Hull construction Proposal pt 1AGM 07

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13 Aug 2007 19:20 #20043 by Trevor Lloyd
Please find attached a copy of my rule proposals for 2007.

This proposal has been seconded and will be put to the AGM. More than happy to take comments, anyone wishing to associate themselves with these proposals please let me know. It might seem like a lot of change but it's only the things we've (the open circuit racers) been discussing and someone has to play devils advocate!.

Existing 1.6.1.12 A bulkhead or strut of plywood or wood may be fitted in each side tank in the vicinity of the thwart.

Proposed 1.6.1.12 Bulkheads or struts of plywood or wood may be fitted in each tank.

Reasoning

The new mark 3 has been designed to be built from 10mm foam bonded using epoxy glass to give a bilge panel thickness of around 12mm. The deflection of the pounding area’s in particular will deflect considerably less for a given force than the existing 5mm ply on the wooden boats. This is an advantage in terms of durability and potential speed.

This proposition allows new wooden boats to be built stiffer on the bottom panel which would compromise the lightness in the ends but would balance the requirements of building stronger but not necessarily lighter. Owners could retro fit if they desired.

The same to a lesser extent can be applied to the decks which need to be strong and stiff under the seating areas but light at the ends. Note: Some builders are already doing this.

Allowing bulkheads and stiffening evens up the balance as strength can be built in but how much is dependent on maintaining the optimum 45.5kg weight limit, so is essentially self limiting.

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  • Roger Clark
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14 Aug 2007 09:04 #15430 by Roger Clark
Replied by Roger Clark on topic Hull construction Proposal pt 1AGM 07
Making panels stiffer will increase the life of boats and I cannot see any problem with this rule change. I believe many rules should be simplified to allow owners to stiffen and strengthen their boats, especially older ones.

The Mk3 Mirror is helping to bring the class into the modern world and possibly change the class permanently by reducing wooden construction. Building in wood is expensive in time and maintenance, therefore costly. Reducing build costs and delivery times should increase interest in the Mirror class and encourage more to buy a Mirror over other classes.

The basic concept of a safe boat will always remain with the design of the hull with its generous hull volume and high freeboard. These factors will always make it suitable for training purposes. I returned to the Mirror after 35 years so I could teach my 10 year old daughter how to sail. I have fond memories of my early days sailing Mirrors and I am surprised at how many people is talk to on the shore or on the water also have fond memories of their times in the Mirror.

I am certainly no stick in the mud type, we need to adopt all of the changes that have been proposed to keep the class alive.

Roger
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  • angus
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14 Aug 2007 13:15 #15433 by angus
Replied by angus on topic Hull construction Proposal pt 1AGM 07
I don't know if people will bother to stiffen their current boats but if it is true that stiffness enhances performance this is a proposal that is needed to keep wooden boats competative in light of the new alegedly stiffer boat from winder.

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14 Aug 2007 14:48 #15436 by Paul Hansen
Angus some builders are already using lighter ply to bring the weight down and then using stiffening, it is not an issue directly related to the Mk 3

Paul

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14 Aug 2007 16:31 #15440 by Trevor Lloyd
Take it from me give the new mk3 a firm prod in the pounding area's under the mast then do it on your wooden boat, you'll be surprised just how stiff the new boat is. Every time a softer boat hits a wave it absorbs a little bit more energy than a stiff boat. Over the course of an hour or so that equates probably to a boat length or two, not much but it all adds up. Not only that but the stiffer boat will remain competitive and last longer.

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  • D Hughes
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15 Aug 2007 09:37 #15446 by D Hughes
Replied by D Hughes on topic Hull construction Proposal pt 1AGM 07
On the racing Mirrors I have built I always fit a triangle of extra 6mm ply either side of the inner tank divider just under the mast step. This gives extra support when putting on extra rig tension.
If you wanted to put in a bit of extra ply to the outer side panel inside the tank, who is to ever know you have anyway?
On two of the boats I have built I have fixed an obishi strut inside the side tank to extend the thwart from side to side of the boat.(So no movement of the centre casing due to side tank flexing).
As I always say, only think about these extra items when you can do perfect starts, sail with a dry boat (not with 3 buckets of water splashing about), and have a boat equipped with the best sails you can afford, and have 100% quality roller ball fittings and a nice stiff board. Ho and be a top of the game sailer. A stiff, light boat will only be of advantage when you master or have all of the above. The Mirror needs less rule changes, just better sailors.
Cheers
DH

X

Edited by - d hughes on 15 August 2007 10:41:24

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  • Tim Smith
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15 Aug 2007 18:13 #15447 by Tim Smith
Replied by Tim Smith on topic Hull construction Proposal pt 1AGM 07
Some pretty good points. I'm sitting on the fence a bit, but I'd have to agree that you need both a good boat and to be able to get good starts etc. The boat is only as fast as the sailor, and the sailor is only as fast as their boat (work that one out!)

