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 Post subject: Proposal for increase in minimum weight to 55Kg?
PostPosted: Sat Sep 10, 2011 3:48 pm 
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Hi All,

I have heard on the grapevine about the proposal for an increase in minimum weight to 55Kg....

..but don't think there has been any discussion here on the forum and wondered if someone would like to fill in those of us who were not at the worlds a bit on what the proposal is....and why it has been suggested and what the hoped effects would be from it.

It sounds like a damned good idea to me, I like it, and it would certainly encourage me to build, but I would wonder if the concept of 'cheap ply boats' is where the class wants to go?? I like the idea, but would it encourage people into the class??
I worry somehow that it seems a step backwards from where we were at a few years ago... But also worry that the concept of 'cheaper', 'easier-to-build' ply boats may be an illusion...?

I would love to read some discussion on this from those who are far better boat-builders and sailors that I ever will be.

cheers

eib

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Sun Sep 11, 2011 9:13 pm 
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Joined: Fri Jul 18, 2003 11:12 pm
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The weight of the new rules boat was discussed at the "open floor" part of the Owner's meeting at the Worlds. The views expressed were that it is challenging to get to the 50kg weight, especially for amateur builders, few new boats built have actually achieved this weight, many hitting the scales at 52 or 53Kg, and getting the last 5kg off to reach 50kg leads to significant expense. In addition, this would open up the possibility of competitive plywood boats (albeit with lots of carbon reinforcement etc) that Steve Clarke has demonstrated is possible.
Any amendment to the weight of the boat would have to go through the normal process for rule changes.
Phil


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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Mon Sep 12, 2011 7:17 am 
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The weight change was talked about, and I was in favour of it, because it seems that although a 50 KG boat will all the bits on you need (fitting and rope weight quite a bit) is possible, everything has to be spot on, and thats on a foam sandwich boat. The ply boats seem to be nearer 60KG, but being 5kg over is not as bad as 10kg over. It always seems to be that the price of hulls is debated when the expensive bits are the other bits, if you want to self build making a ply male mould really does not cost much in the scheme of things, perhaps £250? and carbon foam as a build material really is not that expensive, good ply when coated in epoxy both sides is not exactly cheap and you need to paint both ply and carbon what ever you do. A lot of the cost in a professional build is in the time you pay for, so getting a one off built is quite expensive, but building a one off yourself is not too bad, but it does take time!

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Mon Sep 12, 2011 7:34 am 
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Alistair wrote:
The weight change was talked about, and I was in favour of it, because it seems that although a 50 KG boat will all the bits on you need (fitting and rope weight quite a bit) is possible, everything has to be spot on, and thats on a foam sandwich boat.

Have we forgotten that the very minimalist Tin Teardrop was nearer 40kg... In most of my time in Cherubs - ie before foam sandwich - the 110 lb weight limit was definitely aspirational, and most boats were a few pounds overweight. The techniques were improving though and by the late 80s it wasn't such a problem for wood boats, even ply over stringers.
A lot of ICs have very complex fit outs, and the gear has a particularly poor cost/weight ratio. I'm not sure that discouraging complexity is a bad thing (but then I would say that, not understanding what to do with all the strings I don't have them!). On the other hand I suppose we don't really want to be going to Harken or Allen or whoever to commission titanium versions of all their s/steel bits at twenty times the cost.


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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Tue Sep 13, 2011 12:01 pm 
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Hi jim
No , i have not forgotten TinTear Drop, but that was of a very minmalist hull and fit out. I have found, and beleave me I have tried, that the min fit out still requires a certain amount of tat on the deck, and really 2 sails, I would rather it did not , but two sails and an adjustable rig really is quicker. It does seem to be a backward step to put the weight up, but my idea was so as to encourage people to build boats who may be put off, if very few boats are at min weight then it makes it seem harder than it is to build, but its only a proposal, what do other people think?
Alistair

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Tue Sep 13, 2011 2:39 pm 
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My personal vote would be to keep the weight at 50Kg.

The reason being that there is then a pay-off between saving the weight and adding more adjustability (is that a real word?) to the rig.

I, like Jim, would go for simple and minimalist and aim to keep the weight down (mainly because I don't know what all the string does either), but others may prefer to take a bit of weight penalty to addin rig adjustment.

It also makes you think about ways to save weight on rigs, foils, seats, etc.

It's what a real development boat is about surely?

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Wed Sep 14, 2011 8:02 am 
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My first minimalist version of Tin Teardrop was 40kg, and eventually ended up at 47kg, after adding fore/aft seat tracks, flare/deck extensions, moving the rig back, moving the centrecase etc etc.
If I'd added more rake/rig tension adjustments, it would still have been less than 50Kg even after all the mods / layers of filler and paint.
The hull was light, but all the other parts were too - light foils, 1.5kg carriage, light seat etc .

