Twin 50s vs. Twin 60s for 22' C-Dory

C

Capt'n Bill

New member
I have decided to re-power my 1994 22' C-Dory. It is currently powered with twin Honda BF45s that came with the boat initially. I have 3 batteries, a windlass, 30 feet of chain, a live well, trim tabs and assorted other equipment on board. The boat seems sluggish with the 45s, slow to get up on plane, and I could only coax about 20knots at 5300 rpms out of her on a smooth day.

I've gotten some good prices on a pair of brand new Suzuki 4 stroke outboards. My mechanic has recommended that I repower with twin 60s as opposed to twin 50s to gain more power and provide better fuel economy by being able to cruise at lower rpms. The difference in price is negligible. The differences besides the horsepower are :

The 60 HP engines weigh 359 ponds as opposed to the 50HP engines which weigh 243 pounds. That equates to a total of 232 pounds more for the twin 60s.

The 60HP is 4 cylinders as opposed to 3 cylinders for the 50HP.

The torque for a 60HP engines are 8 to 10 each vs. 6 to 8 each for the 50HP engines(I couldn't make out the units of measurement for those torque readings from the Suzuki brochure

The 60 HP engines have 25 Amp alternators vs. 18 amps for the 50HPs.

The 60HP engine has a fresh water flushing port while the 50HP doesn't and will require rabbit ears to flush.

Has anybody powered their 22 with more HP than that recommended by the manufacturer? Any problems doing so? Does anybody know the rationale as to why the boat is only supposed to be powered with 100HP max?

Thanks,

Bill
Big Island, HI
 
going to a bigger hp would not worry me that much. the c-dorys are now rated for 115hp. Sark has a 115 suzuki on his boat that he really loves. what would worry me and stop me from doing the twim 60's is the weight. less weight is better on the rear then more. I would look at a bigger single or lighter twins, See what the e-tech's weight. I talked to les of E.Q. harbour services yesterday and he had his first e-tech come in for service. It was three years old. Thats the only one that has came in of all the ones hes sold, thats a good record.
 
Bill,

My 22 cruiser from 1991 was factory powered with a 70hp 2-stroke which weighed 250 lbs.

You are considering two 60's which weigh 720 lbs!!

One Honda 90 is under 400lbs!!

Just my observations,
 
I guess that I didn't have any reference point for what other engines weighed. That sounds like enough to steer me towards the 50s since even those sound like they are pushing it with the weight factor(486 pounds total for two of them).

Thanks,

Bill
 
I would also browse this link http://www.c-brats.com/viewtopic.php?t=2746

It has some pertinant points about this subject - for example:
Wefings":174zp7zh said:
We have delivered a number of 22s with the 115 Suzuki. The rating has indeed changed . The single engine is more efficient than twins [due to weight and drag advantage ], and with the new "max power" , the advantages I see is the ability to cruise at a given speed at a lower RPM and easier ability to plane with a big load . Trim tabs are highly recommended with a 115, as the boat will porpoise [or "hobby horse" for you westerners] with that much power . Suzuki 115 and 90 are identical weight on the transom .Honda 115 is way too heavy , Honda 90 is lighter than Suzuki . The new EFI Honda 90 should be a good match as they have trimmed the weight a little bit, added the V Tec valvetrain, essentially copied Suzuki's brilliant gearing , and gotten rid of those darn pesky carbs. Lots of choices . I am a fan of the single and kicker, but its all in what you do with the boat , and personal preferences.
Marc
Click to expand...
 
This months Power Boat reports is supposed to have a comparison of single verses twin. I haven't got my copy yet but it should be interesting to see what they find out. Maybe someone else has received a copy already and might be able to let you know what the results were. I know you have twins already and probably wouldn't change but I though I'd mention it.
Ron
 
Also about the new honda. Its really closer to 96 hp then 90. They cant call it a 100hp because that would be over rating it which I guess you cant do but you can underrate it and claim you have the best 90.
 
Hey Bill, let us know what you finally decide on and how it works out. I also have a '94 Cruiser with twin BF-45's and am looking at repowering. I can get more speed than you do however, I turn about 5800 at WOT and can get near 30mph out of it.

Charlie
 
Charlie,

Sounds like you've had good luck with your 45s. Mine had low hours(about 500) when I bought the boat, and I have had nothing but problems with them from the time I took ownership even though they checked out during the survey and sea trial. Hence the reason to repower even though they now only have about 650 hours. I think that the prior owner must have been neglectful.

Bill
 
Bill, I bought the boat about 4 years ago, the engines only had 240 hours or so on each. The boat had not been used in 5 years when I got it. I have about 400 hours on the engines now and they have never let me down. I did have a lower unit problem on the stbd side, got a fishing line wrapped around the shaft and it cracked the housing just forward of the prop on the lower unit. Pix in the outboard forum. Bill and El sent me their blown power head 40 and I switched lower units with no problem.

