SEAHORSE - NOVEMBER, 2001.

Jason Ker's 2001 IRM designs have impressed many with performance that far exceeds comparable IMS designs. But the still relatively new IRM rule must gain momentum quickly if it is to make a significant international impact

SH: Can there ever be a 'winner' between IMS and IRM?
JK: There is no point anyone imagining that in the foreseeable future there will be IMS racing in the English Channel, or that IR2000 [the umbrella rule of IRM] will take over grand prix racing in Spain while the King races in IMS. The only country at present where IMS and IRM can compete for the grand prix fleet of racing yachts is Australia. There, IRC has pushed IMS out of the cruiser-racer role, leaving it holding on to some of the grand prix end of the fleet.
Grand prix fleets will normally only grow where boats can also be competitive under the local handicap system. This generally means IMS racers for IMS countries and IRM for IRC countries.
SH: What makes an IRM boat so fast?
JK: Unlike other rules, IRM does not try to rate all comers, but instead deliberately typeforms towards a fast and stable yacht, where a low centre of gravity and ample sailplan are encouraged. There is no hull measurement beyond length to the transom and overall beam, which means that bumps and distortions are simply not a feature of IRM yachts. Stability is measured and typeformed, meaning undesirable extremes of waterline beam are not competitive. And displacement is encouraged to be light, but not extreme (about 65 per cent that of a currently successful IMS cruiser-racer).
A competitive IRM boat will be more 'Volvo' than 'Open', making for a tidy style of boat that goes very well both upwind and down and with an inherently large angle of vanishing stability.
SH: And conversely, why are typical IMS boats comparatively so slow?
JK: The IMS rule tries to rate all comers fairly. Therefore for IMS design, a yacht's speed relative to its rating is the only driving factor, not the actual speed. The more accurate the IMS VPP becomes over the years, the more the IMS trend will be to make 'race yachts' increasingly slower.
There are two obvious reasons for this.
First, slow boats are less affected by dirty air - your typical Swan or IMX will soldier on in air that would choke a smaller, lighter boat of the same potential speed.
Secondly, slow boats are easier to sail to potential - a heavy, slow boat can be sailed with less skill and concentration than a lighter, tweakier one which will reward more attention from trimmers and helmsman.
SH: Does the greater speed of IRM yachts mean they are also more costly?
JK: The construction techniques of IRM and IMS racing yachts are effectively the same.
The big differences in performances come only from the combination of hull shapes and the location of the ballast. There should be no cost difference between building and running an IRM racing yacht or an IMS racer, except that the cost of measurement is much higher for IMS. That said, the theory of IMS is that if you turn up to a flat-water IMS World Championship event in a ferrocement yacht with a telegraph pole for a mast, you could win. But go to an IRM championship in a poorly designed or built new yacht and you will have no chance. This is an important point to highlight.
SH: How do existing yachts such as some one-designs remain competitive in IRM?
JK: To facilitate an instant fleet, the rule provides a very generous grandfathering allowance to yachts that fit within the typeform and were designed before 1999. The combined effect of overhang and age allowances can enable a grandfathered yacht to compete well with a new boat, especially until the new ones have been worked up to speed. The generosity of this grandfathering can even enable some IMS yachts to be converted to race competitively in IRM.

SH: IRM, IRC, IR2000, IMS... surely one rule could be developed to replace all of these?
JK: IRC (not IRM) and IMS were both developed to do the same job, ie. attempt to rate all comers at club level. While IRC is more user friendly and all-embracing, IMS tries to be more accurate. If you dual score cruiser-racers at club regattas with these two rules, the results are largely the same. IRM stands apart from these two rules and does not seek to replace either of them, but instead provides a platform for the racing of genuinely fast yachts, between each other, rather than against cruiser-racers and vintage racing yachts. IMS is inherently suited in neither philosophy nor practice to producing good grand prix racing in truly fast boats. To illustrate this point, the recent IMS World Championships featured production cruiser-racers largely dominating the results.
SH: Why did IMS fail to take hold in the UK?
JK: Very soon after its introduction, it became obvious that the sophistication of IMS as a handicapping tool in the conditions of the Solent - where races can start with the tide and wind in a certain direction and end with them both in totally different directions - was akin to measuring sugar into a cup of coffee with a precise set of scales, rather than with teaspoons. The tool was overly fragile and sophisticated for its conditions of use. The RORC patiently supported this rule for several years before they gave up. The fundamental problems could be summarised as:
* Too complicated for use in UK sailing conditions.
* IRC (previously CHS) had already taken hold of the cruiser-racer rating market, depriving IMS of the job it does best.
* Cost of measurement was very high, when the owners had become used to cheap IRC measurement.
* IRC encouraged stability and high downwind sail area, while IMS discouraged these, so boats were not generally cross-compatible.
SH: Why is IRM beginning to succeed in the UK where IMS failed?
JK: IRM does not seek to compete with IRC. It acts as a pressure valve, whereby owners who want to have new racing yachts built to win can do this under IRM, leaving IRC to the cruiser-racers. But for now at least, IRM yachts are also competitive in IRC, allowing owners to commission or purchase a racing boat without fearing that he will be dependent on others doing the same.
SH: Yet IRM has been quiet this year here in the UK?
JK: The first of at least 10 new IRM racing yachts to be launched this year in the UK only hit the water in May. So while there hasn't been much IRM racing in the UK this year, the fleet is growing fast. The odd numbered (Admiral's Cup) years have, for some time now, been short of domestic events to campaign towards, so they have usually been treated as off-years. In even numbered years there is often a burst of activity with the Rolex Commodores' Cup and Cork Week to campaign towards. The UK raceboat building lists bear this out:

