The Cat

matt_unique · Posted: Fri Mar 02, 2007 1:27 pm Post subject: The Cat

I mentioned in a recent post I'm researching for my next boat purchase. Individually I can afford the C-22. I have a regular boat/dive buddy that is interested in going in 50/50 on a larger boat. Together we could buy the Tomcat.

I run a lot of different boats commercially and recreationally but I have never handled a Cat. I understand the basic design purpose is to cruise smooth in chop. I'm curious to learn about the unique aspects of Cat handling. Is the ride experience just extraordinarily smooth in comparison to mono hull boats in say 2-4' seas? Are there unique characteristics to turning? I assume they stay level when you turn. What about operating on one engine - can you plane off on just one engine in case of engine failure? In what conditions/circumstances are they unstable?

Thanks

thataway · Posted: Fri Mar 02, 2007 2:39 pm Post subject:

There are two distinct types of cats--the planning--which the Tom Cat and ProKat are --and the displacement/semi displacement which the Glacier Bay and World Cat are. The Planing cat has to be up on a plane to get the smooth ride. (You have to keep air flowing thru the tunnel below the bridge deck. I have gotten my boat to plane down to 16 knots--some have gotten slightly lower--even to 12 knots with the Permatrim fins (I haven't put Permatrims on yet, but have them). At dispalacement speeds the Tom Cat does not perform as well as the semidispacment boats--there is the issue of the flat bottom hulls, plus the tunnel is submerged aft at lower speeds, so there is no air cushion.

The Tom Cat is faster with the same HP and more fuel effecient in the planning range. I can run directly into 3 foot seas--4 foot seas, I have to quarter off some (I have a back problem so that limits me). Of course in any sea condition it depends on the steepness of seas--and I am speaking of steep seas, not swells. On Beam and following seas, there have been some "squirley" handling of some of the semidisplacement cats--and one capsized last year--in all fairness, the boat was heavly loaded with 6 heavy guys and fishboxes which were not secured, and I believe that these shifted to one side. I have not experienced any handling problems in waves up to 6 feet plus in beam or following seas. Definately the Tom Cat handles better in these conditions. Also the Tom Cat seems to have a slower motion when trolling or slow running in beam seas. The semi displacement cats have a very quick motion.

Most of the semi displacement cats lean outward in a hard turn. The Tom Cat remains flat on a hard over turn. --I am aware of some instances at sea trial where the helm was put hard over, dislodging crew--but the boat remained level--I don't think that could be done in the semi displacement cat.

The other issue is the amount of room in the cabin--again the Tom Cat wins in the cats of that size. You have to go to the 33 to 34 footers to get more room in the cabin--and a price tag which is way high.

teflonmom · Posted: Fri Mar 02, 2007 7:56 pm Post subject: The Cat

Bob,

Thanks for the explanation on how cats perform. We are not interested in another larger boat, but if we were the Tom Cat would be at the top of our list. The space in the forward cabin is awsome.

By the way are your engines counter rotating?

Fred, Pat and Mr. Grey (the cat)

squidslayer · Posted: Fri Mar 02, 2007 10:32 pm Post subject: Wind waves

Bob

Just got back from a run out the GGB San Francisco....
20kt Winds....5 ft swell every 10......4 ft WW every 4 sec...the WW's were breaking... nasty....I'm just learning how to handle the TC under these condition.... Would you say the best approch heading into the waves like these....you should stay on plane ? full trim down....fast enought to skim the tops..or trim up and go down in them?...
I slowed down and trimed up and had to use the wipers ALOT.
Over all... it handled it well and was really stable!!

Should have speeded it up!!!?

Dick
255 TomCat
Shirley
Orinda

thataway · Posted: Sat Mar 03, 2007 10:38 pm Post subject:

Yes, the engines are counter rotating--and my feeling is that the counter rotating engines seem to handle better on the cat than on both right hand rotation. We have the engines reversed (Right hand prop on the port side). Marc Grove feels that they boats handle better this way--and from what I observer I would agree. I did get the Permatrims inatalled today--have to cut off the tops of the bolts and then see how it does in rough water.

I answered Dicks' post which was in a private E mail. Our experience is that you definately have to speed up in rough water and get on top. The tunnel needs to be kept open to get an air cushion effect--if the bridge deck is in the water, it will slam. We are hoping that the Permatrims will allow us to get the planing speed down even lower.

The options also are to tack off to one side so that the peroid of the waves and swells are decreased and the angle of attack is lessened, thus allowing more speed when going into the waves--along with--hopefully being able to keep on a plane at a lower speed.

