POWER for 25 Sport Cabin

[joecfd]

Looking at a new 25 XL Sport Cabin Parker and would like opinion on enging options- 300 HP, Twin 150HP, or Twin 200HP. Any opinions would be appreciated.
-Joe

 

[DaleH]

My choice would be the twin 150s, best available power and economy for that mod-V rated hull, IMHO.
That hull, in any sea less slight surface chop to FAC, can't use all of the available HP you could give it anyway.

More than a few guys I know in my NE toona club run 26' deep-V CCs with those motors and to me, that 4-cyl Yam 150hp is THE best 4-s motor Yam makes.

If forced to make a decision and had to stay with Yam, then I'd go for the 300hp before the twin-200s, which would be an absolute wa$te of $$ to me ...

 

[John_Madison CT]

If it was me, I'd go with a single ultra reliable engine, with plenty of HP for the boat. In your case, i would say get the Yamaha 300hp 4 stroke.

 

[joecfd]

Facts are this from what I am told: twin 200Hp Yamaha's weight @ 400 lbs more than the single 300HP, and the difference between the twin 200HP and twin 150HP is only 25lbs. It would seem in this day and age of reliability -unless going offshore and concerned about redundancy system (two engines) - the single option is way to go. Is there anything else to consider??? Of course cost- twin 200 HP are Alot more expensive than the single 300HP. Is that extra 100HP really necessary? And, it will be pushing the 400lbs!!

 

[got_em_on]

Single 300 or twin 150's if you feel the need for twins

 

[warthog5]

OK....I'm neck deep in this right now.

There is a little thing called "Gear ratio" that people are not even looking at.


Yamaha 300 =1.75:1 http://www.yamahaoutboards.com/outboard ... ifications

Suzuki 300 = 2.08:1

http://www.suzukimarine.com/Product%20L ... 300AP.aspx


Now which one will spin a larger prop and get a better bite on the water?

I know the answer.

 

[joecfd]

How about the new inline 4 200HP from Yamaha? Less expensive than V6 and just slightly heavier than 150HP.
FYI, I am only interested in Yamaha product. Thanks,Joe

 

[warthog5]

That motor is also Fly-By Wire controls.
200 4cyl Yamaha
http://www.yamahaoutboards.com/outboard ... ifications

1.86:1 Gear ratio

175 4cyl Yamaha is not available.


For Compairson.

http://www.suzukimarine.com/Product%20L ... DF175.aspx

2.50:1 Gear ratio

 

[PressureRelief]

I keep seeing everyone talking redundancy with twin motors. It is not truly redundant unless you have seperate fuel tanks and they should be filled at different locations. This is how I use to do it at work after getting stung with bad fuel.

 

[joecfd]

Good point- can run separate fuel filters and get in habit of not takingon alot of fuel at anyone time. The question at this point is do I go for the inline 4 200HP Yamaha twins or the 300HP single- how much differnce really will it show in performance? I know it is 100HP diff- but is that a big difference at that point??

 

[miky2884]

If your not gonna run the boat offshore Id stick with the single 300

 

[joecfd]

so, speed /power is not that much of a difference between single 300 and twin 200( 400 HP). Not running offshore- in Long Island Sound. Is stability a plus with twins?

 

[PressureRelief]

I read a paper by a naval archictect referencing speed/length ratio, displacement/length ratio, above water/below water area, and prismatic coefficient. Basically what I took from the article in reference to your question is that after a certain point, a gain in horsepower will have negligible gain in speed. i.e. if you increase your hp by fifty percent you will not get a corresponding gain in speed. I remember the calculations are simple enough to do on your phone.

I believe it was Kevin who used the example that at work he had two similar boats, one with 150 hp and the other with 225 or so and the speed difference was within 10%. Increasing the HP by 50% most would probably guess a much larger variation. It all comes back to the math.

Do not quote me on the figures but that is what I can recall without using the search function.

 

[joecfd]

All- Thanks for the feedback. Boat is ordered with twin 150 HP Yamaha. Looking forward to many years with this boat. Thanks again.