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NACRA 5.8 SQUARE TOPS


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The first major event with the new NACRA 5.8 was last weekends Qld State Titles.  There are now 8 boats using the new square top and more are on order. 

 

It might be time to get some views from sailors as to how the new sail went, what are its strengths, how the rig needs to be set up and sailed.

 

There were 5 x 5.8’s at the States.   While at times (particularly off the wind) the square top seemed faster than the pin tops - overall the speed around the course seemed similar.  Conversely the finishing order of boats at the end of the regatta was similar to what would have been expected in similar wind conditions should only pin tops have been used.  There were no stand out improvements in results, but what was clear was that while the development of the pin top is at its peak there is significant speed is to be had by the crew who can quickly develop and understand how to setup and trim the square top.

 

Prior to the regatta when asked how to work the new square tops Warren from Bris. Cats he advised :

“We found that once two on the wire with 10 plus knots we rotate the mast around to about 50% as we find the mast has more strength sideways then fore and aft.

If we don’t rotate to this the front of the sail seems to full.

 

I took myself 4 years when jumping of the 5.8 to Infusion to really understand square tops.

We use to sail with heaps of downhaul and keep the mainsheet on like the old pin top.

After years of soul searching and speaking to everyone the answer I got back was to-Ease the mainsheet.

It is a combination of the d/haul and mainsheet that works.

The boat is easier to sail with square top although completely different sailing –I feel that the crews that make the switch early will be the ones that will gain the most as all takes time.”

 

At the start of the regatta the general consensus was that (as with all square tops)  powering and de-powering the main is best by easing mainsheet which loosens the leach and allows excess wind to ‘spill’ from the top of the sail this is in contrast to the pin tops which use downhaul tension to induce mast bend and flatten the sail.  In this regard most boats where set up with a reduced spreader rake (between 18mm and 30mm) and very tight diamond wire tension (31 on the gauge) to reduce sideways mast bend - which if not controlled causes leach flutter.  

 

On the water most crews were using minimal downhaul, the danger with using excessive downhauls was a rapid de-powering of the sail and leach flutter.

 

I spent a few hours on Nic Nac after the regatta and made the following observations which I offer for comment (none of which can be concidered to be expert advice but just my observations and interpretation)  :

 

General Setup.  The reduced spreader rake and increase diamond tension stabilises the shape of the sail from diamonds down and puts a prebend in the mast.  The extent of this prebend (and its effect on the flatness of the sail) does not change greatly with the use of rotation, downhaul or sheet tension.  It seems that the flatness of the main (hounds down) can be effectively controlled by spreader rake and this may be a way for lighter crews to find a setting which will make them more competitive over a greater range of wind strengths.

 

on the water.

Upwind.  we only sailed in light conditions (up to 8 knots) in the very light wind  it seems easy to over sheet the main causing the leach to hook if the clew board position is too far back.  In really light winds it seems that the forward clew board hole works best but once the pressure on the sail increases to point where the top of the square top can be held straight a position further back can be used and then the main sheet tension can be used to prevent the top of the sail “spilling” air and power up the boat.  Conversely reduced sheet tension was a very effective way of “dumping” the power out of the sail by spilling the air from the top of the square top.   

 

What was very interesting was that with a small amount of downhaul tension the top part of the sail (hounds up) could be use to induce the spill of air from the square top - there was a direct connection between downhaul tension and the direction of the upper leach tell tail.  Even more tension would invert the top of the sail.   I think crews will need to focus on this when trimming the boat.  There will be speed to be had to the crews who learn how to change gears with mainsheet and downhaul settings when sailing in and out of gusts. 

 

Downwind.  In a word, fast.  The sail seems to hold a more consistent shape downwind (though the use of a stiff pre-bent mast).   The danger seems to be not using enough mainsheet tension and not letting the traveller out enough (in some respects opposite to what the pin top likes) which de-powers the sail by spilling air out of the top of the sail.

 

I expect that in heavier conditions sailors will need to keep the main sheet on to prevent the top of the sail trying to push the noses in - this is only a guess-, but I have a similar issue on my 18 sq square top.

