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I have a 1983 Outrage 18 with twin 1983 2 stroke 70HP Mercury outboards. Time to repower and I am asking for comments by others who have installed twin 4 strokes on an Outrage 18.

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Sure you want twins? A single 150 will be cheaper to buy, more economical to run and maintain, significantly lighter, and much faster than a twin setup.

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I have a 1989 with a 115 etec and a 8 hp Tohatsu 2 stroke kicker. I love it. The kicker motor will troll well below 2 knots and can achieve 5 knots.

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Thanks for replies. I’ve run boats with singles, and this one with twins for 35 years. Will re-power with twins. Looking for experiance with 4 stroke twins. Thanks.

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You will want to play close attention to engine weights.

You have many good choices. It will really depend on price and service.

If you want to keep your binnacle and gauges consider the Yamaha F70 @ 253 lbs each.

Here is a chart showing the various weights of the models -

http://www.whalercentral.com/articles...ticle_id=5

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I will echo Phil's suggestion to take a close look at the Yamaha 70 for a twin set-up on the Outrage 18. The weight is very favorable on these engines for a twin application. The primary downside is that they are not available in counter rotation (to the best of my knowledge.)

Keep in mind, these Yamaha 70 engines have 4-cylinders but only 1.0L displacement.

I realize you want twins, but a single Merc 115 ProXS fourstroke with 25" CT gearcase will weigh about 370 lbs and offer 2.1L of displacement. These offer about 127 HP per CARB/EPA. Your cost savings would be around $7-8K, leavng a lot of money in your wallet. Or room in the budget and on the transom for a small kicker like Tom Blinstrub uses.

Definitely keep us posted on what you do. I can't be the only one who'd love to see photos and hear performance reports.

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Thank you Phil.

I used NADA Outboard web-site and also found the Yamaha F70 with best power to weight. The old 2 stroke Merc 70's weigh 190 each. Staying with 70's and switching to four strokes adds 126 lbs.

Also, the original 2 stroke engines were 15" shaft while the Yamaha F70's are 20". I don's see 15" option on any of Yamaha's specs.

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Thank you JRP.

I don't have counter rotation in current power set and have not experienced any side step at any speed. Dead rise is sufficient to provide straight tack with hands off wheel at all speeds.

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I forgot to mention testing the weight before buying. Calculate existing engine weight, subtract new weights from old. Get 5 gallon buckets of water (41.5 lbs each) and add the stern to see what static trim will be.

You may want to move batteries to console.

Here is a very apt quote from Finnegan (has twin Merc 90's on his Outrage 18, aka T/T Whale Lure.



Dave Buckalew (Buckda) repowered with twin 90 E-TECS, same weight of 75hp. The boat definately had a stern squat. He was happy.

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I am surprised to read that your original engines are 15" shaft length. I had thought twins should be 20" on the Outrage 18, with singles being 25". (I own a 19 Outrage II - - same hull as your Outrage 18 - - and run a single 150 with 25" shaft.)

I am pretty sure 20" shafts will work well for you.






I have seen a photo somewhere of Finnegan's Outrage 18 (with twins) rafted next to my boat (previous owner), taken from in front of the boats looking back at the bows. The bow of my boat was definitely noticeably lower than his.

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Not unless your original transom has been cut down 5 inches or you are mistaken.

Classic Outrage 18' uses a 20 inch long shaft for twin motors and 25 inch XLong shaft for single motors.
http://www.whalercentral.com/userphot...album_id=2

Any photos of your transom?

Here are some photos of my 1986 Outrage 18' with twin Evinrude 70hp motors with 20 inch shafts.
http://users.sisqtel.net/~jkriz/Outra...age86.html

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With twin 4-strokes on an Outrage 18, you really don't have much of a choice because of engine weight. I have twin 90HP Mercury 2-strokes on mine, at 305# each. It's a nice setup and the boat handles them well. But I would not go heavier. See website link.

Since you are already have Mercury, I would consider the Mercury 60 EFI 4-strokes which cost about 6K each. The Yamaha 70's would be OK also, since they have the identical (curious) displacement. But they are highly overpriced compared to the Mercs (price them if you don't believe me), and I can't believe that much more powerful to justify the cost.

The only options are the heavier 75 and 90 HP 2-stoke DFI's made by Evinrude and Tohatsu, in the wieght range of 330#. All of the other 75 and 90 HP 4-stokes are too much weight. however, performance with these engines will be far superior to the smaller 4-strokes.

The 18 Outrage has always used 20" twins. They should be mounted up one bolt hole, Counter rotation is not need, nor available. Side mount cylinder hydraulic steering highly recommended. See this rigging article for help:

(EDIT: please do not send our members to another boating or forum site to promote their site and wasting WhalerCentral resources.)

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It's interesting that Mercury even offers an optional Command Thrust (CT) gearcase on these 1.0L 60 HP engines. That effectively gives them the same gear ratio and displacement as the Yamaha 70. A pair of these with the CT gearcases might be just the thing for a twin 4-stroke repower on an Outrage 18. Definitely worth considering.

https://www.mercurymarine.com/en/us/e.../30-60-hp/

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A more apt comparison would be the Yamaha T60 - the F60 with the larger gear case. The F70 has the 4-valve powerhead to give it the extra 10 horses at speed. It's a peaky motor that likes to run at speed - don't think I would choose it for an 18, or if you do, prepare to spend some time finding just the right prop.

If you can reuse your Merc controls by staying with the brand, that would be a fairly significant savings. Otherwise, I'd be thinking eTec 75 or 90s - the low end torque would be a good match for the 18. Personally I'd put a single eTec 150HO on there and enjoy a lower price and much better performance, without alarming my insurance company, but we've already had that discussion.

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Converting twins to a single doesn't always save because you have boat transom and gelcoat work. Often the exterior transom needs to be re-gelcoated because of engine bracket damage and difficulty of matching old gelcoat color, to achieve like new condition before re-drilling for the single.

As it is, re-powering from 1983 Mercs is going to require mostly new rigging anyway. The original twin cable steering is now obsolete and has feedback, and should be replaced with side Mount hydraulic, with cylinder nicely installed BETWEEN the engines. A helm back mounting kit will be required also. The original 6 pin key switch ignition harnesses probably need current 8 pin replacements. The control will most likely need replacement, and I would then buy Sea Star XTREME cables which are ultra smooth working.

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The Suzuki DF140 is a great engine for your boat, a four stroke without the weight issues-I agree with the critics on it's HP rating being a bit over rated, but it is a wonderful motor in all other regards-

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I have a 1988 Outrage 18 with a 2016 Suzuki DF140 and 2007 DF6 kicker. For me, this is a perfect combo. About 470 lb. total on the transom, (dual batteries are in the console). With 2 people and a half tank of fuel, she will do 40-42 mph @ 6000 rpm with a Suzuki 14 x 20 ss prop. (engine is mounted 2 holes up). The kicker will get me back to port at about 5-6 mph.