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Dragon tales…

Lurking below the OPUS rig which has been getting all of the attention lately is my new hull design, the Dragon. Construction is a hybrid form of my usual system, EPS foam core, balsa wood sides, stem and transom with a high density foam bottom. The bottom is 5mm thick and this allows the chine to be easily sanded to give a nicely radiused ‘soft’ chine. The deck will be 1/32″ laser cut birch ply and internal structure to our usual pattern, which means simple and as little as possible.

dragon_25 

The Dragon shape is changing a little from the prototype seen above, the stem or bow will be 1/4″ deeper and the transom 1/8″ shallower. This gives a little more reserve bouyancy at the bow and increases the deck rake a little, the transom angle is being increased too. The trailing bulb is an important feature of Dragon which allows the weight to move aft without compromising the distance between the fin and rudder, and therefore rudder efficiency. As the kit version is being built I will be adding a dinghy style spray rail and a lift off wooden hatch as has proved so effective on the recent Pond Sprites.

dragon_24
Production version of the Dragon foam core. 

The Dragon is a long hulled (fits diagonally in the measurement box) ‘new rules’ boat. She is designed to use a 3x AAA cell battery box for race performance but is definitely capable of carrying a 4x AA battery pack in a standard square battery holder. Being designed for and alongside the new OPUS una rig that is how the kit will be set up.

I am really excited about this project and will be moving ahead with it at full pace. As a result I am going to move forward with this boat ahead of the Pond Sprite project. I also intend to trial the Pond Sprite with the OPUS rig because I know that some people prefer a wider, 12″ long plywood boat and if the combination works then Pond Sprite will be a nice beamy alternative to Dragon. More news as it happens.

Graham

housekeeping

I have been doing a little reorganising around here so I thought I should explain. There is now a new tab or ‘page’ at the top called ‘the OPUS rig’, this is where I will collate all of the information about our Scale Sailing OPUS una rig. Some content will be copied from the normal blog postings so as to keep the information easy to find. All new information about the rig, using it and tuning it will appear on that page so please check it out and watch out for updates.

I have secured a supply of 3 cell battery boxes with integral switches. These boxes are in AA and AAA battery sizes. I am converting them for RC Footy use by the addition of a universal receiver plug.

batbox_1

These battery boxes make for a neat installation and save the space and weight of a seperate receiver switch. However you must use ‘Energiser Lithium’ batteries to provide enough voltage from 3 cells rather than the usual 4. These boxes are available from ScaleSailing at $5.90 for either size (AA or AAA). Using any battery size and type you wish is now legal under the new 2009 Footy Rules.

batbox_2

dragon_13

Over the winter I have been developing a different style of una rig and a new footy to test it on. Early talk about flexible rigs and their benefits for use on footys centred around the flexible mast but apparent complexities in their design meant there was little development in that direction. Later the  ‘McRig’ came on the scene and it’s simplicity was infectious and it has become rightly popular. Rather than the mast bending it used a torsion bar for the mast pivot allowing the whole rig to flex from it’s base. I wanted to go back to those earlier discussions and see if I could make a bendy mast rig work.

In developing OPUS I was inspired by the una rig on the Laser dinghy. The curved mast on the Laser is shaped by the sail pocket. I decided to create the mast curve with a backstay instead which allows the mast to be shaped independant of the sail thus allowing some sail camber control. A pure Laser rig would have the mast set too far forward for a short hull like the footy so I have adopted an offset pivot on the main boom so the rig now became a una swing rig. I have been careful to allow no flex at the base and boom mounting so all of the flex and gust reaction is handled by the flexible carbon mast and sail itself.

dragon_18

The OPUS rig was tested briefly in the light Fall airs here before the winter freeze set in. Over the winter the idea was developed further and hand held tests in varying winds were photographed and studied to see how the rig was behaving. Clearly the rig worked nicely as a swing una rig which would make it a nice rig to use were it simply a stiff unit. What I was looking for was how would it behave in gusts as this is becoming a key element in racing footy design.

composite-opus
steady breeze                        stronger                              gust reaction

Well the results looked good, in a gust when the rig is close hauled or in a reaching position the mast bends away to leeward as might be expected but it also curves back more under the action of the sail and induces more twist in the sail. We know that bending away and dumping some wind in a gust is good but increasing twist is possibly even better. The movement adds upper drive due to the twist while dumping air and also keeps the lower area of the sail as set and driving the boat forward.

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‘Laser’ style swing rig in action on the Dragon prototype.

The ScaleSailing Dragon/OPUS combo saw water again on the Friday of the NCR in Orlando, FL. I took the opportunity to sail the boat and with a good but variable wind blowing was able to see how the newest version of the rig behaved on water compared to land in a variety of wind strengths. It looked good on the water, I particularly like the elegant shape of the curved mast which was different from everything else on the water that day. The sail approximates to an elliptical shape which is typically considered to be an efficient planform. Tacking was quick and easy with the sail filling quickly and the boat accelerating away well. I think this initial sail size I have chosen handled the stronger wind well and should make a good ‘working’ rig to cover a range of conditions. Being used to sailing two sailed sloop rigs I did love how easy it was to turn on to the run downwind and not have to hope the jib popped out opposite to the main. Yet there was no odd behaviour as is sometimes reported for the classic two sail swing rig set up. I am prepared at this stage to say that this OPUS rig works and works well. Clearly there will be things to learn in tuning it, controls available are mast shape via the backstay, sail foot shape and initial twist shape via sliding rings on the boom.  

