Here we are at last, sailing with full top rig. I have thoroughly got the hang of the 10R spreadsheet, thanks John. 

Sail area 1.083447 and a rating of 9.97 achieved. I have played with the spreadsheet to optimise the trimming required to suit the balance of the boat. I have marked potential reduction should the waterline not be spot on. Easy !

Pictures here with usual ghosting breeze

Richard

 

Sadly, all this excruciating set of posts convinces me is that I’m so lucky not to care a fig whether my 10R measures or not! More seriously, it is very upsetting that those who wish, above all, to enjoy sailing their boats have been forced to endure the gradual over-complication over time of the 10R rules. Seems totally ridiculous and can only speed up the disintegration of the class for these wonderful yachts. 
I am just watching the rugby Ireland v Italy and here again due to the ludicrous over-complication of the laws, one side has been reduced to 13 men. Another example of how to ruin this one game and gradually discourage people from watching let alone playing the game. PC and rules fanaticism gone mad again.

 

Wow !! did not expect that.

Last post then. 

Richard

I am really sorry if you think I am in any way having a go at you Richard - I am not! All I am trying (possibly unsuccessfully) to say is that the hugely complex measurement rules for such an intrinsically simple class formula seems a great pity and likely to diminish the popularity of the class. Let’s all just try to enjoy sailing them.

Oh dear, here we go into the realms of misunderstanding - again.

Firstly if a boat does not measure in accordance with the class rules it is not a 10R.  That does not mean it cannot be a nice boat to own or sail but it is not a 10R.

Secondly the class rules have not become progressively over complicated.  They have always been complicated.  If you do not believe this then look back at the historic previous versions of the class rules on the ITCA website.  Which version of the rules is less complicated?  Yes there have been changes over the years not least the change from measurement in feet and inches to metric.  Nor the change to certification being for life, if the boat remains with the same owner and with the owner signing an undertaking to maintain the boat within the class rules. (Obviously if the boat is changes so it no longer complies with its original measurement certificate it will need remeasuring). Previously re-measurement was required every 2 years.

The vast majority of changes have been to  reflect 'interpretations' where the rule was not clear and open to different interpretations.  Also the measurement forms have moved from being printed and manually completed to a spreadsheet.  (Largely to eliminate mathematical errors) However the layout and completion requirements have remained the same.  Electronic measurement forms have greatly simplified the processing of certification and registration and reduced the amount of paper used and produced which needs to be kept and stored.

Which previous version of the class rules would  make it less complicated?   

Back again !  Paula I really understand your comments and complex rules can appear intimidating. Unfortunately in this "cheque book" sport philosophy these days, all the classes have lawyers keen to exploit vague rules. I had a few items on the 10R rules that were simply explained by some, more familiar with the class than me. I have become a firm fan of the class; never having raced one against another yet.  I am a sailor that enjoys the design aspects and the consequent experimentation with development classes. The 10R offers the greatest scope and ease for such experimentation. I liked the comment from Brad that he builds a tolerance / safety factor of some 4-6mm WL on his designs, this makes so much sense and does a lot to encourage amateur efforts and avoids owners who demand gramme / mm precision and expect to argue with the measurer. I have built boats for owners who specify such requirements.

This forum provides access to a wealth of knowledge, that I have gratefully plundered.

Anyway;  good 10R sailing,

Richard

 

The 1967 Rules consisted of 2 A4 sheets.  The 2002 rules were 21 pages.  The 2020 rules are 29 pages.

Yes John the document has more pages but the number of pages is not an effective measure of complexity.  The longer document (2002 and later) is formatted in the World Sailing prescribed format.  The content is not more complicated just more comprehensive and spaced out on the pages for clarity. The content is no more complicated.  Also this is the same format as for all other International classes

note: The Marblehead class rules are 25 pages, the IOM class rules are 27 pages and the A class class rules are 30 pages. Are these more or less complicated?

Correction the latest 2022 IOM class rules are 33 pages.

10R design options once more: My Pieces Eight represents one extreme design and I would like to look at the other: Max Wl / min Sail area.

I do wholeheartedly agree that the top 10R's excel in all conditions but the class allows so many opportunities for experimentation that it is difficult to resist. One of the attractions of the Mini40 also.

So what designs stray in that direction ?  The aspects of our scale are so different to full size; particularly with respect to wetted area and possibly block coefficients. Here I am looking for any evidence for / against hull types for the 10R.  Another boat to build ?? Frank Russell's Gothix perhaps ? 

Quick comment on the rules. I was part of Team New Zealand and remember the rule "discussions" that took place in court. Also the measurement process that meant cutting large holes in our expensive and painstakingly made hulls.