1997- I x lRC
1998-4 x lRC, I x lMS
1999- I x IMS
2000- I x lRC, 3 x lRM
2001- 10 x lRM (all designed within IRM typeform, but with strong IRC capability too)

It is true that with the RORC's involvement in the GBR Challenge, and some crisis management around the decision not to run the Admiral's Cup, the RORC has perhaps taken its eye off the IRM ball this year. Despite this, the number of new IRM boats present at Cowes was a wake-up call as to the rule's growing impact.
SH: And yet, after some doubts last year, there has been a relative explosion of IMS activity in Spain this year?
JK: It was announced that the King of Spain would race a new IMS yacht this year, and it has become desirable for other Spanish businessmen to play on the same pitch. As for numbers of entries to the IMS Worlds, for 'IMS Worlds' read 'Spanish Open IMS Championship'. These IMS nationals in Spain are akin to the IR2000 nationals in the UK, and the numbers of entries are actually similar. Look outside Spain and you will see there has been very little construction of IMS raceboats for several years, as owners now see the futility of building slow and expensive race yachts in which they will probably lose to cruiser-racers.
Put a good IRM design up against a similar-sized IMS grand prix design and the latter will quite simply be blown away. Ultimately we can only hope the international marketplace does what it usually does and selects the better, faster type of boat?