As an aside, construction of the prototypes proved difficult to get the required accuracy so I had a friend make a special tool which now allows me to make the boom/pivot/mast stub assembly quickly and with the required accuracy. When the ScaleSailing OPUS rig comes into production the boom assembly will be supplied ready made along with a prefabricated mast/masthead and sail ready to simply plug together and play.
dragon_14

All content of this blog including text, photographs and the model designs are the sole property of Graham McAllister Designs.
Copyright 2009 by Graham McAllister Designs.

The first National Class Regatta for the Footys really was a great event which I thorougly enjoyed despite a raging head cold. Darrell and his crew of organisers did a very good job of keeping things moving along and keeping the skippers happy. The courses set worked out well by using a basically rectangular course to spread the beating and running boats out.  At times the distant marks were well out there which I like, gives you a sense of going somewhere.

As planned I sailed one of the new Pond Sprites which I had built for the event. I chose my ‘working’ size ‘A’ rig as the winds were pretty variable from very light to a stiff blow with strong gusts during each day. There were times when this was just simply too much sail area and the result was the occasional broach and moments out of control when a bad gust would hit while on the run downwind. Beating into  and across the wind the boat handled the wind strength with no problem. But as a few skippers discovered again, even these winds were nowhere near enough for the tiny ‘B’ rig to be of any use so changing to the ‘B’ was not an option in my opinion.

Saturday started with light winds for just the first race or two then increased to give good racing with occasional gusts which created a certain amount of chaos in the fleet. I must admit that I sailed poorly on the Saturday and made some mistakes the most significant of which was to get totally confused after a course change and actually stop racing while in second place because I thought that I had finished! By the time I realised my mistake and returned to the course my 2nd place was a 10th place… very embarassing and costly in the end! By the end of Saturday I was in 7th place and not particularly impressed with my performance! The Pond Sprite was great though and came through from poor starts to good finishes on several occasions so I know it was better than I was.
ncr_2
Pond Sprite (yellow main) makes another poor start.

Sunday again started very light and flukey which I must admit are conditions I like. I won the first race which bucked me up no end and set me off on a much better days racing. Pond Sprite won two other races including the last, took two seconds and three thirds as I remember. By the end of the day I was very happy to take 5th place overall with 51 points, just 2 points behind 3rd and 4th which both had 49 points. Actually I wish that I had been further behind because now my mistakes on Saturday really hurt! Anyway the prize giving was fun and full of laughs which I think pretty much summed up the whole weekend. Once again it was good to meet up with old friends and make some new ones over the weekend, here’s looking forward to next time.ncr_1
I was pleased to see my friend Ed Rohrer finish in 8th place with his Kittiwake K1.5 (that’s an early Kittiwake with a K2 rig). The photo above is Ed and me looking over his set up.

We are still away on our travels and I found an unwatched computer 🙂 so am taking my chance for a quick update. The Orlando NCR regatta weekend was great fun and very well run by everyone involved. I’ll have some photos and thanks to add once I get home. Racing wise I had an average Saturday and a decent Sunday which pulled me and Pond Sprite up into 5th place overall, out of 23 starters. So I am pretty happy with that. Pond Sprite went well, especially in the lighter wind races when she came through the pack for good finishes from bad starts… in other words the boat is better than I am.

Friday gave me a chance to get some more testing time too on a new design called Dragon. Dragon is a ‘long’ fairly narrow design in the current style and is also my test bed for a new style of una swing rig I have been working on which I call the OPUS rig. In the fresh breeze I was very pleased with the rig’s performance and ability to react to gusts etc. OPUS and Dragon drew some nice comments, more about this new rig and boat along with photos next week when I am back on the boatyard computer.

Until later,
Graham

Well the ‘Orlando Twins’ are coming along nicely. Both have been finished in spar varnish over the ply hulls and deck with the balsa hatch covers being spray painted in off white, lead bulbs to match. One of these boats is for sale and I just put details of this at the web site. Click on the ‘Specials’ link on the contents page at www.scalesailing.com
orlando-ps_22

I am fitting my Spektrum DX6i radio control with tiny (3 gram) AR6100 receiver in the boat. I have sailed with this radio quite a bit now and radio range is as much as I need with a footy even with the shorter range receivers such as this one. Next I need to sort out a range of rigs ready for the event. I have three ‘A’ size rigs so far and need to build a small ‘B-rig’ in case the wind gets up strong. I like to use a small ‘A-rig’ rather than the rules specified ‘B-rig’ in windy conditions but over a two day event it is just too risky to go with a small ‘A-rig’ and lose the choice of a larger rig if the wind drops. So I will make the biggest ‘B’ I can! 

