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do cats sneeze? I beg to differ...

 
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C Sniper



Joined: 17 Mar 2019
Posts: 60
City/Region: South Padre Island
State or Province: TX
C-Dory Year: 2007
C-Dory Model: 255 Tomcat
Photos: C Sniper
PostPosted: Tue Aug 02, 2022 8:50 pm    Post subject: do cats sneeze? I beg to differ... Reply with quote

I read the tomcats do not sneeze. Perhaps that is with experienced masters at the helm... which I am not - with the vessel. I would like some clarification on a few points from the true masters. What seas can you run fast and enjoy the air cushion? 2 ft at 4 secs??? more? less?

I was conservatively heading into 3ft at 6 sec at 45 degrees at 14-17 kts and had non-stop sneeze rhythmically timed with the swells smashing into the shallow bow bridge. So the question is, mainly for the GOM guys, is what seas, specifically can you "air cushion" into at high speed? keep in mind i am heavily laden... ft and sec plz....

Any wisdom is appreciated for dealing with mod-hi seas in a tomcat...
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ssobol



Joined: 27 Oct 2012
Posts: 2945
City/Region: SW Michigan
State or Province: MI
C-Dory Year: 2008
C-Dory Model: 22 Cruiser
Vessel Name: SoBELLE
Photos: SoBelle
PostPosted: Wed Aug 03, 2022 9:21 am    Post subject: Reply with quote

I think you'd have to go pretty fast to get any significant lift from the air cushion in the tunnel. It probably helps more from depressing the top of the wave than actually lifting the boat. Venturi effect between the hull and the water would also tend to suck the boat down (or the water up). However, the lifting force from the sponsons planing is a lot more than the suction force of the air.
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thataway



Joined: 02 Nov 2003
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City/Region: Pensacola
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C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
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PostPosted: Wed Aug 03, 2022 1:00 pm    Post subject: Reply with quote

The Suzuki powered boats seem to be faster than the Honda powered. With our TC255 lite about 50 mph was WOT. Heavy boat, was 46 mph.

We would run at 35 mph up Perdido bay into 2 1/2- 3' chop during Northers.

I think you must distinguish spray from sneeze. Sneeze comes from in-between the hulls. Spray can come from inside and outside the hulls. Going into 3' chop there is going to spray. Glacier Bay will sneeze at lower speeds--We didn't have sneeze in same conditions for the Tom Cat 255.

The tunnel narrows toward the stern, because of the attitude of the boat--with loss of vertical height. I have never been able to look under the boat to see if the waves were flattened--but there is going to be a certain amount of turbulence from each hull on both sides of the individual hull. That probably affects the "flattening" of any waves, rather than air pressure. When running with the cushion effect, the boat will ride a bit higher.
'

_________________
Bob Austin
Thataway
Thataway (Ex Seaweed) 2007 25 C Dory May 2018 to Oct. 2021
Thisaway 2006 22' CDory November 2011 to May 2018
Caracal 18 140 Suzuki 2007 to present
Thataway TomCat 255 150 Suzukis June 2006 thru August 2011
C Pelican; 1992, 22 Cruiser, 2002 thru 2006
Frequent Sea; 2003 C D 25, 2007 thru 2009
KA6PKB
Home port: Pensacola FL
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C Sniper



Joined: 17 Mar 2019
Posts: 60
City/Region: South Padre Island
State or Province: TX
C-Dory Year: 2007
C-Dory Model: 255 Tomcat
Photos: C Sniper
PostPosted: Sat Aug 06, 2022 10:14 pm    Post subject: Reply with quote

I was thinking that sneezing was an incredibly fine mist coming from the center (between hulls), which was what I had happening. Correct me if I am wrong.
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thataway



Joined: 02 Nov 2003
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City/Region: Pensacola
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Photos: Thataway
PostPosted: Sun Aug 07, 2022 1:28 pm    Post subject: Reply with quote

C Sniper wrote:
I was thinking that sneezing was an incredibly fine mist coming from the center (between hulls), which was what I had happening. Correct me if I am wrong.


I am not sure I would categorize it as "incredibly fine miss", but it is spray which comes from between the hulls. I too what you posted to be more reminiscent of spray due to waves hitting the hulls.

