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  Merc 90 / Montauk Repower Update.

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Author Topic:   Merc 90 / Montauk Repower Update.
Landlocked posted 04-24-2002 02:35 PM ET (US)   Profile for Landlocked   Send Email to Landlocked  
I have about 6 hours on my new motor now and have a few observations to share.

Top speed with the family aboard ~(380lbs) is 40.5 mph (GPS)at 5250 RPM. I have noted a slight decrease in speed 2-3mph since adjusting the trim tab to counter the tendency to make sudden and unexpected 90 degree turns to the right. Boat no holds a straight course with no pressure on the wheel.

As I noted before - Mid-range is where the motor seems to really shine - tremendous accelleration between say 20 and 30 mph.

Only real negative so far is a tendancy to "list" hard to port while bringing up to plane. Once on plane, condition stabilizes with only a very slight list. Problem is not fuel tank related as the condition is present no matter with either tank full or with only the starboard tank full.

All in all I am very pleased. Motor is quiet, sips gas, and barely smokes. I'm considering going from a 21" pitch prob down to a 19" to get the extra 250 rpm out of it in the future but not too concerned.

Ll.

jimh posted 04-24-2002 06:14 PM ET (US)     Profile for jimh  Send Email to jimh     
Is this 90-HP Mercury a 2-stroke or 4-stroke?
David Ratusnik posted 04-24-2002 07:36 PM ET (US)     Profile for David Ratusnik  Send Email to David Ratusnik     
Landlocked- I take it you have tabs on the boat. I suspect you list hard to the port be/c the starboard tab has gone down further than the port tab. Give them " a thousand one, a thousand two" more to both get all the way depressed. May solve your problem coming up to plane. .03 David
David Ratusnik posted 04-24-2002 07:36 PM ET (US)     Profile for David Ratusnik  Send Email to David Ratusnik     
Landlocked- I take it you have tabs on the boat. I suspect you list hard to the port be/c the starboard tab has gone down further than the port tab. Give them " a thousand one, a thousand two" more to both get all the way depressed. May solve your problem coming up to plane. .03 David
kamml posted 04-24-2002 07:43 PM ET (US)     Profile for kamml  Send Email to kamml     
I agree that the mid-range acceleration of the Merc 90 is terrific. It feels sorta like an old Mustang 351 my wife and I had years ago (1970), we added traction bars to handle the torque,you know sorta trim tabs for cars. In those days top speed on the street wasn't possible running light to light. It was a gas. That Mustang could hang with a Boss 302 until about 70mph then the Boss would slowly walk away, its small block singing away all the while. Oops another life, I digress. I very seldom ever run at WOT, so mid-range is where I want my performance. There was a previous thread on Merc 90 performance improvement where with the right motor height and prop they said you could see 50 mph out of a Montauk. The thread provided specific prop suggestions and other cool tuning tips. It sounds like, given a full load, you have really good performance with the 21" as it is. Ken
David Ratusnik posted 04-24-2002 07:55 PM ET (US)     Profile for David Ratusnik  Send Email to David Ratusnik     
Landlocked- One other thought re 2-3 mph decrease in speed. Sounds like you may not have your tabs all the way up since you seem to be fighting a list to the right. Even with the tabs slightly depressed drag/resistance will be encountered with top speed impacted. Rec- Drop tabs all the way down at idle (go check), slam it to WOT, as you get on plane (or a little before) bring up tabs (all the way) and finally trim out motor just abit. Just a thought- maybe I'm all wet. Good luck David
Landlocked posted 04-24-2002 10:05 PM ET (US)     Profile for Landlocked  Send Email to Landlocked     
90 is a 2 stroke - sorry jim... I plan on running several extended tests at varying RPM's and posting the results when I get a full day out and some calm weather. Just put the boat on Kentucky Lake and so far its been too rough for any extended cruising everytime I've been out.

David, sorry about the confusion - don't have tabs on the boat - was referring to the trim tab on the motor itself. When I first got the motor with the tab in the neutral position - the boat pulled very hard to the right. Had to move the tab to the left about 45 dgrees to get equal stearing pressure at the helm.

I suspect the list is due to Prop torque.

Ken - a fair amount of my mis-spent youth was in the passenger seat of my friends Mach 1 mustang. 351 Cleveland, Holly double pumper. The feeling is indeed very much the same.
Only this time, I get to drive ;)

Still having a little trouble getting used to the motor being raised - feels a little on the verge of control at times.

