IMS

[ErikG]

< Admin Note: Thread split from Yacht performance comparison >

Personally I doubt that you get any good info from current IMS boats sins these are pure rule boats and not really concerned with true speed a such.
Internal lead ballast and wooden keels says it all, don't you think?

[Jeff H]

Originally Posted by ErikG

Personally I doubt that you get any good info from current IMS boats sins these are pure rule boats and not really concerned with true speed a such.Internal lead ballast and wooden keels says it all, don't you think?

Where have you seen an IMS boat with a wooden keel and internal lead ballast? While you do see IMS boats with composite foils and all of their ballast in a bulb, I have not seen internal ballast (or wood keels) since the IOR rule.

Jeff

[ErikG]

Jeff, I see that you haven't looked at the European IMS fleet lately have you?
I'm by no means an expert but I know a little.
IMS punishes modern good keels with a low CG soo badly, so that building a boat with all ballast internally an as little weight in the fin as possible seems to be a good idea for wuite a lot of designers.
Internal ballast, no bulb, composite keels (perhaps wood is toooo heavy to use).
It all makes for tippy, unstable, slow and heavy boats. Sure you can design a fast and goodlooking boat under IMS, but the rating rule will kill you and you'll never win!

Even the designers themselves does not think that the new breed of IMS boats as the IMS 600 are good offshoreboats, guess why... They typically max out at around twelwe knots! Beam reach, downwind whatever they don't go any faster...

An excerpt from Sailingworld:

"Ilatel" an IMS 600; Italtel benefited greatly from being designed to rate well in IMS; during the 195-mile distance race held during the Worlds it struck a rock early on in the race and lost the bottom half of its keel. On most boats, that would have spelled the end of the race and most likely the regatta, but because Italtel carries all its ballast high, and only lost the hollow fiberglass shell that makes up the bottom half of the keel, it was able to complete the race.

Sailingworld

This does not look like good design to me!

And besides in th US, I believe only two or three IMS boats have been built since 1999 (or so I'm told). Sounds like a good thing?

And the certificates are expensive prohibiting most "normal" boatowners competing in the class.

I'll shut up now as I don't intend to hijack Wardis thread with an IMS discussion. I just wanted to make sure that Wardi knows a bit about the IMS boats before he uses them to see if there have been any design improvmets lately...

[Jeff H]

Eric I am not sure whether it would make sense to start another thread on the current state of the IMS or to continue this discussion here but I did want to comment on your reply. First of all, thank you for the quote from SailingWorld on 'Italtel'. I had not seen that and it does disturb me to see that the European IMS 600 boats are going that way. I am not familiar with the IMS 600 so it is not clear to me what these boats actually are.

In the States the IMS rule seems to be relatively healthy and the IMS typeform seems to be becoming much more common. I do not know whether Grand Prix level IMS boats are being built over here but there are a lot of dual purpose racer cruisers being constructed to the IMS rule in the US. If you consider dual purpose IMS type form boats to be IMS boats, then it is certainly inaccurate to say that only one or two IMS boats have been built in the US since 1999.

Beneteau alone has built something over 40 (that number was quoted to me as not including the early EU built boats that came to the states) First 40.7's which were designed here in Annapolis and built in South Carolina. Before you dismiss the 40.7 as not being an IMS boat, I was mainsail trimmer on the 40.7 that won the IMS North Americans last fall. Other IMS oriented racer cruisers that come to mind that were built since 1999 would include the Beneteau First 36.7, C&C 99, Farr 395 and J-109. We see a lot of European and Australian built IMS racer cruisers such as the Swan 45's, Syergia's, Sydney's, and IMX's. All of these that I have sailed aboard seem to be very wholesome boats that offer a major jump in performance, and ease of handling, and which do especially well at the more extreme ends of the wind range compared to pre-IMS type form designs.

My other point is that the polars produced as a part of the IMS certification process seem to pretty accurately describe the performance of these boats. In that regard, I was recommending that the IMS rating would be a reasonable metric to compare performance oriented boats.

Respectfully,
Jeff

[nico]

Actually, the newest IMS boat Talisman (US boat) has a similar keel to Italtel, and they plan to race in the US.

[Jeff H]

Originally Posted by nico

Actually, the newest IMS boat Talisman (US boat) has a similar keel to Italtel, and they plan to race in the US.

Talisman was at the IMS NA's in Annapolis last fall. I don't quite understand why this is happening with IMS boats, but I agree that this is not a healthy trend.

Jeff

[nico]

THis is a new Talisman, B&C 56 i think. They plan to use it for 1 year, and build something else after that. Nice

[Jeff H]

Originally Posted by nico

THis is a new Talisman, B&C 56 i think. They plan to use it for 1 year, and build something else after that. Nice

That is wild. The Talisman that we raced last fall was doing its first ever race. I am amazed that they have already built a new one.

