WWW.RLYACHTS.NET
RL24, RL28, and RL34 Trailable Yachts
from Rob Legg Yachts

RL Yacht Owner's Discussion Forum

Your Name:
Email Address:
Password: ( Needed to edit or delete this message.)
Message Title:
Text of Message:
Add an Image:
An image can also be attached to this listing. Click "Browse" to select the image file on your PC. It can be a JPEG or a GIF file. The file will be uploaded to the server, scaled to fit, and will appear beside the entry.


Replying to:RL24 versus J24
RL24 versus J24 I remember reading a British RORC article on how the very popular and ‘tippy’J24 with its high SA /displacement ratio managed to upset all the relevant measurement handicapping and rating systems in use at the time. The then new J 24 was designed by Rod Johnston for some Minnesota ex scow racers and USA Midget Ocean Racing Club members, they wanted a boat that was different and more exciting than was available in the Great Lakes Area. The article also stated that the J in J24 came about because the owners of the first five boats on order were named ‘John’! They all wanted a small and exciting one design that would give them a cheap ‘round the can’ and passage racer without the hassles of handicapping. The resultant boat from Rod Johnson had a bigger than normal sail plan along with a small and relatively light keel which meant the boat would require substantial crew weight on the gunnels to get her to go well to windward. The light but relatively beamy boat would then in the right conditions hopefully plane downwind with help from a large spinnaker! The short 24 footer was very successful and had all the IOR race organisers pulling their hair out when they started mixing it with the faster rated 34 footers on a regular basis. The article went on to say that the prototype J24 ‘Ragtime’ which was built in 1977 was the big break through that sailboat racers were waiting for! Apparently the popular one design J24 forced yachting authorities all over the world to modify their measurement handicap systems to curtail their success. Other race organisers introduced a new division for these ‘Sports boats’ and anything that was light displacement, had minimal accommodation and planed was quarantined or dumped into this group. Now the yachting authorities are saying it is all happening again a couple of decades after the J24 was introduced and this time it is at the top end of the rating range. Apparently neither yardstick nor the measurement handicap systems can curtail or cover these long, sleek, canting keel and water ballasted boats that are built using modern high tech materials which are supposed to make the hull and rig bullet proof and stiff. If we have a closer look at some of the smaller so called ‘break through boats’ we find them all to be light displacement, off the wind flyers. It is quite obvious to me that it is the crew weight on the beamy gunnels and the boats ability to plane downwind that is giving them the advantage. I can hardly believe that this could be claimed as something new in sailboat racing as boats have been planing now for at least 75 years. Uffa Fox’s Flying 30 and Flying 35 cruiser racers which were based on the smaller flying fifteen’s hull shape were known to plane in the right conditions when built in the late 40’s/50’s. I have always thought that Uffa’s 1928 built 14 footer Avenger was the first planing sail boat in the world but after a wee bit of researching this week I am now convinced that the lightweight USA racing scows were definitely planing on the Great Lakes in the early 1900’s All these so called ‘rating rule wreckers’ were found to have the following in common: • A high Sail Area/Displacement ratio. • Lightweight planing hulls. • Small, low head room, uncomfortable and lightweight accommodation. • A low ballast ratio which gives them a low stability index. • A relatively large crew to pack the gunnels to enable the boat to perform well when going to windward. I find the above claims all rather misleading as Rob Legg’s wooden prototype RL24 which meets all the above criteria was first raced in 1972 before the J24 ever saw the light of day. The first production RL24 was fitted with only a 100 kg keel and when she was launched on 13 March 1974 in strong winds it took only twenty minutes before she was up and planing down wind! The J24 may be able to beat the older style IOR 34 footers home but I have witnessed the RL 24 knocking off the even faster 36 footers on all legs of the course. We all know that Rob Legg designed the RL 24 to be fast and also to break out of the displacement boat speed restrictions by planing down wind. Unlike Uffa Fox, Rob Legg encouraged owners, foil makers, mast makers and sail makers to experiment and improve the RL24’s boat speed. He was always in favour of the class association keeping the RL24 a restricted class which would encourage development in certain areas. With reference to CA Marchaj’s book “Sailing Theory and Practice” the famous USA yacht designer Nat Herresshoff skimming dish yacht ‘Wenonah’ built in 1892 could or might be the boat that takes the title of the first planing yacht away from Uffa Fox. She looks like she could plane in a breeze. I quote from the book ‘ Fin-keel yachts with bulb ballast were unmatched in speed and in beating to windward. Their reputation was established mainly in short races, as they were not suitable for living aboard for any length of time. The secret of their success was attributed to the evasion of the measurement formulae’!! I am convinced that the ‘Wenonah’ was definitely a rating rule wrecker and she could be classed as a sports boat. She might have the right hull shape, mind you I would have to get a second opinion on this as I would have liked the transom to be closer to the water line giving the hull a flatter run aft to be totally sure. Anyway, many yachtsmen were opposed to the unhealthy tendency developed by these skimming dishes and the famous Hydrodynamicist R F Froude was in 1896 commissioned to change the Linear Rating Rule. He proposed that “A good yacht should aim at comfort, be fast, habitable and safe”. He apparently failed in his attempt to penalise the shallow hulled yachts with their bulb keels enough and a second Linear Rating Rule was introduced in 1901. All these changes discouraged fin keels with lead bulbs but the damage had already been done and designers stopped relying on the old method of using internal ballast and moved on and fitted a large external cast lead keel suspended low down on the hull. Nat Herreshoff ‘s highly successful ‘ Gloriana’ built 1891 is a good example of this and she can definitely be classed as a ‘break through boat’. The new built in, bolted on underslung lead keel enabled him to increase sail area and therefore gave the boat greater speed through the water. In 1906 all the sailing nations got together and formed the International Yacht Racing Union IYRU (centenary next year) to encourage and oversee international yacht racing. They introduced the first ever international metre rating rule in 1907 which placed a factor d in the formulae for the first time. This was to really penalise bulb keels heavily and in this they succeeded enough to stop their use for a lengthy period afterwards. The International metre Rule in 1907 was as follows; Rating in metres = L+B+ 1/2G +3d+ ½ x square root of (SA-F) 2.5 Where L = length on the waterline B = maximum beam G = wrapround Girth measured 60% back from bow on the waterline F = Freeboard d = Gp – Gn The d factor was a girth comparison measured from the waterline to the bottom of the bulb (Gp = wrapround and Gn straight line). I can now see why Ben Lexen’s keel wings do not run the full length of his keel. The girth measuring point in his modern 12 metre formulae was only 55% of the waterline from the bow so he started the wings on his keel after this measuring point! All of the above and the fact that an un-modified mark 1 would probably fail the new AYF trailer yacht pull down test but pass the NZ sports boat pull down test surely confirms that the Queensland designed and built RL 24 was the first sports boat in the southern hemisphere. In view of this do you not think we can all chip in a few dollars and find an as built mark 1 and have it tarted up and presented to the Brisbane Maritime Museum. I find it a wee bit of a surprise to realise that our so called development class is progressing forwards/backwards using developments targeted by the great R F Froude way back in the 1890’s. With regard to the current move to fitting Nat’s bulb ballast to RL24’s racing in the drop keel division, I may as a design exercise use the latest metre boat formulae and work out how much extra sail area a drop keel RL24 would be allowed to have if not fitted with a bulb! It would not cost too much if added to the jib or Spinnaker!