		SEAHORSE - NOVEMBER, 2001. ONE CHANCE SALOON. Jason Ker's 2001 IRM designs have impressed many with performance that far exceeds comparable IMS designs. But the still relatively new IRM rule must gain momentum quickly if it is to make a significant international impact The Ker IRM 11.3m has had a good first year - 10 boats have been sold and the design has proved quick on the water, trouncing most existing IRC, IMS and similar or slightly larger one-designs. SH: Can there ever be a 'winner' between IMS and IRM? JK: There is no point anyone imagining that in the foreseeable future there will be IMS racing in the English Channel, or that IR2000 [the umbrella rule of IRM] will take over grand prix racing in Spain while the King races in IMS. The only country at present where IMS and IRM can compete for the grand prix fleet of racing yachts is Australia. There, IRC has pushed IMS out of the cruiser-racer role, leaving it holding on to some of the grand prix end of the fleet. Grand prix fleets will normally only grow where boats can also be competitive under the local handicap system. This generally means IMS racers for IMS countries and IRM for IRC countries. SH: What makes an IRM boat so fast? JK: Unlike other rules, IRM does not try to rate all comers, but instead deliberately typeforms towards a fast and stable yacht, where a low centre of gravity and ample sailplan are encouraged. There is no hull measurement beyond length to the transom and overall beam, which means that bumps and distortions are simply not a feature of IRM yachts. Stability is measured and typeformed, meaning undesirable extremes of waterline beam are not competitive. And displacement is encouraged to be light, but not extreme (about 65 per cent that of a currently successful IMS cruiser-racer). A competitive IRM boat will be more 'Volvo' than 'Open', making for a tidy style of boat that goes very well both upwind and down and with an inherently large angle of vanishing stability. SH: And conversely, why are typical IMS boats comparatively so slow? JK: The IMS rule tries to rate all comers fairly. Therefore for IMS design, a yacht's speed relative to its rating is the only driving factor, not the actual speed. The more accurate the IMS VPP becomes over the years, the more the IMS trend will be to make 'race yachts' increasingly slower. There are two obvious reasons for this. First, slow boats are less affected by dirty air - your typical Swan or IMX will soldier on in air that would choke a smaller, lighter boat of the same potential speed. Secondly, slow boats are easier to sail to potential - a heavy, slow boat can be sailed with less skill and concentration than a lighter, tweakier one which will reward more attention from trimmers and helmsman. SH: Does the greater speed of IRM yachts mean they are also more costly? JK: The construction techniques of IRM and IMS racing yachts are effectively the same. The big differences in performances come only from the combination of hull shapes and the location of the ballast. There should be no cost difference between building and running an IRM racing yacht or an IMS racer, except that the cost of measurement is much higher for IMS. That said, the theory of IMS is that if you turn up to a flat-water IMS World Championship event in a ferrocement yacht with a telegraph pole for a mast, you could win. But go to an IRM championship in a poorly designed or built new yacht and you will have no chance. This is an important point to highlight. SH: How do existing yachts such as some one-designs remain competitive in IRM? JK: To facilitate an instant fleet, the rule provides a very generous grandfathering allowance to yachts that fit within the typeform and were designed before 1999. The combined effect of overhang and age allowances can enable a grandfathered yacht to compete well with a new boat, especially until the new ones have been worked up to speed. The generosity of this grandfathering can even enable some IMS yachts to be converted to race competitively in IRM. SH: IRM, IRC, IR2000, IMS... surely one rule could be developed to replace all of these? JK: IRC (not IRM) and IMS were both developed to do the same job, ie. attempt to rate all comers at club level. While IRC is more user friendly and all-embracing, IMS tries to be more accurate. If you dual score cruiser-racers at club regattas with these two rules, the results are largely the same. IRM stands apart from these two rules and does not seek to replace either of them, but instead provides a platform for the racing of genuinely fast yachts, between each other, rather than against cruiser-racers and vintage racing yachts. IMS is inherently suited in neither philosophy nor practice to producing good grand prix racing in truly fast boats. To illustrate this point, the recent IMS World Championships featured production cruiser-racers largely dominating the results. SH: Why did IMS fail to take hold in the UK? JK: Very soon after its introduction, it became obvious that the sophistication of IMS as a handicapping tool in the conditions of the Solent - where races can start with the tide and wind in a certain direction and end with them both in totally different directions - was akin to measuring sugar into a cup of coffee with a precise set of scales, rather than with teaspoons. The tool was overly fragile and sophisticated for its conditions of use. The RORC patiently supported this rule for several years before they gave up. The fundamental problems could be summarised as: * Too complicated for use in UK sailing conditions. * IRC (previously CHS) had already taken hold of the cruiser-racer rating market, depriving IMS of the job it does best. * Cost of measurement was very high, when the owners had become used to cheap IRC measurement. * IRC encouraged stability and high downwind sail area, while IMS discouraged these, so boats were not generally cross-compatible. SH: Why is IRM beginning to succeed in the UK where IMS failed? JK: IRM does not seek to compete with IRC. It acts as a pressure valve, whereby owners who want to have new racing yachts built to win can do this under IRM, leaving IRC to the cruiser-racers. But for now at least, IRM yachts are also competitive in IRC, allowing owners to commission or purchase a racing boat without fearing that he will be dependent on others doing the same. SH: Yet IRM has been quiet this year here in the UK? JK: The first of at least 10 new IRM racing yachts to be launched this year in the UK only hit the water in May. So while there hasn't been much IRM racing in the UK this year, the fleet is growing fast. The odd numbered (Admiral's Cup) years have, for some time now, been short of domestic events to campaign towards, so they have usually been treated as off-years. In even numbered years there is often a burst of activity with the Rolex Commodores' Cup and Cork Week to campaign towards. The UK raceboat building lists bear this out: 1997- I x lRC 1998-4 x lRC, I x lMS 1999- I x IMS 2000- I x lRC, 3 x lRM 2001- 10 x lRM (all designed within IRM typeform, but with strong IRC capability too) It is true that with the RORC's involvement in the GBR Challenge, and some crisis management around the decision not to run the Admiral's Cup, the RORC has perhaps taken its eye off the IRM ball this year. Despite this, the number of new IRM boats present at Cowes was a wake-up call as to the rule's growing impact. SH: And yet, after some doubts last year, there has been a relative explosion of IMS activity in Spain this year? JK: It was announced that the King of Spain would race a new IMS yacht this year, and it has become desirable for other Spanish businessmen to play on the same pitch. As for numbers of entries to the IMS Worlds, for 'IMS Worlds' read 'Spanish Open IMS Championship'. These IMS nationals in Spain are akin to the IR2000 nationals in the UK, and the numbers of entries are actually similar. Look outside Spain and you will see there has been very little construction of IMS raceboats for several years, as owners now see the futility of building slow and expensive race yachts in which they will probably lose to cruiser-racers. Put a good IRM design up against a similar-sized IMS grand prix design and the latter will quite simply be blown away. Ultimately we can only hope the international marketplace does what it usually does and selects the better, faster type of boat?