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Old 20 January 2012, 15:03   #1
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Osprey Eagle - 90hp Optimax

Need to buy a new engine and thinking about a new Mariner 90 Optimax to replace my 1997 Yamaha Beto 130. Will the new engine give me the same performance seeing as the 130 was probably not putting out anything like a new 130 would be as it was 15 years old.
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Old 20 January 2012, 16:03   #2
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i very much doubt it, those old yams (V4 is assume?) were torque monsters.

i would think even though it was 15 years old it is probably healthy compression wise? if so there will be a notable difference in performance when you change.

you may be better looking for something around the 100-140hp mark to replace.

that said a 5.6m boat would run nicely on a 115 2 or 4 stroke depending on needs/budget etc.

cheers
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Old 20 January 2012, 17:49   #3
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Hi Shog,
If memory serves me the 90 Opti uses the same engine block as the 115 so is the same weight as the 115 (170kgs). So you get the same weight penalty with less horsepower.
A 90hp TLDI or ETEC is quite a bit lighter which would give you a wee bit more oomph.
For comparison my 115hp Tohatsu TLDI pushes my Ocean Pro 5.5m (3 onboard with dive gear) at 50mph. With 4 divers, 2 x 12 litre twinset, 4 x 12 litre singles, weight belts etc the top speed is down to about 33mph.

The 90 would be slower than your current engine but will burn alot less fuel and still give you a decent cruise speed (prop dependant).
Just don't let Loudy near it with his lump hammer.

Both Opti and TLDI are great engines (same technology), the only gripe I have with mine is to power the compressor etc you need a big battery. Mine won't fit in my console so is housed in a battery box at the stern.
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Old 21 January 2012, 04:10   #4
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Also been offered a very good deal on a Mariner 125 Optimax, just the 90 was so much cheaper
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Old 21 January 2012, 04:12   #5
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Quote:
Originally Posted by Shog69
Also been offered a very good deal on a Mariner 125 Optimax, just the 90 was so much cheaper
My old 130 would push the Osprey along at 40mph at WOT.
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Old 21 January 2012, 04:13   #6
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My old 130 would push the Osprey along at 40mph at WOT on flat seas
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Old 21 January 2012, 04:14   #7
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That was with just me and no dive gear
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Old 21 January 2012, 08:01   #8
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That seems a tad slow to me. Get a TLDI . I've had mine at 50mph (after tinkling with the power trim) on Loch Fyne heading back to Strachur after diving the Minards. That was 3 up with 2 twinsets and a dug . What pitch of prop are you using? What sort of revs show at WOT?

With regards to engine choice the following rules seem always to apply.

1. If you decide to go DI 2 stroke, you'll wish you went 4s.

2. If you decide 4s, you'll wish you went 2s DI.

3. If you buy 90hp, you'll moan about the poor performance and wish you'd gone for the 125hp.

4. If you go for the 125hp, you'll greet about the fuel consumption and wish you'd gone for the 90.

4. No matter what make you go for EVERY other brand would have been better/cheaper/more reliable.

You get the jist

There are a lot of mid 5m dive boats out there with 90hp engines. It's a good balance between power and economy. I went 115 because thats what was on the boat. It's nice to have a wee bit more oomph when the boat is a bit heavier. I reckon circa 100hp is ideal for a mid 5m boat.

Anyway you'll need to get at least a 115 to ensure I don't beat you over to Arran in the summer when we head out to dive the Tuscan.
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Old 22 January 2012, 14:09   #9
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Looks like the Mariner 125 Optimax is getting purchased now.
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Old 22 January 2012, 14:17   #10
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Quote:
Originally Posted by Mr Flibble View Post
If you decide to go DI 2 stroke, you'll wish you went 4s.
Hmmm not sure I would agree with that
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