I sea trialed a number of other cats in the size of the TC 255 and a few of them such as the Glacier Bay did have significant sneeze in what I would consider relatively mild conditions.

When we run up Perdido Bay with the heavy chop, there is water flying everywhere. But more off the hulls than between the hulls only. The Caracal cat is only 18 feet, but it's hulls are very similar to the Tom Cat, but the tunnel clearance is better.

Certainly all cats are very weight sensitive. A boat with low tunnel clearance will have even less with loads. I first sea trialed a Tom Cat 255 at Marina Del Ray in Ca. It had a full gas powered dive compressor in the lazarette section. Plus dive tanks in racks and 4 persons aboard. It was also Honda powered. Because it had Micro Commander controls, the trim was no on the throttle lever, and the owner declined to allow me to fiddle with the motor trim. He stated that it took him a long time to get them right and he wanted to keep there at that position (Not the proper way to use trim). I was disturbed by the handling.

Next I sea trailed a 255 with the 150 Suzukis, and a very light boat. We were in 2 1/2 to 3' chop the boat ate it up (no sneeze). We were also doing as well, or maybe better than a 26' Regulator (very deep V) running on a parallel course.

Gulf of Mexico conditions can vary immensely. I have only lived in Pensacola for about 30 years, and I did some boating off of Galveston in the late 1950 era for 4 years, so I have limited experience in GOM. So I cannot answer if you conditions are like those you have experienced. Our Pensacola waters drop off a little more steeply than some other parts of the GOM.
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gulfcoast john



Joined: 14 Dec 2012
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City/Region: PENSACOLA
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C-Dory Model: 255 Tomcat
Vessel Name: Cat O' Mine
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PostPosted: Sun Aug 07, 2022 8:09 pm    Post subject: Reply with quote

C-Sniper,

Where exactly did you “read that TomCats do not sneeze?”

Under some rare conditions I suspect any catamaran (even the 170 foot Key West Express) could ‘sneeze’ with the right combination of sea conditions and captain mis-management. I’m not implying any mis-management on your part.

In our almost ten years running our boat, your ‘heavily laden’ comment is a big red flag for performance. Full gas alone is 900 pounds (75g x 2 tanks = 150g x 6.1 lbs/gal = 915 pounds), add 250 pounds for water plus all your buddies and ice and gear and your ‘heavily laden’ 26 foot boat becomes a big fat pig on the water.

As just a practical matter, even in ‘heavy cruise mode’ we have never experienced significant ‘sneezing’ in less than official NOAA Gale Warning or Small Craft Advisory conditions with two exceptions.

One was in the Key West cruise ship channel with a vicious ripping tide vs wind short event with standing waves that sent green water over the top of the bimini; the other in similar circumstances on the Stono River AICW for only 20 miles that emptied our cabinets. When we had the prior rooftop AC replaced, the tech said, ‘this unit is secured to the roof with four big Stainless Steel bolts. Three were broken off and the fourth was bent. Where the hell do you take this boat?”

I’d offer that your ‘three foot seas’ (which NOAA would define as every 100th wave would be a six footer) would likely have been official Small Craft Advisory conditions, and none of us should have been out there then. Even in a TomCat, you don’t want to hit a six foot wave at 47 MPH. Can we all agree on that? That is the official definition of ‘three foot seas.’ Many captains including me often overestimate sea states in our small but capable boats.

Newer owners often under-estimate how much bow-up the TC255 ‘likes’...almost to ‘trailering’ position (3.5 bars of 5) on my Yamaha F150 gauges. Get a inclinometer gauge and aim for 4% incline bow up at 3200-4500RPM cruise.

PM me to exchange numbers if you’d like to chat.

I think you’re on the right track to make your boat work out best for you.

Hope this is helpful.

John


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2010 Tom Cat 255, Cat O' Mine
Yamaha F150, LXF150
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C Sniper



Joined: 17 Mar 2019
Posts: 60
City/Region: South Padre Island
State or Province: TX
C-Dory Year: 2007
C-Dory Model: 255 Tomcat
Photos: C Sniper
PostPosted: Mon Aug 08, 2022 6:24 am    Post subject: Reply with quote

Good info! Agreed, not 3 ft seas by that standard. Buoy 42020 was showing 3 ft at 6 secs for the primary swell that day.
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