sailing performance

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djmarchand

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Since the question as to how well do IPs sail has come up several times recently, I thought I would start a topic on the subject, post my thoughts and invite discussion.

 

IMHO all IPs sail about the same. This is because of the traditional full keel, conservative design that is the trademark of an IP. Sure longer boats are faster than shorter boats, and the newer boats with a wider beam to length ratio may be a bit slower. But all in all they sail about the same.

 

No matter how you compare them, IPs sail slower than other modern fin keel sailboats. You can compare by overall length or displacement and IPs sail about 20-50 seconds per mile slower than other fin keel boats.

 

Let me cite a couple of examples. Using the New England PHRF ratings, an IP 37 (one of which I owned a few years ago) rates 156. The IP 37 is probably one of the better sailing (for its length and displacement) boats in the IP lineup. It was the first of the new "full foil keel" and it has a reasonable beam to length ratio. For example, it is 30 points better (lower) than the similar dimensioned IP35 (too much IMHO, but that is the way of PHRF ratings).

 

One boat to compare with similar LOA is the Beneteau 381 at 138. Others of similar length will be in the 110-130 range. This means that over a 30 mile sail of about 5 hours the IP will come in about ten minutes behind the Beneteau.

 

But LOA is probably not the best comparison parameter. Displacment may be better because that determines (more or less) hull volume and therefore useful space below. The IP 37 weighs 19,000 lbs and an equivalent Beneteau is the Oceanis 411 with a PHRF of about 110. So on a displacement basis the IP is even slower.

 

Why is this? Three basic reasons: 1) Greater underwater drag due to the full keels higher wetted surface area 2) More leeway going to weather due to the full keel and 3) Most other boats have a higher sail area to displacement ratio. The latter is not necessarily bad, and will even out in higher winds where the competitor will have to reef earlier.

 

FWIW the full keel is the culprit here, but no amount of criticism is going to convince Bob Johnston to change. His design formula is well accepted and it is what makes an IP. And compared to some direct competitors like the Caliber lineup it isn't so bad.

 

So, IPs are slower, but what is good about them. Well in addition to the superb build quality (try to find a flanged seacock on your Beneteau) the IPs sail plan makes it very versatile. As the wind picks up you can reef the main and the genny and then douse the genny and sail with a reefed main and staysail. Also the greater mass of an IP makes it more seakindly relative to a lighter boat.

 

But who would want to buy a slow boat? Well it depends on how you are going to use it. Years ago I looked hard at the then new IP 37 versus comparably sized (LOA) fin keel boats. I picked a Jeanneau 36.2 then because it is light and responsive for day and weekend sailing on Galveston Bay (and about $50K cheaper).

 

Some years later I sold the Jeanneau and bought an IP37 to use as a live aboard cruiser on the East Coast and Bahamas. In this case I didn't need lightness and responsiveness or speed. I wanted a boat that was strong, comfortable and safe. That is the IP!!!

 

Strong, comfortable and safe are virtues no matter how and where you sail. Maybe one is right for you.

 

David

 

Last edited on Fri Apr 23rd, 2010 01:07 pm by djmarchand