Latest News: Forums Technical Mast Head Buoyancy Wind Resistance

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  • #26646
    Sylvain Caro

    Hi to everyone 🙂

    I’m back with a new question :
    I want to build a mast head buoyancy, made of glass reinforced polyester.
    It sounds easy because I use to work with it, but I’m afraid of the wind resistance it can create.
    To make you understand what I’m talking about, here is, joined to this message, a simple draw of what it will be like.

    As it will be fixed on the top of the mast, and so won’t turn with the wind, do you think it could be an important wind resistance, or that it is absolutely not important?

    Many thanks from France!



    Hi Sylvain – did you ever make a mast head float, and if so do you have any thoughts on the size chosen, how it works and wind resistance. A photo would be interesting to see too if you have one.




    During the recent Internationals in Greystones,  one of the other sailors had a Hartley supplied mast buoyancy device fitted to the top of the mast.  We were both sailing reefed and in MKII’s though his was a +S.  It didn’t seem to make any difference to their speed compared to mine and when they capsized, they didn’t turtle, unlike nearly every other capsized boat, which was a big advantage in the sea-states we experienced that week.

    It consisted of 4 individual modules about 6-8 inches in diameter and approx 1 foot in length which slotted into each other and slid down  and surrounded most of the upper mast but with space at the rear for the sail to continue up the sail groove to the top. It was held to the mast by nylon bolts running through captive nuts in the modules and tightened onto the mast surface.  Non damaging and quite ingenious, I thought.  The buoyancy remains effective at the top of the mast even when reefed completely down.

    A picture of them can be seen on the Hartley chandlery site under “accessories”. Type “float” into the search facility for a quick find.  Pricey but effective.

    You are probably looking to make something like that.  For cruising, it probably is less of an issue as regarding wind resistance, though of course, there will be additional resistance in comparison to not having it there, but the security of knowing you are far less likely to turtle.

    Regards davdor.


    Hi  Sylvain,


    In the recent Internationals in Greystones, one of my fellow sailors was using a Hartley supplied mast-head flotation device consisting of 4 modules of approx 150-200mm in diameter and approx 300mm in length each, slotting into each other and attached to the outside of the mast by nylon bolts threaded through captive nuts in the modules and pushing against the mast but not cutting into it.

    Picture of said flotation device can be found on the Hartley Chandlery site by searching for “flotation”. Pricey but a very neat solution.

    Both of us sailing MKII’s and were reefed down because of the strong winds and the sea-state was quite rough.  I didn’t notice any great loss of performance due to his mast-head buoyancy, but when he capsized, the buoyancy did a good job of preventing him from turtling (turning completely upside-down) , unlike many other of the capsizes, some of which turtled 2-3 times before being able to stay upright.

    On balance, I would say, for a non-racer, the role played by the buoyancy in preventing inversion (turtling) in the rough seas we encountered outweighed the relatively small amount of additional wind resistance which would be caused by the mast-head buoyancy.

    Hope this is of some help.  davdor.

    Sandy Goodall

    Hi Sylvain, I see you are in France. Where in France? I am in Annecy, with W 6778, a wooden MK1 from 1979.

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