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Author Topic:   90 hp Merc on '82 18 Outrage?
bkovak posted 08-28-2003 06:32 PM ET (US)   Profile for bkovak   Send Email to bkovak  
Does anyone have any experience with repowering a classic '82 18' Outrage with a smaller motor? I have a new 2001 90 hp Merc and was considering putting it on an 18 Outrage that I believe weighs around 1250 lbs. The motor pushes a 17 Montauk (1000 lbs) about 45 mph. What can I expect it to do on the Outrage (35?). Thanks, Brian
bkovak posted 08-28-2003 08:38 PM ET (US)     Profile for bkovak  Send Email to bkovak     
The boat will mainly be used for bay and lake fishing. I think the minimum hp rating is 75. Will the 90 be too underpowered for 2-3 people and gear? If so, what is the least HP I should consider, 120? I see quite a few with 125 - 150. Thanks, Brian
Peter posted 08-28-2003 08:45 PM ET (US)     Profile for Peter  Send Email to Peter     
Theoretically it should achieve about 35 mph with a full tank and two people. Although the Whaler literature suggests that it will plane with that little horsepower, from a practical perspective that really isn't enough motor for the 18 Outrage. It is just 60 percent of the rated maximum whereas on the Montauk it is 90 percent. You really have no working headroom with a 90. Load it up with 4 people and a full tank of fuel and you might not get up on a plane.

You will be working the 90 pretty hard just to cruise at 25 to 28 mph. For comparison purposes, I used to have a Johnson 150 on an 18 Outrage and rarely did I have to run it above 3000 rpm to go 28 mph. To go that fast, I estimate that a 90 will be running at 4000 rpm assuming it can turn a 17 inch propeller. I'm not sure about Mercury 3 or 4 cylinder engines but I know from experience with both Yamaha and OMC V6s that once you get over 4000 rpm they start to consume a lot of oil. Also, the efficient zone for these engines is usually between 3500 and 4000 rpm. If the Mercury 90 follows this trend, you could find yourself frequently running it outside of the efficient zone.

In my opinion, you are better off selling or trading the 90 in for something bigger, preferably not less than a 135hp V6.

Jimm posted 08-28-2003 11:20 PM ET (US)     Profile for Jimm    
My Montauk 170 has a 2 stroke 90 HP Merc. The boat weighs 1400 lbs. At 3000 RPM I'm doing 24 mph with two adults and 24 gallons of gas.
bkovak posted 08-29-2003 08:00 AM ET (US)     Profile for bkovak  Send Email to bkovak     
Thanks for the info. I thought it would be on the low end for performance, just wanted to hear some other opinions. It currently has an '85 150 on it. I guess I could just run that until it goes and then repower with something similar. Just hate to sell that new 90 merc. It only has 25 hrs on it and warranty thru 2005! Brian
Peter posted 08-29-2003 10:36 AM ET (US)     Profile for Peter  Send Email to Peter     
The classic 18 Outrage with a deep vee hull is a different animal than the 170 Montauk and therefore requires more power to peform satisfactorily than the 170 Montauk.
Bigshot posted 08-29-2003 10:52 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
18 is not really a deep v. I have been on an 18 with a 115 and she did about 40. I think a modern 90 might be Ok if you don't expect much. If people are happy with 50's on Montauks, I think a 90 on a 300lb heavier boat will do fine.
Peter posted 08-29-2003 12:32 PM ET (US)     Profile for Peter  Send Email to Peter     
BS, whether or not you call it a deep vee, the hull shape is clearly different than the Montauk. The Outrage requires more power relative to a classic or modern Montauk due to its vee hull shape. While a 50% of maximum rating might be OK on a Montauk due to its flatter hull shape, 60% of maximum on an Outrage is going to be mediocre at best.

Tom2697 posted 08-29-2003 01:00 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
My brother runs a 90 hp on his '94 17 Outrage. I don't know about the weight difference but his boat performs excellent! He is on plane almost immediately and runs in the low-to-mid 40's. I would guess that on an 18', mid 30's is possible. I have 140 horses on my 18' and I rarely ever use full throttle. As long as you don't plan to waterski behind it, you should be fine...

