Too Much Horsepower?

[Keith Knecht]

Hi Gang,

I am wondering what a concensus might be about repowering my 1986 250 Osprey with twin 200 Yammies.  I currently have twin 140 Johnsons and it's definitely underpowered when I get 4 people in the boat.  The boat has no Coast Guard tags to show the maxium hp but I know that it is only 300.  Don't know what effect that would have on getting insurance.  I would have to rebuild the transome anyway because it is currently 20" and the motors are 25".  I imagine it could be beefed up a little at the same time.  The weight of twin 150's and two hundeds on the Yammies are the same.  I don't want a bracket so leave that out of the equation.  I now know that the boat has twin 100 gallon tanks so fuel will only be a problem at the wallet.  What do you think?

Sharkark

[Finster]

I think you'd be fine with twin 200's boat wise, but insurance is another matter and I would have to guess no.
I can't believe a 25' boat is only rated for 300 hp. I have a 23 seacraft seavette thats rated for 500 hp, which I plan on putting twin '80 eara 200 merc's on. I am going with the '80 eara for the weight consideration, their only 350lbs. each compared to 475lbs.+- for hpdi's.
You may want to do your homework and make sure your boat can handle the weight of those motors. I would think your VRO's would come in at half that weight.

Good luck

[Keith Knecht]

Hi Finster,

Yea, don't know about the insurance thing but most agents probably wouldn't even ask. I think the weight of my 140's are 365 each and the yammies are 453 each, so I'd be adding about 200 pounds.  Pretty much like adding another person.

sharkark

[Finster]

Hi Keith,

Yeah the OS's are a bit lighter. Still 200 addional lbs on a transom is not the same as adding another person. I know when I put a 115 DF115 on my Aquasport 200 the additional weight was noticable. It pulled the stren down just low enough so the waterline catches the scuppers across the middle, giving you wet toes at times
As far as the insurance thing goes, they may not ask, but if something happens it could be an issue...

[Radioshop]

The insurance company is definately going to ask.  They want to know exactly what they're covering.  They'll ask for make, model and, year for hull, motor(s), trailer.  All of these things factor into what they're risking.  Now, the question is, once they have this data, do they know what to do with it?  

Also, what year are those 140's?  How worn out are they?  Also remember with that deep vee hull the more weight you add to it, the greater the displacement tendancies get.  If I was you, I'd look for the lightest 140's I could find (which incidentally is Tohatsu).  

If it wasn't for the reliability issues, I'd reccomend the 300 HPDI for this application, since you can max out your horsepower with one engine and, it only weights 543 pounds, versus 453 pounds for one OX66 two weigh 906 pounds.  That's a weight savings of 363 pounds, which equates to one beer swilling fishing buddy (and his stuff) or four 90 pound runway models.  By the way, more useless data, the F150 weighs 466 pounds and, the F115 weighs 402.  Yamaha doesn't spec out torque ratings, but four strokes are known for having better torque.  More torque is more better for boats.

[Anonymous]

Hey Radioshop,

Thanks for the ideas.  The 140's are 86's and they just don't do a great job of getting the boat up out of the water when you have more than two people on board.  Don't know if that's just not enough HP or they may be ragged out.  Haven't done a compression check.  Once the boat gets up on a plane they do just fine.  Have to run them at about 4000 rpm and then they sing.  It's a real pig with four people though.  That's why I was considering the 150's which are 6 cylinders - lots more torque.  Then I may have a shot at a great deal on a pair of two hundreds that weigh the same as the 150's.  My boat already sits pretty low at the stern but I figure I would move the scuppers up a little when I rebuild the transom.   Gotta have twins though.  I've come in from 20 miles out in the Gulf more than once on one motor.  Makes you a believer in twins.  Hey, I thought the 4- Strokes were heavier and had less low end torque than a two stroke.

sharkark

[Radioshop]

Keith, your engines are almost 20 years old.  Sounds to me like they've seen the prime of their lives.  I've been 20 miles out too, on a single.  Tred Barta, along with killing tunas with his bare hands, used to run a lot futher than that on singles too.  Heck, my neighbor with an Angler goes to Bimini relying on a 2 stroke Suzuki.  If I had Johnsons, I'd also want two.  Maybe a single with a 25 kicker? Yes four strokes are heavier, but I'm pretty sure they've got more torque.  At work we have two 28' Whitewaters one with twin 250 Optimaxes and, the other has twin 225 Hondas, they run about the same with one or, two MPH less top end from the Hondas.  The hole shot was a little sluggish on the Hondas until they got four bladed props.