Only two weeks away now and I must admit I am getting pretty excited about our trip down south to race and of course holiday.

windy weather footys

Over the weekend I was asked for my thoughts on windy weather footy sailing by a group in Florida. I thought more people might be interested in a few ideas of how to handle strong wind conditions and  I can perhaps expand here on how I answered them.

The first thing to say is that the wind can get too strong for any size rig, even the tiny ‘B-rig’ as specified by the footy rules will simply be too big for extreme conditions. So these thoughts will assume that although the wind is strong it is not enough to change down in sail size. So we will look at how to tune the sails to manage the conditions better. Also this discussion assumes you are using a sloop rig with a main sail and a jib sail. 

Your main tool to combat strong wind conditions is sail twist. Allowing the sails to twist away from the wind towards the top of the sail will dump more air from the upper parts of the sails but maintain a good drive from the sails. The mainsail twist is controlled by the kicking strap or vang fitted from the main boom to the mast. The jib sail twist is controled by the ‘topping lift’ which is the line running from the rear of the jib boom up to a point on the mast or mast head where the forestay is attached.

By loosening the kicking strap the main boom will be allowed to rise and in doing so will control the amount of twist in the main sail. Likewise tightenning the topping lift will raise the rear end of the jib boom (you may have to ease the forestay tension a little) imparting twist in the jib. Set the jib twist to echo the shape you see in the mainsail, look from the rear with the wind filling the sails to see this.

Pond Sprite showing sail twist in main and jib

Pond Sprite showing sail twist in main and jib

The balance of the boat in high winds will tend to gain more weather helm, in landlubber talk that means that the boat will turn up harder into the wind when you are close hauled sailing close to the wind. Using more twist in the main than the jib and flattenning the foot of the main more than the jib are ways to control this ‘luffing’ into wind. Also you can move the jib pivot further forward on the bowsprit if you have one to combat weather helm in strong winds.

Sail foot curve is generally reduced too in strong winds. Set the outhauls (rear bottom corner sail attachment on booms) to allow about a 1/2″ curve from the sail edge to the boom at the mid point.

For a strong wind racing day I like to have a rig (about the size of the original Kittiwake I rig) which is set up with the ability to add a lot of twist in the main and the jib. The rig can then be detuned to be almost like a B rig and tightenned up considerably if the wind does ease a little. Then if the wind does get even stronger you can still change down to a rules size B rig.

Victor V12 with nicely set twist in a blow

Victor V12 with nicely set twist in a blow

Those windy days can be enjoyed, not avoided with the right set up and tuning, give it a try… footys on a B rig can handle just about anything, just make sure they are watertight! And unsinkable is a plus!

Graham

inauguration

What a wonderful day it was yesterday to see the mass enthusiasm for the new President. As a still relatively new immigrant to these shores I have been drawn into the whole process since the beginning of the primaries and thoroughly enjoyed it all. I am one of those people who enjoy watching politics in action and this cycle has been well worth watching.

I know that as time goes on I am feeling more attached to my new country but for me it has been a very slow process. Not because of the people I know and love here, not because of my friends and the people I meet day to day. But because of the leadership and direction it has taken us in. To my British view it has not looked or felt good. With the promise of this change however, whichever way it had gone but especially as it has turned out, I have felt a growing attachment and of pride in what has gone on here. Until yesterday I had only lived here under President Bush. I am very much looking forward to at least the hope of seeing America become again what it should be. I think it will under President Obama.

Ok back to boats…


As mentioned in the last post I have just started to build a brace of Pond Sprites. These are serving a dual purpose in checking my latest laser cut parts plus providing two boats to take to the Footy National Regatta in Orlando in March. The prototype Pond Sprite came second in last year’s Sheboygan Footy Fest against some very stiff competition. Since then the design has gone through some changes on deck to give easier access to the internals with a single bigger hatch. The sides and bottom are now ply rather than balsa which is so much easier to finish smoothly and tougher too to resist the occasional bump. This is a medium width boat, 105mm (4 1/8″) at the waterline with a low rocker and blunt rounded bow. She handles very nicely, beats hands off and is very good down wind.

In changing to ply sides and bottom the weight will increase a little which will suggest the use of the lighter Lithium Energiser AA batteries to lower the battery weight. This new version of the boat is taking into account the change in the battery rules (for racing footys) which will allow any size or type of battery to be used. Once the rule is in effect I will most likely change to 3x AA Lithium Energiser or 4x AAA batteries of any type. I will do the same in my Kittiwake K2 also.

In the photo above I have just added the decks which are taped down while the glue dries. Next I will be fitting the rudder mount and fitting the keel fin. Then will come the finish, I am pondering how to do these two boats. I like varnished wood and usually varnish the deck and paint the hulls. I have found that all varnished wood can be difficult to see at distant turns when I am racing. However, I am thinking that a varnished hull with painted deck will make a change and will be easily visible. I also might do something outrageous and artistic… we’ll see.

Graham