john 90 v rude 115 ficht

[jnick]

I have recently switched from a barely broken in Johnson 90 2003 to a Evinrude 115 FICHT 2003 not yet broken in and am sort of shocked that they both push my aquasport 17.7 at 40mph and both running about 5500 rpm. I expected to see at least 5mph difference in the 115 even though not broken in. Does anyone have any useful comment on this.<br /><br />Thanks<br />Nick

 

[Dhadley]

Re: john 90 v rude 115 ficht

Welcome!!<br /><br />Thats not really suprising. Same bore, same stroke, same displacement, same gear ratio. Same prop? The Aquasport is a good boat but doesnt respond that much to small hp or torque increases. Even on a small pad bottom boat 5 mph is a lot.<br /> <br />Good luck!

 

[jnick]

Re: john 90 v rude 115 ficht

ok - well, I would think an 28% increase in HP would make a measureable difference

 

[Dhadley]

Re: john 90 v rude 115 ficht

A lot depends on the hull design. That boat is made to plane off quickly with a relatively small motor -- many folks put 70's on them. Ive got a 196 Aquasport and have had a 150 cf and a 200 cf on it and spun the same prop the same rpm. Guess what? Same speed. <br /><br />The injected motor will definately get better fuel economy. I think youll like it. Once it gets broke in play with the set up and see if we can get the rpm's up a bit with the same prop. You may gain a little speed there.<br /><br />Good luck!

 

[G DANE]

Re: john 90 v rude 115 ficht

I´d say too ( being no expert at all ) that 40 mph with a 17´with 115 hp is a bit lower that one should expect. Must be improveable somehow. What does your boat weigh with crew/gear/motor ?

 

[jnick]

Re: john 90 v rude 115 ficht

Thanks - I am looking for tweaking - once the motor gets past breakin i may play with the prop selection and make sure that the installer made the throttle linkage approriate for the changeup<br /><br />i will have to get back to you on the weight, etc you asked about.

 

[Dhadley]

Re: john 90 v rude 115 ficht

I would still opt for the set up tweaking before spending money on a prop(s).<br /><br />Good luck!

 

[jnick]

Re: john 90 v rude 115 ficht

I am not sure what set up alternatives you might be referring to since this is the first time I've been through this?<br /><br />The boat weighs:<br />dry 1740, gas 300 lbs, motor 369, crew/gear 300 = 2,800<br />other specs:<br /><br />dry boat L.O.A. 17'4" (5.28 m) <br />Beam 6'9" (2.06 m) <br />Fuel capacity (gas) 33 gal. (124.91 L) <br />Max power @ prop 120 hp (89.5 kw) <br />Transom height 20" (.51 m) <br />Deadrise 12° <br />Draft: engine up (approx.) 10" (.25 m) <br />Draft: engine down (approx.) 22" (.56 m)

 

[lschmidtka]

Re: john 90 v rude 115 ficht

Some Hulls are built with top speed concern. I believe you may have this problem. Grady White builds hulls to go a max of 50 mph by turning the stern of the hull at the transom downward which pushes the bow down the faster you go hence top speed predictions for the rated motor can be achieved. Hope this helps. You should notice a difference in time to plane though.

 

[G DANE]

Re: john 90 v rude 115 ficht

If you try JB's Speed formula you should have: "formula for predicting top speed if ideally propped and trimmed."<br /><br />Prop HP=A<br />Boat gross wght.=B<br />Bottom factor=C: 180 for V bottom, 200 for nearly flat, 225 for Flat.<br /><br />Take the square root of A/B and multiply by C.<br /><br />115/2800 = 0,04107 SQRt = 0,2027 * 180 = 36,5 !!!<br /><br />Your 40 is clouse at ( i edited posts, calculated wrong first time.

 

[Cricket Too]

Re: john 90 v rude 115 ficht

jnick.....I think 40 is a pretty good speed for your setup and weight. I have a 19.1 Mako with a 2000 Evinrude Ficht 150, and that Mako weighs alot more than that Aquasport and with the 150, a full tank of gas and two people I get about 50 or 51mph fully trimmed out. I do agree that you will be happier with the Ficht, I have never had a better, smoother running or quicker responding motor in my life, just break it in right and it will treat you good. Good Luck with it.

 

[jnick]

Re: john 90 v rude 115 ficht

thanks guys - I was really happy the first outing - its start, no oil fumes, smooth idle - etc. The transition from the 90 to the 115 with no speed change still freaks me but the engine does need to loosen up, burns double oil for a little longer, etc - so we shall see - not too concerned - if I wanted to burn speed then i should get a different kind of boat - but this one does it all for me - dive,fish,ski and holds its own on the Atlantic better then a similar sized speedy boat.