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Author Topic:   Mercury 90-HP c.1979--Can it Troll?
Renrak posted 09-23-2003 02:40 AM ET (US)   Profile for Renrak   Send Email to Renrak  
My fishing buddy and I just bought a 1980 Montauk with a 1979-1/2 vintage (yeah, that's what it says) Merc 90. We're refurbishing the boat for fishing (primarily lake trolling), not a ski boat (which previous owners obviously were interested in).

We're complete novices with the Montauk/Merc 90. Haven't had the boat in the water yet, because we're trying to get the motor operable and safe and are working on the boat, but we have had substantial experience on water with a smaller trolling boat, rigged for fishing/trolling.

The foolish question: Has anyone had good experience trying to run the Merc 90 for trolling, or is this just something we need to give up on and buy a 6-8 hp kicker motor for trolling?

Alternatively, is there a good bow or stern mount electric trolling motor anybody can recommend for the Montauk? Pros, cons, foolishness?

If the Merc can be reasonably used for trolling, has anyone had good luck with a trolling plate for this motor? Any suggestions?

Not to make this too long. Hope for replies and suggestions from fishing folks on this rig for lake trolling (small lakes, California).

We want to go fishing! (But want to be prepared).

Thanks in advance for any replies and suggestions.


[Moved from another thread--jimh]

jimh posted 09-23-2003 07:08 AM ET (US)     Profile for jimh  Send Email to jimh     
Is a 1979 Mercury 90-HP a six cylinder "tower of power"?

Those were/are great engines. They're probably not the first choice for a trolling motor, but they are quite smooth running machines and should be able to run at idle without much problem. Heck, if one cylinder misses there are five others to take up the slack.

Perhaps you will need to choose a propeller pitch that gives you good a nice speed at idle.

Jarhead posted 09-23-2003 08:56 AM ET (US)     Profile for Jarhead  Send Email to Jarhead     
Give the 90 a try. If you have a problem with plugs fouling, not slow enough or rough iding you can always pick up a kicker. :)

My pesonal opinion is you'll be happier with a kicker.

My 2 cents...

Bigshot posted 09-23-2003 10:43 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
That engine uses surface gap plugs....not recommended for trolling.
brisboats posted 09-23-2003 03:19 PM ET (US)     Profile for brisboats  Send Email to brisboats     
Second the plugs and that engine is pre ADI ignition another strike against it for trolling. You can try it and maybe a sea anchor or (gasp) trolling plate would be a solution.


