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Working up a Britpop

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As most of you know I gave in and bought a Britpop mid 2021 to take out the one variable to boat speed that was unknown to me.  It was not that my Alternative was slow, it was just all the fast designs today have a significant chine and volume at the back end and that sowed an element of doubt in my mind over my boats overall performance. Funnily enough I thought that any tiny lack of performance was in light weather rather than heavy.  In a breeze on flat water, I felt the Alternative had a slight edge 

The road to glory is not as simple as buying a Britpop or similar modern design and does not lead to race winning performance.  Here is my story so far.


The initial set up

The third hand hull (2014 Robot build) was sound with a few scratches on the hull and bulb that I was able to polish out however it had a couple of chunks taken out of the trailing edge of the fin.  It had an excellent RMG winch and fittings so nothing had to be done to the hull fin and bulb. There was no RC so I bought a Futaba I6 transmitter and receiver which I found to be excellent and replaced the rudder servo with a futaba 3010.  The reason for using a Futaba instead of the Flysky was the Futaba had a ratchet on the winch.  I coated all the connections in Corrosion X to stop any corrosion in salt water.  However I found that was not enough as when the radio pot leaked with salt water and I left it for a couple of days, the connectors showed signs of corrosion and had to be replaced.  A cut down kilner jar rubber seal inserted in the lid fixed the leak or so I thought and replaced connectors got the electrics back up and running reliably.  The hull is cleaned with T cut and left at that.  There are a couple of chips in the trailing edge of the fin but I have not noticed any problem with that but are now repaired.

I had worked up good rigs on my Alternative and all I had to do was transfer them to the Britpop.  The rigs are BG sails set on PG spars with 11 and 7 mm pre bend on the A and B rig.  The settings are almost identical between the boat designs.  You can see the rig set up here. although I have made a few changes to the jib attachment at the head because the loop knot I used to attach the topping lift slipped on the B and C rig with disastrous results so I attach the topping lift and jib luff direct to the hook on the mast (See the story here) .  On the A rig, my loop knot is a bowline with a locking half hitch coated in super glue to make sure there is no slippage.  there are more pictures of the current rig below.

The sheets are 35kg line as is the line to the winch.  The sheets need replacing regularly but I find anything heavier does not ease effectively in very light weather.  I have tested the 35kg line in 25-30 knots of breeze with the C rig and top end of the A rig so they are strong enough.  I use the standard setup settings on the BG website as my starting point and always carry a rig stick to make sure the rake is correct and therefore the boat is balanced and run a tape over the foot and leach measurements.

A wise man in Birkenhead said to me, the secret in setting up the boat is to have a list of goto settings and keep everything as simple as possible.  

There are changes made to my original rig setups which I have previously documented but the latest are from events occurring at the 2 Islands ranking event  where I broke a shroud and had no spare.  I now have spare A and B Jibs on booms, and completing spare A and B masts with mains, along with spare shrouds and backstays. 

The last thing was to put the boat in the measuring tank to look at two things. One was the fore and aft balance of the boat which I am happy to say is good. The bow was out of the water for just under an inch from the back of the bow bumper so no need to do anything. The other thing was to see if I could drop the bulb/fin as I know we had approximately a 5 mm gap to the measuring bar when last measured. Sure enough, it could drop 4.5mm which does not sound a lot but sailing hard up wind, moving 2.5kg, 4.5mm further out is quite a bit of righting moment.  Of course, now I need a securing bolt with an extra 5mm on it. 


To drop the fin, I put together spacers on top of the fin (three section of cable tie stuck together with super glue and packed out the trailing edge with Isopon so the fin was nice and snug in the case.


The last thing was to replace my futaba 3010 servo with a BLS471sv. It was not a cheap replacement but the rudder is tighter with no movement and centres perfectly every time.  WIth the 3010, if you move the rudder, there was about 5mm movement on the trailing edge.  With the 471 there is no movement at all.

Once the Britpop was set up and sailing it was time to apply some magic which I hate to say only seems to come through experience, racing and practice, or as my old 470 sparing partner and super coach said, you just need many hours on the water.  The observations below are my learnings from the racing so far.

