Thread: 105 Sq Ft Lug for PDR ?? is it to much??

There's a picture of Mik sailing a PDR with a 105 square foot GIS sail on his website here.
From his comment:

"The PDR handled the big lug rig beautifully, sailing upwind and down sedately under control and accelerated quickly to quite high speeds in the light breeze. It tacked and gybed reliably as well."

It would seem the standard mast position is fine for the bigger GIS rig in terms of fore and aft balance.

Also from the same place he expresses concern that the PDR mast is too light/flexible for the bigger rig:

"I was only game to sail in quite a light wind as the standard OZ PDR mast is too lightweight and flexible for such a large sail area – I was worried about breaking it."

I guess you'd have to do a mast at the GIS mast dimensions and size the mast step/partner accordingly.

It might go quite well in light conditions, unless you were tall, heavy and fit and keen to hike out like the laser sailors, you'd be reefing pretty quickly as the wind got up.

Mik was last seen in Europe, (Loire Valley?), people who follow him on Facebook might have a beter idea of what he's up to at present, but I think he's having a break from all this online communication/support.

Ian

I have the balanced lug on my pd and it works well, i just did it all to Mik's plans, as a bonus the mast is shorter and easier to pack and transport, I put the reef points on the sail from Mik's plans and after washing and drying the sail pack it up with reef points tied, I also made lazy jacks and the reefed sail is really easy to set up on the beach and then once I am out and in a clear spot I unreef. My mast is 11mm wrc and while it bends like crazy in a big blow it has never looked like breaking even when I put the nose under a couple of times when being a bit dumb in big wind I also did the sail in polytarp as per Mik's plan and have had it out 20-25 times and the sail is still ok!

Thanks for the reply...I have MIK plans for the lug for the PDR...I just can't find anywhere in them, the measurement from the front of the mast to the end of the boom.....He refers to the GIS skiff, but then says each boat is different....

Does the Balanced Lug just wind up in the right place or can you move it forward and backward as far as the length the boom sticks out in front of the mast. I guess that is determined where you have the block on the yard???

Maybe Im missing something

Thanks for any info
Mark

MIK's guidance on setting the GIS rig has been pretty flexible. Fix the halyard lifting point somewhere between 40-50% from the yard's leading end.* It can't be more than 50% because the yard needs to hang cantilevered out from the lifting point. Plus, the rig will set closer to the hull the closer you come to the yard's mid point. In the other direction, you get a variety of effects: greater cantilever force (that you are pulling against as you haul the halyard); higher and higher set of the rig; movement of the center of effort farther aft, affecting helm balance.

All of these principles will apply to the OZRacer hull, but to a different degree. I think MIK's intent is for the skipper to have a general starting point from which to dial in and tune based on how she behaves.



*P.S. It does occur to me the the GIS lug is a higher aspect than his OZRacer lug plan. It is possible that the lower yard angle of the OZRacer lug might call for a change in those numbers to 35-45%. You'll find the sweet spot and it might change with differing conditions.

I heard he was up here in Sydney for a PD Racer launch on Sunday.

I just shot an email through to the people i bought the plans off and they forwarded my question on to Mr Storer

How do you know when you find the "Sweet Spot".....Is a Balanced Helm or is it when the sail shape looks the best??

Assuming I will have off set daggerboad that I can tilt forward and back to adjust the Helm balance to the CE of the sail....is it better to have the sail yard at 45%, which would place the boom farther forward, ahead of the mast, which in turn gives me more sail area in Front of the mast, on the "bad tack", which I assume is less sail area in the "good" zone....

Or

Is it better to have it at 35% back on the yard, Which would place the front of the boom closer to the front of the mast which would have less sail area leaning against the mast on the "Bad Tack".....I will be racing, so thats why the nit picking.....Or Does it Matter?? . Inquiring minds want to know

Thanks again
Mark

Mark, if you haven't done so already, check out AlexN's thread on "Wood Duck." His recent launching pics should give you more insight into MIK's lug and how it sets ont the OZRacer. MIK attended the launch and sailed with AlexN, so there's a good chance that the rig is set up in it's optimum spot (but not guaranteed).

Howdy .. the standard sails for the OzRacer are
Balance Lug 89sq ft
Three sided sprit sail 82sq ft

The quotes about the 105sq ft were from a time when we had the Goat Island Skiff sail on the OzRacers to win the "largest sail area record" for that year.

The standard sizes work really well. I've had the sprit out in 25 odd knots and the lug rig reefs of course.

We used the Goat sail on the OzRacer sprit sail mast. This is not recommended because the top of the Ozracer mast is too tapered so too delicate for the bigger goat sail.

As a testament to the stability of the boat and the efficiency of the foils .. it handled beautifully in light wind with the turbocharging.

Best wishes
Michael

Thanks MIK,
Do you know where I should put the block on the yard, for the lug rig???

35% back...40% back....from the front of the yard or throat of sail?? Just wondering if you have a number? or how far the boom should be in front of the mast, but I guess that is determined by where the block on the yard is placed..

It goes about halfway back Mark.

It feels counter intuitive .. but it works correctly there.

Michael