I would suggest a hydro-foil though.

goodad posted 08-29-2003 02:57 PM ET (US)     Profile for goodad  Send Email to goodad     
Brian..I'm sure not an authority because I post more questions than answers but..I have an older 86 18' Rage powered with an older 86 90hp Evin..When it's running right, it is now, WOT it gets 34 @ 5300.. ( 3 people and gear)I don't need that speed all the time, but it's there and its all I need..The 90 is at the low end, but it's bought and paid for and I'm not in a race..I just cruise and smile..For what it's worth, Bill.
bkovak posted 08-29-2003 06:33 PM ET (US)     Profile for bkovak  Send Email to bkovak     
Well, that really muddies things up...Maybe I should try hanging the 90 merc on her and see how she goes. A few of you (Nick,Tom and Bill) seem to think she might run OK. Kinda my gut reaction initially after running a montauk so fast with the 90. Since the weight difference is only 300 lbs. it might be worth a try and see what happens. I'll be picking her up this weekend. I'll probably take her out for a spin with the old 150 first before finally deciding. Hey Nick, if you're up in Barnegat Bay, NJ next weekend and want to take a ride, let me know! Thanks, Brian
Peter posted 08-29-2003 08:09 PM ET (US)     Profile for Peter  Send Email to Peter     
Let me help clear some of the mud. As a prior long term 18 Outrage owner with well more than 750 hours behind the helm, my advice is that if the 150 is running ok, keep it on there and run it until it stops running -- which may be never (it might corrode apart before it wears out)! Once you run the 18 Outrage with a good 150, however, you WILL be disappointed with the 90 so if you don't want to know the difference, put the 90 on before you run it with the 150. The difference between the two boats isn't just the 300 lb weight difference. Adding 300lbs to a Montauk hull doesn't get you to the ride of an 18 Outrage.

Based on goodad's data, I estimate that his 90 is turning nearly 4000 rpm just to cruise 25 - 26 mph (a comfortable cruising speed for the 18 Outrage). If that estimation is correct, at 4000 rpm the 90 is at the threshold of breathing hard just to maintain a comfortable cruising speed. Based on that estimation, 3500 rpm will push the 18 Outrage only to 22 mph and his Outrage will not get on plane until he is pushing the engine close to 2200 rpm or so, maybe even higher than that.

As Hooter said in another thread, why would you want to power a Corvette with a Beetle engine which is what you would be doing? The only thing worse than an underpowered car is an underpowered boat. If I were you, I'd be hunting for a new or lightly used two stroke carburated 150 (Johnson, Mercury or Yamaha) before they stop making them, which could be any year now. Trade or sell the 90 while it still has the warranty backing it and put its value toward a new or newer 150 (or 135) if your having doubts about the reliability of the 150 that's on there now.

acseatsri posted 08-29-2003 08:27 PM ET (US)     Profile for acseatsri  Send Email to acseatsri     
It all depends what he's gonna be doing with the boat. If in somewhat choppy water, I cruise at 14-16 knots with a stingray fin, rarely more than 25 knots. I boat mainly on LI and Block Island Sound- you don't get many days where you can run 25 knots, never mind 30+. I have 150 HP on mine and usually turn 2600 RPM at around 16 knots. If I were to repower, I'd definitely opt for 115-140 hp 4-stroke, weight being the primary consideration. I think that would be a sweet little ride with the 90 on it as long as you're not a speed demon and like slower but reasonable cruising. It won't be a speed demon out of the hole or a raceboat, but it would be quite an economical package, especially if the 90 is paid for. If the present 150 is a crossflow block, it's definitely a gas hog.
whalersman posted 08-29-2003 08:35 PM ET (US)     Profile for whalersman  Send Email to whalersman     

I tend to agree with Peter.... I really like my 1985 Evinrude 150hp on my Outrage 18. I have contemplated the idea of replacing it with a 4 cylinder 115hp some day but am concerned about the top end speed.. Not that I am a speed freak, but when I need or want the extra power, it is nice to have it there...

I also own a 1978 Montauk with a 1985 Evinrude 70hp and am satisfied with the speed but a 90hp would be better top end..