Jeff

[nico]

Yep IMS is great, i saw it being built last february at Green Marine.

[SeaDrive]

My thought is that the IMS rule was created to encourage dual purpose cruiser/racer boats. As such, it rewards a high CoG, because it was supposed to give the freedom to create a curising interior. Thus when a single purpose racer is built to the rule, it has to waste some go-fast potential in order to let the boats with cruising accommodation to keep up.

So, does the blame go to the rule which had a reasonable objective, or does the blame go the owners who should be racing in a full-bore, cruisers-need-not-appy class?

I object a little to the notion that 14kts is slow. By any historical standard, it's blisteringly fast, and can't be achieved without features that cost a lot, restrict the boat's usefulness, or both. It's no wonder that sailing as pastime is dying.

[Jeff H]

I don't think that the IMS rule was created to encourage anything specific within the actual rating. As originally written IMS included minimum accommodations standards which set minimums for such things as headroom, tankage, galley size, number and size of berths, etc. This was partially lifted in the early 1990's when the IMS created the Grand Prix and the Racer-Cruiser categories. (Grand Prix boats did not have to meet the accomodations standards and were only intended to be raced against each other).

The rating itself is supposed to be VPP based which means that, unlike a measurement rule like the IOR, IMS only attempts to determine the relative speed potential of any two designs and correct for any potential speed differences between the boats in question. Assuming that the VPP formulas are accurate, adding or subtracting stability should not help you at all in your corrected performance.

At one point in the early 1980's a decision was made to decrease the penalty for ballast stability in an effort to produce safer boats. That opened the door for the high stability boats that had become identified with IMS (at least until recently). I have not been following IMS lately so I don't know what has happened to the rule that it seems to be encouraging heavier displacement and lower stability boats. Obviously, there is a glitch in the rule that over penalizes light weight or stability that designers are exploiting. My only hope is that this glitch gets closed before we live through another IOR type distortion (of the type that IMS was created to prevent) of the boats that we race.

Jeff

[Wardi]

Forgive me for not fully understanding..... do you mean that the specified "Ballast" for these IMS boats may be say 50% of the total displacement, but this ballast is split, some being in the keel bulb and some inside the hull?

This would mean that the effective ballast ratio may be only say 40%.
Is this really the case?

[sorenfdk]

Yes, that is - unfortunately - the case.

And the effective ballast ratio is probably even lower, since some of the newest designs have keels almost without any ballast at all!

It has come so far that even the currently most succesful of the IMS-designers, Marcelo Botin, says that there is something terribly wrong with IMS.

Søren

[tspeer]

It's an unfortunate fact of life that handicap racing is not about building fast boats, it's about building a boat that's not as slow as it's rating says it is! Even as sophisticated a rule as IMS will eventually encourage a race to the bottom as designers figure out where the weakness in the rule lies.

So any handicap rule has a definite life span - it may work for existing boats, but if it becomes popular and boats are built specifically for it, it becomes obsolete. IMS has definitely reached this point in Europe.

Jeff, the Benny 40.7 is not competitive any more in European IMS racing; pity, 'caue it was cheap (for what it is).

The IMS 600 class was intended to cater for medium-speed cruiser-racers, specifically the Benny 40.7/IMX 40 style. However, almost as soon as it was announced, the Synergia 40 (no connection with Synergy) from Bottin & Carkeek came out and started beating the Ben and X Yachts (althoough the North Sea or Euro c/ships went to a Sydney/BH 41 against good boats).

I spoke to Marcellino Bottin when he put out the Sydnergia and he confirmed that its extremely full stern, slab sides, poor stability and the trim with the bow knuckle above water were all "just for the rule". At the same time Fritriche Judel (from Judel and Vrolijk whose Rodman 42 takes the Synergia concept even further) insisted that the rule maths were simply based on the Delft series - but he (or Rolf Vrolijk) then said that a lovely 37 footer they designed was too fast to be an all-round IMS winner!

I was impressed by the fact that Aussie designer robert Hick was designing boats that look/sail a lot like the current IMS boats (apart from the fact that the Hicks have loads more stability, thank god) back in about 1996.

Hey Jeff H, the early IMS boats may have nice motion but have you tried a lighter one? It's not just the weight or the shape, but the fact that our Aussie boats (which are rarely as tippy as Euro boats) don't lose speed when they pound. It's not like non-rule lightweights or IOR boats, where to keep the boat moving in a nasty sea you had to weave, because pounding was slow. The IMS boats are best when you just let 'em drop straight off the back of a Bass Strait swell. And boy, do they bang.....I assume Sydney 38s etc (IRC boats) are the same but I;'ve only sailed them in flattish water.