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Old 01 December 2011, 07:38   #1
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anyone running Ribcraft 585 with 90hp opti ?

Hi , just got a 1999 RC 585 and thinking about engine. I can get a decent 2007 90hp opti , does anyone have a similar setup. I know it's a heavy boat so is this enough?
boat is mainly for cruising and fishing , 4 adults on board and propped for decent cruising speed rather then fastest out of the hole. Is the 90hp enough and what sort of performance can i expect. will use the boat approx 200 hours a year so fuel is an issue thus the opti or 4 stroke ( little / no weight diff between em ).
Other option is to step up to 115 ( adding about 30kg depending on motor) so anyone with this setup also would be useful.
Any feedback greatly appreciated as ever.
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Old 01 December 2011, 08:13   #2
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I have a Mercury 115 4 Stroke on my 585, a little tail heavy, I reckon just over 36kn flat out and happy cruising at 30. Not really had enough use to properly judge fuel but seem pretty good so far.
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Old 01 December 2011, 08:21   #3
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My RC 5.85 is exactly the same vintage as yours . it has a Yammy F100 on the back . Our best speed is around 34 knots ( but we often run very heavy with fuel & additional tut and we have an antifouled hull ! ) . I reckon we average out at around 1 litre per nautical mile .
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Old 01 December 2011, 09:05   #4
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Yup we are running a 585 with a 90hp 2 stroke Mariner.

It gets 33-35knots on flat water 3 up no problems.

Video under way here; Ribcraft 585 with 90Hp Mariner Outboard on Vimeo

Chris
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Old 01 December 2011, 09:16   #5
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thanks gents , weight on the transom is a concern as where we fish there's a constant 2-3 ft swell and despite the size of the boat there is'nt that much freeboard. They do seem to sit well back in the water , are you using any ballast in the bow at all ?
30+ kts is plenty speed for me , is anyone specifically propping for cruising over get up and go ?
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Old 01 December 2011, 09:24   #6
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115 opti is the same block as the 90. Therefore same weight.

We had 90 opti on SR 5.4, that was ideal, but perhaps not so ideal on the heavier RC 585

IMHO 90 isn't quite enough, but it's horses for courses. 115 on RC 585 is perfect combo! That would be a lovely boat. But I agree, if you move up from a 1.5L block for more horses it will get v stern heavy.
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Old 01 December 2011, 09:29   #7
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IMHO 90 isn't quite enough, 115 on RC 585 is perfect combo! That would be a lovely boat.
I would agree. We are hoping to move up to a 150hp in the next year or so.

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Old 01 December 2011, 09:34   #8
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fair point , 115 ELPT 4 stroke is 181 kg vs 2 stroke opti 171 kg , so not much in it . Was hoping i'd be able to prop a 90 opti to cruise 25kts at 3/4 throttle and rely on the extra 2 stroke thrust to give it equal ish out of the hole.
Also , 2nd hand 115 opti's are like rocking horse poo
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Old 01 December 2011, 09:40   #9
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Bit like the 175 opti. That's the 2.5L v6 which is used for 135 and 150.

Didn't know ors was so rare until we got it.

Evidently 75-90 and 135-150 are just ecu changes, but to get to 115 or 175 on respective blocks there's a raft of manifolds injectors etc that also need changing, hence a large increase in retail price, leading to v few being sold. Most go for 90 or 150, as theyre the best value hp per . I've not seen another 175 yet. Though have seen a few 115s.
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Old 01 December 2011, 09:42   #10
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Quote:
Originally Posted by viking61 View Post
Hi , just got a 1999 RC 585 and thinking about engine. I can get a decent 2007 90hp opti , does anyone have a similar setup. I know it's a heavy boat so is this enough?
boat is mainly for cruising and fishing , 4 adults on board and propped for decent cruising speed rather then fastest out of the hole. Is the 90hp enough and what sort of performance can i expect. will use the boat approx 200 hours a year so fuel is an issue thus the opti or 4 stroke ( little / no weight diff between em ).
Other option is to step up to 115 ( adding about 30kg depending on motor) so anyone with this setup also would be useful.
Any feedback greatly appreciated as ever.
I had a 90 (4stroke) Merc on my '545' (Heavey lump) 31 knots WOT. Changed to 130 etec which was lighter! and got 46+ made it a diiferent anima! Used e-tec 150 would be blistereing! All depends on what you want.
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