Motor size for Tom Cat

O

onwater4fun

New member
We will be buying a Tom Cat and would like suggestions or experience input with regard to motor size. We do not fish but cruise long distance 95% of the time at 6-7MPH. We would like to equip our Cat with motors that would offer good economy while putting but would be powerful enough to cruise on plane when necessary. :idea :thup :thup
 
I would not consider the Tom Cat 255 as a boat for long distance cruising at 6 to 7 knots. My experience is because of the drag of the bridge deck being in the water, the mileage at 7 knots is the same as at about 24 knots. Also the Tom Cat needs to get up on a plane to be on top of the waves for the smooth ride.

The boat in the Chesapeake which I belive is still for sale, has used 115 Suzuki's--the 115's and 90's seem to work fine on the 24's. I feel that the 255 is a better boat with the 150's. The reason is that it is more responsive--when you have to drop down speed, it gets up on a plane a little quicker. I am sure that some will feel that 115 hp per side, is OK and many will vote for the 130's. However, the mileage seems to be about the same for 115 to 150's. (Don't know of any 175's--but suspect it would be similar with that power).

If you want the slow speed seriously consider the C Ranger tug 25.
 
I can keep on plane with my TomCat 255 as low as 8 -10kts with permatrims.... you can get just as good mpg at 15kts too..the 25 C-Dory is goes for 70 k.....the TomCat 100k but the TomCat is TWICE the Boat......
I went with 150 Hondas because they get about the same MPH as the 130 or less....its not how much horsepower you HAVE that is you MPG..its how much HP you USE to push x amount of weight
Plus Honda will finance your WHOLE BOAT including electonics..trailer...for 6% 15year

Dick
255 TomCat
ShirleyMae
Orinda
 
As mentioned above, the hull shape has much more wetted surface at hull speeds than planing speeds, thus less efficient. However, Brent and Dixie on Discovery have used a single engine at slow speeds for cruising efficiently in smooth water (they have Honda 135's).

The Honda 150 pretty much behaves as a 135 until you get the rev's up. It is really nice to have that extra power when storms are nearing, or have already caught up with you.

I have 150's and feel that's the best available at the time.

However..... with the TomCat's sensitivity to aft weight, if they were available, I'd be looking really close that the new Evinrude E-Teks.... they are hundreds of pounds lighter than the four strokes and no break-in, no 20 hour maintenance, no 200 hour maintenance.... That would be nice.

John
 
The difference between a Honda 150 and an E-Tec 150 is only 59 lbs (20") or 58 lbs (25") So times 2 it is 118 or 116 lbs..I guess significant on a stern sensitive tomcat. (the weight issue gets very noticable when comparing to the Verado) The big weight to power ratio occurs when using twins on a non cat. For example, when using 2 Hondas to achieve a total of 150 hp @ 384 lbs ea. for a total weight of 768 lbs vs a single 150 @ 478 lbs. Now THAT is significant! Lower mpg too. Of course the peace of mind and slight mauverability (they are closer together than say on a tomcat which REALLY gains low speed manuverability from 2 engines) increase are the tradeoff.
My offshore buddies tell me that low end torque on a 4 stroke make riding the throttle in large swells almost a thing of the past, whereas it is a must on a 2 stroke.
Having said that, I am a 2 stroke geek all the way, having had 2s all the way back to the 60's and seen them hold up as long as 40 years with minimal maint.
 
Jim -

I had not realized there was such a small weight difference on the Honda/E Tek comparison. You imply that the Verado is different. Is the Verado heavier?

John
 
drjohn71a":3d34vxjl said:
Jim -

I had not realized there was such a small weight difference on the Honda/E Tek comparison. You imply that the Verado is different. Is the Verado heavier?

John
Click to expand...

Yeah, the Verado 150 weighs in at 510 lbs :roll: ( hehe maybe a lot more alternator) :mrgreen:
 
drjohn71a":3a3mjiq7 said:
Jim -

I had not realized there was such a small weight difference on the Honda/E Tek comparison. You imply that the Verado is different. Is the Verado heavier?

John
Click to expand...

