J/30 Class Association Forums J/30 Forum One Design Class Rules Keel "Tolerances"

I'm starting to fair the keel. Generally it's short on chord length about a half inch with and blunter leading edge than the templates. Makes the leading 15% or so noticeably thinner than the templates. Aft of 50% or so it's thicker than the templates all the way back to the trailing edge that's 10 mm instead of 5.

Rule 5.5.3 says:
Coating of keel may be by any synthetic material provided the shape and weight are within template tolerances.

Question: What does "tolerances" mean?

I can't find actual mention of how big the tolerance is or if it has a direction.

Mark,

The keel offset interpretation is consistent with the rudder offset interpretation where it is specifically stated

Thanks! I can do that with just a little bit of lead shaving.

Something to think about...the keel as it came from the factory is not legal. The front 15-25% is clearly inside the templates. I'd guess this is true of most and maybe all (?) boats that still have factory keels. It's certainly not fast.

Yup - same as I found on Rhapsody too.

As Bill noted, the Drawings & Specs page in the rules for the rudder say the offsets are minimums and half widths may be two mm greater. There is also a limit on the trailing edge of the keel and rudder (5.5.4 & 5.6.1).

That's a pretty tight spec. As Mark points out virtually every factory keel excepting maybe those on single digit hull numbers would probably not comply. I think the same holds true for original factory rudders, though those from our our new supplier may. Sometime in the 1990s the Annapolis fleet measured a dozen or more boats in our fleet before Spring launch. We found what you already know, un-faired keels were short in the chord and fat in cross section and those that had been faired were spot on the templates. Rudders were generally just fat.

Its also important to get the measurement from the transom so you can figure out if you need to add to the front or the back of the keel When I faired out Falcon I ended up added almost and inch to the trailing edge using a old batton
At one point they were building them so fast that Plus /minus and inch was good enough

An inch forward...wow! Keel stub seems to be molded in with the hull. Wonder how they managed that one.

My trailing edge is 2mm short of max forward. Kinda fat, but placed pretty well. Not bad.

The cord length though is almost 15mm short.

My rudder is more than 5mm fat in max half width. I'm just going to buy a new one instead of trying to fix it.

Probably a good plan on the rudder. From what I've heard from those who tried, unlike the keel you cannot just grind and fill or your end up into the core. Having a spare rudder can be handy.