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16 Aug 2007 22:44 #15454 by Trevor Lloyd
Hi Dave

The reason for bringing this up is that to add bits of ply to stiffen the boat is illegal today, as is building or repairing boats using parts from non approved sources. My reasoning for this proposal is that the boats are being modified illegally, but often for good reason. An eagle eyed measurer or indeed another mirror owner might spot it and protest, rightly. After all that's why we ended up with a big hatch cover in the front tank. This allows people to build boats that are the right shape, but stiffer and stronger and lighter and heavier and anything else you might want, at the end of the day the bit in the water is still the same shape.

I absolutely agree that sailing a good course and handling the boat well makes a huge difference and more than tweaking boats.

Having jointly measured the new MK3 I can assure you that the bilge panels are immensely stiff. Allowing additional stiffeners in wooden boats is a good thing and as you point out, you do it already. The only difference is that you could do it legally!

I personally would like to see simplified rules, ours is a book! Other classes seem to manage very well with very little in the way of prescription and still look like they did when designed.

The writing is on the wall for wooden boats, the future is about to hit the water in the shape of the MK3. In the last class I had sailed in for years, when this happened, almost overnight, wooden boats dropped out of fashion and some of us lost 000's.

Allow the wooden boats to modernize and keep them going what have you got to loose.

All interesting stuff and debate is fun

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  • ASW
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17 Aug 2007 07:23 #15457 by ASW
Replied by ASW on topic Hull construction Proposal pt 1AGM 07
All good stuff but the rule change does not seem to address the areas that do need stiffening.
A stiffener fitted in the side tanks will really only benefit the lateral stiffness by providing support to the thwart and therefore c/b case - very good practice (it completes the triangulation out to the chines)
However, allowing stiffening to the bottom panel by adding a second plywood skin (say 3mm) would immensely increase the hull stiffness where it matters and could easily be retrofitted - hey we could even do away with those dreadful floor battens. The solo class allowed this a couple of years back - it works.

Granted, this would add more weight on older boats but new wood boats would be easy to build down to weight (and well under!!)
Whilst on the subject - this has highlighted the need (again) to forget the old constraints on plywood & wood types (ie as per the kit or officially produced panels) and time to open up the building methods. Light plywoods, balsa, foam, glass skinning etc... have all been used by other classes to good use.(2or3mm light-ply with glass skinning both sides is pretty stiff & light)

As has been pointed out, the new Winder boat will completely out-class any other as has happened in other fleets but only if the Association & particularly the ISAF do not remove the archaic and restrictive wood building methods.
I recently decked a Winder FRP solo shell for my own use and the greatest struggle was to get it anywhere near weight. This was with Sapele faced ply! This was excellent as I put all the weight in the Centreboard case (low and central) allowing the ends and sides to be very light. I was offered a cheque for 9k for the boat at the first open i attended (2.5k more than an all FRP Winder)
Can`t wait to do a Mirror, I reckon I`d need to lead line the Thwart and c/b case though.

Just some thoughts!!

Andy

ASW Boatbuilding & repairs. 07966 513147

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  • Roger Clark
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17 Aug 2007 08:45 #15458 by Roger Clark
Replied by Roger Clark on topic Hull construction Proposal pt 1AGM 07
Besides having a boat we all love to sail, we must protect the market for secondhand boats as this will always affect us at some point in the future.

New generation materials should be readily accepted. This should widen the appeal for this classic class and having new blood keeps the class alive.

Alterations to the stiffening of the hull should not only benefit the eventual life of the existing wooden hulls, but the value of the boat as well. If the class is perceived as active, the boats last a long time and hold their value, then there will always be people wanting to buy secondhand Mirrors. We certainly do not want the situation where the Mk3 completely outclasses all existing Mirrors as it will affect the value of all older boats.

As a class we should be thankful we are not dependant solely on being a racing class, it is having an active following of people not interested in racing that also keeps the value of older boats higher than many other similar sized boats.

We have many advantages over other small dinghies, please do not let us forget that. The class must modernise or die. Let us simplify the rule book and accept the changes as necessary. Life now is not like the 1960's when the class was conceived. If we do not change then we shall all loose out to other classes.