Where is the magic

A simple rig setup

Articles on setting up the rig on an IOM may talk about how the mast control is split into 3 sections. The bottom third is controlled by the mast ram, the middle third is controlled by the spreaders and the rig tension and the top third is controlled by backstay tension. That is the easy bit. The hard bit is to determine what your initial racing setup should be based on your understanding of the mast bend/mainsail relationship. The experts are able to set their boats up almost by feel. They have done it so many times before and know what works and what doesn't work and have good reliable base settings.  The ultimate test of a correct set up is to tack your boat on the limit of a rig and have the boat accelerate away with little or no helm interaction.


To learn about the impact of different adjustments, I like to experiment by laying the boat with the mast horizontal. Bear in mind I use BG sails which has luff curve built in so giving great flexibility in the way you shape the sail and these are fitted to a PG mast (10mm prebend) on a Britpop. My goal is to understand how the mast bend works given different settings from one extreme to another. Once I have been through this exercise, I identify one mid range setting, mark everything up to this setting and this will be my start point for racing. If there is more or less wind, I will make mm adjustments to the backstay, and maybe shroud tension.


  1. The first thing to do is set the mast up with relatively slack shrouds for light weather. The leeward shroud must not go soft when on the wind and then apply enough backstay so the mast is as straight as possible even through the deck. You should have a couple mm of rake on your spreaders. This is the starting point for light weather.

  2. Now if you apply more backstay you begin to de-power the rig, the mast will bend evenly but more in in the central third. If you keep the shroud tension the same and apply more backstay, the main will end up flat at the middle/ bottom third and be too full at the top and may even break down in the middle, if you overdue the backstay tension. Our goal is to keep the power low down and blade out or flatten the top.

  3. As the wind builds above an imaginary 5 knots or so, gradually stiffen the mast low down by applying a little more rig tension and add a tiny bit of reverse bend at the deck with the mast chock. Remember the rig tension will affect the middle third of the mast. As you stiffen the bottom and middle third of the mast, you encourage more bend at the top which will help blade out the sail effectively depowering the rig.

  4. The rig tension is gradually increased through the wind range, 0-5, 5-10,10-15. At the top end of the A rig you need max rig tension to get as much bend as possible in the top third of the mast so you blade out the top of the sail. You should end up with slight reverse bend at the deck level, an even bend through the mast with slightly more induced at the top. If it all works out when sailing upwind, your main should fill evenly top to bottom and invert at the top as the rig becomes overpowered.

  5. The goal of this exercise is to develop an understanding of how the rig works not to develop a myriad of settings for different wind ranges.

  6. Once you have tried this indoors and understood how everything fits together, find a mid point setting (5 to 10 knots) and test it out on the water. If you are happy with what you see, mark everything up so you can repeat the setup when you next rig your boat. The usual rules apply for rig set up, set the kicker for downwind, use the backstay for upwind leach tension, make the jib slot parallel to the main as well as using the BG measurement for distance from leach line to jib leach and main and jib foot depth.

  7. From this setup you will only need to apply mm adjustments to the backstay, and maybe a slight increase of decrease on shroud tension.

When I set up, I have marked positions for the shroud bottle screws (locking nuts), sheet hooks, sail foot depths, mast rake and leach twist distances from the topping lift, sheeting angle for the main and jib. With these as a starting point, I know I have a reliable setup and if I need to adjust anything by more then a few mm, something is wrong in my initial setup. 


Some pictures of the extreme setting to see their impact on the mainsail


1 The shrouds are as slack as they can be with a straight mast.  Perfect starting point for light weather

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The effect of too much backstay with little rig tensions. The sail has inverted at the numbers and the top of the mast is still relatively straight at the top third.

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The same setting as above only I have Increased the shroud tension to the max. Note how the middle has straightened out.  I could straighten the middle of the mast more if I want with a little more mast chock.

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Setting adjustments are subtle for any given condition and needs only mm's of change but one must read the settings guide thoroughly, otherwise basic mistakes can be made.  In light weather I noticed at one of the ranking events, that Chris Harris who won the day, using more depth in the jib foot in light weather and I estimated it to be 25-30mm.  The BG standard measurement is circa 22mm.  It was the same on his mainsail, so I tried the same and went from 22 to 30 and saw an increase in speed with the boat pointing at the same height or higher to windward.  Of course you still need to sail fast and free to maximise speed around the course.

