Potential 10R sailor

[Eric Finley]

Richard, P of 8 is a Roger Stollery design, does this mean it was designed for Swing Rigs?

If this is the case what modifications were required to fit a conventional rig? When you get round to a maximum size rig will it be swing or conventional and reason for choice?

[Richard98]

Hi Eric, nice to hear from you.

Roger uses an offset mast fitting on his swing rigs and this allows conventional sails to be used. The 10R class seems to favour conventional rigs, based on all the advice I have received from those experienced in the class. I will be going that way and consequently do not even have a swing rig mast tube. The Pieces of  Eight has the mast in the correct position as a result. I checked out a few designs and found the mast / fin relationship pretty much standard as is the main / jib ratio. Actually a simple class to put together; well, just as straightforward as a One Metre anyway. Standard mast /  finbox mouldings are available which further removes any guesswork.

 

[John949]

Brad,

I assume you've seen this:

https://www.sailsetc2.com/downloads/waterline end checking device 10R.pdf

It shows that Mr Bantock thinks the waterline is measured where the waterplane intersects the hull, not where the meniscus touches the hull.  When Roger Stollery checked my Bentley for me he also used a device that used the same principle.  If you measure by sighting the meniscus you will get a value some 5-25mm longer than if you use the Bantock / Stollery method (depending on the hull shape) so it is significant.  Unfortunately the rules don't help because they use the term ''waterline ending" without defining what this means.  One of the difficulties with the Bantock  / Stollery method is that you can't set the 'gauge' by sight, you have to 'feel' when the boat touches it - hence my original comment about it being difficult and error prone.

One of the reasons swing rigs aren't as universal on 10Rs as they are on Marbleheads is because the 10R rules require the B rig sails to fit within the profile of the A rig sails.  As swing rigs need to use a tall narrow jib, this severely compromises you if you want to use a conventional B rig, as ideally you would want to use a much bigger jib for the B rig (as Marbleheads do).  Some 10Rs use a B swing rig but I'm not convinced this is a great idea.  In my view this rule is unnecessarily restrictive  and is one of many I would change if I ruled the world.  The current rules require you to re-measure the boat and get a new certificate if you want to change the profile of the sails but keep the area the same, surely it is only necessary to measure the new sails and confirm that they do not exceed the area quoted on the original certificate?

[Derek Priestley]

On a lighter note............

 

As someone who raced in & placed 2nd, to my good friend John Cleave, in the first ever r/c 10r National at Poole in , I think 1976, I can offer the suggestion that more people are not racing the class is that although they are fabulous exciting boats to sail lots of us can no longer keep up with their speed!!  if you race them on big open waters where they should be raced.

 

 

[Brad Gibson]

John, 

The method I use with a mirror sighting through the undersurface of the water to where it bisects the hull, ignoring the meniscus. I am fully aware if taking a visual waterline marking from above the surface of how much the meniscus would add, hence the mirror method sighting below. It is accurate as any complicated system, as has been shown repeatedly when my designs have been checked with other elaborate ‘tank methods’. No need to overcomplicate things.

On swing rigs the jib area issue in getting lower rig suitable sizes can be solved with an off set pivot rig as Roger has shown and Richard mentioned on the measured rig. It can be done, but not a direction I would favour…

[Brad Gibson]

1 hour ago, Derek Priestley said:

On a lighter note............

 

As someone who raced in & placed 2nd, to my good friend John Cleave, in the first ever r/c 10r National at Poole in , I think 1976, I can offer the suggestion that more people are not racing the class is that although they are fabulous exciting boats to sail lots of us can no longer keep up with their speed!!  if you race them on big open waters where they should be raced.

