Stepped Hull Critique

[centerisland]

http://themarineinstallersrant.blogspot.com/2011/08/steps-and-second-steering-stations-on.html#more

I haven't been paying attention...does anyone have experience with the Cutwater to report? I've never driven a stepped hull, but this post doesn't sound encouraging to me.

[Catch 22]

i have seen many different versions of stepped hulls on racing boats, the unlimited hydroplanes use this technology to decrease drag.

[ipsbishop]

Just a little food for thought, 39 foot boat , (maybe a new 42 ft version) trip Yamahas, hull # 3, step hull, 2nd trip on boat, and 2nd steering station up top.

http://myfwc.com/news/news-releases/2011/august/22/boating-death/

http://video.tbo.com/v/44007720/homosassa-boat-accident-remains-under-investigation.htm

[thataway]

Bill Bishop, Welcome Aboard C Brats. You may have more knowledge than I do about this incident, but I have been following it since the day it happened on several forums because of my interest in boat safety. (There are 8 pages of discussion on The Hull Truth)

The boat involved was a double stepped 39' Contender. I am not sure if it was the second trip in the boat--but Bob Phillips (who was killed in the accident and was at the helm) had owned the boat several months, and was a very experienced boater. I am not critical of the handling of the boat, but it was reported that prior to the accident (when the boat capsized) that it was traveling at about 40 knots. However, the boat slowed prior to capsize--and from there there is some dispute as to what happened to cause the capsize--and if there was a "blow out" because of the stepped hull and a sharp turn involved.

The Cutwater has a different bottom pattern, and is an inboard, with lower speed potential. Generally stopped hulls are in racing boats and for speed. I doubt if the Cutwater would behave the same as the contender with triple 350 hp outboards. I had sent a PM to CenterIsland about this incident.

[ipsbishop]

Bob, thank you for the greeting. I agree with your comments about the Cutwater. I took a look, and although it does have steps, they are not the same as the full beam width versions seen in the higher performance boats. This coupled with a much lower center of gravity, the keel, and lower speed potential makes for a much more predictable, and traditionally behaving hull. I have also been a Ranger tug fan for a long time.

I was aware of the accident very early on from a local friend, and I will be the first to say I wasn't there. I was told it was a 42' Contender, it was hull #3, and it was the second real trip on the boat. There is no 42' Contender listed on their website,or elsewhere, so the fall back is that it must have been a 39', although the low hull number is puzzling. I'm sure the FWC will do a comprehensive job. I was also told that there were three passengers riding at the the second station at the time. The new Garmin chart plotters have a good chance of surviving the immersion, and since tracks "On" is the default, it is likely a good record of the vessels tracks showing the route traveled is available, along with the engine data from the ECU's. I have been following the the Hull Truth's postings, and I am, as always amazed at what people will say, and how many experts are over there. It was an accident of tragic proportions, and heart wrenching for family and friends.

The point of my story was that step hulls have some very real handling idiosyncrasies that owners must be acutely aware of at all times, and as I mentioned, the performance gains in my mind, are not worth the increased handling problems these hulls can have under some circumstances. I did communicate with an experienced step hull designer prior to writing the piece. Many thanks Bob, Bill

[thataway]

Thanks Bill,
For "disclosure" I believe that this is the same Bill Bishop who writes the
excellent "Marine Installers Rant", which was linked to above. And I suspect that his article on stepped hulls and second stations was motivated by the accident involving the Contender. This is another "link" that we should all be looking for good and timely thoughts about our boating world.

I have not seen any information from the other 9 people aboard the boat, which would enlighten us about what happened just before the capsize.

The only stepped hulls I have ridden in have been either offshore power boat racers or a Formula one racer. Looking at the Cutwater page, they have utilized a "keel pad", and bulge in the aft end of the keel/skeg. The steps seem to tend to work air away from the keel, and perhaps decrease any incident of ventilation/cavitation. They also claim some increase in efficiency, but it would probably take some tank testing to verify that. I have spent a lot of time in a sailboat (55' ULBD, daggerboard) with a keel pad and wide keel to get the machinery weight down low. That boat would plane in some specific conditions, and would power up to as much as 12 knots with a 110 inboard diesel. But at low speeds, the steps would not help efficiency, and might even increase drag.

There are some interior issues which I don't like on the Cutwater, and for several personal reasons would not buy one, although they are up to the excellent standards of the Ranger Tugs, also produced by Fluid Motion.