Merlin 111  has the original(but shortened)wooden mast with the rotating foot.  However although she is keen enough to swivel on to the starboard tack there is a distinct reluctance to go to port and it needs helped over by twisting it by hand - not difficult but a nuisance and when the mast is set at the right angle the difference in performance is huge (well, certainly for a 58 year old!!! If only that was all it took!!!)  This is also associated with the top batten being reluctant to flip.  If I relieve the tension on the top batten do you think this will help both problems. The sails are brand new.  It was suggested that a fixed gooseneck would sort it out and I can see the logic but on a run the angle stops on the base plate would not allow the boom to go right out.  Anyone else have these problems? Any other suggestions?  Thanks in advance.

Try a mast spanner, as used by cats and Tasars. It controls the degree of rotation, and makes a convenient handle for the crew to flip the mast round...

Garry, Just a thought but is there anything holding the mast back on the port side? I have an OK as well as the merlin and i have the same problem on that. The mast rotates and has a fixed gooseneck. It goes out no poroblem on the port side but will not go out to starboard. What i found is that the kicking strap was holding it back when cirtain wires crossed and the only thing i can do is let of all the kicker tension. I found the same thing in my Merlin when i changed the kicker on that. Because the control likes where to far forward of the king post and quite wide apart they hold the boom in on the runs and again i have to let all the tension off to get the boom out.
You may find something there which is under tension when the boom is on port but not on starboard.

It might be possible that the jib halyard is a bit tight I suppose not allowing the strop at the hounds to run round the block although a little unlikely.  The problem is that all these movements ae=re so small it's quite difficult to see exactly what's going on and of course you are trying to sail the damn thing at the same time!!!  Chris Barlow found that his rotating mast on No 6 worked better when there was little tension on the rig generally so I suppose that it is early days yet and time will let me sort it out.  Will likely get the new shroud shackles on, readjust the length and find that the problem has disappeared!!

In the 50s I sometimes used to sail a beautiful 'banana boat' called 'Excuser Moi',no. 195. She had a neat system to rotate the mast. 

The mast was stepped on a hefty piece of wood (let's call it'the lever')which extended a foot or so into the cockpit. The forward end of the lever was mounted on the origional mast step. The the foot of the mast was stepped on the lever behind the origional step so that the mast and lever rotated together. The kicking strap was taken from it's normal boom position down to the after end of the lever. 

The result was that the mast always rotated automatically, the amount of rotation depending on the tightness of the kicking strap. The only snag with fitting it to an existing boat is that you would have to cut an amount off the foot of the mast equivalent to the thickness of the lever.

Robert - I tried to email you with some info but the link here did not work and my mail was returned.  Contact me on [email protected]

i think there is an S missing from his surname in the email address!

Thank Mag,  mised that - perhap I am pised!!!

It could be that your shrouds are not perfectly equal in length and so pull ing the mast off to one side. A mm or two is all it takes.

Rotating Masts:. I purchased MR3231 design NSM in GRP from Spud Rowsell and had the boat fitted with a geodesic space from of stainless steel and aluminium to support a cold drawn aluminium tapered mast designed and fitted to rotate. The suuplier was a company called Tenspar based in wales near Chew Valley. Tenspar had designed new dinghy with rotating mast and after discussions with TENSPAR and ROWSELL I had their design transplanted within the rules into the dinghy.

Er? Chew Valley was in Somerset last Friday - I didn't have to pay a toll to get there!

I'm about to move to a new house near Cheddar in a couple of weeks and they never told me I was about to be Welsh!!

Useful information on rotating masts from welshmen living in somerset required, droll is not.

The beginners guide refers back to the very early designs with wooden masts that were made to be rotated,and notes that the move from deck stepped to hog step provided more power to the rig combined with a number of rigging trade offs. Recently there has been a switch to deck step again with a new range of fiber-glass masts. My adoption in 3231 of the geodesic(spaceframe) design means there are no mast compression strains placed on the hull, only wind derived momentum and forces accruing from the attachment points of the geodesic to the hull. These attachments are embedded in the fiberglass at the time of manufacture. The design is such that the base plate of the mast can be raised or lowered such that the base plate supporting the mast can be close to the plane of triangulation of the outer support arms. It would be interesting if a builder were to undertake some basic research exploring the possibilities further of embedding a carbon fiber design such as this into an experimental boat based on a design of known good well documented capability. Clearly in a hobby product expense has to be a consideration, but if MRs want to move the class on as a development class new design ideas need to be considered. I believe my design integration whilst based on solid physics was hampered by the use of an aluminium frame adding significantly to weight, but certainly capable of an superior upwind sailing angle. Since the mast resides inside a space frame all rig adjustments are up for grabs, including a dynamic mast bending tensioner, and spreader adjustment on the fly. Over to the 'experts'. Further sail dynamics see Marchai 'Sail Performance'

Integral space frames are normal in boats like Skiffs, Cherubs and Canoes and have been for many years. They're not really apparent these days because there is so much strength in a carbon bulkhead that you don't need any special structure, but the load paths are there. That's why well engineered boats have the front bulkhead angled back so it meets the shrouds rather than straight across from the mast.

