Sun Fast 26 Rig tuning

[pedbic]

Hi everyone,

First let me introduce to you guys. My name is Pedro, I'm from Portugal and I own a beautifull sun fast 26.

Last week I've been trying without success to tune my rig, in order to get a good handling and performance from my boat.

I'm getting speeds upwind of 6.5 knots when sailing port tack, and 5 knots on the starboard tack....

Has anyone had these kind of problem? Any Sun Fast 26 owner as the tuning guide for the boat?

Best Regards, Fair winds,

Pedro Bica

[Don Reaves]

I have had a couple of boats that sailed better on one tack than the other, but not to the same degree that you have. There are a number of possibilities:

Is the boat loaded more heavily on one side? You would see this at dock or a mooring as a list to that side.

Is the mast really perpendicular to the deck? The best way to check this is to haul a long tape measure to the top of the mast using the main halyard. Measure to a corresponding point on each side, such as the shroud chainplate or the base of a stanchion. Be sure to use the same amount of tension on the tape on both sides.

Are you trimming the sails the same way on both tacks? In particular, are you leading the jib/genoa sheets to the same point on both tacks?

There is another reason why you might see different speeds on different tacks, at least on a single day. If the wind and waves aren't from the same direction, the waves will slow you down on one tack more than another. Be sure you make your measurements under a variety of different condition.

Good luck,
Don Reaves

[pedbic]

Hi Don

I've noticed this problem on the boat, since I've bought her.

The weight distribution on board is well balanced, and I've tried with different wind and wave condition, and the result is the same.

I think the problem is the mast tuning and I'll give it a try, and measure it as you suggest.

But one question still remains, if the mast is perpendicular. but the inner shroud's aren't well tuned, can it be the answer to this?

I'll leave here some feedback.

Thank you for your reply!

Best regards,

Pedro

[tedp]

Hi Pedro

Did you measure your speed using an onboard log instrument like a Raymarine ST60? On my SO32 the log reads differently on the starboard and on the port tack. In my case I think this is caused by the paddlewheel sensor under the hull being positioned to starboard about 10 cms off the centre line (side by side with an echo sounder sensor which is on the port side). If I read the speed using the GPS it's roughly the same on both tacks.

Ted

[rene460]

Hi Pedbic, I am assuming that tedp is correct and that you are using your paddle wheel sensor instrument to measure speed, not a GPS. These instruments are very sensitive to the direction of water flow over the wheel. As localized flow direction past the paddle wheel varies greatly from one tack to the other due to heel and leeway, they will not normally show the same speed on each tack. Apart from the effects noted by other replies above, your speed on each tack is probably much closer than you think. But I also find the slow reading discouraging. Even a cheap GPS with no maps will give accurate speed, (and heading to compare with your compass for leeway indication) though no allowance for current if you are on a river or tidal stream. But preferably buy a cord to plug it in to your boat battery supply otherwise battery life will become an aggravation. If it is any comfort my instrument can show 2.5 knots on one tack and 5 on the other, but nearly the same on GPS. So do not worry about it, though it affects any true wind direction and speed calculation, so worth striving for best average. Just go for best speed on each tack.
But to your main query, mast tune is a very fine tweak on boat speed apart from the necessity to get a curve similar to what the sail maker expected so you get good sail shape. If you have a bendy mast and an adjustable back stay you can adjust on the run for good sail shape. On a more fixed mast, such as my SO 30i, shroud and back stay tensions must be adjusted to get curve that gives best sail shape. Brouse www.mysailing.com.au/ for some very good technical articles on mast tuning. Main common requirement is mast should never, never, never bend forward at middle, and preferably the lee shrouds should never go slack, though this is more important as wind strength rises. Bend mast to give moderate main sail draft with max in front half of sail, and sufficient fore stay tension to get jib shape and draft looking good. Remember sail shape is first and main priority.
rene460