What he said!
--Dave S. (Demitri)
PS--Very little to add, but if you think of all the items that can create
windage and wetted surface drag, and how any one of them might be sufficient
to negate any putative incremental advantage from a super-slick sail (not to
mention a badly shaped or trimmed sail), it doesn't seem like a fair fight.
On 1/16/09 9:30 PM, "[email protected]" <[email protected]> wrote:
> I'm pretty skeptical on this.
>
> Laminar air flow over a sail membrane, whether it's PET, PEN or a
> laminate, is subject to a lot more surface variability than, for example,
> laminar water flow would be over a hard object like a hull or a foil
> (keel/rudder). Studies have shown no benefit from an application of an
> emulsion to a properly faired, finely sanded fiberglass hull, as far as I
> know. When you factor in the lack of surface uniformity of an airfoil
> defined by modern sailcloth, from having been folded, bricked, furled or
> rolled, and then take into account the seams on a paneled sail, then the
> addition of an emulsion to a less than perfect laminar flow surface seems
> negligible. It can't hurt, but is probably a waste of money (SailKote
> being 15 bux a can). Maybe a non-paneled sail like a North molded sail
> (3DL) might benefit, but I would imagine the material used in the laminate
> would be more likely to generate a laminar flow without the addition of an
> emulsion...an emulsion is going to be subject to all the flexing and
> stressing the sail material would experience, except the emulsion hasn't
> the physical properties (material memory) to then resort to it's original
> configuration on the substrate...go it gets bumpier.
>
> The benefits of spraying the sail would be less friction when being furled
> and less friction when the sail is dragged against potential chafe
> spots...it could tack faster and experience less wear and tear, but I dont
> think the increased laminar flow theory, pardon the pun, holds any
> water....
>
> tf
> big fan of SailKote though!!! (e.g., McLube)
>
>
>
>> It makes the sails slippery somehow. The wind flows over their surface
>> with
>> less friction.
>>
>> David Hoyt
>> Sovereignty
>> Catalina 27 #65
>
>
>