 

 

A good point Derek, very similar in the effort it takes to chase after a Vane boat under spinnaker down the full length of Fleetwood or Gosport lake. Numbers were reduced in those disciplines a few years back but what we see now with good promotion and energy, is the Vane classes coming back to life with younger generations. People have the boats and want to use them again. People coming back enthused, who would have thought…

The 10R sits as the fastest and most modern in design of the International classes. The attractiveness of the rule to anyone thinking they are a designer is obvious for a real test. Yet the class is again floundering. If newer skippers have not been attracted to it like they have in other countries like France, Italy and Australia, then that falls on calendar and it’s promotion. If current owners are not coming out to race there is a problem. A poor calendar is hard to promote or sell someone on. Sort the calendar, then tell the world. Tell them regularly, make anyone not there feel like they are missing out. It goes the same for any class as the re growth in the Ms, IOMs and 6M classes have shown. Like in other countries we could then have our MYA be positive in supporting all of its classes as an avenue into the sport, through buying used boats instead of pushing the one avenue of entry.

There is a 10R ranking this weekend. How many know about it? Who would want travel for 1 day at this time of year?

Sorry Richard for the hijack and happy if this gets moved elsewhere.

Brad

[Darin Ballington]

Dumb question from a non technical person....

If a boat of a similar design has a waterline length of say 5mm more or 5 mm less so a tolerance of +/-5mm what is the sail area difference?

Darin

 

Edited January 19, 2022 by Darin Ballington
Spelling

[Brad Gibson]

Hi Darin, the amount of the leech of say a mainsail would be so small not to make any difference, if boats were the same weight. Now if the waterline is changed through a weight change, then that difference multiplies. I.e lighter boat with a bit of extra sail vs a heavier boat with less sail. The larger the change, the larger the multiplication difference.

As mentioned I’m happy to factor in a safety value from my actual waterline, making my boats 4-5mm longer for measurement than they actually are in the tank. The loss of that slither of sail is far less important than getting the whole project right I think. Remember it is only the largest measured sail for light airs that will have that slither off it that the lower ones need to fit inside of on the grid.

Brad

[Richard98]

I would like to add / reply to the recent comments here. In order:

John; just looked at Graham Bantock's gauge that you referenced. My idea was also a floating gauge. A length of wood floated alongside the WL with a right angle fixed at one end and sliding the other. Sharpened "jaws: set to declared WL and used as a simple Go / No go gauge.

Derek; Pieces of 8 hurtled across our lake and several spectators asked what was powering it. I had difficulty keeping up with my iPhone to video and steer at the same time. Very impressive, particularly as Have been investigating speed sailing for a long time now.

Brad; No hijack at all and keep it coming. This boat was deliberately built as an extreme end of the rule for a reason and has resulted in me becoming interested in the class.

Darin; From previous I have distilled the following results out of data from Pieces of Eight and Bentley designs; summed up below.

WL 1150 & 1344 respectively Sail area 1.08695 sqM & 0.93005 sqM this is a difference in allowed max area of 0.1569 sqM.  This may not sound much in sqM but is 1569sqCm and this equates to > 39 X 39 cm of sail area allowable difference in area for the two designs. Amazing or what !   I think your specific 5mm is easily extrapolated from the rule.

Add to all this is the actual shape variation available to designers and many, many characteristics to play with. 

I don't think I have a measurer nearby so I will incorporate a tolerance on sail area and WL to ensure that I know the boat will be legal but not necessarily fully optimised to the rule.

 

[Darin Ballington]

Thanks Brad/Richard,

From what you are saying there is (obviously) a difference but I am seeing that the difference in measurement technique assuming a degree of competence from the measurer is not going to make as significant a difference as the build quality and skipper ability. And is not something that we should get too hung up on.

From a performance point of view I would suspect that a decent rig and keeping my boat dry would have a bigger impact than losing the last mm of WL.

Cheers

 

[John949]

Unfortunately this picture doesn't show the meniscus as well as I'd hoped.  It does show how bad my paint job is though!   The blue line marks where the meniscus ends (if you look closely you can see the reflection of the bushes behind ends at this point because the water surface is no longer horizontal).  What I was trying to show is just how far apart the waterline mark and the meniscus are - it's around 25mm!