Sea Wolf · Posted: Sat Mar 03, 2007 11:33 pm Post subject:

Bob-

I know some folks will think I'm off the wall for asking, but simple curiosity makes me ask if there's ever been a catamaran designed with the air tunnel height adjustable underway so as to change the air cushion and ride characteristics in small chop and whatever else?

Of course, it might be hard to do, and the benefits limited, but who knows until it's tried?

Thanks in advance!

Joe.

Wefings · Posted: Sun Mar 04, 2007 10:37 am Post subject:

Bob , good cat description! I am anxiously awaiting your analysis of the Permatrims on the Tomcat . My guess is they will improve handling and stern lift , which should be good . I am especially curious to hear if you get more "leverage" to lift the bow . And of course, if it has an effect on efficiency .
Marc

thataway · Posted: Sun Mar 04, 2007 9:44 pm Post subject:

Joe, Not to my knowlege has a cat been built with an adustable tunnel height. Some have had foils added or had foils built as part of the design--and with foils, you can change the height of the boat out of the water. This brings up a entire host of other problems, including prop shaft length.

I had thought about puttin a set of foils on the Tom Cat--but they would preclude the center bunk in the trailer--and probably have to have longer shaft engines.

Kerry and Lisa · Posted: Sun Apr 22, 2007 10:22 am Post subject:

Is there someone out there that can tell me the approximate planning speed and engine rpms at plane for a 24 Tomcat. The Kid'n'me has 100 Yamahas.

Bob Austin, You mention that you can run directly into 3-4 ft seas in your 255. Is that on plane? In very rough seas (say 4-6 ft), would it be best to run on plane or off, and with (following) or into the sea?

Thanks.

Kerry

Kerry and Lisa · Posted: Sun Apr 22, 2007 11:17 am Post subject:

Ed,

If you check this forum, perhaps you can tell me your 24 Tomcat's speed and rpms at cruise and at full throttle. Also, is it safe to run outboards at full throttle for more than very brief periods?

I apologize for being so full of questions this morning!

Kerry

Kerry and Lisa · Posted: Sun Apr 22, 2007 11:48 am Post subject:

Bob,

Your second posting about "having to speed up and stay on top" answers my question of how to best ride rough seas in a Tomcat.

What are the speeds and rpms for the Thataway at cruise and full throttle, respectively?

Kerry

thataway · Posted: Sun Apr 22, 2007 9:12 pm Post subject: o

Kerry,
I do take my outboards up to Wide open throttles occasionally for a minute. I get about 5800 RPM top currently. You can run an outboard at 85% of WOT for sustained peroids. I rarely run at those speeds, but this afternoon it was blowing 25 knots with a 6 to 8 mile fetch and the chop was about 3 to 4 feet. We ran at from 10 to 35 knots (the latter at 5100). Most of the time I am running in the 3800 to 4200 RPM range and getting about 22 to 24 knots. The Permatrims do give me a bit more flexability--and I have been playing with them in rougher water.

We tried dropping down to 10 knots--but the boat was much more comfortable at the highers speeds (at least to us). We had the bow high at 8 knots and the boat was not planing--the ride was better up on top.

A friend who has a 30 foot diesel trawler actually turned back and waited for the tide to change and the wind to die down. We also breezed by a Glacer Bay 2640.

If it is rough, I would run across the seas or "tack" into the seas, as one does with a sailboat. That is to avoid going directly into the seas, but go across the seas at a 45 degree angle. If it is rough, I "work" the boat in the seas--vary the trim angle of the engines, and vary the speed.

Kerry and Lisa · Posted: Sun Apr 22, 2007 11:12 pm Post subject:

Thanks Bob. I hope I can get to know my 24 TC as well as you obviously know the Thataway. The TC seems a remarkable boat alright, especially with a knowledgeable pilot at the helm!

I researched what the market had to offer in the 25-30 ft range for about a year and a half before deciding on a C-Dory and eventually on the Tomcat. One doesn't see many used ones on the market. But I was lucky to find one in excellent condition, with low hours, and at a great price at the Bulldog Boatwerks in Fort Myers, Fl. It will be fun learning to pilot the Kid'n'me in a way that complements her potential for outstanding performance.

Kerry

mikeporterinmd · Posted: Mon Apr 23, 2007 3:31 pm Post subject:

What kind of RPM and speed are you getting?

Mike

Kerry and Lisa · Posted: Mon Apr 23, 2007 7:09 pm Post subject:

Hi Mike. I have only taken my "new" 24 Tomcat from the ramp to her slip, so I cannot tell you anything about its speed at any particular rpm.

However, I suspect its performance parameters will be similar to those described above for the Thataway, a 255 Tomcat. All that I have read tells me that Tomcats are fuel efficient and fast. I only have 100 Yamahas, considerably less hp than a 255 TC, but the 24 is substantially lighter.

Kerry