Pre-Bend

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fjviola
Professional
Posts: 90
Joined: April 21st, 2011, 4:06 am
Boat Make/Model: ARC 21 and Supercat 17
Location: Seabrook, TX
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Pre-Bend

Post by fjviola » April 11th, 2017, 5:52 pm

So how did I celebrate year no. 58 last week?

By putting "Pre-Bend" back into my Stick!
_FVA1537.jpg
100 lbs (5 gallons deck paint + two sheets of steel) hung off the diamond spreaders = 1.75-inch Pre-Bend
_FVA1539.jpg
We could really tell the performance difference last weekend when tacking in 20 knot winds with 3-4 foot chop in the bay. Not one tack missed! :D
Franklin Viola
ARC 2101

Disclaimer: Stick Pre-Bending did not last more than four (4) hours, therefore No seeking of immediate medical attention was required 8)

Eric2101
Professional
Posts: 205
Joined: August 16th, 2004, 2:42 am
Boat Make/Model: Supercat 15
Location: Davie, FL.

Re: Pre-Bend

Post by Eric2101 » April 18th, 2017, 5:52 pm

Great looking boat Frank......
Eric Arbogast
Supercat 15

Eric2101
Professional
Posts: 205
Joined: August 16th, 2004, 2:42 am
Boat Make/Model: Supercat 15
Location: Davie, FL.

Re: Pre-Bend

Post by Eric2101 » April 18th, 2017, 5:54 pm

I think the 4 hour rule applies tp pre straightening... Just sayin...
Eric Arbogast
Supercat 15

Bill Roberts
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Posts: 464
Joined: November 17th, 2003, 7:13 pm
Location: Stuart, Florida

Re: Pre-Bend

Post by Bill Roberts » June 18th, 2017, 7:21 am

Hello fjviols,
I see much confusion here. PREBEND is a structural thing. It is not a performance thing. Prebend, ~3", tends to stop masts from inverting when carrying a spinnaker. Remember when the I20 first came out and owners were breaking masts left and right when flying spinnakers. THEY HAD NO MAST PREBEND ! Prebend is a forward bend in the central area of the mast , mid height, achieved by tightening the diamond wires with a" swept aft spreader bracket". With this arrangement, rig, as the spinnaker pulls forward on the mast above the hounds, the central area of the mast tends to try to bend aft, invert. This causes the diamond wire tension to increase and this increases the forward push of the spreader bracket on the central area of the mast thus avoiding mast inversion and breakage.
The PREBEND should be taken into account when the sailmaker is selecting the luff curve for a new main sail.
It really leaves me speechless when A Cat sailors come up to me and ask how much prebend they should run??????

Bill Roberts
Expert
Posts: 464
Joined: November 17th, 2003, 7:13 pm
Location: Stuart, Florida

Re: Pre-Bend

Post by Bill Roberts » June 22nd, 2017, 7:24 pm

Question: Does everybody understand mast PREBEND now? As long as you guys understand it. that's good. You all are the most important.

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