Ll

David Ratusnik posted 04-24-2002 10:18 PM ET (US)     Profile for David Ratusnik  Send Email to David Ratusnik     
Landlocked- Just trying to help. I was all wet. Good luck. David
Landlocked posted 04-25-2002 09:47 AM ET (US)     Profile for Landlocked  Send Email to Landlocked     
I appreciate your input David. I've only used the boat mounted trim tabs one time on an old 33' monarch work boat. Got them out of sink and felt like I was about to turn the boat over on its top!

Ll.

kamml posted 04-27-2002 08:45 PM ET (US)     Profile for kamml  Send Email to kamml     
Landlocked
This is getting off the subject again, our Blue Mach had the full kit, spoiler, wing, slats, but a Windsor block, motor blew on the interstate in CT. I found a 351CJ and dropped it in. Unfortunately...I never finished the project, I sold it to buy a pastel blue BMW 2002. I sold a Triumph GT6 to buy the Montauk. I like cars, but those are other stories. I am glad you are enjoying your Merc as much as I am! Too bad Merc didn't build the Shogun for Ford rather than Yamaha. Ken
whalernut posted 04-28-2002 11:56 AM ET (US)     Profile for whalernut  Send Email to whalernut     
My cousin has a nice Blue Mach 1 with the 351 Cleveland, I like them, but a `Cuda will eat tham alive along with all stock mustangs. I especially like the `Cuda with the 426 Hemi. Jack.
Landlocked posted 04-28-2002 10:47 PM ET (US)     Profile for Landlocked  Send Email to Landlocked     
Ken - You sold a 'stang to get a BMW? Man, That's like trading a vett for a mini-van ha ha. Just kidding - At least your a whaler owner.


426 Hemi vs 351 - now that's like comparing apples to water-Mellons. My money would be on the Cuda as well. Mustangs and whalers have a lot in common in my book. There are better looking and faster things out there but they just don't have "it" whatever "it" is.

kamml posted 04-30-2002 07:39 PM ET (US)     Profile for kamml  Send Email to kamml     
In those days I had a company car and the wife needed reliable transportation. We had a Sportcraft 19.6 cuddy cabin with a 60 Evinrude that would pull 35mph and I thought that was fast on the water. Cost $1.00 a ft. for dry storage too. The Sportcraft had a pump out head, twin outriggers, 12gal tank, big cooler in the cabin, and seating for 4. It was a fun boat and great for fishing in Penn. where we lived a that the time. Today Sportcraft doesn't sell that boat, nor do I miss it. Yeah I agree Cuda Hemis ruled the street in those days. Ken
Landlocked posted 04-30-2002 08:55 PM ET (US)     Profile for Landlocked  Send Email to Landlocked     
We all make sacrifices.... Traded my Jeep for a Full size sport Utility when I became a dad. Something about mom's 360 degree experience one summer day on the interstate convinced her it wasn't a safe family car.

We have our memories though...

Ll.

COWBOY posted 05-01-2002 08:22 AM ET (US)     Profile for COWBOY  Send Email to COWBOY     
LANDLOCKED, THANKS FOR STEERING ME TO THIS SITE. SENT YOU PHOTOS OF MY MONTAUK "FLATS BOAT" WITH TECH INFO ON INSTALLATION OF NEW 90 MERCURY. DID YOU SWITCH TO 19" PROP? THAT'S WHAT I HAVE NOW.THIS LITTLE BOAT IS A WONDERFUL PLATFORM TO FLY FISH FROM HERE IN FLORIDA.THANKS AGAIN. JA
Landlocked posted 05-01-2002 10:27 AM ET (US)     Profile for Landlocked  Send Email to Landlocked     
Welcome aboard Cowboy!

Haven't switched to a 19 yet. My goal when I decided to repower was improved fuel economy and speed increase from my old 31/32mph to something around 40. I achieved both with my current set-up. When my little girl gets old enough to want to go skiing I'll probably have to switch. Right now I'm happy. Need a spare prop though so as funds materialize, may buy a cheap allumninum 19.

Ll.

tomol posted 05-02-2002 10:33 PM ET (US)     Profile for tomol  Send Email to tomol     
Landlocked,

I just changed props; jumped from a 19 (stainless) to a 21. I run a Yamaha and I don't know if it runs the same prop as Merc, but if it does, I'd gladly unload my old one on you cheap.

Contact me privately if your interested.

Nate Baker
nbaker@perfpress.com

Landlocked posted 05-03-2002 10:32 PM ET (US)     Profile for Landlocked  Send Email to Landlocked     
Anyone know if a yamaha prop will work with the merc?

Ll.

Clark Roberts posted 05-04-2002 12:05 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
The yamaha and merc prop shafts are splined the same (Yamaha uses some Merc lower units) and props will work on either. The Yam prop lacks the locking ring and usually requires a cotter key... I use Yam props on mercs and visa versa.... Clark.. SCN

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