Dart 15 Forums

I agree with Paul. What would seem sensible is a gentleman's agreement (without the need to wait for the AGM) where people with the new boats add weight as that seems to be where the immediate problem lies.

The easiest way to do this is to drop a bag(s) of lead shot in each bag (easy to buy on eBay). If anyone is unable to measure their boats to get them to 65kg total then just add 3kg / hull?

- Stuart Snell
- Kevin Kirby
- George Love
- Jim Bowie
- Gerald Sverdloff

Would you be happy to do that?

Or just grab some gravel for now.

There's an old saying that goes, "A good tennis player with a lousy racquet will always beat a lousy player with a good one". In other words, I'm fairly certain a new boat would make little, or no difference to my performance.

The over-riding imperative is that the class continues to grow. We've made a good start with the latest line of boats which cost about the same a second-hand Ford Focus. If we have new boats coming off the production line, our spares are guaranteed. Let us not put this into danger.

What danger?

Andrew Hannah wrote:There's an old saying that goes, "A good tennis player with a lousy racquet will always beat a lousy player with a good one". In other words, I'm fairly certain a new boat would make little, or no difference to my performance.

Andrew, yes I can see that but it is not the right question. Surely the question is: can 2 equally good helms stand the same chance of winning if one sails an old boat and the other a new boat. The answer is no because the new boat will always be better as it is stiffer, everything is tip top and works like it should, but it was not intended that they would be 7Kgs lighter than any other boats racing were when they were new. We have collected lots of weight data over the last few months including the QC reports from 15 hulls that were weighed at manufacture by Reg White's staff. All of these were in the weight range of 32.5 -34Kg. We have collected lots more hull weight data of used boats and now have data on 64 hulls. If used hulls are dried before we weigh them we end up with another group of 19 hulls with weights that range from 33Kg to 35.5Kg. If we apply statistical analysis to both groups of hulls both groups predict with 99.98% confidence the minimum likely hull weight at manufacture/dry conditions was 32Kg before these new boats were delivered. That is the very lightest that could have been made most would have been heavier - we only found ones that started with weights of 32.5 to 34Kg. Hulls get heavier with use due to repairs and moisture absorption and so old boats are often much, much heavier than the new boats. We have measured some at 38Kg/hull (some 18Kg/boat heavier than the new boats) but that is a fact of life if owners do not keep their boats dry and slap filler on them to repair them. We are only comparing the new boats to existing boats when they were new and they are about 7Kg lighter.
The motion we passed at the 2012 AGM to allow the new boats was as follows:
Proposal 3
It is proposed that the inner moulding of the cocktail cabinets on new boats is replaced by a mesh bag below the hatch cover provided that the boat has the same overall total weight.
Rationale: This is a cost saving that is enabled by the creation of new tooling. The weight will be made up by increased strengthening around the hull and by the larger section front beam. It is uncertain if the mesh bag will be big enough to enable storage of the Praddle.
Proposer: Bob Carter
Seconder: Nick Dewhirst
It seems only right to fit the new boats with corrector weights to correct their non compliance with this proposal which we passed unanimously.
Regards
Bob

Dear Bob,

I defer to the wealth of your technical data. Good job we have someone as yourself, on whom we can rely for this information. My contribution is more subjective.

Judging by what you say, respective weights are but one part of performance. As you say, there are other criteria such as new boats being 'tighter', presumably with less play in the beams etc.

With this in mind, are correcting pieces such a big deal? I don't think I would gain any satisfaction if I won in a boat that is out of class.

Andrew, I have strong views on it but I get criticised by others on the committee for being too forceful in expressing them and trying to "railroad my views through"
It would be interesting to hear what other sailors in the fleet think.
Regards
Bob

Well the way I see it, with the new construction methods that have been adopted, no cocktail cabinets, the new beam, foam filled rudders, stiffer hulls, the only true option would be is to have an all up minimum sailing weight!

I think the issue with the new underweight 15s is very easy to solve.
As I understand old boats without cocktail cabinets always should have had to carry corrector weights. The new boats should have to do the same. I would suggest that Steve Sawford comes up with an average weight of a pair of cocktail cabinets (including the weight of the fibreglass that holds them in place and that is added to the new boats in the form of a corrector weight in each hull. This could then be easily checked at all events. I don’t think the Sprints should get into weighing every hull at events as that would not be in keeping with the 'Sprint way'!(as well as taking up a lot of time. Just checking to see if boats have cocktail cabinet or corrector weights is easy and takes 10 seconds per boat!
If its not a rule to add correctors if there are no cocktail cabinets - then one should be proposed - I hope to come to the Nationals this year and I for one would be in favour!
The weight difference of the front beam is also a Red Herring as there is a big benefit of it being stiffer that will more than offset that!