Since then though, I have had a problem reaching full RPMS on that unit, it seems to max out at about 4500 while the other unit will reach 5800-6000 with no problem. Have tried everything, got help from folks on this forum but throughout last season it persisted. I'll try again this spring when I relaunch but am seriously thinking about repowering, either with twins again or a single new Honda ETEC 90 with Fuel Injection.

What have you decided to do?

Charlie (Captain USN, Ret)
 
Twin 50's should be plenty of power. They should top out at about 30 knots. If you want more power you could get twin Yamaha 60's which weigh less than the Suzuki 50's. Lots of options out there.

Bill
 
Say aloha to the Joe Adams and Robert Kennedy at Windward for me , if that is who you are dealing with . The new Honda 90 is actually around 100 H.P While in Miami, Boattest.com and Honda tech dept. did tests on the 22 Cruiser. They should be on the sites very soon .
To sum it up , the motor is very strong , very light and will way outperform the twin 45s .
I actually saw 36 MPH on the GPS at one point when the boat was light with 2 people . I think it still got 32 with full fuel and a number of people on board .
But, I know that you Island folks like twins and I concurr that the twin 60 Suzukis are way too heavy .
The 50s need to be propped right . The redline for the Suzys is an industry high 6500 R.P.Ms . If you get them turning where they should , they will perform better than the Hondas .
And they dont have those pesky carbs.........
Marc
 
Charlie,

Checking the gear ratio is a simple test.

Remove spark plugs (SAFETY ITEM), remove flywheel cover (if any).

Mark one prop blade and flywheel(tape or marker).

Put gearcase in forward.

Manually rotate flywheel(normal direction only)(watch your fingers!).

Count flywheel rotations till prop makes one rotation.

Compare port and starboard motors.

I would also compare the two lower units in the exhaust passage area, any restriction in the replaced lower unit could be choking that engine.
 
marc , how does that 9-0 do on the cruise ship? have you loaded it down with the typical gear for cruising? i was supprised to see that engine on that 25. Is the old 25 lighter or heavier then the new 25?
 
Capt'n Bill,

Have the motors ever reached maximum RPM?

Have you tried lower pitched props?

Is the bottom clean and smooth? A small amount of growth can slow the boat.

Larry H
 
Dear Bill:

I agree with several other respondents: two 60s would put you into an overweight situation. With several hundred extra pounds hanging off the back of your CD-22, you might find it even harder to get up on plane (at the least, it might require more horsepower and require a higher speed to stay on plane). The extra hp (and weight!) could significantly unbalance your CD-22 and ultimately prove self-defeating.

I have a 1999 CD-22 with twin Honda 40s (which weigh 210# each = 420 # total). WOT (in smooth water at 5200 rpm) = 33+ mph; it cruises nicely at 4000 rpm = 25 mph. It gets on plane--and I can keep it on plane (as when cruising the Erie Canal)--at 10 mph.

I suspect that new motors would give you more speed, even if you were to stay with twin 40s or 45s. Certainly, given the choice you present, I wouldn't even consider the 60s. The 50s should prove more than adequate for speed, and keep your CD in better balance.

For what it's worth,
Wayne
 
I have twin 40hp Yamaha's.....but if I was to do it over again...I sure like that new Honda 90... lighter and sure allot more power... the new engines are so trouble free that it almost is not an issue...unless ya hit something.... and I guess that could do in any engine.... that's why ya carry a kicker..

Why do you want to go so fast ??? without a bunch of load I can do 30 but almost never do...it's uncomfortable in the ocean...most of our cruising is done at 15 to 17 or less.

Joel
SEA3PO
 
Thanks everyone for all of the excellent reponses to my inquiry. No, I am not some sort of speed freak but reading what others have had to say it just sounds as though I have never experienced the full power that my 45s should have provided. Having no other reference point, I had grown a bit paranoid that 100HP was not going to be enough. Now, i see that it will be more than adequate with new engines and the correct prop for my boat.

Appreciate all of you single engine fans, but here in the islands we all like the added security of twin engines. In fact, the last time I was out I found myself limping home on one engine when the other failed. I knew all along that I would most likely be replacing with either the Suzuki or Yamaha 50s, since they are the only fuel injected engines in that size range. I've had it with fussy carburetors, particularly since I can only get fule with 10% ethanol here. I know the Yamahas are lighter, however, I have access to a great deal on the Suzukis right now where they will cost around $1000 less per engine and will come with a free 6 year warranty like the Yamahas have through the end of this month. Also, the mechanic that I have used for the past year is a Suzuki dealer and I can continue to use his services for any warranty work. I am sure that they will be good, reliable engines.

So, thanks again,

Bill Showalter
 
Bill said: "I have access to a great deal on the Suzukis right now where they will cost around $1000 less per engine and will come with a free 6 year warranty like the Yamahas have through the end of this month. "

Bill, as you know, nothin's "free", it's just factored into the price. That having been said, you made the right choice, in my mind. I haven't decided what to do yet, my 45's are still going strong. Keep us posted on the replacement progress and the things you run into. That is a topic that hasn't been covered here! Would be interested in what you find about mounting holes, steering, controls, etc, etc.

Charlie
 
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