60mm

Don Case · Post by **Don Case** » 16 Oct 2008, 02:32

Can someone explain the necessity of the 60mm draft rule? What advantage is there in having a boat with a deeper hull draft? The keel depth is limited by the 420 rule.
Thanks
Don

Barry Fox CAN262 · Post by **Barry Fox CAN262** » 16 Oct 2008, 20:57

Someone with the history and marine design smarts I don't have will need to answer so the best I have is - because.

Don Case · Post by **Don Case** » 17 Oct 2008, 03:20

Thanks Barry
Why I am wondering is because the average guy is supposed to be able to design and build an IOM at his kitchen table(or so the story goes). It is tough enough to get the displacement right without the constraint of the 60mm depth. Because of this I thought there must be some advantage to a deep boat and I couldn't figure out what it could be. I guess I'm stuck with your answer.
Thanks
Don

Steve Landeau · Post by **Steve Landeau** » 17 Oct 2008, 04:29

I'll venture a guess that it was at least partially intended to keep the boats relatively close enough to fit within a specific range.... keeping the extremes of a design at least somewhat close. I'm sure that this rule has had some effect on the ability of a 12+ year design to win at the highest level.

CHATIN Achille · Post by **CHATIN Achille** » 24 Nov 2008, 10:50

It is quite easy to check out the hull depth : on a table, boat positioned in its lines, and measuring the gap of fore and aft waterlines of the boat between it and the table (fore and aft measurements must be equal). An keep in mind that 60 mm is a max.

Furthermore, I believe that allowing an increase of the hull depth or abandon that measurement, would increase the performance of the IOM, notably in light airs.
Naviga rules for F5-E (the One Meter of the origin) has no restriction on hull depth, but a max draft for the keel (38 cm, which gives an approx. 42 cm boat draught), but as the competition level is lower in Naviga thab Isaf, I am unable to strickly confirm the avantage of a free hull depth.

I hope to be helpfull to you Don Case!

awallin · Post by **awallin** » 24 Nov 2008, 11:43

If you have a very deep very light hull then you could potentially place corrector weights quite low in the hull.

soeren_andresen · Post by **soeren_andresen** » 25 Nov 2008, 11:03

There is one more reason.

You could make the keelfin a part of the hull, and thereby get all the keel-weight in the bulb.