650 TECH TOPICS
New Boats vs Old Boats
The following article was put together by long time 650 campainer Ted Philipps.
Ted’s resume includes winning eight Victorian 650 titles.
Since launching Kindred Spirit we have been asked many times "Does the new boat go any faster than Veterans Affair?".
In this article I shall attempt to answer these questions to the best of my ability, but in doing so please accept that these are my opinions and our sport is so complex another persons opinions may well be equally valid.
The first subject is the question of sailing weight.
Both VA and KS displace 900kg in racing trim ie meeting all legal requirements without crew.
Sailing weight makes very little difference in hull speed, except in acceleration, this is most noticeable on leaving a star line or a quick tack or surfing down waves in strong winds.
For those who choose to race their 650’s with all their cruising equipment in situ (for eg 1000-1200kg displacement) will not feel much difference, but a lighter boat should be quicker at the end of any given day.
Subject no 2…mast and rigging.
VA had 3 masts while we sailed her. First was a castle Marine 76mm diameter tapered and welded ali section supported by 4mm cap shrouds and 3mm lowers and forestay.
This mast was OK but failed when a lower shroud broke on a 15kn broad reach (corrosion).
The second mast was very similar except it was 80mm diameter. This mast worked fine, except when we determined the best rake setting and the mast bent under sailing load, the base loaded up the forward part of the mast support which subsequently collapsed.
For mast number three I wnet for a Spunspar section 80mm diameter because I had seen them on other boats and liked the concept. The main feature of the Spunspar mast was the pivoting mast step that carried the load under the centre of the mast regardless of rake angles or mast bend. Unfortunately without the added support of the flat mast step this mast failed in compression 2 metres above the deck on a day gusting 35 kn and we were trying to set a kite. This was a rather silly move on my part.
For the mast on KS I went for the same Spunspar sectionand the same nast step design except I fitted a sleeve up from the base for 2 metres and increased all the wire rigging to 4mm diameter.
The tuning of the mast on KS has taken us a full year to get right. To achieve the combination of correct mast rake, correct prebend and correct lower tension takes hours of fiddling. I was amazed how the boat responds to very fine adjustments.
Mast rake adjustment is carried out to get the best headsail leach setting. Prebend is done to achieve an even mainsail luff curve and is controlled by spreader angles and lower tensions. The tension of the lowers is critical to the amount of forestay sag that is occurring which effects the boats pointing ability.
It can be observed on many boats racing that not too many have an even mast bend and subsequently are carrying mainsails that are too full. Many boats have excessive luff sag which creates too much headsail fullness which in turn overpowers the boat and backwinds the mainsail.
Subject number 3 …Sails.
The controversial method of making mainsails with too much roach in the top section is heading in the wrong direction (again my opinion). I believe that the hull design does not have a lot of power, therefore does not support a lot of force aloft. The fastest boats in recent years have had mains with minimum girth dimensions in the upper sections. As far as headsails go a medium cut sail is adequate. The hull does not support the No 1 sail above 18 knots, it is so easily driven in 0-5 knots that a special lightweight sail is not required.
On KS our No 2 headsail is 100% ie it fills the fore triangle only. This sail is carried up to 25 knots then we go for a small storm jib.
We very rarely consider reefing the main and if we do then it is time to go home ASAP.
Our thoughts on spinnakers are based on the fact that the boat will not carry its sailplan well on anything shy. Therefore spinnakers should be as full as possible.
I disagree with sheeting jibs on the cabin top. Because the hull is relatively short, the slot between the headsail leech and the mainsail needs to be fairly wide once the wind pressure is up. Sheeting off the deck close to the inner edge is quite satisfactory. Sheeting sails as close to the clew as possible enables good leech control under a wide variety of pressures.
Subject number 4 …The Rudder
This part of getting KS right took a while to figure out. VA always had very good control under all conditions but when beam reaching in moderate to heavy air the helm was very heavy. When fitting out KS I decided to rake the ruder forward as far as possible to make steering lighter.
This was successful…however two problems occurred. A - the boat had no control at all in 0 to 0.5 knots hull speed. And B - when reaching with spinnaker in 15+ knots the boat would round up uncontrollably as the flow would break away and cavitate totally. VA never did this, so I rebuilt the rudder stock to position the drop blade leading edge at right angles to the waterline. This overcame all the problems and I am still willing to put up with heavy steering.
Subject number 5 …Centre Plates and Ballast
This part of the castle 650 has the opposition and the "experts" looking for reasons to penalise the class for improved performance on CBH. However I believe there is insufficient evidence of this sofar. The designer/builder has, by taking the all the ballast from inside the hull ad placing it in the keel, made the boat far safer by improving the self righting factor whilst at the same time retaining the ratio of ballast to hull weight.. Again this is my opinion.
The differences between VA and KS are as follows:
KS is much stiffer in light winds and requires more crew weight adjustment to keep the angle of heel correct for optimum performance. In heavy air the boat seems stiffer and allows 3 crew to perform well against 4 crew on the earlier boats. It appears that the wind range that the boat can best perform at its best has gone up about 5 knots, all other aspects of the boats performance have remained the same.
As far as performances in 2000/2001 were concerned, KS only won a couple of races in mixed fleets, but in the remaining races we managed to be well placed.
I believe the changes made to the newer boats has not made the older boats non competitive and by sailing well every dog can have his day.
I hope sharing some of our experiences can be of benefit to fellow members of CYOAV…we wish you all good sailing.