 

in summary I bought my first  new 5.8 from Roscoe in 1988 and have owned 7 more since then (and have just bought a new one).  My first impressions of the square top are the same as they were with the pintop in 1988 - an awesome boat with so much untapped potential.  I for one can't wait to see what some of the more talented 5.8 sailors can do with this new piece of kit.  

 

My first 5.8 would now be 28 years old and probably in some club racing fleet or under a tarp in someones shed or back yard (and most likely parked under a tree),  if not being sailed it could be with some TLC.  I am confident that given the overall build quality of the 5.8 the latest version  will extend the life of this magnificent class well into the future.

 

If any of our sailors from the weekend have something to offer on the square top it would be great if you can post it here so some of our newer crews can get and understand of how they can go faster and better enjoy their sailing.  

 

Craig

 

PS for all of you out there counting sail numbers, when the Bridle foil was introduced the run of sail numbers was stopped and reset at 1500.  Brisbane Cats have decided to do a similar thing with the square top.  The  current run of sail numbers has now ended and has been recommenced at 1700.  Any new boat supplied with a square top as standard equipment will be numbered 1700+

 

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Good summary Craig. I'd just like to add that as a bystander, sitting out near the start line on Sunday, I watched a couple of pin tops (one of the venom boats at least) and 4 square tops all sailing upwind in a row in good two string conditions.

Warren was noticeably faster than the two pin tops, seemed to have no downhaul on and was well powered up, whilst nic was somewhere in between the Warren and the pin tops but looked to have significant downhaul on and might have been starting to get into the overpowered region. 

I suspect that a good regatta in moderate conditions will highlight the differences.

I'd be interested to see if the fleet transitions to the crew working the main sheet as is common on other two crew square to boats and the skiffs.

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I used mine for the first time today in a distance race, wind was around 18 to 20 kts plus some puffs, distance raced was 61 km got a bit of time to get used to it, got soundly flogged for the first 5km beat including by a 1400 series pin top but then got used to it and managed to get a good result. Pointed well against the taipan 5.7s etc, was told to let downhaul off in the tacks but just roll tacked it and it tacked just fine, used plenty of downhaul, not as much as the old sail but got the sail a long way down the mast. I'm very happy with the way the sail goes and the workmanship is spot on. I have to cleat due to injuries and found the cleat angle is one more hole higher than before

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Excellent summary Craig, and interesting observations nickopen. The Qld States was the first time we had sailed with a square top. Up until that point we had sailed with a pin top that was approximately 8 years old.  I tried the sail the day before racing with the same settings as the pin top - lose diamonds, spreader rake of around 41, mast rake about 100mm in front of the hatch cover and lose rig.  We found the same bend in the mast was achieved by using much less downhaul and a little more main sheet. The only change I made for racing was to tighten the diamonds and decrease spreader rake to the settings mentioned by Craig above. As neither myself or Pauline had sailed with a square top rig before, we sailed the boat as we had with the pin top, ie. with Pauline working the downhaul and me working the main sheet.

While racing we didn't really observe the technical aspects of the sail, we just focussed on what we were used to doing. So without going into technical detail I can offer the followings observations on points of difference:

Downhall - In the moderate conditions when we were two on the wire, a small increase in downhaul had a greater effect on the boat than it would have with the old pin top. It was noted that less downhaul was needed to control the boat.     

Main sheet tension - In the light conditions it was very easy to over sheet.  This was consistant with Craig's observations above. In tight situations when height was needed, traditionally I would strap on and pinch, however the square top didn't seem to like this.  We found ourselves getting buried time and time again at the start by strapping on too tight and choking the sail. The pin top seemed to be more forgiving in this respect.  When the wind increased the main sheet had more effect on mast bend.  We found that the last bit of main sheet tension would pull the sail down the track and override the downhaul.

Smoothness of the boat - it's hard to describe this, but the boat seemed smoother with the square top.  Upwind, once we found the groove, the boat seemed to want to hold itself there for longer.  Subtle changes in wind pressure that would normally alter the lift of the hull did not appear to have the same effect as it would have with the pin top. 

Downwind - This is an area where we have always felt strong in light air so it is hard to say what the differences were.  We sailed with more mainsail twist than 1700 and deeper than most other boats. Which seemed to work well against all boats except 1700. 

We were happy to have achieved a second place given the calibre of sailors within the fleet.

Nick

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