 

Brad,

I don't understand your comment about 'ignoring the meniscus'. If you look under the boat with a mirror, all you can see is the edge of the meniscus.  The sketch below reflects my understanding of the physics of surface tension.  I agree you can see where the meniscus attaches to the hull and where it stops distorting the water surface, but neither of these is where the hull intersects the waterplane.  In other words, you can see Point A and Point B but you can't see Point C

 

[Brad Gibson]

Hi John, 
I'm afraid things are probably a little lost in translation. I appreciate your picture and drawing as accurate. My point that i'm trying to get across is that in looking at the underside of the water surface, you can quite accurately see where it bisects the hull at point C on your above drawing. I ignore what is happening at point A & B (the meniscus). The mirror is held at an angle and you are sighting the under surface of the waterline to get a bisection, not holding the mirror up under the hull to see where the meniscus ends. 

Brad

[John949]

Brad,

Ah I think I understand what you are saying at last.  I've just emptied the tank otherwise I'd have a try.

Richard,

sorry for the thread hijack, I promise to stop now, except.... how have you put the WL marks on your boat if you haven't made the A rig yet?  Setting up a 10R is a bit iterative as you have to sort of guess a waterline, make an oversize rig, weight it, re-do the WL, trim down the rig and so on. In practice one iteration is usually enough but you do need to know the weight of the heaviest rig (almost always the A) before you can finally set the marks.  I shall be interested to hear how it goes against other 10Rs.  I suspect it might go well until you have to change down to the B rig i.e. give up your sail area advantage but suffer with a shorter WL.  The Bentley's party piece is to be able to carry more sail area than most in a given wind strength, of course the wind has to be strong enough for everyone else to need to reduce sail area below the Bentley's maximum.  It's on these days that I remember why I like sailing it so much.  Makes up for all the drifting match days when I get embarrassed by well sailed IOMs!

[Richard98]

Just getting around to the A rig now. I did the initial flotation with a dummy weight; adding a little to that last rig pictured. As you say, this is going to be iterative.

Not going for outright maxing out on the rule at the moment though. Pof8 has longer overhangs than Bentley, having LOA of 1930. Just like the J's of old and should heal to a greater wL as a result. I use the word "should" because I have not got any generated waterplane lines and have to wait for a nice sailing wind and see how it looks.

Have hit one problem with sail measurement though. Expected no problems here and made the measurement grid and took all the relevant measurements.  Appears straightforward until I tried entering the data on the IRSA spreadsheet. After having to make a few assumptions from a spreadsheet that is not particularly intuitive, I began.  Mainsail worked ok but when I entered the data for the jib I keep getting an error message. "Foot length does not match number of heights".  I did get that with the Mainsail also, initially, but found the error. I have spent hours trying to resolve the jib error and have got nowhere.  I know this must be a simple mistake and Have been back through the database figures and studied the cross width diagram; all to no avail.

Is there any guide for this ?

Have I Hijacked my own thread ?

Should I stick to the One Metre ?

Brain hurts.

 

[John949]

There is an error that I found in the on-line forms in this area (which I have reported).  The spreadsheet counts the number of heights you enter and checks that this matches the length of the foot.  So, for example, if your foot length was 425mm there should be 9 entries - h0 to h8 at 0, 50,100 .... 350, 400.  Unfortunately there is a bug in the spreadsheet that if one of the entered values is zero, then it ignores this value and counts one less height than you have entered.  I don't know if this is your problem but try adding / removing entries until the error goes away and see whether it wants too many or too few entries.  Or if you post your data I can check it for you.

You may also notice that the graphs it draws of the sail profile look odd at the head.  This is because it assumes that the head width is zero (why I don't know) so if your sail has a reasonable head width (my mainsail is 90mm) then the graph is not very helpful.

