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Old 08 April 2013, 04:53   #1
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Is this motor going to fit :)

Anyone here had an Osprey Eagle with a large motor?
Iíve currently got an old Mercury 135 plus a Yamaha 2.5hp all hanging off the back but would like to replace them both with a single more modern engine, Iíve got the offer of a 2003 Yamaha 250 2stroke with very little hrs, my logic is the Mercury will cruise at 35+mph and hit 47 flat out, with the 250 I was hoping it would allow me to cruise at 40+ with much less revs or strain on the motor, plus the top end would be much higher if needed J

My concern is will it fit and will the rib take it, Iím not sure of the dry weight of my Merc but I canít see it been much difference, and my second question is would a boat shop fit a oversize engine when the osprey states its max size is 120hp I think.
Thanks J
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Old 08 April 2013, 05:10   #2
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Quote:
Originally Posted by Crezzlin View Post
Anyone here had an Osprey Eagle with a large motor?
I’ve currently got an old Mercury 135 plus a Yamaha 2.5hp all hanging off the back but would like to replace them both with a single more modern engine, I’ve got the offer of a 2003 Yamaha 250 2stroke with very little hrs, my logic is the Mercury will cruise at 35+mph and hit 47 flat out, with the 250 I was hoping it would allow me to cruise at 40+ with much less revs or strain on the motor, plus the top end would be much higher if needed J

My concern is will it fit and will the rib take it, I’m not sure of the dry weight of my Merc but I can’t see it been much difference, and my second question is would a boat shop fit a oversize engine when the osprey states its max size is 120hp I think.
Thanks J
Way to big will chine walk like a bitch, been on one with 150 merc was horrible above 40 knots
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Old 08 April 2013, 05:18   #3
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This is a multi part answer:

1) Will your insurance want to play? Only a call to them & an answer (in writing) wil lanswer that.

2) You are proposing to nearly double the boat's rated HP. Most transoms will be build with a bit of safey margian in their construction, but you will be bl**dy lucky if it survives double, regardless of the make of boat..... And then there's the deadweight of the engine. A 250Hp is going to clock in significantly heavier than a Low 100s machine, regardless how many strokes. Generally the "one lump fits all HPs" normally only kicks in above about 180-ish HP. Plenty of 130s share with as low as 90 - There are lots of old brochures here - go look at the data.

Boatinfo - The library, containing manuals, brochures and other technical documents from the last hundred years!


You are also talking about removing the aux. Have a search - there are plenty of discussions around main reliability / Seastart etc etc, but at a basic level you are still replacing the Merc (presumably a known reliable runner?) with an as yet unproven 10YO engine...... Also depending o nthe afge of the merc, if you got a Clamshell they are ridiculously light when compared to other engines of the same vintage. (My 60 is only 15Kg heavier than the 25HP that was on my SR4...


I guess if speed is your ultimate goal and you don't mind a massive rebuild of your transom and some potentially atrocious handling / chine walking etc there's nothing to stop you. I'm sure the racing bods wil lbe along soon to tel lyou the best way to go if you decide to go.
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Old 08 April 2013, 05:22   #4
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My first thought is that this is a very good troll attempt.

I really hope it is.
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Old 08 April 2013, 05:55   #5
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My first thought is that this is a very good troll attempt.

I really hope it is.
It was worth asking wasnt it..

The Merc i have is a 87 model, itís been ok for the last year, ive only replaced the plugs and filters.. It can be a pain to start once hot but when she goes its no problem, as much as i love the Merc i would like to cross over to Scotland and Ireland at weekends when the weather is good.

I didnít think the motor weight would be much of a difference but i will take your words for it, my mate has an Osprey sparrow hawk, we just put a Merc 150 on and its now pulling away from me, i understand i canít have the best of both worlds for the money but the 250 was at a good price, looks like i will need to cross the pond and find something around the same size as now.
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Old 08 April 2013, 06:05   #6
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Notwithstanding the weight issue & assuming the new engine has a rev limiter, you "could" prop it to limit its max speed to to mid 40s. I'm thinking a 17 or 19" 4 blade prop. This would limit your top end but give you "interesting"
Holeshot. Or you could be sensible.
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Old 09 April 2013, 11:52   #7
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It was worth asking wasnt it..

i would like to cross over to Scotland and Ireland at weekends when the weather is good
Don't ditch the Aux! ....or go twins!


In all seriousness, if your mate going a bit faster is your only issue, move some weight around the boat & play with the engine trim - plenty of posts out here about how to optimise that.

Does it stay afloat? - time to clean / antifoul?

etc etc.

Or go when the weather is a bit sh!ttier - then the lumpy water will slow him down to match you!
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Old 09 April 2013, 19:30   #8
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Don't ditch the Aux! ....or go twins!
not sure a 2.5HP on a boat that size is going to be much serious help though...



...especially if the transom has fallen off!
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Old 10 April 2013, 00:38   #9
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"I’ve currently got an old Mercury 135 plus a Yamaha 2.5hp all hanging off the back but would like to replace them both with a single more modern engine, I’ve got the offer of a 2003 Yamaha 250 2stroke..."

You can't be serious? On second thought, I wouldn't mind seeing that for the entertainment value.
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Old 10 April 2013, 01:22   #10
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My concern is will it fit and will the rib take it, Iím not sure of the dry weight of my Merc but I canít see it been much difference, and my second question is would a boat shop fit a oversize engine when the osprey states its max size is 120hp I think.

Your Mercury 135 engine weight is 172 kg
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