Keeps pointing into the wind

Discussions on the characteristics of the EC12. Yes, it handles different than most R/C Sailboats

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Keeps pointing into the wind

Postby lmazoway » Wed May 31, 2006 6:46 pm

I'm new to the EC-12 Class and so is the boat. Just launched it and it constantly wants to point into the wind. I have to add a fair amount of rudder to get it to track straight. I understand that using the rudder adds drag. I've moved the mast step to the last hole and it still persists. I'm looking for suggestions as to what remedies might be suggested.
Thanks
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Postby tag1945 » Wed May 31, 2006 8:30 pm

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Postby yachtie » Wed May 31, 2006 9:19 pm

This article as well [:D]

Weather Helm -- Causes and Cures

Series-built yachts and dinghies are, as a rule, so constructed that if properly handled they are pretty well neutral on the helm. Indeed, a little weather helm should be welcome; lee helm is always undesirable. Excessive weather helm arises if the aggregate sail centre of effort lies aft of the underwater hull lateral pressure centre. This could be due to too much mast rake, or the sails bellying too much or being badly trimmed. Sometimes however, it is the designer’s fault or the builder’s; if that is so then there is nothing for it but to make constructional changes such as:

• moving the keel surface aft

• extending the keel surface aft

• moving the mast forward

• moving ballast further aft.

The last-named remedy can to a limited extent be applied by the owner himself; heavy pieces of equipment are stowed further aft, which brings the forebody up making it easier for the wind pressure on the headsail to push it to leeward However, we want to concern ourselves with trimming steps the crew can take as regards the rig

In most cases the responsibility for excessive weather helm rests with poor trim of the mainsail, particularly a leech that is too closed. That produces very high wind pressure on the battened part of the sail. The battens are aft of the boat’s centre of rotation,’ so the after part is pushed to leeward, the bow to windward. Result: weather helm. To remedy this, the leech must be trimmed to open it more, by

• setting up the main halyard hard.

• setting up the luff tensioner hard.

• setting up the foot outhaul hard.

• easing the mainsheet slightly.

• increasing the mast bend.

• sliding the traveller to leeward.

• taking in a reef, if she is heeling too much.

Another possible cause of weather helm is to oversheet the mainsail, with the foresheet lead outboard. To remedy this, the wind angle-of-attack must be about the same for head and mainsail; their surfaces should be substantially parallel. Either move the foresheet leads inboard or set the main boom further to leeward if there is a traveller, it should be pushed to leeward; this leaves the sheet pulling vertically on the boom and avoids the sail twisting. If there is no traveller, the sheet must be eased. Simultaneous lifting of the main boom and thence twisting of the sail is avoided by setting up the kicking strap halyard.

Yet another possible cause of excessive weather helm is a Genoa bellying too much. Wind pressure on the leech then becomes so high that it sets up a luffing moment, because with the boat heeled the leech is aft of the centre of rotation Remedies for flattening the Genoa and opening the leech are by:

• hardening down on the forestay.
• hardening down on the Genoa halyard.
• moving the sheet lead aft.

Lastly, in the case of modern yachts with a flat underwater hull, Too much heel produces weather helm. It results in distortion, as it were, of the underwater-hull lines past which the water is flowing; this tendency can be demonstrated effectively in a boat with the tiller belayed amidships. If you make it heel by transferring weight to leeward, it takes on weather helm; if, on the other hand, you make it heel to windward it takes on lee helm. This sensitive reaction associated with modern hull shapes must be allowed for by sailing upright. That includes reefing in good time.

Three causes of weather helm

A.) The mainsail is set too full and with the leech too closed Wind pressure becomes very high towards the leech, a luffing-moment is established

B.) The Genoa is set too full and with the leech too closed, wind pressure on that region becomes very high This is aft of the boat’s turning point, the boat luffs up

C.) The headsail sheet lead is very far outboard on the sidedeck; at the same time the main boom is hauled in practically to the centreline by means of the mainsheet A luffing-moment results.



Chris
NZL1 Longtack
NZL110 Swept Away NZL128 Ketch me if U Can
yachtie
 

Postby IanHB » Thu Jun 01, 2006 1:44 am

" I have moved the mast step to the last hole"
I do hope you mean the most forward position?
Your mast needs to be moved forward.
If you have run out of holes then you need to remount your mast step.

DO IT NOW, Before it`s to late
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