[gofish]

I have twin 150hp, 1999 efi Mercury's on my 25 CCP and it runs almost 70 mph.  I would think a V-6 would do it for you. I would also look at your props, sounds like you might be running with a high pitched prop if it's not wanting to jump on plan. The only way to get the best performence out of any motor is with the correct prop matched with the boat. I would look at running a lower pitched prop for your hole shot. Somethimes when we want hole shot and speed on flats boats we run a small hubbed prop, not sure what that would do on larger boats.

[Keith Knecht]

Hey Gofish,

Thanks for the info.  I probably should try some other props as you suggested.  The props were on the boat when I bought it and the motors were obvious replacemnets.  The guy who had the boat didn't know much about it.  I've never oppened up the motors very much because of their age but they could be too small.

How low does your ccp sit in the water with the twin 150's? My 250 Osprey only has a 20" transom and the scuppers are right at or below the water line depending on how many people I have in the boat.  Sounds like that ccp flies.  I've heard that the ccp hull is the driest boat that Aquasport ever made.  I love the ospreys for fishing but they are definitely wet boats.  I was surprised to see that the ccps are actually a little lighter hull.  Thought they would be heavier with that highter cap.

Sharkark

[gofish]

The ccp also has some what a low transom and the outlet scuppers are always under water but the deck inlet for the scuppers still works great, not sure how the scuppers are in the Osprey. But I would think twin 200's would have little affect as fars depth, there should be more floatation in the Osprey (being there isn't that much foam in the CCP).
What is the top speed with the 140's, If your up around 50mph, then the 150's would be fine with the correct prop. Do you know what prop size you currently running.

[Anonymous]

Hey gofish,

Don't know what the top speed of the 140's is.  At 4000 RPM I'm running about 27-30 MPH.  I've never taken it up over 4500.  Worried about blowing those old engines.  I know that sometimes when I'm trying to get the boat up on plane I may overrev one of the engines and it hits 5-6 grand pretty quick so those props may be too small.

sharkark

[pedoyl]

I really have to see this 25' Aqua w/ twin 150's do 70 MPH!!!

[RickK]

I have a buddy that has a 25' family fisherman (I think) with twin 150 Mercs and he was clocked at 58.  I think he was pretty empty at the time.  It does move though.

[gofish]

Keith, the high rpm's when powering up could be incorrect or warn out props, there not hooking up basically.  I know the props I'm running are to high pitch props (why I have top end speed) and when the boat is loaded, it also takes more to getting going but still able to troll. But when you change motors you may want to try a few out to get it just right, also cupped props really work will, just keep them out of the sand.
I do know that Yamaha does (or did) research / testing with props to find the   correct props for motor and boats. When you pick the motors your getting I would contact the motor manufacture or a prop manufature like power tech props and sould get you in the ball park. Bad thing is, props the same size and pitch from different manufactures never perform the same.

[ddd222]

i just repowered and weight of the new motor was critical in my decision, and i went wth a leftover 250 hp yamaha model year 2002, over the 2004 hpdi, just because of the weight. The efi weighed 475lbs(don't quote me), and the hpdi was 560lbs or something like that, I remember it was almost a 90lb difference. From what the dealer told me the hpdi pump was responsible for most the weight. My best suggestion would be to find a dealer whose got a pair of c/r efi 150 hp pair, that can still be warrantied. After my recent problems, transom sitting low would scare me