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Ask The Experts

Richard Rosenthal

February 14, 2018 “I have a 1980 Bermuda 40 Mark III Sloop with Quantum Sails. These boats were not fitted with backstay tension adjustors nor is there a Cunningham. There is an outhaul, boom vang and of course the mainsheet. How effectively can I change sail shape with what I have and are there any tips? Do I assume that the mast on a B-40 is not meant to bend?”

David Flynn

February 19, 2018 Quantum Expert Answer

You do have more limited options since your mast is not designed to bend. As a result your mainsail starts with a flatter design shape. You still can control depth in the lower third of the sail with your outhaul. Tension to flatten when you start to get overpowered, ease when you can use the horsepower. You don’t need a cunningham to control luff tension, you can use the halyard to achieve the same effect. If you have horizontal wrinkles perpendicular to the luff, try applying more halyard tension. This is related to the amount of apparent wind you are sailing in. Luff tension needs to change as a function of wind speed. Less in light air, more as it gets windier. When it comes to the mainsheet and boom vang, they work the same as the do with any sail to control twist (leech tension). The mainsheet, of course, also controls angle of attack. For more on the essentials of mainsail trim check out our mainsail trim guide and this article on sail twist. Hope that helps!

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