Measurement Practice

[Chris Maas]

I am fairly certain that the intention of rule 5e is to check for bumps and hollows along the BMS, both fore and aft and athwartships. Leaving the 2m tape stationary on the centerline does not achieve that. Relying on a spirit of the rules clause to catch whatever hull shape it is that the measurer thinks is not within the spirit of the class seems to me too vague.

[Paul Scott]

+1

For reasons unclear to myself, I'm still waiting to order build materials....

I think I'll go with the only measurer (I think) with the grace to respond (gracias, Colin), so I pull the trigger tomorrow?

Warning Will Robinson! Warning Will Robinson!

[jimc]

My only advice, as someone with no official position in the class, but an involvement in the original discussions, is to make the lengthways tape alignment match up to Steve's diagram (which I've put different lettering on to make it a bit more web friendly).

Whilst I have found it impossible to articulate in words exactly why the alignment of the lengthways on the topsides should be as shown, there is no doubt in my mind at all that is what the rule intended and what folk have built to.

[Paul Scott]

The 2m tape can slide anywhere on the hull, at any angle defined by the interplay of the relative designed aesthetic gravitational pulls of the keel, waterline and gunwale, as long as the 2m tape is centered on the (infinite extension) of the BMS. I will go with that.

I'd argue that is in the spirit of the IC: for example, Herreschof wrote that poets, authors and artists have always been drawn to the class...

[SteveC]

Well this it is only a proposal but I can say is not what has been used by designers and not what is actually defined in the ICF approved rules which are far less specific.

The M2 chine rails do fall within this area as it happens and also has a concavity in the sides above the chine but only vertically. The UK Measurers statement is what we have designed to and we have two moulds based on this. One for the ICF I think, to review in the summer.

[Paul Scott]

Thinking within Steve Clark's (USA Div.) M2 intent, I don't see chine rails being legal mainly because of their interplay with rocker.

(I tried a hull effectively built without rocker, thinking that heel would create it, even control it. Didn't work very well- and a paucity of freeboard didn't help.)

Colin's M1 & M2 measurement, objectively, would allow rails. Or flares. Subjectively?

Tongue in cheek, perhaps a scoring system like Olympic ski jumping? Race results would be multiplied by a beauty coefficient centered around 1, plus or minus, voted on by skippers before a regatta. Or even better, after.

[Andrew Eastwood]

I agree with Chris Maas, Colin's restricted method of measurement certainly doesn't seem to achieve the objective that the rule is designed for! I think the diagram with Jim has posted is good and shows how the measurement, reasonably but not exactly, is to be done. I had always thought of the Beam Measurement station as a section through the hull, not a point on the keel line of the hull. Thus you could cut the hull into two parts ( hacksaw not provided) at the beam measurement station. The fore and aft tape centred anywhere on this cut , from the keel to the gunwale both sides, will satisfy the instruction in the rule, thus it seems that the tape must sweep the hull from gunwale to gunwale and not find hollows of more than specified.

[Paul Scott]

No hurry on this, but while it's fresh, and if anyone is willing to respond, any info on how canoes are measured, post 2014 worlds?

I hadn't realized that canoes had such a low wind limit....

Congratulations to everyone involved!

[SteveC]

The Measurers met at the worlds and have come up with a proposal which will be put forward shortly on this and a number of other issues.

[Paul Scott]

Thanks Steve.

[Paul Scott]

So is the BMS 2d or 3d?

[SteveC]

2D obviously. My understanding that a clarification will indicate that the string will be drawn across the hull parallel from the centreline towards the chines, 1m either side of the BMS. Within a certain distance from the chine area you may need to gradually move the string parallel to the chine before you check down the sides and I think the wording of this is is what the measurers are considering. You will need to wait a little longer as these things have to be done through international agreement and synchronising this is not always quick.

[Paul Scott]

Thanks Steve. A bit hard to describe, isn't it?

I guess some destruction testing will keep me in catharsis until the wording comes down.

Pictures of strings on hulls would be nice .....

Paul

[cc284]

Was there an outcome to this discussion? Or is it still a bit grey?

I suppose the real test is, would a vertical 'bump' (when looking from the side) to meet the 275 measurement be acceptable as long as it meets the plan view restrictions? If not, do all boats have a gunnel that run out 1m behind the BMS without dropping in height?

[Alistair]

Was there an outcome to this discussion? Or is it still a bit grey?

I suppose the real test is, would a vertical 'bump' (when looking from the side) to meet the 275 measurement be acceptable as long as it meets the plan view restrictions? If not, do all boats have a gunnel that run out 1m behind the BMS without dropping in height?

As i understand the rules then a vertical bump meeting the 275 rule on the bms is acceptable as long as it meets the plan view rules and Rule 5 e.

e) A 2000 mm tape centred on BMS and pulled tight fore and aft against the outside skin of the hull, shall bridge no hollow in excess of 1mm in depth. A 1000 mm tape centred on the keel at BMS and pulled tight transversely against the outside skin of the hull, shall bridge no hollow in excess of 1mm in depth.

In practice we sweep the 2m tape to the extent of the 1m tape.
in theory you might have the 2m tape off in space, not sure if this would measure or not? I guess not as it would be a hollow greater than 1mm....