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Old 13-02-2011, 19:58   #1
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Mast Trimming Help !

Hi there! Yesterday I went sailing in my 25 footer and I noticed that when beating on port I `ve felt more weather helm that on starboard (same wind, same sail trim). Ive checked the mast set up with some locals and it seems ok, (rake, shroud tension). I sail on the Parana river in Argentina which has a 2.5 knot current!. Could have been the current the responsible for that? or is it something more serious like keel askew, etc.
The boat is brand new.
Thanks for your insight!
Juan
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Old 13-02-2011, 20:13   #2
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I sail on the Parana river in Argentina which has a 2.5 knot current!. Could have been the current the responsible for that? or is it something more serious like keel askew, etc.
Short answer? Maybe. You don't mention your heading relative to the current.

I would suspect the rig before the keel, & even if not, it's certainly easier to adjust! It's easy for the mast to be straight without being vertical. You can disconnect your halyard from the mainsail, & see if it hangs in line with the sailtrack, like a nautical plumb bob. This requires calm weather.
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Old 13-02-2011, 20:19   #3
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Originally Posted by JuanCH View Post
Hi there! Yesterday I went sailing in my 25 footer and I noticed that when beating on port I `ve felt more weather helm that on starboard (same wind, same sail trim). Ive checked the mast set up with some locals and it seems ok, (rake, shroud tension). I sail on the Parana river in Argentina which has a 2.5 knot current!. Could have been the current the responsible for that? or is it something more serious like keel askew, etc.
The boat is brand new.
Thanks for your insight!
Juan
Same angle of heel on each tack?Heeling often increases weather helm.
Current will affect heel and or helmif it is not directly in line with wind,as well as a freshwater-over-saltwater effect(fresh stays on top -the currents could be different underneath)

Is the rudder attached to keel or a skeg or not?Is thekeel a fin bolted on?

Details needed....
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Old 13-02-2011, 21:12   #4
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Next time you are out sailing check your rig tension on both tacks. Have someone sight up the mast to check for excess bend in the top section. Pick a day when you have a nice stiff wind and experiment.
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Old 13-02-2011, 21:20   #5
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Current will not affect weather helm, heeling, sail trim, nothing. It only affects your destination, your speed over the ground.

Sighting up the mast on both tacks was a good suggestion. As is headsail sheeting angle and main traveller position. Or how stuff is stored below. Inches can make a difference.

It really doesn't matter too much. Simply trim for best effect.
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Old 13-02-2011, 22:05   #6
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Messure from the tip of the mast to the starboard and then the port chain plates to check the top of the mast is centred .Greg
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Old 13-02-2011, 22:07   #7
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There are a few tests you can do.

1. Run a tape measure across the deck at the mast. Check that both the mast and its collar are in the centre. Don't laugh. A few years ago a prominent 24 foot boat was sold in the hundreds with an off centre mast collar.

2. Check that the mast is vertical by cleating a halyard and then checking the distance that the shackle is above each gunwhale. Should be the same.

3. Check whether a shroud might be too loose or tight by sighting up the mainsail track. It should be straight. If there is an S bend then a shroud must be tightened or loosened as necessary.

4. Check that both jib tracks are mounted in the same position. Measure them from either the centre of the boat or the gunwhale to check that the sheeting angles are the same.

5. Check that the mainsheet car was in the same position on each tack. Cleat your traveller car on the centre line and sail around for a while on each tack.

6. Check whether the mast has been raked too far aft by raking it forward. Write down the number of turns you ease the cap shrouds and tighten the forestay so positions can be reproduced. Start with 4 turns and see how the boat feels. Your objective should be only a small amount of weather helm.
When the boat is sailing in 10 knots of breeze and fully loaded the forward end of your tiller should be about 5cm above centre. Let go of the tiller and the boat should slowly round up to weather. If you are being forced to correct weather helm too aggressively with the tiller then you are just turning your rudder into a handbrake and that's slow.

If none of the above works then I give up.
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Old 14-02-2011, 10:32   #8
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Current will not affect weather helm, heeling, sail trim, nothing. It only affects your destination, your speed over the ground.

Sighting up the mast on both tacks was a good suggestion. As is headsail sheeting angle and main traveller position. Or how stuff is stored below. Inches can make a difference.

It really doesn't matter too much. Simply trim for best effect.
With respect,I disagree.