The other boats I've made ( 2 x Morrison and Dragonfly ) were similarly light hulls,and came in just on the 50kg limit as far as I know, using all the tweaky rig controls and relatively heavy seats/carriages.

If the weight was increased by 5 kg.... that's a lot of carbon! ( in weight, time and cost ) - and where would I put another 13 sq m of carbon?
So this would make pro-built boats more expensive ( maybe + £400 for extra carbon on the hull)

It's not as though the light boats are too weak or bendy, but you do have to carefully consider everywhere and everything that might add un-needed weight.


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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Wed Sep 14, 2011 9:00 am 
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Location: Australia
Andy P wrote:
If the weight was increased by 5 kg.... that's a lot of carbon! ( in weight, time and cost ) - and where would I put another 13 sq m of carbon?
So this would make pro-built boats more expensive ( maybe + £400 for extra carbon on the hull).


5kg of lead would would be cheaper.

However, I'm with Jim and Bob on this one. I like the idea of the trade of between the lightweight minimalist rig and the heavier more complex rig. And lets face it, a plywood hull is never going to be fully competitive with a carbon hull. Even at the same weight, the plywood hull will be softer and less durable. Anyone who is really serious about winning (as opposed to tinkerers like myself) will aspire to a full carbon hull. My point being that the argument that raising the weight limit to make plywood boats competitive is a bit of a red herring.

The idea of reducing the beam and weight restrictions was to make a significant difference to the performance of the IC, in order to make the class more relevant in the 12st century. So far it seems to be working and if the current crop of new boats is still a bit short of the mark, it means we still have potential for further improvement. I think we need to be very careful about watering down the current level of progress.

Also, 50 is a nice round number.

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Wed Sep 14, 2011 11:26 pm 
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Scarlett, the Morrison that Andy built me, now sold to Perham Harding, was spot on 50kg in Australia, and since then, I added about another 2kg in extra fittings and pro-grip (which is excellent). On the next boat, I reckon I might be able to get the boat down to 50kg by having a lighter seat carriage and tracks, but there really is no further scope. I recall great effort was put in to reduce the weight of every component as far as possible. It does rely on having someone with specialist skills like Andy Paterson to get to that weight -not sure how many professional builders could achieve that weight, let alone amateur builders. It also relies on getting the lightest foils, spars, fittings, rigging etc, which does add expense. The boat seems sufficiently strong/rigid not to require any additional carbon or thicker foam, so if the min weight increased by 5kg, I would explore the scope for an additional layer of material (probably not carbon) to increase resistance to dents. Would welcome thoughts on what material would be best and how much weight would be added.
Phil


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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Thu Sep 15, 2011 8:45 am 
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My experience is using foam/carbon and I find that unwanted weight is added by an amateur when using too much epoxy in the layup and when not knowing what you can get away in terms of bracing and re-inforcement and this comes with experience. There is always doubt about how much material and epoxy you need to add at various stages of the build to give the strength required. This can be solved by producing some guidelines on proven techniques and designs and help amateurs and the sharing information by those of us who have done it. An anateur with no experience can easily add 5kg to a boat and therefore we have to be careful to make sure the amateur will still be attracted to a self build and not have too many issues in getting to a sensible weight.

Assuming all of the above is right and we have a well proven set of build procedures, the weight it is also a trade off between lightness and longevity. It is possible to build a carbon/foam hull for under 25kg but to do this you need to be using a single thickness of carbon on the decks and hull. A single layer of carbon on foam dents very easily and adding an extra layer will massively improve appearance after a few seasons at the slight expense of weight. An extra layer of carbon or preferably glass for scuff and dent resistance to reduce long term maintenance issues will add about 3kg on the decks.

Skimping on the hull is false economy in my view and do we want to produce a load of new boats which all look like golf balls after a couple of years? Not sure if that would be too good for the class if we have Moth like wafer thin hulls.

So what is the best achievable weight? I'll reserve judgement until when Rob finishes painting Sapphire but it will certainly not be as low as 50kg. However I can see immediately how I can save some weight through small improvements in technique. 55kg seems a more reasonable figure to me based on the above.

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Thu Sep 15, 2011 7:06 pm 
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As someone who’s attempting to build a SHC ply variant IC I thought it might be worth me adding some observations to this thread (just for the record I have, in the past, built a number of dinghies )

I must begin by saying that I reckon that with the current build it will be absolutely impossible for me to get anywhere near the 50kgs.

First I haven’t got a vacuum pump at present and so there’s no doubt that I’ve used lots more epoxy in the lay-up than I should have. Second as SteveC says the difficulty is knowing just how far you can go in skinny-ing down the internals. One of the major problems with the IC is having sufficient strength in the hull to control the twisting moment caused by mast and sails v’s seat and driver. Maybe after I build a third or fourth hull I’ll have a better understanding of the problem.