My views may surprise many as I am not involved with racing at the moment, and I certainly am not in my youth, but I do think my voice should be heard for the many not involved with the racing circuit.

Roger
59725

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17 Aug 2007 08:54 #15459 by Trevor Lloyd
Hi All

To address Andy's point one that I forgot to post although it has been submitted to the agenda at the AGM

New Rule 1.5.9. The panels shall be of constant section throughout their length and shall conform to the following table.

Finished Thickness mm
Panel Minimum Max
Bilge Panel 5mm 12mm
Side panel 4mm 5mm
Deck panels 3mm 6mm


Purpose: to allow builders the option of increasing the stiffness\ strength of the boat utilizing standard timber of metric dimensions. This allows for the equalization of panel stiffness with the Mark 3 utilizing 12mm foam floors.

Cheers

Trevor

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  • doodiboo
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17 Aug 2007 16:21 #15460 by doodiboo
Replied by doodiboo on topic Hull construction Proposal pt 1AGM 07
I upgraded my kids to a new GRP boat last year after the introduction of the one piece mast, without realising that more significant changes were going to be introduced to modernise the Mirror - the hull design variations which lie behind the "Mk3", and the centre main/GNAV. I now own a one year old boat which is about to become obsolete, with a reduced resale value as a consequence (no matter how often the mantras "old boats can be as fast as new boats" or "it's skill that counts really" are repeated).

I know that pure "one design" is a fallacy in any class, they all develop at intervals and there are always tweaks and upgrades - but if the Mirror class rules are going to keep changing annually, then there must be a risk that modern classes which are closer to being "one design" start to look attractive on cost grounds. Surely that is the opposite of what is intended.

The Zone Squad/National Squad parents will always spend the money. The woodworkers will reach eagerly for their tools (and all power to them). The non-racers won't be bothered. However, I suspect that my constituency - parents whose kids are fairly keen racers but whose decision to buy new boats or components has to be balanced against other interests - is quite a sizeable one! For us, it would be a good thing if these rule changes could be the last for a while. So if a bowsprit, asymmetric and trapeze are on the cards, please say so now!

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  • Simon Lovesey
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17 Aug 2007 18:24 #15461 by Simon Lovesey
Replied by Simon Lovesey on topic Hull construction Proposal pt 1AGM 07
Doodiboo

We are nearly at the end of the modernisation programme, the objectives have been two fold :

1. Address the old fashioned elements like the gaff and transom sheeting that were putting off people

2. Make the boats easier and cheaper to build, and improve durability.

The aim has not been to outclass the existing fleet and the evidence to far would suggest this has happened. When the Mk3 was approved, it was agreed that the class should look at the wood boat, many of the proposals for the AGM are focused in this area.

It is the Committee's intention to freeze changes, once the wood boat has been refreshed.

With regards resale prices this is a difficult call, but the modernisation process in attracting and rejuvenating much interest in Mirrors, a healthy and active class will lead to strong resale values.

A good example is the Firefly class, which has recently undertaken similar changes that we are now implementing, these have helped the class survive and benefiting the existing owners.

MCA Secretary

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17 Aug 2007 19:19 #15462 by Trevor Lloyd
Doodidoo

I recognize that the class is going through huge change and that we appear to be tinkering. The mirror rules are quite prescriptive but also seem to be open to interpretation judging from looking at the boats.

Nothing in the new proposals is designed to outclass the existing boats and the changes are designed to be low or nil cost. I like you have a new boat so am hit by the same issues like many of us, though mine is wood. Having built a mirror for the first (and only) time I can see that some of the changes that were introduced in the past were perhaps half baked, floor battens for one.

Some of the changes have been proposed to allow boats to be build using modern techniques reducing build time and allowing boats to be built stronger and last longer.

The bits that matter will not change, like hull shape, foils, sail plan etc. Actually all the wood ones are a bit different in shape, they were even when bell made them. The changes will allow the wooden boats to remain competitive particularly the new builds if the changes are ratified.

The handicap remains the same as nothing is being done that is performance enhancing.

Nothing, I propose will change the essence of what is a terrific boat that teaches better than most of the new tupperware classes and actually is pretty close to a one design.

I am committed to trying to generate interest in the classic mirrors, we even have a new national classic mirror trophy to race for.


NO ASYMETRIC's or BOWSPRITES

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  • HannahJ
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17 Aug 2007 20:08 #15463 by HannahJ
Replied by HannahJ on topic Hull construction Proposal pt 1AGM 07
Bother <img src=icon_smile_tongue.gif border=0 align=middle>

64799 "Dolphin"

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