lhg posted 09-23-2003 03:58 PM ET (US)     Profile for lhg    
I Great Lakes salmon trolled a Nauset for several years with a 1973 Merc 150Hp in-line 6. No problems at all, as long as the engine is in good shape. If you're doing a lot of idling, run Mercury Quick Clean through the gas about every 4th tank, at higher RPM. This will keep it de-carboned. Those small bore 6's idle quite smoothly.
outragesteve posted 09-23-2003 06:27 PM ET (US)     Profile for outragesteve  Send Email to outragesteve     
I had a Montauk/115 Merc: It trolled great! I did have to change props, as the low speed to high speed carb transition is in the low 1100-1300 range: no big deal. As far as plugs, that Merc ignition is still one of the most reliable, and produces 40,000 volts. Keep the distibutor cap clean, and use only good oil: Merc's IMHO is the best. Watch the ratio, we all tend to richen up the mixtures on occasion. Surface gap plugs do not hinder low RPM spark delivery: On the contrary, OMC did have problems with their ignition systems having the ability to fire gapless plugs: Mercury has used these plugs throughout the model lines since the 70's! Good luck. BTW, each carb has an idle adjustment screw on the top front of the carb: A little patience will give you a super smooth idle control. (High speed is fixed)...
vince kelemen posted 09-23-2003 07:26 PM ET (US)     Profile for vince kelemen  Send Email to vince kelemen     
If I understood part of your question, you wanted to know if you can put a electric troling motor on the front of your boat. Yes you can, but like all whaler additions it takes a lot of thought. I put a Min Kota on my boat 4 years ago (900 hours of use) and it has operated flawless. To mount it, I used 4 special bolts. The process was easy, well as easy as drilling holes in my boat. The bolts I selected provide back plating by using a type of rubber washer. The idea is to drill a hole slightly larger then the bolt. Then a special rubber washer/nut fits tightly through the hole. When you turn the bolt it draws the rubber washer/nut upward and it smashes against the glass/wood and expands. I think I could only get 3 of the four in because of space, but they worked so well that I have never had to tighten them. I think I got the bolts at a place called Fastenal in Colorado Springs. In adition to the bolting process I had to put a 3/4 inch spacer where the top of the troling motor rests on the boat while traveling. You need this because the hull is not perfectly level. I used a trimmed peice of white cutting board and two screws. The end product looks and works great. I am not very mechanical so I apologize for the lack of technical definitions. I hope this is enough to get you started. It has greatly enhanced the usefulness of my boat.
whalernut posted 09-23-2003 07:32 PM ET (US)     Profile for whalernut  Send Email to whalernut     
I troll with my 1975 85h.p. Johnson on my Currituck, but it didn`t troll very well or for very long without stalling, until I tried a bunch of brands of plugs, and settled on Denso plugs, they seam to be much better for trolling than the other brands, that is in my engine, maybe yours will like something else better. Jack.
whaling away posted 09-23-2003 07:36 PM ET (US)     Profile for whaling away  Send Email to whaling away     
I have a '81 Montauk with Johnson 90 with 14 x 17 prop. Speed measured with GPS at idle is about 2 mph, way too fast for trout. It does not troll adequately for trout and idling for long periods is really tough on the big motor. I have experiment with a lower pitch prop and still trolls too fast. You can hang a 5-gallon bucket with a float and pull it along, but is is still too fast. I have a 46 lb. thrust MinnKota stearn mounted trolling motor that that on setting 2 or 3 trolls at the perfect speed (about .8 to 1.1 mph). This little trolling motor is great for getting into those tight little coves and sneaking up on the bass too. And I can get a couple of days of trolling all day long with a group 27 battery as long as I am not at WOT. I am considering getting a kicker for ocean outings and making sure I can get back to the dock. I have heard for the Montauk 3 1/2 to 5 hp is the perfect combo. Definitely get a 4-stroke kicker. It's great on fuel and can idle down much better. I would invest in a good electric trolling motor if you plan to fish the lakes. Good luck.
5 mi E of Milwaukee posted 09-26-2003 09:45 AM ET (US)     Profile for 5 mi E of Milwaukee  Send Email to 5 mi E of Milwaukee     
As with most fishing/boating questions, the answer is, “yes, no, maybe.”

I have a ’99 Montauk with a ’99 Mercury 90 hp classic (3 cyl, carb’d) and troll for Salmon on Lake Michigan with it happily.

To do this I change the prop down two inches in pitch from 19 to 17, and use Quick Clean religiously.

This works swell at the speeds you troll for Salmon and there’s enough oomph available to push into wind or climb up and down waves.

A 4 stroke kicker would be nice, put one in my boat and I won’t throw it overboard, but it ain’t in the budget anytime soon.

If, however, your idea of trolling is in more sheltered waters, or is in search of some species for which a slower trolling speed is indicated, then you’ll probably want a trolling motor. In that situation I believe I’d lean towards a bow mounted electric.


baybug posted 10-01-2003 01:46 PM ET (US)     Profile for baybug  Send Email to baybug     
I'm one of those Lake Erie walleye guys. If you're happy with the motor but can't slow it down enough try an Amish Buggy Bag off the front cleat. I can get down to .6 with my 90 Yamaha. This was a lot cheaper and simpler than a kicker.

I had an old 1976 V6 Merc no an Outrage that just hated to run at idle and had to go with a kicker.

skred posted 10-02-2003 10:57 AM ET (US)     Profile for skred  Send Email to skred     
Had a Merc-built 1991 Force 90 (no oil injection) on my Montauk, and trolled for 6 seasons. Just insured that I ran it up to WOT for a few minutes to clear any fouling which may have built up, and I used Merc fuel conditioner every 5th tank.... Never had a problem.
Also had a '85 Merc 4-cyl 50 with separate oil reservoir, and trolled with that for 4 seasons, same procedure - same lack of problems....
Renrak posted 10-07-2003 06:45 PM ET (US)     Profile for Renrak  Send Email to Renrak     
Just want to thank you all for your replies. Great info. Hope there are more coming! Good options and perspective!


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