I recently acquired a hull which is about 56” long and maybe 11” beam - not in front of me this minute so I can’t tell you exact dimensions but it’s carbon. I showed it to Martin Roberts - I thought it might be a Bentley but Martin thought not, maybe more Squire Kay and with a Bantock carbon fin. It’s no doubt not competitive compared to modern designs but it’s never been finished so I think it deserves to be. Any thoughts and opinions appreciated! Any idea where I get a copy of the class rule?

Many thanks 

Simon

How about looking at the 10R section of the Classes Tab on the mYA website??

https://www.mya-uk.org.uk/kb/ten-rater-class/

Thanks Pete - there had to be a way!!

Simon

 

So I have a copy of the class rules to peruse and I can see that the waterline length is a consideration in defining the maximum sail area. I also see that some designs do not have overhangs but I’m not sure if this hull will or not. It strikes me that I need to fit the fin and rudder and then put it into some water to see how it sits. I need to put radio gear into it but I wonder how much I should ballast it up to equate to a maximum sized rig? Apparently i need a carbon mast and spars and not necessarily a swing rig. I’ve never built a yacht with a swing rig but I recall Martin R saying the mast was in the wrong position for a swing rig but okay for a conventional one although I can’t remember what the criteria were now!! 

Any suggestions appreciated!!

Thanks

Simon

The 10R rule is LWL x Sail Area x 8 = 10, so the longer the LWL the less the maximum sail area allowed.  Most modern designs have an LWL of between 1200 & 1250.  A Bentley has an LWL of around 1340 and is still a great boat in a blow but struggles in the light stuff.  I suspect you will want to keep everything as light as possible in order to maximise the sail area.  Leads are usually around 3.1 to 3.6 Kg.  You measure the LWL in sailing condition so you will need to estimate the weight of the rig (about 400g). 

Any boat can be a 10R if it rates less than 10 and several Marbleheads were dual registered.  A standard M rates about 7.5 so a bigger rig is used and this makes a very competitive light airs 10R.  Proper 10Rs have overhangs as this increases the LWL when heeled, which is an advantage.

A conventional mast is normally positioned 10 to 20mm forward of the leading edge of the fin.  A swing rig mast will need to be positioned about 50-60 mm further forward, as the swing rig main has to be bigger.  Conventional rigs are around 60:40, swing rigs 70:30. Graham Bantock and Frank Russell have actual dimensions for their designs on the web.

Hi John,

Thank you for summing it up pretty much in a nutshell, that is just what I needed.  The first thing I need to do is to establish what the LWL is when ballasted. I know from the rule that some 10R's don't have overhangs but I understand why it's preferable that they do. I am slowly reading through the rules - isn't it LWL x SA divided by 8 = less than 10? I am really interested to know what the hull is - carbon fibre, longer than 48" so not marblehead, quite beamy. Martin Roberts  thought it might be from the stable of Squire Kay but I'm not aware that he designed and manufactured 10R's and there are no SK designs on the internet. Martin also said it had a GB carbon fin. But I think it deserves to be finished anyway!

Edited December 21, 20241 yr by SimonCornes

LWL is in metres, Sail area is in square metres so for a typical 10R  1.25 x 1.0 x 8  = 10

3 minutes ago, John949 said:

LWL is in metres, Sail area is in square metres so for a typical 10R  1.25 x 1.0 x 8  = 10

Thanks for correcting me John!

I wonder if the hull is a Squire Kay Skua? Derek Priestly refered to that design in his obituary to Keith Partington so I wonder if it’s one of Squire’s or even Keith’s as it’s a carbon hull?? I don’t think I’ve ever seen a Skua. Any thoughts?

I’ve got the hull in front of me now. No bow bumper but length from stem to stern is as near as dammit 1.5 metres. The beam at the broadest point is 27.5cm. The fin length from the underside of the bulb to the bottom of the hull is about 53cm and weighs about 4.15kg. Carbon rudder about 18cm long and maybe 7cm maximum chord. 
Is it a 10R ? I’ll take some photos but unfortunately I can’t upload them but I can email them if that helps?

Simon

Edited December 21, 20241 yr by SimonCornes

It  ould be a 1.5 metre ya ht there were a few of these around, I know John Lewis did at least 2 designs and Oliver Lse did at least one they tended to look like oversized Marbleheads

13 minutes ago, Mike Ewart said:

It  ould be a 1.5 metre ya ht there were a few of these around, I know John Lewis did at least 2 designs and Oliver Lse did at least one they tended to look like oversized Marbleheads

I was going to say I wondered if if might be a 1 1/2 metre but I checked the deck length and I think it would be more they 1.5m from stem to stern.