I have been on several other whalers with 115hp on them like the 1996 to 1999 Outrage 17 and they have performed well... Even my own 1997 Outrage 17 with a Mercury 115hp, yet these boats are rated also for a 150hp...

The other day a friend of mine who owns a 1996 Outrage 17 with a 115hp Johnson Oceanrunner came on board with me on my Outrage 18.. We were cruising along at about 3500 RPM and about 33 to 35 MPH and I warned him that I was going to hit the throtlle.......... This was a good thing, as when I hit the throttle, both of us would have gone over the back end if we weren't hanging on.... The 150hp on an Outrage 18 is awesome...... I admit, most times you cannot run WOT, but when the water is smooth and you want to rip up some water, the 150hp has it....

On the down side, I would sometimes much rather have a 4 cylinder 115hp for the fuel economy but there is a trade off for top end power... We all have to make that final decision on what we want from our boats and motors... Water skiiing? Hole shots? Top end? Fuel economy and so forth.....


bkovak posted 08-29-2003 09:55 PM ET (US)     Profile for bkovak  Send Email to bkovak     
Thanks again for the great comments and experience with your whalers. Peter, Joe and Acseatsri all make good points. I think I'll put the 18 Outrage in the water and try her out first with the old merc 150 before deciding which way to go. Since my new Merc 90 is already paid for, I can just hang on to it for a bit before deciding or, maybe even hang it on another classic whaler...Thanks, Brian
Lou posted 08-29-2003 10:50 PM ET (US)     Profile for Lou  Send Email to Lou     
You'll be unhappy w/ the 90 on the 18 Outrage.


Tom2697 posted 09-01-2003 09:40 AM ET (US)     Profile for Tom2697  Send Email to Tom2697     
Brian, I've stated that I believe the boat will run fine for cruising. It will not work too well for long off-shore trips or waterskiing. Think about how you will use the boat and base your decision on that. While it is fun to go 45+, I am reminded of what my friend once told me: "All boats go the same speed once the leave the inlet." I rarely go more than 20 knots when running offshore.

I don't know your mechanical ability, but I would recommend hanging the 90 on the back and see how it goes. If it doesn't work to your liking, sell the 150 while it still has some life left, and hence some value. Sell the 90 while you can still get top dollar for it. Buy a newer motor. You don't need 150 hp for that boat move well.

padrefigure posted 09-03-2003 09:38 AM ET (US)     Profile for padrefigure  Send Email to padrefigure     
Why not find a twin for the 90 that you already own? Then you would have the advantage of the new power (squared) and the security of twins that the Outrage 18 was designed for.
hauptjm posted 09-03-2003 12:13 PM ET (US)     Profile for hauptjm    
Now you're talking! Twin 90's on a Classic 18 Outrage is my secret obsession.
Tom2697 posted 09-03-2003 12:35 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
Doesn't one of the members already have this setup? Twin 90's...
tbyrne posted 09-03-2003 01:11 PM ET (US)     Profile for tbyrne    
I believe "lhg" has that set-up. Try doing a search or two.

I don't believe 90 hp would be adequate. I owned an '82 Outrage 18 with a 150 (on LI Sound) and couldn't imagine how it would have performed with only 90 hp. I know my 18 was billed as weighing 1250 lbs, but I always felt it was much heavier. When I scraped the keel one year, I found out why - gallons of water in the hull/foam!

bkovak posted 09-03-2003 02:56 PM ET (US)     Profile for bkovak  Send Email to bkovak     
Outrage Update: Just got the 18 Outrage this past weekend and it looks good. Started on some restoration work. The 150 Merc will be staying on the back for a while. For some strange reason, it never ocurred to me to check the transom size of the Outrage - it's 25". My new 90 Merc is for a 20" transom! That answers that question. So, I will have to take good care of the 150 for a while longer. As far as the twin 90 issue, I had twin Johnson 90's on a '75 21' Classic Outrage. It ran like hell! I tried running it once with just one motor and was going around 30 mph. With both running WOT I was hitting 55. It would be the ultimate setup for the 18 Outrage...if you owned a gas station. Brian

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