IOM, US1M, ODOM, 1MULY and others? - Page 2 - RC Groups
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Nov 20, 2016, 10:53 AM
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Dick L.'s Avatar
Also keel depth needs to be watched as well.
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Nov 11, 2017, 08:33 AM
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A class legal IOM in many cases....can be dual rated as a US1M.
You can go out and win your local US1M series in the right conditions with your IOM hull, you just need a US1M rig.
(a US1M A is between an IOM A and IOM it can have its moments)

Some comparisons...

The US1M is an open design class with no minimum weight, hull material restrictions, a maximum keel length and a sail area measurement. (Most have bow bumpers, and many are kevlar or carbon hulls). The IOM has 4kg minimum weight, hull draft restrictions, max keel draft and weight restrictions, and restricted rigs. (and a limitation on building materials in the hull)

So...US1M tend to be lighter (6 lb range) vs IOM are 8.8 lbs. A shallow hulled IOM can have a longer than legal keel for the US1M class. (TS2 IOM had slightly longer fin)

An IOM A rig is not a legal size for a US1M, but the B and C rigs are legal size.
US1M sails have lots of roach, as by rule it doesn't measure the roach in the sail area calculation.
Possible sail legality issue on battens on IOM sails, which US1M rule says can be twice the roach and IOM has limited roach.
But if you put a US1M rig on the right IOM in the right conditions...

An IOM with the right amount of draft, can have a legal keel in the US1M class. With a class legal US1M rig.... it can be a US1M.
A 6lb carbon US1M will never be an IOM.
Last edited by modelyacht; Nov 11, 2017 at 08:14 PM.
Nov 12, 2017, 07:23 PM
Thomas Armstrong
"Can be" is of no use to me - for, class A is subclass of class B is >all< legal boats of class A are also legal in class B. This is not the case between US1M & IOM, so they are registered as separate classes.

If a specific hull is legal in both, its just a coincidence. I'm sure the designer of the hull was only thinking about one specific class when drawing lines...