A River or Tidal current will have an effect on apparent wind.If the boat heels more it will often have an effect on helm beyond the distraction of any marks on the shore showing "leeway" or the even the opposite! But currents can be very different side to side in a channel and currents don't always go merely against or with the wind- itself variable,given "tidal and river" is going to be in inshore water.Rivers are different from tide but the possibilities are all there,especially where they hit the sea and the tidal currents there!
It's quite possible to heel more on one tack than the other given the simple question of the OP.If he'd said the apparent wind never varied,then,I'd put current further down the possibles.

I've sailed through some big whorls and the effect is very marked!
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Old 14-02-2011, 11:11   #9
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Old 14-02-2011, 11:23   #10
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With respect,I disagree.

A River or Tidal current will have an effect on apparent wind.
In the context of this thread, i.e. sail and rig trim tack-to-tack, current has no effect.

Tacticians worry over currents, sail trimmers do not.
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Old 14-02-2011, 12:01   #11
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Current will effect where you end up but it should make any difference to helm pressure. I presume the trav is in the same relative place on both tacks. I would check the symetry of the rudder. Are you experiencing any rudder "flutter"?
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Old 14-02-2011, 12:53   #12
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If your hull speed is in the neighborhood of five knots, you'll certainly feel the effects of 2.5 knots current on the helm. The more perpendicular the wind direction is to the current, the more you would feel the effect.

Assume a perpendicular wind. On one tack, you'll be heading about 40 degrees upcurrent, while on the other you'll be heading about 40 degrees down. Let's assume a deep forefoot on the keel. On the upcurrent tack, the sideways pressure of the current against the forefoot is actually going to push the bow towards the wind, which means you will feel this as being greater weather helm. On the downcurrent tack, this same pressure will naturally help relieve the feel of weather helm. While what you're feeling is not technically all wether helm, your rudder doesn't know that. All it knows is that it's taking this much helm to hold the boat close-hauled.

Try this experiment on a windless day: Take the boat out and stall it sideways to the current. Does the bow or stern quickly head downstream, or does the boat remain sideways in its orientation for some time. If the former situation is the case, you've found the source of your mysterious feel on the helm.
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Old 14-02-2011, 14:09   #13
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If your hull speed is in the neighborhood of five knots, you'll certainly feel the effects of 2.5 knots current on the helm....Try this experiment on a windless day: Take the boat out and stall it sideways to the current....
That's not the way it works. Without reference to a shoreline, or GPS, or something external, you and the boat will be completely unaware of a current. It's undetectable. Sailing from calm water into a current will seem like a change in the wind. You cannot know if it's a current without some external navigational clues. The current will not affect the helm in any way.

If the current changes rapidly you may see eddies, but that's not relevent here, and you still won't know if you've sailed into or out of a current or even which way the overall current is taking you.
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Old 14-02-2011, 14:37   #14
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Go on flat water and try again without current. Normally the wind comes from angles that will have the boat behave differently when sailing cross-current on opposite tacks. Fact of life and can be used to your advantage once you are aware of its existence.

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Old 14-02-2011, 15:46   #15
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That's not the way it works. Without reference to a shoreline, or GPS, or something external, you and the boat will be completely unaware of a current. It's undetectable. Sailing from calm water into a current will seem like a change in the wind. You cannot know if it's a current without some external navigational clues. The current will not affect the helm in any way.

If the current changes rapidly you may see eddies, but that's not relevent here, and you still won't know if you've sailed into or out of a current or even which way the overall current is taking you.
That is the way it works.Sailboats are not airplanes.The keel is in water,the sail is in air.A change in the apparent wind velocity is huge especially in a 25foot boat.
Consider as Vsquared times Constant air density.Wind Force for 10 knots is 100x Density. 12.5 knots would be 156 x Density.
Personally,I do know when I am in current.It's impossible not to, if it's a 2.5 knot current.Even a motor boat would notice without looking for eddies because it builds up the chop quite a bit...or smooths it.
Since the question this pertains to is different heel,different tack,there are other possibilities.Bent keel,bent rudder,bent rig,bent tiller,Even a bent hull changing the underwater profile is a possibility...heavy stuff stowed wrong on a sensitive hull-ie the OB to the side for instance.But all else checking out,the current is a possible too.
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