Dinghy hull weights

Still leaves a couple of questions though. I know the minimum weight is 72kgs but what is standard weight? and are the modern ones made to the same weight tolerance as thew 10yr old ones or are the built closer to 72kgs now?

Apologies for late response ... 'standard' and minimum weight for the Blaze are the same thing – and it is 72kg.  It includes full wing system, centreboard, all fittings and lines but excludes rig and rudder assembly.  After the switch to epoxy many years ago it became easy enough to build all boats a few kg below 72kg.  They were/are all weighed after fit-out and correctors are then added - so all are on the nail at 72kg.   This means that IF a hull has a major smash the hull can be easily repaired and if more ‘structure’ is involved in any repair the additional weight can be offset by adjustment to the correctors (btw these are generally ‘bonded’ into the hull so it becomes more difficult to ‘forget’ them on a day to day basis - if you get my drift  ).   The ‘spread’ of weights amongst the polyester boats has probably widened over the years for the reasons already discussed but the best are still v.close to 72kg and remain highly competitive against the later boats.  We weighed all entrants boats at one National Championships ( a right pain for all concerned of course but there was no wind that day!) and all epoxy boats were very very close together at 72kg.  Polyester ones had a much wider spread which we suspect was as much to do with moisture uptake over the intervening years as it was the original build tolerances.  Would ‘we’ build any new boat in polyester today ourselves – No.   Vinyl-ester and/or epoxy are worth the price differential imo.

Could we have reduced the class minimum weight ?  - Very probably but this would have made the early polyester boats at a disadvantage and produced in effect a ‘two-class’ boat.   Usefully at this weight  the Blazes is not particularly fragile (though some owners do try to prove otherwise and drive them extremely hard in just about any conditions – the boats are simply superb fun in F4+) …. but if owners do have a problem the hull can still be easily enough sorted.

Edited by Cirrus - 30 Aug 16 at 12:37pm

Possible perhaps given a large quantity of not-very-closed-cell-foam reserve buoyancy.

Originally posted by RS400atC I am surprised there's no carbon at all in a mid 90s 505, not even around the mast/bulkhead/chainplate area? Was it around the end of the 80s Parker had their 'type 25' 5-oh? and that development was going on in all the rival builders too.

I can assure you there is no carbon in this particular 505 hull, built by Kyrewood, they did build some hulls around that time in carbon, but they continued to offer both options so there was a lower priced hull and the carbon one. However even without carbon it is still very stiff, certainly in comparison to similar age boats from other builders. Some of the build is is purely glass, and in the high stress areas end grain balsa sandwich.
I guess during the 80's 90's as you say there were several 505 builders, all trying to get an edge on their rivals, but I guess my point, given what this thread is about, is that not all boats, even those of more "basic" construction will take up water. Perhaps the secret lies in the build process as well as the care taken with the boat over the years?

Somebody suggested earlier in the thread that a boat may have taken up 20kg of water, really?, that would be aprox 20 litres, is that realistic in a 4-5m long dinghy, it may be of course if there is a lot of timber under the fibreglass as that would hold water very easily if it got in and have difficulty getting rid of it, I have certainly heard horror stories in some classes.

Certainly weighing boats should not be a major problem and could save a lot of trouble. At Phantom nationals in the past we used to simply place the boat on a bench scale similar to these https://www.ourweigh.co.uk/bench-scales/WS12000AAZAAAA.html?gclid=Cj0KEQjw0f-9BRCF9-D60_n4rKcBEiQAnXW4-5yvE2Bo0GpirmGIdU0qeeUtDeBiIisSLrWWVYJFYzUaAp7m8P8HAQ  once you knew where the balance point was it was simple and took very little time, I have also seen the same used with a custom made V or U shaped pad on top which you can rest any hull on. For the sake of £80 a set of scales would be a good investment.



Edited by Roger - 26 Aug 16 at 10:49am

Tha heaviest phantom, polyester rather than a wooden one, weighed in the last 15 years at the nationals I think was approx 14kgs overweight,making it 75kgs without rig.

Edited by maxibuddah - 26 Aug 16 at 8:13am

Originally posted by Sam.Spoons The 505's 127.4 'sailing weight (hull, fittings, foils and rig but no sails) is pretty impressive for a 50 year old design but exotic materials (CF, kevlar, epoxy etc) are commonly used in their construction. Given all of that the RS400 at 129 kg is not so heavy, it's a bit shorter than a 505 but is built in relatively conventional materials (vinylester resin, not epoxy and not much, if any CF).

This year my 21 year old 505 was weighed at 1kg overweight, and it still carries 2kg of lead, so a full reweigh would put it minimum weight. It is built from polyester resin with end grain balsa sandwich in high stress areas, it also has an alloy boom, the only carbon is the twin poles and tiller, there isn't anything exotic in the hull.