The reserve buoyancy as required by the Rules. - foam boats can include the amount of foam in the skin and structure in calculating the overall figure for foam needed, ply boats don’t have this luxury and foam will add another couple of kg’s to the all up weight. Ok, so use bags, that’ll save a bit, but once you’ve got a decent amount of structure in there to support the dance floor there’s not much room to stuff even a 48” x 7” pillow bag. What about punctures? I also reckon that it will be virtually impossible to be sure that every epoxy nib and carbon needle has been dealt with.

The all important carriage tracks, weight-wise, are also a wee bit of a problem. The standard Holt/Allan alloy tracks and s/s runners must surely weigh a couple more kg’s. So I guess I’ll be attempting to make carbon tracks and parts and no doubt in my quest to make them strong enough will inevitably over build ‘em. At least I can make good use of shrink wrap tape to consolidate the lay-up.

I started this project with the thought of transferring bits over from the current Nethercott, but realise now everything will have to be new build - seat, carriage, dagger and rudder. It all takes time. Hey-ho!

As Mal said 50kgs is a nice round number, but just perhaps that’s why 50kg was chosen. :wink:

Ian

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Thu Sep 15, 2011 7:34 pm 
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wee mcp wrote:
foam will add another couple of kg’s to the all up weight. Ok, so use bags, that’ll save a bit, but once you’ve got a decent amount of structure in there to support the dance floor there’s not much room to stuff even a 48” x 7” pillow bag.


Did you not consider using your foam to support the dance floor?

Thinks 257 came out about 74kg after her rebuild. She's probably lighter now with an ex TT plank instead of the wooden one. That was a first canoe interior... Of that extra 24 s'pose 10kg was in the hull shell which was one of Rob's earlier carbon foam ones (much heavier than current ones I understand) and the most spectacularly built shell I've ever come across - I normally expect shells with no structure in to be floppy but that one was so solid that I gave up any idea of trying to manipulate the shape. Reckon there was at least 5kg, probably not as much as 10 in the reused plank and the stainless steel carriage rails: should have got alloy... The dance floor is 4mm ply plus a layer of kevlar: foam would have saved a good kg. Its also probably over supported with foam: reckon there's more there than needed for the buoyancy but I was also nervous about deck support, but apart from one bit near the stern past the main trample zone that I think probably didn't glue down properly as its always felt a bit bouncy the dance floor still feels completely very solid three seasons on

There's some extra internal framing round the daggerboard that I'm sure was unnecessary, but I was feeling nervous, and the mast stump is built like several brick outhouses because I'm terrified of a failure there, but I reckon its worth the weight to have confidence in that... If I were an engineer I could do sums I suppose but I just bunges lots of extra carbon on. I think if I did the same job on a new shell now it ought to come in under 55 and I'm no great craftsman.

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Thu Sep 15, 2011 8:02 pm 
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My shell ( Morrison ) expertly built by Andy P and completed by myself at home came out at 52.5 kgs. Its a wonderful canoe but I do wish the hull was a little more dent resistant. If the rules are changed ( and all members will get there say worldwide ) and weight increased to 55kgs, I'll add a layer of glass on the outside for added dent protection, most of the dents h happen ashore or while launching etc. :lol:


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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Thu Sep 15, 2011 8:33 pm 
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Hi Jim
Quote:
Did you not consider using your foam to support the dance floor?


That was my first plan but not being built to Razorback standards the 3mm ply+200gm black stuff needed something more beefy in the way of internals

Quote:
I normally expect shells with no structure in to be floppy but that one was so solid that I gave up any idea of trying to manipulate the shape.


The ply job could be moved in and out it was definately floppy

Ian

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 Post subject: Re: Proposal for increase in minimum weight to 55Kg?
PostPosted: Thu Sep 15, 2011 10:05 pm 
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That was my first plan but not being built to Razorback standards the 3mm ply+200gm black stuff needed something more beefy in the way of internals [/quote]

Not easy to see in the photo is a full height carbon spine right down the middle (well, it stops a foot or so in front of the mast stump) and a full height carbon bulkhead each end of the seat track. Neither has lightening holes because I was feeling lazy and persuaded myself that the extra strength would be worth the weight. My "oh bother it: all that work that won't be worth the weight gain" feelings I find to be a major enemy when on a weight budget. When I ripped out the original build there was all sorts of diagonal bracing under the deck but I found it hard to believe that it could do very much more than a 4mm ply deck with kevlar underneath would contribute... There's a surely unnecessary bulkhead from the shroud position to the front of the daggerboard; what I reckon should have done was just put a wide piece of 10mm foam/carbon between the front bulkhead and the fore end of carriage bulkhead to support the top of the daggerboard case... I don't vacbag at all, having neither the facilities nor the experience, but what I do is send Andy P some drawings and have him make me some nicely vac bagged flat panels so all I do is trim and glue in.

Internal structure requirements for lightweight ICs sounds like a reference we ought to have: I have trouble visualising in my head what needs to be there to resist the dooubtless vicious torsional loads...


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