rig tension

[tom h Capri 22]

After stepping my mast for the first time with every thing snug and backstay cranked down I really have no rake in the mast except for the top which is controlled by the back stay. my question is how much rake does the mast need or is level ok. i checked the turn buckle under the CDI and its pretty much maxed out in length as far as adjustment. maybe the PO cut the headstay to short when rigging it new?
should I use a longer toggle or some how lengthen it with a tang,or should i leave it alone and see what happens.
how much effect does rake have with these boats.

 

[MrSkeet]

Tom,
I don't know about rake but I do know prebend. My wing keel/standard rig's mast, when viewed from the side, looks a bit like a long bow, that is, the top shrouds (35 on the Loos gauge) pull the mast sternward creating a big bow; the lower shrouds (25 on the Loos) pull the middle of the mast aft, diminishing the "bow" effect. With the main's halyard pulled tightly down to the goose neck, I can see a few inches (3 or 4) of vacancy between the halyard and mast half way up.
This has been my set up for several years and it works for me.
Wooster back from season's first sail - sweet !

 

[tom h Capri 22]

Great info, what about the back stay when using your method of tuning. Should it be tight or leave it loose and let the shrouds create the mast shape.

 

[MrSkeet]

FWIW, I set the backstay at 12 on the Loos gauge. I think most tuning guides for our boats call for little or no backstay tension. The uppers and lowers are sufficient create the bow shaped mast.
Somewhere in the capri22.org website is a "stickie" connecting to tuning guides. There, the recommended upper/lower tension is less than I employ; however, the guides describe a bow like shape as the goal.
Wooster

 

[tom h Capri 22]

Thanks, I'll try it and see if I come up with the same result as you. Hopefully I'll launch next weekend and get this sailing season started.

 

[shnool]

Sailmakers usually give you setup for a particular boat for their own sail shape.

3-4 inches of pre-bend sounds about right for a 3/4 to 7/8 fractional though.

Backstay should be adjusted as winds pipe up.. so NO backstay in light air, and bring on the backstay to maintain bend in the mast or increase bend (what you are primarily after is reducing headstay sag from the increased force on the genoa/jib, and also to tighten the the luff of the mainsail... this will effectively pull the draft forward in both the genoa and the main).

You likely will only add 2-3 extra inches of bend (in a static state) from full off to full on for the Capri 22 backstay adjuster. How much it ACTUALLY adds is another story.

 

[jepomer]

I set my shrouds to the tension recommendations on Page 91 of the "Capri 22 NA Intro Pkg.pdf"

WIND SPEED (mph)
Shroud Tension - UPPER
Shroud Tension - LOWER

0-7
42* (420 lbs)
15* (120 lbs)

8-15
44* (520 lbs)
26* (220 lbs)

15+
45* (600 lbs)
32* (300 lbs)

* Measurements made by Loos Model A Tension Guide
Since most of my sailing is below 15 knots, I chose the middle tension. All of the standing rigging was replace in May and set to the middle tension. Winds have been light this season when we have gone out. I checked the tension last Thursday. The tension is now set for the 0-7 mph wind speed. Yes, the rigging does stretch over time and should be checked/adjusted regularly.

 

[Rightbrainer]

I found the Selden mast tuning tips to be very useful. Be sure to take the weight of the boom off the rig before setting prebend.

http://www.seldenmast.com/files/595-540-E.pdf

Before you get started, hoist the dumb end of a tape measure to the main truck and make sure that your mast tip is centered side to side.

Regarding mast rake, (speed issues aside) it has a big effect on the balance of the helm. If you have excessive weather helm, move the center-of-effort forward (reduce rake) to push the bow down. Vice versa for lee helm. Beating with the tiller cranked over to offset excess weather helm is not fast. Lee helm makes a boat feel twitchy, plus it won't round up and wait for you if you fall overboard.