I am no gearhead, but being a teen in the late 60's early 70's I had a "hot rod" and was really into cars. We used to "blow" (supercharge) in order to get more hp for a given size (displacement) of engine.
Maybe someone can explain to me what possible point it is for a Verado of any given horsepower to weigh more than any other manufacturer's? Power to weight ratio is most important in boating both for performance and economy. I know materials are far better now, but even so a "blown" engine works harder and develops more heat so it's life is still shorter, albeit maybe not like the old days.
I guess (I don't know) a supercharged engine would have better hole shot (smoother power curve)? Well, real skiers and wakers use specialized inboards. That leaves what; drag racers and bass fishermen? :P
Plus the Verado costs alot more. :cry
 
My experience with low speeds is if one goes much over 6 to 7 knots, there is a fair amount of drag and turning effect of the single motor.

Some what contradictory is that although the widely spaced motors of the Tom Cat should give much more maneuverablility, the "keel" effect of the two narrow hulls tends to resist turning, so one has to use a fair amount of power to manuever with just the twins (not using changing direction of the props by steering)--so I tend to steer as I do with a single motor. The effect of twins seems much more with inboards than with the two outboards of the Tom Cat.

Good question if one put a much lighter engine on the boat if the bridge deck would be clear of the water. My neighbor has a TC 24 and his bridge deck also drags with twin 115 Yahamas, so I suspect that one would have to get well dtown in HP (weight) to get the tunnel clear aft. I haven't seen one of the Tom Cats with no engines. But if you wanted to run at only displacement speeds, than you could consider mounting only a single engine--that would get the weight way down--and with 25 to 40 hp you would get speeds of 7 knots or maybe a bit more with excellent economy....but then, you have lost the real feature of the Tom Cat--which is speed. (in my opinion).

I don't see the TC as being "twice the boat" as a CD 25--the TC does have a bigger bunk and I believe a bigger cockpit--but if one only wanted displacement speeds, the CD would be considerably cheaper with a small single engine....
 
As long as we're discussing Honda motors, let me try this one, an honest question. When we bought the CD-25, we were offered the Honda 135, but I went for the Honda 150.

Now these engines are both the same motor; as near as I can figure out it's the Accord 4 cyl set on end. Honda claims the difference in horsepower comes from "V-Tech" and Scott Reynolds claimed it's only good over 4000 rpm, a number I rarely see. Honda has never defined what V-Tech is, though they charge $850 for it.

I just read that on a motorcycle V-Tech lets the engine run on 2 valves/cyl at low rpm, and uses 4 valves over 4000 rpm. That wouldn't let an engine go from 135 to 150 hp but it might increase the bottom end torque.

Anyone know what V-Tech is on an outboard? I assume it's some change in the intake, but what exactly is it?

Boris
 
TomCat's sensitivity to aft weight ?????
I have not noticed any ....if fact I think alittle more weight would help in the aft......I could trim the bow down a little for a change instead of negative and up.

Dick
"ShirleyMae"
 
squidslayer":br4s06gt said:
TomCat's sensitivity to aft weight ?????
I have not noticed any ....if fact I think alittle more weight would help in the aft......I could trim the bow down a little for a change instead of negative and up.

Dick
"ShirleyMae"
Click to expand...

I had always heard that..never having ridden one myself :mrgreen: I think some would like to see the aft "bridge" out of the water at displacement speed cruising?
hehe did you see my post in another section where I used the Shirley Mae as my template for my perfect boat pending my lottery win? :xnaughty
 
I would not characterize the Tom Cat 255 has being sensitative to weight aft--it does with the 150 hp engines--but if you start adding more weight aft it may change the handling characteristics. The issue is that the tunnel is not open at low speeds--the boat has to be on a plane before the tunnel is open and air can pass thru. The cushion of air allows a pillow like affect. If the bridge deck is dragging (which it does) there is more resistance to progress thru the water, and there is more propensity to slap when you hit a wave. Many of the other cats have air under the bridge deck and the tunnel is open at displacment speeds, giving a better ride.

The trimming bow down brings the stern up and opens the tunnel, but only at planing speeds. We will have to so some photos at different speeds (from another boat)--to see at what speed exactly the tunnel opens up. I will be very surprised if it is open at 8 knots, even with the bow fully trimmed down. But I'll document what I find with photos--have friends from the PNW arriving tomarrow, and that will be a good oportunity to do some tests.
 
