Motor Upgrade?

[Bencarpenter112]

I currently have a osprey 200 1987 that is in the process of being rebuilt. Found a great deal on enough coosa for the floors and transom so I have some reduced weight there. Floors are raised three inches as well to get the scuppers above the waterline. I also refoamed the sides and removed about 250 lbs of weight foam. Reason Im posting here is because I have the mercury 115 carborated 2 stroke. I also have a tower and 35 gallon live well. Prior to the floor and transom change plus the wet floors my WOT was 31mph with 2 people and 20 gallons of fuel. Im wondering if the 115 is gonna be enough before mounting it or if im in need of a larger hp motor. Boat is used inshore primarily other than the runs to 7 and 12 miles out of egmont key florida. Could be propped wrong? not sure looking for advice

[Bencarpenter112]

Transom is also closed now  for reference.

[RickK]

I don't think that a 115 is enough power for a 200 Osprey.  Max HP is 185 for that model, so I would think a 150 is about right.
Are you putting a jack plate, swim platform or bracket to get the engine back a little so you can tilt it, since you've closed in the transom?

[mshugg]

As Rick said, the 115 is marginal for a 200 Osprey.  Most were rigged with a 150.

 Even so, 31 sounds slow even for a 115.  What RPM were you turning at max speed?  Max RPM for your motor is probably in the 5000-6000 range. Check to be sure   If you’re not somewhere in that range, you need a different prop.  For max economy, you probably want to cruise at 25 mph in the 3500-4000 RPM range. 

You’ll loose some weight with the coosa, but most builders add a bit more glass here and there.  So there may not be much weight difference between stock.

[Bencarpenter112]

Yes it will be getting a 12 or 14 inch set back plate from bobs. I was thinking 150 or 140 is appropriate. the 115 WOT is around 5200-5400 rpm. It is fitted with a tower as well. I thought it was a bit low also so I repropped from general propellers. Buddy of mine has a 135 opti with a four blade on the same boat and gets about 35 out of it but much better hole shot and he also has a large top. Seems 150 is the answer to get into the 40's which would only be done in emergency but I would like to take my cruising speed to about 28-30 instead of 22-25 depending on load.

[boatnamesue]

As mshugg mentioned, knowing if your engine is able to reach top of rpm range at WOT is more important than using top speed as a measure of engine performance.  And of course if the prop isn't dialed in this will skew performance.   

With that said, I believe top end of 31mph is pretty darn close to what I'd expect a 115hp to push your hull.  I'm using my 2 stroke 115hp on my 170 as the reference.  My rig is significantly lighter, dialed in prop, and I top out mid 40s.

If you can afford a bigger engine I'd definitely step up to minimum 150hp.  You'll be adding 100+ lbs but you'll rig overall will perform better.  Good luck.

[Dano]

I have an 04 Osprey 200 with a Yamaha F115 with a 3 blade 17p prop. I cruise at 30-31 @42-4400 rpms and top out at about 39 with a light load. The boat has a T-Top also.
Fully loaded with 3 guys, ice 1/2 tank fuel and forward bait well going I get the same cruise but top speed is down to about 35ish. Wish someone made a 150hp 4 stroke that only weighed 400lbs.

[mshugg]

The Mercury Four Stroke 150 is only 455 in 20” shaft.  Would be perfect for an Osprey 200.

[Dano]

Hard to find out the weight in a 25” model. I’ve heard good stuff about the new Merc.
Yamaha is in the 490 range for the 25”. I don’t want anymore weight back there than the 115...... just a little more power.

[wingtime]

Mercury 150 four cylinder  fourstroke is the way to go.  Blueagavehas one on his 19-6 with a full tower and bracket. Pushes it great. He runsaid all around Tampa Bay with it.

[mshugg]

Hard to find out the weight in a 25” model. I’ve heard good stuff about the new Merc.
Yamaha is in the 490 range for the 25”. I don’t want anymore weight back there than the 115...... just a little more power.

Weight on the 25” is 465.  It’s the lightest 150 available.

[Bencarpenter112]

150 seems to be the right answer here and it would seem the suzuki 175 would be overkill even though they do weigh the same. buddy of mine runs a 135 opti and he seems to do alright with it which pushes me north of the 140 as well. Thanks for all the opinions. My deck has been rised now 3 inches and the transom closed. Everything done in coosa and epoxy. still have to weigh her but hopefully a good bit lighter

[Aquasport17]

Well I just got this 170. Have an old boat with 85hp jonhson.  Have a guy that might want to trade old boat for susaski 115hp 2 stroke it might be short shaft. He checking that later.  Is the motor a good trade. Heard good and bad things about them. Plus not if short shaft will work with my hull ok.

[boatnamesue]

Is the motor a good trade. Heard good and bad things about them.

What you've heard is expected, really, because the answer to your question is completely subjective.  I don't expect too many objections from this statement, so here goes....maintanance, maintanance, maintanance.  That's the end all be all when considering a used motor, no matter the brand.  Personally I'm a yamaha guy, always been.  With that said, I'll take a meticulously maintained suki, rude, you name it, over a poorly maintained yamaha everyday.  Find a well maintained 2 stroke, continue to maintain it, and it will run like a beast till forever.