Progress v's fixing
Wazza
I have been sitting on the sidelines for sometime and would like to
add my perspective to the discussion.
Whilst I generally agree with the principle of a one design class,
where all the boats are the same, I do think there should be room to
fix or repair any shortcommings in the original model.
I would like to see several things fixed on this model and whilst they
would have little effect on performance they would make the boat look
more professional and attactive to others. To convience others to
change class you have to have an attactive well thought out and
performing model. Minor changes, fixes, now whilst there are not to
many boats out there could help with its future servival.
I applaude Neville and others for their proposed developments and am
disappointed to hear the rudder development has stopped as this is one
area that makes the class look a little ordinary.
Other areas we should look at are
;- a moulded rubber bumper that actually looks like the hull, the
current crop of adhoc protection makes the model look cheap and
unrealistic (no performance gain here)
:- Rudder
:- Check the symetery of the mould at deck level. ( no performance
gain here)
:- a review of the deck hatches, although they are very effect and
provide great access, I would like to see something more in keeping
with the overall look of the model.( no performance gain here)
Maybe others could add there wish list of things that they would like
to review and we could have a discussion and a vote of all the boat
owners on a way forward.
Regards
Wazza
KA7
Jim Brown
Regards
Jim Brown
Papakura, Auckland
NZ
Warren Norrie
Hi Guys,
I know this is not an N12 question but,
Does anyone have a drawing or sketch or pictures of a floatation tank I could make to measure my IOMs.
Had a great day sailing the N12 on Saturday at or club Bob and Gerry from the Ancient Mariners came down and sailed with us and we had a BBQ before racing started.
We had 3 N12s, 1 A class, and 6 IOMs.
Regards
Wazza
Mr bob Atkinson
If you look in the hand book for the EC12 i think there is a drawing
bob
Mr bob Atkinson
2006 IOM Nordic Championships »
Depth Gauge Test
One
problem with the current IOM class rules is that proper event measurement
requires the use of a cumersome and not very accurate measurement tank to
check for the overall depth and hull depth. During the winter Olof Ginström
came up with this jig to do the job - here are some pictures and comments from
the first trials.
Here is the basic design of the gauge/jig. The hull is positioned between the
vertical posts with the fin and keel in the middle slot.
Here is the crucial part of this measurement process: When the boat sits in the
jig, the supports under the bow and the stern (wooden blocks) can be moved fore
and aft. They should be positioned so that the waterline of the hull sits at
the jig-waterline, indicated by the plexiglass edge. This jig can’t determine
where the waterline actually is, that has to be done by other means, perhaps at
the time of fundamental measurement. This waterline posistion could then either
be marked on the hull, or perhaps recorded in the certificate (XX mm from stern,
YY mm from bow)
After
this waterline position is found, using the gauge is pretty straightforward:
Check for overall length of hull. This homebuilt Lokki was actually very close
to 1000mm, many of the commercial IOMs we put in the gauge were up to 7-9mm
shorter (see below!).
Check for hull depth. There is a slider of plexiglass that can be positioned
under the hull to check that the maximum depth from the waterline is <60mm.
Check for overall depth. The 420mm depth has been accurately trimmed by placing
a piece of plexiglass where the maximum depth for a typical IOM is expected. We
don’t have a test for minimum depth right now - but competitive IOMs with
anything but close to maximum depth are very rare…
One of the shorter boats we tested. This boat is actually sold as a
‘meterboat’, maybe the proper name should be ‘99cm boat’ ! 
Finally, some examples of how different designs look when they sit in the gauge:
The designs from top to bottom and left to right: Ericca (light blue), TS2 (dark blue hull), Noux (translucent), Noux (yellow topsides), Italiko (green), Italiko (Black), Cockatoo (red), and Bagheera (Black).
To conclude, if at fundamental measurement the waterline can be found (with a tank or in the pond on a very very calm day) and recorded, then event measurement can be performed by placing the boat in a jig and aligning the previously found real waterline with a reference line on the jig. Measuring overall hull length, hull depth, and overall depth can then be done without a measurement tank and with better precision than is usually achieved with a tank.
We will trial this gauge at the upcoming IOM Nordics where we expect around 20 competitors, hopefully I can report back with more pictures and comments + any problems or issues found.