You have to trim the bow up???

Apparently, we need to take into account the differing loading patterns between users. For instance, I have absolutely nothing in the forward storage area, so the bow is almost always "up". If some of you have the bow always "down", I'd be worried a bit and consider shifting loads.

Also, I rarely am in the boat more than a day or so, unlike you cruisers. Cruising demands alot more equipment and supplies, so probably more weight there. Give me a few years of 'losing' things and gradually packing all the remote recesses and maybe I'll have the same problems...

Squidslayer - I don't know about your boat, but most of the TomCat 255s are riding with 1/4 to 1/3 of the cockpit draining scupper outlets under water - even without extra batteries and a full livewell. I don't see how the aft hull could be driven much further into the water without water actively entering the cockpit!

John
 
JimD":2ia3vych said:
drjohn71a":2ia3vych said:
Jim -

I had not realized there was such a small weight difference on the Honda/E Tek comparison. You imply that the Verado is different. Is the Verado heavier?

John
Click to expand...

I am no gearhead, but being a teen in the late 60's early 70's I had a "hot rod" and was really into cars. We used to "blow" (supercharge) in order to get more hp for a given size (displacement) of engine.
Maybe someone can explain to me what possible point it is for a Verado of any given horsepower to weigh more than any other manufacturer's? Power to weight ratio is most important in boating both for performance and economy. I know materials are far better now, but even so a "blown" engine works harder and develops more heat so it's life is still shorter, albeit maybe not like the old days.
I guess (I don't know) a supercharged engine would have better hole shot (smoother power curve)? Well, real skiers and wakers use specialized inboards. That leaves what; drag racers and bass fishermen? :P
Plus the Verado costs alot more. :cry
Click to expand...

As far as the weight issue, it is probably the supercharger itself, a true internal engine geared supercharger is a heavy unit. That does not explain the other engines though. The new Mercury 90's are much heavier than my 2003, same horsepower. I'm with you on not getting what the constant weight increases gain (other than lost customers).
 
I have to take a little exception with this - assuming we are talking new prices, rigged, with a trailer, a nicely rigged CD25 these day is closer to $90K than $70, and a nicely rigged TC255, well, I wonder how Squidslayer got one for $100K, I'll bet it is $140K or more - how about it, other new TC255 purchasers? How much did you end up spending, ready to cruise? Whether a TC255 is "twice the boat" is also quite debatable - they are DIFFERENT boats, as is the Ranger R25 - all nominal 25 foot boats. The big advantage of the TC255, which we all acknowledge, is its awesome ride and ability to handle rough water at speed. I am quite anxious to see how the new BF15 Les installed two weeks ago pushes Daydream for slow cruising. For a slow cruiser, though, no debate at all - go for the Ranger R25. But look at Wild Blue, Anna Leigh, Daydream, and the other CD25s on this site, how people use them, their satisfaction level...the CD25 is a great all-around cruiser.

squidslayer":16qas9rd said:
..the 25 C-Dory is goes for 70 k.....the TomCat 100k but the TomCat is TWICE the Boat......

Dick
255 TomCat
ShirleyMae
Orinda
Click to expand...
 
Pat - I agree about the TC 255 price levels. That aft steering station demands complete dual sets of electronic controls and the base price is nudging 10 grand just for that setup. I think a total, equipped price level is closer to 140-150 grand. Prob' Squid was comparing base price levels.

The TomCat cockpit seems to have alot more usable space than the CD 25 and that solid Armstrong bracket/Diver's platform is like the back veranda!

John
 
JimD":3srib35h said:
go here http://www.honda-marine.com/outboardprofessor.aspx# and choose "vtec" on the right column
If you rarely see 4000 rpm at wot then change your prop pitch. If you just cruise slowly then have fun!
Click to expand...

Thanks, Jim, that was just what I wanted.

Our boat cruises @ 7 knts, because the throttle is way back. This gives good mileage (6 mpg) and we get to see the scenery. If we need to go fast, why we have vtec.

Boris
 
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