On making further enquiries about the main and jib foot depth, I had assumed that the BG measurements were from the centre of the boom to the foot of the sail.  I emailed Brad Gibson and he replied saying that the measurement is from the edge of the booms which make 5mm difference.  Took me 6 months to work that one out.

The second setting adjustment was on the mainsail in a breeze.  I have always struggled to keep the top third of the main from backwinding at the top end of the A rig, even with the jib leech well open.  I found by flattening the foot by 5mm, increasing the shroud tension to move the bend up the mast with 1-3 mm of extra back stay, the top of the sail is flattened and works more effectively and does not backwind so much in the gusts.  It seemed similar to when we used to blade out the top of the mainsail on fractional rig yachts.  When you measure the luff curve on the mainsail luff of a BG sail, there is a max of 10mm in a smooth curve from the mast head to 600mm down.  This is the ideal curve one needs to achieve on the mast so the top of the sail flattens evenly and remains stable.  I slightly flatten the jib on flat water at the top end of the A rig but only by 5mm or so.  

The third adjustment is with the shrouds.  Starting lose in light weather they should be progressively tightened as the wind builds.  The critical thing to look for is that the mast stays in column on either tack when set up for windward work and the leeward shroud should not go slack when the boat is under pressure otherwise the windward spreader will push the middle of the mast to leeward.  The shrouds should not be so tight that the middle of the mast cannot flex fore and aft to de-power the rig in a gust.  

Check that the shrouds are of equal length when pulled down the front of the mast so you know when equally tensioned the mast will be upright and when you rig the boat, lay it on the ground or stand so you can see down the mast to make sure there is no sideways bend caused by uneven shrouds tension and double check the backstay crane is central.

When the boat is set up correctly it rarely needs changing.  I have sailed for a whole day with variable conditions without changing a thing.  If you find yourself tinkering after each race your boat is not optimised.  If the wind does build during the day you will need to tighten the jib luff slightly which has the effect of tightening the jib leech.  A loose jib leech will cause the boat to luff up in a breeze and that is slow.


If you have a transmitter with a ratchet sheet, you have a huge advantage with the precision you can set the sheeting angle of the sails.  The video below show the effect of easing the sheets 1 2 or 3 clicks.  Double click on the screen for full screen view.

Once your boat is set up, the rest is down to your sailing skill which I cover on another page.

See my latest setup checklist at the bottom of the page but I regularly re read the BG setup tips to make sure I have not made any silly mistakes.

Finally a couple of pictures.  The first is the method of keeping the jib boom as low as possible.  I use a sheet hook with a series of holes spaced 2.5mm apart so I can get the jib as close to the deck as possible.  The only downside with the use of the clamp on the boom is that the line wears after several weekends and has to be replaced however this is only a 5 minute job.  I have changed to tying the tack line onto the boom which eliminates there clamp, sheet hook and ring

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The next picture shows how I have lowered the mast by 7 to 10mm to get the lower band below the deck level by 5mm.  It involved modifying the kicker fitting, shortening the length of it by 10mm which I explained in a thought for the day.  I also learnt how salt crystallises inside your mast if you do not flush them out on a regular basis.  Note that if you lower the mast too much the gooseneck will not be able to but up against the mast ram and stop any mast rotation.  I use a standard Cunningham arrangement feeding to the two cable ties and the bowsie is to tighten the jackstay (luff wire of the mainsail).

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This one shows my final jib head arrangement for the A rig which allows the jib to freely rotate in very light weather.  The design is the one suggested by sails etc however I have gone back to attaching the leech line and jib luff to the hook on the mast

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Here is the sailsetc boom end fitting that eliminated the wear on the elasticated topping lift.  The elastic runs inside the boom.

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Here you can see the velcro in the radio pot which allows me to position everything at the top of the pot so I have no issues if salt water accidentally gets in.

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A note for open water compared to inland sailing

In open water there is a good chance you will be sailing in waves.  The boat is constantly accelerating and de-accelerating.  The sails will nearly always require more depth and twist than on flat water to power through the waves.  Again we are only talking a mm or two of change in your setting but it will make a huge difference.

One last thing.  I picked up a rig tension meter in mid 2022 and found this to be invaluable.  Bearing in mind the impact of rig tension on the middle third of the mast, you must have a base starting point.  If you want one, email  He is based in the UK.  It is a quality product and each one is individually tested.  

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