PS.  I do sail

Richard

There is no max length of course but the sail area penalty starts to bite once you go over about 1350.  The problem with a long boat is how to make it competitive in light airs.  I generally leave the Bentley at home in the light stuff and have recently made a '10R' swing rig for my Starkers Marblehead.  I now have two very competitive boats; as long as I sail the right one for the conditions.

To make a long boat fast in light airs then you obviously need a low drag hull form, so something with round sections to keep the wetted area low and perhaps a light displacement?  You also need to make the most of the sail area you are allowed, so an efficient rig is called for.  Tempting to go for max luff, narrow foot and wide head, (to get the area high (where the wind is stronger) but this compromises the lower rigs thanks to the silly 10R rules.  I've been toying with ideas for wing masts / fully battened sail but haven't yet found a good solution to 'popping' the camber when you tack in light winds.  

I made a Gothic Marblehead and wasn't too impressed with it's light airs performance.  It was however my first attempt at CF moulding and came out quite heavy so probably more my fault than the designer's.

I used to sail Contenders (a long time ago now) and many new owners were dismayed when the measurers insisted on drilling a hole through their pristine wooden foredecks to check the thickness of the ply used!

You've hit the nail on the head, John, regarding light airs performance. I have discovered, possibly the "B" obvious, that there are other factors that apply to shortening the WL that do not have the same relative effect at full size.  I also suspect that a  Marblehead is the way to go, as you have done. I have sailed Pieces of 8 with a One Metre (2.3Kg) ballast ,on max length fin, in light winds and seems to work ok.

I began to look at wing sails and there are plenty of scale modellers who have made them. But not to race. I wanted a full wing shape with hinged trailing edge. Super efficient but also super complicated. So many bits required to maintain the camber all the way up that the whole thing becomes too heavy and complex. Once again; so much easier full size. Popping a semi soft sail is tricky and takes power off just when you need it.

I like the pocket luff rigs and there is scope to develop in that area.

What happened to your Gothic hull ? Did you build over a foam core ? Any pics ? The reason for my interest is my dormant project for a foiling hull. The old carbon Kevlar M hull that I acquired as a "skip job"  has too much volume and is a very old design. Wish I had not sold my Starkers, also acquired as "needing work".  Have you tried a lighter ballast on the Starkers for light winds ? could be interesting.

 

Pic of Pieces of Eight sailing with a Starkers M, rigged as a 10R.

Thought it liked nice.

Richard

 

Another interesting chined 10R

Saw this on the Australian 10R site. Very similar concept to "Pieces of 8".     Has a pronounced tumblehome.   I believe it is a "Doubloon" by Peter Mitchell. Does have a UK registration number though. Anyone recognise it ?

Richard

GBR3435 is a Doubloon registered in UK in 2015 by Peter Mitchell, the designer.  Registered to a new owner in Uk in 2018.

Re the Doubloon, it was my first 10R design which was intended to be a development of Roger's PoE, i.e. short WL length, large sail area and light displacement. Although the WL length as built turned out a little longer than designed it is nonetheless a fast boat in light winds, but would have benefitted from more buoyancy forward above the waterline. It has an offset swing rig very similar to the PoE. It has a luff length of 2.3m - registered just before the rule change to 2.2m max. (not sure I saw the point of that rule change though).

The attached photo is of Doubloon and PoE together at Frensham Pond in 2017  2017-06-13 FPSC 10r challenge.pdf

No doubt some will notice that the sail markings on both boats are incorrect!

I managed to meet the 1150 WL on my PoE. The only alteration I made to the lines was to make the bow vertical; possibly a slight benefit in forward buoyancy (very slight, I know, but at a long lever)

What WL did you end up with, also resultant SA ? Did you note any advantage to the tumblehome ? 

As you know, I had a conventional rig. Also would have gone for the 2.3 luff. I know there must have been a reason for the rule change, but It seemed to detract from the boats' possibilities and was one reason I did not pursue the class any further.  This is based on my predominately light to nil wind sailing venue and I admit I am a bit biased here.

 

Slightly embarassed (!) to report the measured WL length was 1256 - the hull unfortunately turned out a little heavier than planned plus I used an old fin and bulb combo from Roger S, resulting in a slightly deeper draft. The SA was 0.994388m2 - rating 9.99. Despite that the boat absolutely ghosted along when there didn't appear to be any wind at all.

I know the tumblehome was a bit excessive but it did mean that even when heeled the deck edge was rarely immersed. It's sad to hear you, and clearly others as well, haven't pursued the 10R class as I do think they are the most handsome of boats, even with 100mm chopped off the top! The wind at Frensham is often light and a few of us there are still looking at designing / building more 10s.

I have recently acquired a f/g Nookie Bear 10R hull. Not meant as a serious race contender , just as a "toe dipper" Suspect the end result might turn out quite heavy , added to the fact that I don't know anyone sailing 10R's so no comparisons available.