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Author Topic:   Top speed/ overall performance
Aldog posted 06-24-2003 05:56 AM ET (US)   Profile for Aldog   Send Email to Aldog  
I have a 98 Montauk with a 98 mercury 2 stroke (new to me) It has a 4 blade stainless prop, Mercury Trophy, a long set of numbers engraved ending in 21P. I assume this to read 21 pitch. This is my first Montauk and am not sure what to expect, it has good holeshot but only runs 38-39 mph (gps) WOT. IT revs just over 5,100. Am I getting what I should expect?

38 is fast enough, and the fuel consumption seems to be VERY reasonable I do want to get optimum performance, however.

I have on order a hydro fin, the one with the trolling plate built in, from Cabela's, I needed the trolling plate for our mountain lakes sub 2 mph trolling. After reading the positive on fins from this site decided to pay the extra few bucks and get the plate with the fin built in, we'll see what it does for my overall performance. The purchase is for the slower trolling speeds, if the fin helps the performance that will be bonus.

I love this boat!.

Again my questions are;
1)What should I expect in top end from this boat/ motor?
2)does this seem to be the right prop?
3)If its underperforming what are the suggestions?

All input is appreciated.

newt posted 06-24-2003 06:58 AM ET (US)     Profile for newt  Send Email to newt     
What horse power is the engine?
Aldog posted 06-24-2003 07:48 AM ET (US)     Profile for Aldog  Send Email to Aldog     
Duh. 90 hp


I have lots of questions and thoughts at 5 a.m., just not very smart. I actually proofread to be sure I had everything covered :o)

Bigshot posted 06-24-2003 10:15 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Drop down to a 19P 4 blade or a 20-21 3 blade and you should see low 40's. Your revs are a tad low. What is redline on the 90...5500?
raygun posted 06-24-2003 10:19 AM ET (US)     Profile for raygun  Send Email to raygun     
The next question you'll be asked is what hole is the motor mounted on? Is it all the way down on the transom?
Aldog posted 06-24-2003 10:54 AM ET (US)     Profile for Aldog  Send Email to Aldog     
Its mounted in the very top holes (as low as it will go) The manual says WOT range from 5000 to 5500 rpm's.
newt posted 06-24-2003 11:10 AM ET (US)     Profile for newt  Send Email to newt     
If the '98 is similar to the '03, then redline is 5500. On my '84 Montauk, I am running a Mercury 21 pitch aluminum prop at 42 mph. My engine is mounted 1 hole too low (soon to be changed), and I think my tack is off (with the engine off, it reads 800 rpm - not sure if it is correct when rev'd up). So, top speed may be even faster than 42 mph.

Oh, 90 hp 2-stroke Mercury.

Sal DiMercurio posted 06-24-2003 11:23 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Bigshot & Raygun nailed it, drop down in pitch & raise the engine 2 more holes & i'd say very close to 45 mph.
lhg posted 06-24-2003 12:11 PM ET (US)     Profile for lhg    
The Mercury 4 bladed Trophy prop is an ultra-high performance prop, with little steering feed-back, tremendous holding power, hole shot and top speed. It gives total lift to the hull also, which you can see in these bass boats running on a pad, skimming over the water. It is predominantly for the flats and bass boats, and with hydraulic jack plates. Because of it's extreme high rake, it takes a lot of torque to turn it, usually a V-6, and it takes a huge bite on the water and needs to be run elevated 2" - 3", higher than then the same pitch Laser II for instance. It is not the right prop at all for a Montauk unless you are set up like above. Running it fully submerged kills it's properties and effectively adds about 3" or 4" of pitch, so you are really running a 24" or 25" pitch prop. The fact that the engine can turn that prop up to 5100 fully submerged means that if you switch to a 3 bladed Laser II or Stiletto/Rapture (approximate copies of the Laser II), you would need a 22" pitch in the 3rd mounting holes according to Mercury's prop charts. This prop would perform similar to a 23" Stiletto, if you are interested in that brand.

How do I know all this? I purchased a set of these Trophys, 24" pitch, for my 18 Outrage with twin 115's. The engines, which easily turn a 23" 3-bladed aluminum up to 5800, could only turn these things up to 4500rpm! To get the RPM up, I had to lift the transom plates up 3", and the engine were clearly taking in air on a twin installation. Way too much bite for even my relatively high powered rig. So I sold them for $275 each, having paid $400 each. Lesson learned the hard way.

If you want to keep the Trophy, the engine should at least go into the middle holes, or maybe even the 4th set of holes. But not sure this is appropriate for a Montauk, definitely not for one with bottom paint. If you go into the 4th set of holes, keep an eye on engine cooling, but the thing will run like a scalded dog on calm water. Not recommended for Offshore use.

