the brand at events, chat to sailors, and see people enjoying the sport. That’s the best bit. Every now and then people think I’ve retired — which is quite funny, because I haven’t! I’ve just changed my outlook. My wife finally retired from a high-pressure job in school senior leadership, and together we’ve managed to share the workload I used to carry — particularly on logistics and factory liaison. We even split my salary, which has given me a better balance… it’s less five or six days a week now and more like two or three. Handing over the day-to-day running of Rooster to Luke Morrison wasn’t hard at all. Luke had grown up with Rooster — he first joined us as maternity cover, but quickly showed himself to be a real force. He’s brilliant at building relationships with our dealers… a total diplomat, to be honest. In fact, I think I was holding him back! Luke’s got so much drive, it made complete sense for him to take the lead. You might think that would be hard as the founder — but I know Luke’s as committed to Rooster and its ethos as I am. So now, I’ve got plenty of time to keep working with our factories, stay close to the logistics, and enough “playtime” to keep me fired and excited for the years ahead.

This a short article on how to cut a neat slot in your alloy mast or boom to fit a typical sheave box.  This example is fitting a small 15mm diameter sheave block (from Ronstan) into a boom for the adjustment of the outboard end of a mainsail flattener.   Tools required: Pencil. Masking tape. Ruler. Vernier Callipers. (Optional) Hand/Electric drill and bits. A center punch. A small metal file. (Flat or triangular). A 'Dremel' tool and cutting disc attachment. (Optional)   Self tapping screws or pop rivets to fix the sheave box. Duralac Anti Corrosive Compound. A typical Sheave box  e.g a..- RONSTAN RF15711. or the Spinnaker 4mm sheave box from Super Spar PN 409 Procedure First make sure you choose the correct fitting for the job, based on the control rope size, and expected load that will be used on the fitting - and the position of the fitting in the spar.  As you will be cutting a slot in the spar, you need to keep the slot/hole to a minimum and locate the new fitting away from areas of possible high stress areas such as spreader brackets, gooseneck areas, kicker and mainsheet take off points for booms and the like.  For a typical dinghy mast the front of the mast is normally one the strongest sections of the mast, especially in the alloy tapered section, where it will be welded, as this area will be thicker. For booms, the top and bottoms of the section are the strongest areas. Measure carefully the cut-out dimension for the sheave box.  Manufactures dimensions can be used -  but have been known to the incorrect, so use a pair of Vernier callipers to measure the actual fitting. You could even make a small cardboard template first to test fit your new sheave box.  In this case the dimensions are 28 x 9.5mm for the RONSTAN RF15711 sheave box. Using masking tape affix this to the area where you wish to cut the slot, and mark with a pencil and with a small Engineering ruler and square, mark out the area to be cut out.  Measure and recheck before any drilling or cutting…. Using a 4mm drill bit (depends of the fitting slot cut out size width), now carefully drill 4no.holes inside the measured-out rectangle. Use the metal centre punch to tap a light mark, so the drill bit does not wander when you start to drill the 4mm holes. Now, if you have a Dremel tool you can cut down the sides to join up the 4 holes to remove the bulk of the metal.  If you do not have this tool, then simply drill more holes down each side and then file down to create a neat rectangle slot. Remove the masking tape, and now test fit the sheave fitting and mark the position for the affixing holes. Now drill the holes for the screws or rivets.  For self tapping screws you will need to drill the correct size hole by selecting the correct drill bit size for your self-tapper screws and then let the s/s self tapper cut a thread into the alloy material to tighten correctly. Apply a smear of Duralac Anti Corrosive Compound to the base of the s/s sheave, the edges of the new slot, and the screws or rivets you are using. Now screw in the self-tappers (or pop rivets with a suitable gun) to fix the sheave into the slot. (Note : Just before you fix in the sheave box, you might wish to feed in the rope or line before final fix - or feed in a 'mouse' line...) A guide to select the correct drill to match the gauge/number of self-tapping screw Self Tapping Screw Size Sheet Thickness (mm) Guide Pilot Hole Size (mm)* No. 4 (2.9mm) 0.45 2.21 0.91 2.31 No. 6 (3.5mm) 0.45 2.70 0.91 2.80 No. 8 (4.2mm) 0.71 3.00 0.91 3.08 1.22 3.20 1.62 3.40 No. 10 (4.8mm) 0.71 3.51 0.91 3.59 1.22 3.71 1.62 3.81 When using self-tapping screws, the chart above shows the suggested drill size that you should use to drill the pilot hole. As you can see, it is not an exact science, there is a range for each screw size. Broadly speaking, the thicker the material that you are drilling, the more you should move towards the top end of the range when selecting the drill size. So, all you need do now is feed through your rope or halyard line and go sailing.....! A typical valley cleat fitting, using 2 no. Pozidrive self-tapping screws (no.10) to attach. Pilot hole used was a 3.5mm drill.