As Liam pointed out in an earlier post, under the current Rules for National Championships 5.3 '...Boats without cocktail cabinets in each hull shall carry correction weights.' So we have the rule in place to allow the new boats to carry correctors. In fact this rule REQUIRES the new boats to carry correction weights. It is not explicitly stated, but it is fair to assume that the correction weight in/on each hull should be equal to the weight of the missing cocktail cabinet & its related fixings. Neither is it stated where the correction weight should be, but it is reasonable to assume that the correctors should be positioned as close to the location of the missing weight as possible, in the new boats this is either in the nets under the hatches or embedded in the foam immediately below the hatches.

Unless a rule change is proposed to 5.3 our committee needs to ascertain & publish the weight of the cocktail cabinet & its related fixings to allow all boats without cocktail cabinets to be able to comply with Nationals rule 5.3. While not required for any other event, it is reasonable & honourable to assume that the correctors will be carried.

As I see it:-

1) publication of the cabinet weight is the end of the cocktail cabinet debate & can be put to bed before the start of the summer season.

2) if the corrector weight in 1) above is significantly different from the 4kg per hull difference identified by our committee's analysis then the committee then I would expect our committee to issue a statement of intent regarding any proposed rule amendment at the same time the corrector weight is published. This will allow all members to consider a next step, should this be required.

3) the overweight boat issue is a completely different thread which, if required, can be pursued once a clear baseline for moving forward with the new boats is understood and agreed. In any case as previously stated, Sprint 15 Class Rule 6.(b) states '...Any alterations to the hull construction, equipment, spars, sails or running rigging, as supplied by the manufacturers, except as specifically authorised by these rules, is prohibited.' Thus a rule change would be required to state any part of the designed boat which can be removed or altered in 'Amendments to section 10'.

Some good points.. The easy one to focus on is:

“5.3. A boat shall be allowed to race only if it satisfies the requirements for a valid Measurement
Certificate. Boats without cocktail cabinets in each hull shall carry correction weights.”

Surely that means boats without cocktail cabinets and without correction weights are not allowed to race.

The only questions we therefore need to answer are:

1 - Do we add a fixed amount to all new boats - if so how much
2 - Do we make hulls up to a certain weight - I will open the bidding at 32.5kg (equivalent to the lightest previous boats whilst ignoring the additional 1kg for the beam)
3 - Correctors in the vicinity of the cocktail cabinets (where the majority of weight is lost) sounds sensible but how do we fit it
.... a) mounted to the hatch covers
.... b) in the bag e.g. bags of lead
.... c) in/on the VERY lightly glassed in foam

My hulls are 29.82kg & 29.46kg (or 30kg and 29.5kg in round numbers). If the other new boats are between 29 and 30kg, No.1 seems an easy solution if not as robust as No. 2. If there are hulls being made that are 27kg (as Paul mentioned) we need No. 2.

I feel that we are getting close... Can the committee make a decision - even if it is not official until the AGM?

That was meant to say 37kg. Boats in the colours of double trouble seem to be around that weight. I don't know the weights of any of the other new boats

The accuracy and the precision between weighing devices has worried me a little in the reporting of the weights. Commercial calibrated (calibrated by standard weights) load cells, e.g. 100Kg maximum weight has a typical variability of 0.025% or 8g in 30 Kg, but I came across the article below that shows that bathroom scales are not as good - I should get out more! Many are out by as much as 0.9Kg and some, admittedly <2% were out by 1.8Kg which would be crucial for the weights that are being discussed here.


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3890563/

kind regards

Keith 1840

A very valid point Keith. To weigh my boat I used a Salter Brecknell WS60 Bench Scale with a resolution of 20g and an accuracy of +- 20g up to 60kg (http://www.oneweigh.co.uk/salter-breckn ... -186-p.asp). Even though you can get a calibration certificate for an additional £36, I am assured that, when calibrated, they never need adjustment.

There are 4 sets of analogue scales at Shanklin and, if I weigh myself, I get up to 3kg difference so I certainly wouldn't trust them.

I think that Liam is going to Draycote this weekend so could send my scales with him in case anyone is interested.

...except they did weigh your hulls to within a few hundred grams of what your fancy scales did.