Don't even think about putting about a hydro-fin on a boat with a Trophy prop. Montauks plane off easily and they are not needed, only a drag on acceleration. With an elevated engine, it will not be in the water on plane anyway (which is good).

There is a big market for used Mercury Trophy props, so it should be easy to sell if you can't make it perform for your needs. Even though it is a 4 1/4" gearcase prop, they are run on the 4-3/4" V-6's with exhaust gas blow-by. On a Merc V-6 150 or 200, the 21" small hub Trophy is a 60 mph prop at least. I would install a 22" Laser II and you'll have a nice setup.

Sal DiMercurio posted 06-25-2003 01:05 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Ihg, excellent post.
Aldog posted 06-26-2003 06:22 AM ET (US)     Profile for Aldog  Send Email to Aldog     
Thanks guys for the input.

I will now ask, when buying and selling props.. is online the way to go? I am 2 hours from a quality prop shop.

If I take the advice of IHG (and it would be hard not to) I get a Laser II 22, do I need to move into a different set of holes? OR maybe just change props and then evaluate I guess would be best.

The hydro fin raises another set of questions. I have never used one, but I need the trolling plate for slower trolling or a kicker motor... the plate is just a better arrangement for me right now (the wife might blow a gasket if I spent another chunk on a small outboard). I have used one sucessfully on my previous 120hp. I am now second guessing the purchase of the plate with the fin combo.

Sounds like I need to get my prop situation sorted out and then make a trolling plate decision fin or no fin.

Thanks again guys.

Landlocked posted 06-26-2003 10:02 AM ET (US)     Profile for Landlocked  Send Email to Landlocked     
My montauk is powered with a 2002 Merc 90 2stroke with a 21pitch black max 3 blade aluminum. I get 42.5 gps at 5250rpm WOT. Motor is mounted 1-hole up so that the cavitation plate is exactly 1.5 inches above the bottom of the keel. With this set up my boat can get a little squirrelly at times when trimmed all the way out - I would hesitate raising it more. Others don't seem to have this problem.

I'd start with the 1.5" up and see how you like it before going more.


BQUICK posted 06-26-2003 11:46 AM ET (US)     Profile for BQUICK  Send Email to BQUICK     
Hey Aldog......I have a brand new in the box 22 in Laser II for sale. Cost close to $500, you can have it for $275.
I needed a 24 (16 ft AllisonCraft)


lhg posted 06-26-2003 03:12 PM ET (US)     Profile for lhg    
Now I'm a little confused, based on Landlocked's information. In his case, a 20" Laser II would be called for, but speed would increase due to the prop's bow lift.

With Montauks, there can evidently be quite a variation in performance depending on bottom paint, engine height, loading in boat, etc.

Assuming Bruce's prop is one of the newer designs, with interchangeable hub and vent system, it's a great deal. Two years ago, I paid $365 for mine, after considerable shopping around. Prices have gone up since then.

If it helps, Mercury's prop charts on the 90 show the

Total Load 1100-1900lb - 22" pitch - 44-48 speed range
Total Load 1400-2300lb - 20" pitch - 40-44 speed range

So a lighty loaded Montauk could handle the 22, a heavier one the 20. For the 22" I would recommend the 3rd set of engine mounting holes, unless ventilation occurs. Prop pitch is always somewhat of a guessing game!

Aldog posted 06-27-2003 07:14 AM ET (US)     Profile for Aldog  Send Email to Aldog     
Going to use the boat again this weekend and formulate my next move based on this new wealth of information and ideas.

I'll update.

Landlocked posted 06-27-2003 09:46 AM ET (US)     Profile for Landlocked  Send Email to Landlocked     
The following is an email from Chuck Bennett that I recieved in response to a request for information on prop selection I made when re-powering. Hope this helps to muddle the situation more...


From: []
Sent: Wednesday, February 27, 2002 7:56 AM
To: Chris Catron
Subject: Re: Montauk Repower

The Mercury 90 two stroke is the standard engine that the factory installs on the Montauk. Whaler installs this engine with one empty bolt hole showing at the top and uses a 12 3/4 X 21 Pitch Black Max as a good all around prop. Estimated top speed (depending on conditions) should be about 42 mph.

Aldog posted 07-20-2003 08:11 PM ET (US)     Profile for Aldog  Send Email to Aldog     
I hope you guys will read through this again and make sugestions with my new information.

My 4 Blade Trophy 21 gives me a great hole shot, however, my 90hp 2 stroke is only turning 4700-4900 RPM WOT trimmed out completely. My original 5100 post was not accurate, I have boated every day for the last week and know much better now what she's doing.

Should I try the laser II 3 blade 21 or start 20 or even 19?

The boat is very responsive and jumps up on plane but lacks top end for sure.

Bigshot posted 07-21-2003 10:20 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Jack it 2 inches hoher and try again....we'll go from there.

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