Go large or barely adequate for power

[micel]

I have a 18' cc hydra sport(v-hull,19" deadrise,1,200lb no/power) that has a '97 dt200 with a 20" three blade prop,it gets bad mpg so Im thinking of a new or used outboard.A 90hp 4-stroke suzuki weighs 340lbs,the etec 150 weighs 420lbs.Dealer says stay below 440lbs which does not leave too many options.If this was your boat do you think you would be content with the torque of a 90 4-stroke performance?

 

[robert graham]

Re: Go large or barely adequate for power

refer to Yamaha Outboard Performance Charts for your boat and motor combination, keep the motor you have and cut back on the throttle to around 3500RPM's for more economical cruising, then you'll have the extra power and speed if and when you need it. my Yamaha 90HP sucks gas big time in the 5000+RPM range, so I usually run in the 2500 to 3500RPM range for best economy.

 

[divimon2000]

Re: Go large or barely adequate for power

Not sure what your dt200 is or weighs but I assume its a 2 S Yamaha 200? If so, its lighter than 340lbs?

I am VERY happy I re-powered my little 15 Whaler with a Yamaha 4 S 60 (added 70 lbs). Amazing gas milage, super top end. Only lost some oomph out of the hole (pulling a skiier).

I like Yamaha, Suzuki.

 

[simplystressed]

Re: Go large or barely adequate for power

refer to Yamaha Outboard Performance Charts for your boat and motor combination,

Where do you find these charts?

 

[robert graham]

Re: Go large or barely adequate for power

go to google and type in: Yamaha Outboard Motor Performance Charts, then you put in your boat type and motor and it will give you the whole scoop on miles per gallon, gallons per mile, gallons per hour. Good Luck!

 

[micel]

Re: Go large or barely adequate for power

A little more info on my situation.I have a 4 mile no-wake zone to inlet every time I go out,with stratified or 4-stroke efi I would be getting .5 gph as compared to 2.5 gph with my 2-stroke efi.I would be saving almost 2000$/yr going out 4x a week.My big concern is getting on plane especially with a full load going to happen with the new df90 suzuki?Suzuki claims the df90 on the 18' prolite will do it in 5 seconds plus tops out at 42mph and it weighs 400lb more but has 4 degrees less dead rise at transom.I could save alot of money going with the df90(gauges,4000$ cheaper and save 40-50% on fuel).This is a big decision for me because I do not have alot of money.I also have the issues of warranty,resale and feasibility of putting a new engine$ on a 20yr old boat.Any input will be much appreciated!

 

[micel]

Re: Go large or barely adequate for power

Still have not re powered yet,ant input? THANKS

 

[99yam40]

Re: Go large or barely adequate for power

What hp is the boat rated for?
If you do not put at least 75 % to 80 % of the rated hp on it I do not think you will be happy, but who knows what you will get out of it

 

[yamatech43]

Re: Go large or barely adequate for power

There's no easy answer here.....if I had to go thru a 4 mile no wake, I'd move....no kidding, that's stupid...try to find better place to launch? 90hp isn't
gonna make you happy at all with that boat...unless all you do is operate like a pontoon...since you can't go big enough due to weight restriction...by
the way, if you slow down to 800 rpm and still only get .5 mpg on two stroke there is something wrong...at 1200 that would be true, but not 750 or 800 on an 18' boat....sick motor to do that.

 

[user64]

Re: Go large or barely adequate for power

Yamatech making all VERY valid points, IMO.

 

[micel]

Re: Go large or barely adequate for power

robinso.michael764@gmail.com Still have not repowered my 18' cc kevlar hydra sports yet,a boating accident and lack of funds made sure of that.Everyones imput here helped me from making a expensive mistake repowering with the 90hp Suzuki.My boats max power rating is 150 which I believe is limited by the less than 20' loa limit than actual hp.Ive been hoping a manufacturer will make a (150+) 4-stroke at less than 440lbs,but no luck.The old 140 suzuki 4-stroke only weighs 420lbs but it has the torque of a 100hp 2-stroke if lucky.I definitely need the extra torque when I get caught out in gulf stream in summer and a storm pops up.For now Im going to keep my Suzuki dt200 until a manufacturer makes a torquey 440lb or less 4-stroke.I did change from a 14.75x20 prop to a 14x19 and found better cruising mpg.Thanks again for saving me with the 90 and if anybody has any other ideas they will be appreciated.

 

[99yam40]

Re: Go large or barely adequate for power

what was your WOT RPM with old prop and now with the new one?
Just wondering if it was and still may not be propped correctly

 

[MARV1]

Re: Go large or barely adequate for power

Get anF90 or F115, both very capable and reliable outboards...