This entry was posted on Saturday, May 20th, 2006 at 23:12 and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
2 Responses to “Depth Gauge Test”
Marko
Says:
May 24th, 2006 at 14:47
Hi Anders,
The gauge looks wonderfully designed and built!
However… It seems to me (having spent a while ago some time pondering the waterless measurement) that the fundamental flaw in the whole procedure is that, as part of the FUNDAMENTAL measurement we are measuring a highly variable component that is under a direct (and easy) influence by the owner (waterline position), while at the EVENT measurement stage we are measuring components that are rather static (hulls don’t grow on their own - so if length and depth are once found to be right than they should pretty well remain so).
In fact, variances in the waterline position (inadvertant or as part of trim-setting) which are easily achieved by weight re-distribution (perfectly legal if done prior to the event, and with new RRS/E possibly even during event) are, in my experience, the leading cause of event measurement failure! You can easily see what would happen to any of those hulls (either in the gauge or in the tank) if, say, you shifted some weight aft causing a 1 degree stern-down attitude change (especially given a relatively huge lever provided by the keel)…
So, in other words, the approach of let’s agree that this is your waterline, and based on that I’ll check the other dimensions is flawed (IMHO) - as it is, in fact, the waterline that SHOULD be the main thing checked at the event measurement (since it clearly has a key role in at least two of the three measurements that you propose to measure with the gauge). Or, conversely, if people feel that it is “OK” to use the “reference waterline” deteremined at the fundamental measurement stage - then why not do the other 3 measurements at the fundamental measurement stage as well?
Cheers,
Marko
- Administrator
Says:
May 30th, 2006 at 11:44
Hi Marko, nice to hear from you.
The gauge is not without its problems… it seems that at an
international event we will have to use the tank anyway.
But I think for local smaller events this gauge can serve as an quick check
that nobody has a boat that is grossly out of spec. I don’t think weight re-distribution
does much to the overall depth of most boats, the one degree you mention is
equivalent to about 17mm of movement up or down of either the bow or the stern
which is way more than will happen by moving the batteries.
From: naut...@googlegroups.com
[mailto:naut...@googlegroups.com] On Behalf Of Warren Norrie
Sent: Sunday, 18 May 2008 8:23 p.m.
To: naut...@googlegroups.com
Subject: RE: Progress v's fixing
Hi Guys,
Warren Norrie
Thanks Bob,
I have seen this jig and it’s a great Idea but you still need to float the boat to establish the water line.
And I may go this way because it very easy to do.
Regards
Wazza
-----Original Message-----
From: naut...@googlegroups.com
[mailto:naut...@googlegroups.com] On Behalf
Of Mr bob Atkinson
Sent: Sunday, May 18, 2008 6:47 PM
To: naut...@googlegroups.com
Subject: RE: Progress v's fixing
1.
Marko Says:
May 24th, 2006 at 14:47
Hi Anders,
The gauge looks wonderfully designed and built!
However… It seems to me (having spent a while ago some time pondering the waterless measurement) that the fundamental flaw in the whole procedure is that, as part of the FUNDAMENTAL measurement we are measuring a highly variable component that is under a direct (and easy) influence by the owner (waterline position), while at the EVENT measurement stage we are measuring components that are rather static (hulls don’t grow on their own - so if length and depth are once found to be right than they should pretty well remain so).
In fact, variances in the waterline position (inadvertant or as part of trim-setting) which are easily achieved by weight re-distribution (perfectly legal if done prior to the event, and with new RRS/E possibly even during event) are, in my experience, the leading cause of event measurement failure! You can easily see what would happen to any of those hulls (either in the gauge or in the tank) if, say, you shifted some weight aft causing a 1 degree stern-down attitude change (especially given a relatively huge lever provided by the keel)…
So, in other words, the approach of let’s agree that this is your waterline, and based on that I’ll check the other dimensions is flawed (IMHO) - as it is, in fact, the waterline that SHOULD be the main thing checked at the event measurement (since it clearly has a key role in at least two of the three measurements that you propose to measure with the gauge). Or, conversely, if people feel that it is “OK” to use the “reference waterline” deteremined at the fundamental measurement stage - then why not do the other 3 measurements at the fundamental measurement stage as well?
Cheers,
Marko
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