I to have been entering my own data into the on-line forms and have many comments on the layout of the forms, the fact that huge parts of the final certificate are just guidance (and may be totally irrelevant to your particular sails), and the lack of any instructions / explanation on how to fill them in (even to the extent of which fields you have to enter and which are automatically generated).  The fact that all the formulae are hidden doesn't help you understand what they do and hence resolve issues like this.  If you want to see the formulae then is is pretty simple to unlock a sheet - you just take a copy of the spreadsheet and each sheet will then unlock without a password.  Unlocking the whole workbook is a bit more complex but Google is your friend.

 

[Richard98]

Thanks for that, John.

I have now substituted value 1 for h0 mainsail and 1 for h9 jib, instead of value 0;  and errors disappeared. Hooray for that. 

Spent some time trying to make sense of the mast and spar form and sort of got a figure with no errors. However my total SA is way out. Have checked the old fashioned geometry way to confirm this.

So difficult to follow the form. I know a spreadsheet is going to make life easier for a class with variable sail areas like the 10R;  but it is so difficult to understand what is expected. As I said, I have made a few assumptions just to get started.  I know that anyone who has successfully done it once will laugh at my problems and I am a bit cautious about expressing any strong opinions.

Samples: why does sail 2 total have a title "Sail 1" as does sail I ?   What is spar 1 "E" measurement. and quite a few more.

I am using Excel for Mac 2008, which is the same age as my MacBook. Works ok for everything else I do.  I have been looking at the formulae in each cell but that is all. I feel the fault lies in the data I am entering, but cannot find out what yet. 

How did they measure the sails before Microsoft appeared ?

[Solent]

In relation to measurement Forms Try reading this document from the 10R section of the IRSA website.  When using the spreadsheet form the only areas which need completion by the measurer are those highlighted in blue.  It is important to pay attention to placing the sail/mast spar on the measurement grid correctly.

[Richard98]

Thanks Solent, I did that before I started.

Thanks to John sending me a copy of his calculation forms I have realised that the forms I downloaded from the MYA IRSA page were not the same as his. Hence my earlier comments about the Sail 2 page having the same title of "Sail 1" and showing the picture of the Main. I just assumed that this was a generic sail shape.

I have just re visited the same source and downloaded the spreadsheet again and it is completely different. Now I have the same as John. Sort of irritating that the form I downloaded back in December was so different and I have spent two days finding out. Anyway; will try again in the morning. Taking note of the "fudge" that appears to get rid of the error messages because the spreadsheet cannot count from 0.

Appreciate all the help here.

Richard

[Richard98]

Update to my last:  Thanks to John I have discovered that the spreadsheet I have been using, downloaded in December, was out of date. It was version 5 and the current version is 6B. Frustrating or what !

Unfortunately I am still getting a huge error in my sail measurements compared to old fashioned geometry calculations. Will persevere, of course. Have now spent more time on sail measurement than it took to build the 10R hull. Maddeningly I am aware that it must be something I am doing something wrong  However it is interesting that I can reduce the Sail area without incurring error messages by leaving out a few measurement values.

[Solent]

Richard,

I am unclear where you downloaded the version 5 form from but obviously not the IRSA website as the Version 6 form replaced the version 5 on their website in January 2020.  

Note: with the formation of ITCA all 10R documents have now moved to the ITCA website ( tenrater.org ) from the IRSA website.  

I am not sure what you data entry problem is but a common error is to double enter the last (top of the sail) measurement.

The uppermost cross width is always entered into the box marked cn

The aftermost height is always entered into the box marked hn

[Richard98]

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

 

[Paulabrooks8]

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.

 

[Richard98]

Wow !! did not expect that.

Last post then. 

Richard

[Paulabrooks8]

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.

[Solent]

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?   

[Richard98]

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

 

[John949]

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

[Solent]

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?

[Solent]

Correction the latest 2022 IOM class rules are 33 pages.

[Richard98]

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