Vang Adjustment to Stop Flapping Main Leech

[KZW]

I have C-310, sail no 307. The boat was built in 2005 and has in-mast furling. The leech of the main flaps or pulses when hard on the wind. I’ve tightened the leech line to the point where the leech is very slightly cupped, and that helped. However the problem persists. The last time I was out I put my hand on the end of the boom and put some pressure on it to pull it down slightly. The flapping stopped. So, it would seem the solution would be to add a but more vang, lowering the boom slightly, placing more tension on the leech. There is an issue doing that. Catalina installed vangs in later model C-310s with in-mast furling that don’t adjust. There is no vang control line. This was done to fix the boom angle to the mast to resolve issues with furling the main. However, the vang can be adjusted. There is a pin located mid-vang. Removed the pin, move the vang until the adjacent locking hole appears, then re-insert the pin.

Questions:
1. Have any C-310 owners with in-mast furling experienced the flapping leech issue?
2. Has anyone adjusted the boom down in an attempt to fix the issue?
3. Did moving the boom down make in-mast furling more difficult?
4. Does anyone know the spacing between the adjustment holes in the vang?

Cheers

 

[LeoLambert310]

We have haul 44 with in mast system what we have found is the boom must be level (90 deg) to the mast. I use the vang only in high winds (20 + kts) but use the top lift to hold the boom 90 deg to the mast for furling.

 

[c130king]

I have Hull #178 with in-mast furling and a boom vang. But I have never experienced main leech flapping as you describe. I really don't use my vang much. It is a combo "rigid" / "normal" vang with a "shock absorber" type pole that holds the boom up as well as the normal lines/blocks to pull the boom down. I also have an adjustable boom topping lift.

After I furl in the main I yank hard on the boom topping lift to lift the boom higher for head clearance (I am a fairly tall guy). Before I deploy the main I release the boom topping lift so that boom falls down to fairly level position held up by the "rigid" part of the boom vang.

With roller furling main there is no roach and thus any "twist" of the main is difficult to see...at least in my mind's eye. My leech always seems to be pretty tight. The natural weight/tension of the boom keeps my leech tight.

Good discussion though...keep the observations coming.

Cheers,
Jim

 

[Albanach]

[
Questions:
1. Have any C-310 owners with in-mast furling experienced the flapping leech issue?
2. Has anyone adjusted the boom down in an attempt to fix the issue?
3. Did moving the boom down make in-mast furling more difficult?
4. Does anyone know the spacing between the adjustment holes in the vang?

Cheers[/QUOTE]

Had the same problem fixed by having the leech re-cut (sail 13 years old but otherwise still very good). North Sails did an excellent job at a reasonable price.

My sail furls best at a slightly increased angle that allows the main’s foot to wind itself up in an upwards spiral rather than the thick parts rolling up over each other. I use the topping lift for adjustment.

My furler is a Charleston Spar. Changing from the spec 10 mm to an 8 mm furling line also makes a big difference. The 10 mm tend to swell after time and exacerbate an already highload friction at the furling screw. Your setup may be different.

 

[KZW]

My boom is set an an angle so that the main does wind up without overlapping the seams.

I will try to lower the boom a bit by adjusting the vang, but then check how the main winds up. I won't be able to get to it and test sail for a couple of weeks due to weather, work, and honey-dos. Will report back on results.

If I can't get it right, then I may take to main to Sabre Sails in Pensacola.

 

[Scotty C-M]

I have a 400, so my ideas may not apply to your boat, however...

Have you lowered your traveler when the wind freshens up? This might help.

Perhaps you might change to an adjustable vang. I use mine to adjust sail shape. When furling (Charleston system) I release the vang, and it brings the boom up to a position that works well for the in mast furling.

 

[KZW]

I have lowered the traveler, to the point where the main luffs with only slight moderation of the leech pulsing.

 

[KZW]

I tried adjusting the vang to lower the boom. When I do, the main seams overlap on furling, which is not a good thing.

Looks like the choices are:
- Get the main recut, or
- Install an adjustable vang.

Neither is quick, easy, or inexpensive.

 

[KZW]

I've experimented in the last few months.

- For furling, the vang is screwed in or out, with the main sheet eased, until the bottom of the boom is 77.5 inches above the deck at the companion way. This is the datum position.

To reduce the main leech from shaking (and by leech I mean from the center of the sail to the leech), when hard on the wind, I screw in the vang (lower the boom) based on my guess at the apparent wind speed. The vang is adjusted before departing the dock.

-- 5 knots and below: Leave it alone
-- 5 to 8 knots: One full turn
-- 8 to 9 knots: Two full turns
-- 10 to 12 knots: Three full turns
-- 12 to 15 knots: Four full turns
-- 16 to 17 knots: Five turns
-- 18 to 19 knots: Six turns
-- Above 19 knots: Reef

This is manually grabbing the barrel of the vang and rotating the barrel. It can only be done with the main sheet completely eased and sometimes the MAIN OUT line must be eased as well.

Using the above, I've been able to eliminate the shaking. This evening, in 14 to 15 knots apparent, I sailed with the vang in the furling setting and then the four turns in setting. The difference with the four turns in the vang was 0.5 knots boat speed to the good, making 4.5 to 5 knots going to weather (GPS, not impeller, which lags). This is with my 10 year old (original) Dacron main. I'm sure it has stretched a bit. I use a grease pencil to mark the boom how many turns in I've made so I remember to turn them out, raising the boom, before furling the main.

 

[Sprega]

Have the sail recut or get anew sail.

 

[KZW]

Have the sail recut or get anew sail.

Well, that is on the list, but it is down a bit. The next two items are:

- Fixing the leak in the hatch on the coach roof. I'm planning to obtain a gasket/seal kit from Select Plastics.

- Ring, track, and whisker pole

An asymmetric spinnaker in a sock is also on the wish list, but that is well down on the list.