First 3- day cruise: Good time & bad suprise? Help!!!

[bei.beckers]

Hi Scampers,

i had 3 days off with my son on a lake in northern Bavaria in winds of 0-3 Bft. We tested my new scamp SØSYG (danish: seasick) and the new tent.
Both of us had lots of fun! In force 3 sailing is really a pleasure (no ballast, no reef). We could tease some much larger boats as long as we didn't reach our hull speed provided the other boat or crew weren't explicit race oriented.

But i must admit i am disappointed from the low wind abilities. Of course i didn't expect to catch a catamaran with 20ft² sails, but at low wind force it was a quite chewy matter, making me testing the oars more often than expected.

But what is really irritating for me is the following:
At approx. 1 Bft, wind from portside, the rudder was neutral and i creeped along with a lot adrift making nearly no way windwards. Just if i tryed to go too close i had a "stall", so i needed to get some speed leewards - not nice but OK. Tacking was tricky, but possible.

With wind from starboard it really sucked: the Scamp had a strong leehelm so i had to give ca. 25° rudder windwards (which of course is a nice brake)! At low winds it was impossible to tack- Scamp turned without any controll 90° - 180° leewards! Did anyone spot something like that?

My build shurely is not perfect, but using a kit and paying attention to have rudder and CB with symmetric profile and skegs parrallel to the CB i don't have a f#~*$* idea, why there is such a difference! Any ideas?! Help!!!

cheers, Martin

[scamp14]

Simple answer: your sail is not set optimally.
Complex answer: the centre of effort of the sail is too far forward.
Simple solution: check out this link
https://www.storerboatplans.com/tuning/ ... lug-sails/, make sure you sail is set up as the drawing on sheet 1 of the plans and put the down haul on hard.
Then experiment: lee helm, move whole sail backwards, weather helm move, whole sail forwards, keep centerboard fully down.
Paul

[bei.beckers]

Hi Paul,

thanks. Good approach, i'll study the link carefully. But i doubt this is the problem: with wind from portside everything is not perfect, but still OK. Nearly no lee- or weatherhelm. Scamp isn't a racer, so this could be accepted.

But the boats behaviour is significant worse with wind from starboard. Why? I set my sail left of the mast, so i'd expect better thrust on this side. The of- centerboard is located on starboard, so if any there should be weather helm from the CB's off- mid- resistance.

Adjusting the sail makes sense every time. But where is the root of this inconsistent performance with the wind on one side or the other? A poorly set sail would cause the same poor drive on both sides, wouldn't it?

cheers, Martin

[wdscobie]

I've sailed SCAMPS in light winds and found the boat did just fine - better than a larger boats could do as the SCAMP is light and has a large sail area for her size.

Sail trim and boat trim are are important. Especially sail trim on a lug rig.

The above link about sail trim is a good start. Others can give hints as I'm not the best at trimming a lug rig.

For boat trim how were you both sitting in the boat? How were you heeling the boat to windward, leeward or keeping her flat?

Each boat design sails differently and needs different 'tricks'. Basic sailing experience helps but time 'in the seat' is needed as some things that worked on a boat you have sailed before may hinder on the new boat. I call this 'unlearning' as one learns the new craft's tricks.

[bei.beckers]

Hi Dave,
we were sitting in the middle - slightly aft..

I preferred to heel Scamp a little leewards in oder to avoid the boom joggling due the wind "pressure" was close to zero at 0-1 Bft. So my son beeing 30kg lighter than me was sitting windwards.

I attatched a pic. of the sail as it was on this trip.
I tied to have the downhaul quite stiff. In light air i released the rear clew of the sails foot a little bit in order to have a more balloon- like, fuller sail.

Any comments or improvements to what i wrote here?

best, Martin

[Rob Hazard]

Martin,
In addition to Paul's link to Mik Storer's article about tuning a lug sail, I would suggest that you make sure that your centerboard is staying fully down. How much lead did you put in it?

[bei.beckers]

Hi Rob,

thanks for this idea. I don't remember the weight, but i had well 1kg more than the plan suggested. The uphaul was under tension in 4 Bft even with wind from aft the CB down (i know, that doesen't make the best speed...- but i wanted to try exactly that the CB is well ballasted). So i don't think the CB is a problem. The boats crazy way to move exists only in very light winds from starboard.

[scamp14]

Looking at the photo: the gap between the yard and sail at the front end could be producing considerable drag and upsetting the flow over the sail; also the luff is not parallel to the mast which means there is a bit more sail area in front of the mast and high up which changes the centre of effort.
The mis match in performance that you have experienced is unlikely to be due to an build problem as other wise more people would have reported on it. It is very difficult to build a boat which is symmetrical.
Paul

[bei.beckers]

Hi Paul,

so your suggestion is to get the sail closer to the lower end of the spar and to move the boom to the bow in order to have the luff parrallel with the spar remaining in the current position. Did i get you right (English can be tricky for me sometimes...)?

[scamp14]

No, my suggestion is to tightly tie the head of the sail to the yard so that there are no gaps between the yard and the sail for the full length of the head of the sail, this is after you tied both ends of the sail to the yard under tension as shown on Micheal Storer's web page. Then to adjust the suspension point of the yard so that the luff is parallel to the mast.
You can see from the photos of Scamp 14 what works for me.
Paul