Waiting for Scotty to post his experiences with the rotating mast...
Has been tried in Merlins 3 times in the recent past - the Scotty experiment was pre-carbon & the minimal gains were offset by having to get sailing because otherwise the boat fell over sideways.  I think Simon Blake experimented with it over one winter at Chichester & then Steve Neal created a boat to exploit the rotating rig.  Unfortunately the gains upwind in some conditions did not offset the losses trying to make the rest of the rig work downwind or depower in a blow.  Maybe time to give it another go if someone has the cash and the time?

I found the rotating mast in space frame provided excellent upwind speed and the boat (an original Rowsell Fibreglass NSM)would lay closer to the wind, and as mentioned above in  ablow I could not find the formulae to depower the rig to make it feel and sail right. On one memorable occasion at BVSC Lamberhurst with two sitting near enough on the transom it would fly of the top of short chop (force 6 gust 7 allegedly) I am not nearly enough of a rig tune expert to categorise the performance, however, all I have read about space frames supporting rotating masts points to the superior performance, provided some one has the time to learn the appropriate techniques. Not much point to a development class if all we do is follow the rest of the world in carbon fiber doohickys everywhere including sails -hardly development stuff-!

However restricted not development class.  The development classes (Moth, I14) have gone down the path of max straight-line speed but this is not terribly useful on a river if it compromises manoevrability.  Lots of interesting rig controls on Jon Turner's new boat but it has not been devastatingly quick as a consequence, will be interesting to see what gets adopted and what not.  As the ability to depower for lighter crew weights in windy conditions has been the major rig improvement of the last 2 decades not sure wing masts that can't do this easily will catch on.

My rig comprised the following:- Space frame with forward point at the bow, two side attachment points at the shroud normal points. Adjustable forward shroud on tensioner, shrouds taken up to a spreader unit affixed to small plate forward of the mast allowing the mast to rotate, aft shroud tensioners = usual bottle screws, mast stepped in a pin and cup unit with PTFE washer for reduced friction mounted with large SS bottle screws from each triangulation of the forward and shroud points. Mast over-rotated and held in place/tensioned in place by large ugly spring attached to mast rotation handle and attached to mast just under goose neck. Multiple way pulley block attached forward of the mast at deck level on forward shroud controlled mast prebend adjustable on the fly. Overall the rig could flatten a standard sail completely for upwind pointing, could be slow going but still high attack angle and controllable. The problem was downwind/reaching the CLE of the sail plan moves to far forward irrespective of my rig adjustment(ignorance is blessed) such that the combined sail plan center of effort moved so far forward that in a blow crew and helm had to hang over the transom/aft quarter to stop the boat behaving like a submarine. I beleive that for the rig to work properly a sail make would need to be able to cut and sail a number of sail plans/ares to dientify the most usable combination, for sure a standard off the shelf set will tip crew in water unfailingly in a blow.
Now remember that this attempt at space frame/rotating mast was a year after Rowsell introduced the first approved batch of fibre glass NSMs(circa30 years ago). Most of these early hulls were under weight and needed adjustment to comply with the rules. This may have made initial weight distribution uneven, I have no way now of knowing or measuring the effects since the boat has been scrapped, though I still have the mast and most fittings.(dont ask). I sailed 3231 for around ten years. After this time I found the hull had absorbed significant amounts of water and unable to easily find the entry points I found the boat even for casual sailing unusable and a couple of years later scrapped the hull entirely.

Addendum:- The kicker is attached to both the base of the mast inside the space frame and to the boom. The kicker can be adjusted on the fly exactly like other boats, the adjustment controls were led to both sides of the hull such that the boom kicker could be released even when sat out hard. The exercise was aimed at utilising a rotating round section tapered mast to provide a more uniform air flow across the back and front of the sail, and to exercise extra rig control without major hull stresses leading to more predictable performance.

Thought experiment:- Mount championship winning rig in a fixed space frame outside of a boat using readily available electronic strain gauges and PC read and evaluate the heeling forces and the driving forces whilst subjecting the rig to multiple set ups. An initial condition (essential) would be the rig set up as used by the National Champion in the preceding year. This would provide a baseline from which to evaluate the capability of rotating masts, mast cross section,rig tension and rig set up. And even better have a very low cost, something that a sailing undergrad could usefully undertake and would have a wider world application outside of MR