Black Velvet Bimini- the wind-tunnel champion

by David Pilvelait/Sail-World Cruising on 29 Apr 2014 There's nothing more unnerving on a casual afternoon sail than being caught in a sudden and unexpected blow and having to worry about the bimini as well as the sails. Now some smart manufacturers have come to the rescue and designed a bimini to withstand wind speeds of up to 33 knots.

Florida-based MATE USA has introduced the Tessilmare Black Velvet bimini top. This wind tunnel tested, easy to assemble Black Velvet features a patented plastic cylinder system that adds strength to the supporting tubes and keeps the assembly screws perfectly aligned.

The new top also features unique spider netting that reduces ultraviolet (UV) radiation and enhances air flow throughout the covered area on board. A fast-mounting storage cover is included - and they are offering a 'life-time warranty'.

More about the product:
The support pole system allows the closed sun-top to be in a resting position, avoiding any encumbrance. The sun-top is ready to be used and can be easily and quickly opened. This system can also improve the stability of the sun-top when open, holding it firmly.

So why test the bimini inside a wind-tunnel?
Already, much testing had been done. Technical tests on the fabrics had been performed by specialized textile laboratories; traction test, capability to tear and fatigue to the several components tests had been carried out by the company. Practical tests had also been executed on boats of different sizes and at high speeds.

However, the final step was to find out how how the Tessilmare sun-top would 'behave' at extreme conditions rarely reproducible in practice.

All sun-tops are made up on an average of 40 components; Tessilmare wanted to verify which of these components
would give in or be altered and at which speed the suntop would collapse. They wanted to know in which way the collapse would take place, if suddenly and therefore potentially dangerously for the user.

Here is what was found:
At over 20/22 m/s a compression of the top cover in the front and a considerable aerodynamic lift in the back takes place. At higher speeds a sudden stall takes place causing a clear compression of the top cover which thus compresses the frame of the sun-top towards the bottom allowing thus a further increase of the speed in full safety conditions. Thanks to this compression there will not be the risk that the sun-top could 'fly away' from the boat.

At a speed of 100 km/h a sun-top 300 cms. width and approx. 9 square mts. surface starts with an aerodynamic lift of approx. 200 kgs. to an estimated compression of 80/100 kgs. The sun-top structure goes down towards the boat deck without the frame suffers any deformations.

Thanks to these tests it was confirmed that an average speed of 60 km/h (which is considered a high cruising speed) does not weigh on a big-size sun-top. The max. speeds reached inside the Wind Tunnel have been of 120 km/h for sun-tops till 2,20 mts. width and 100 km/h for sun-tops till 3 mts. width.

Collapse speed was not reached.

For more information about the new Black Velvet bimini top and other MATE USA products, visit www.mate-usa.com or call 1+954.463.5757.

If this is not practical for geographic reasons, you can get more information or buy online by clicking here or consult your local marine supply store.