IOR... Or not?

[sailordave]

I know all the general objections against old IOR boats; they are squirelly on a run, they have bad handling characteristics, you need a ton of rail meat, you need an ape to grind home the big gennys.... Etc.

YET, some of them are awful darn purty to look at. The ones that aren't extreme, stupid exaggerations of what a boat should look like.

With that in mind I started comparing the sail area of the foretriangle to the Main and that got me started thinking... (always dangerous )

WHAT would you say is a poor ratio of FORETRIANGLE sail area to MAIN sail area?

I went through sailboatdata.com and pulled a bunch of random boats' numbers and made a spreadsheet. I limited this to Marconi rigged sloops only. No cutters, yawls, ketches.
Very interesting to see the results and in some cases the evolution of how things changed w/in a particular brand of boats.

Ration is Foretri./Main IE anything over "1" means the foretriangle has more area than the main and less than "1" means the Main is larger.

Notice especially the difference in the Cal 40 v. the Cal 39 just 10 years later. And the Tartans too. The Albergs, designed late 50's, early 60's, definitely not IOR!

So my question to you, Sailnet fans, is what ratio do you think defines an IOR boat, or more importantly what ratio would you think is too extreme?
What boat would you not want to be the genny grinder on?

boat	foretriangle	main	ratio
swan40	388	320	1.213
swan411	517	355	1.456
swan431	529	366	1.445
NY40	450	297	1.515
Norseman 447	529	408	1.297
Frers 33	299	256	1.168
Frers 38	392	334	1.174
Tartan 27	170	205	0.829
Tartan 30	253	195	1.297
Tartan 34	287	240	1.196
Tartan 37	376	249	1.510
Tartan 41	445	279	1.595
Tartan 3700	388	316	1.228
Tartan 4100	320	253	1.265
Hunter 31	262	206	1.272
Hunter 340	247	352	0.702
Hunter 50CC	450	503	0.895
Alberg 30	189	220	0.859
Alberg 35	268	275	0.975
Alberg 37	309	337	0.917
Luders 33	260	264	0.985
Luders 36	292	305	0.957
Cal 34	268	234	1.145
Cal 34 Mk3	284	195	1.456
Cal 39	425	313	1.358
Cal 40	350	350	1.000

Alerion Exp 28

146

206

0.709

[sailingdog]

I don't think that the headsail to mainsail ratio is the most important factor in whether a boat will be "squirrelly" downwind or not. There are a lot of other factors that go into the motion and handling of a boat, like hull form, keel design, etc. To try and do a comparison based on just the headsail to mainsail ratio is pretty ridiculous IMHO.

[SimonV]

I love my Ericson 39b it is an IOR boat and yes it does not like going dead down wind, but then who does, especialy in a lumpy sea. With the big genny not reduced in a blow the weather helm comes on big and strong. I single hand mine all the time and find it a very fast and a predictable boat.

[BubbleheadMd]

I definitely think it's more related to keel and hull shape, especially at the stern than sail plan.

I agree that they're gorgeous boats. If you want one, buy it and forget the nay-sayers. You can still club-race with 'em.

[tommays]

The Cal 40 is still a race winning boat

[sailordave]

Originally Posted by sailingdog

I don't think that the headsail to mainsail ratio is the most important factor in whether a boat will be "squirrelly" downwind or not. There are a lot of other factors that go into the motion and handling of a boat, like hull form, keel design, etc. To try and do a comparison based on just the headsail to mainsail ratio is pretty ridiculous IMHO.

SD, that's not what I'm saying. I just noticed that as the boats got more and more extreme, the headsail/mainsail ratio changed quite dramatically. Interestingly the Tartan 37 has one of the highest ratio's on that list and I don't believe it's ever been considered a poor handling boat.

OBVIOUSLY, hull shape determines handling characteristics, but the hull shape changed somewhat in concert w/ the increasing size of the foretriangle. I was just wondering at what point do fellow forumites find the foretri. to be getting too big relative to the main.
This was not intended to be a scientific study, just an observation. And I certainly wouldn't want to race one. (although there is a Carter 41 that looks pretty sweet from the rear!)

[sailingdog]

The boat's underwater profile will often determine whether the boat's sail plan will be extreme or not... As you pointed out, the Tartan 37 has one of the higher ratios, but I don't think of the Tartan 37 as an extreme design. I don't know where you're getting the idea that it is an "extreme" design.

[GeorgeB]

Having raced a Cal40 to a 2^nd in the 2009 HDA season and a 3^rd in the Rolex Big Boat Series, I certainly have a tender spot in my heart for the class (and especially #72!). However, this boat, designed in the 60’s predates the IOR by a whole bunch of years. The boat was designed as a game changer for the TransPac race which as we all know is 2,000+ NM of spinnaker flying. Fun boat. Fast for it’s age, but the ergonomics in the cockpit are very dated.

[sailordave]

SD, I said no such thing. Actually I was pointing out that the T37, while having a high ratio really doesn't look or act like the typical IOR boat of the second half of the 1970's.

BUT, when you look at a lot of the designs that were carried to the extreme, you find this ration increases. I'll say it again, at what point do people find that the size of the headsail (foretriangle) is too large relative to the size of the main?
I'm not here to argue over one particular boat and whether it does or doesn't behave nastily or has too much sail area, I just chose a wide selection of boats to make comparisons to each other.

And I believe the Cal40 came into being around 1963 or so and IOR around '69 or '70.

[sailordave]

GEORGEB, I know of two Cal40's here on the Chesapeake. Saw them both this summer. Gorgeous boats!