MONTAUK: 100-HP Mariner: 15-, 16- 17-inch Pitch Propellers

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Author Topic:   MONTAUK: 100-HP Mariner: 15-, 16- 17-inch Pitch Propellers

nanzpac posted 09-28-2006 06:11 PM ET (US)
Hello. I have a 1980 Montauk with a 1991 Mariner 100hp. I have 3 Merc 3 blade props for it. They are 15, 16 and a 17 pitch. I want the highest top speed out of the boat. Does anyone know which prop would be the best.
Thank you.
brisboats posted 09-28-2006 07:32 PM ET (US)
Takes less than a minute to switch them why not try each one and see. Generally if your motor can spin it the greater the pitch the faster the boat will go at it's top end.
Brian
nanzpac posted 09-28-2006 07:55 PM ET (US)
Thats what I will do. I have a 15 on there right now and floored with me alone the boat hits almost 6300 RPM's and the motor manual calls for 5700. The boat is crazy fast out of the hole, but I'm afraid to even see what the top speed is becasue of the high RPM's. I'll probably go up to the 17 pitch I have and see what I get with that. I want top speed to increase at the max RPM of 5700
galtsfan posted 09-28-2006 09:12 PM ET (US)
I'm no authority on props or pitch but I know if you're running an engine above the max recomended you are killing the engine. The prop has to be matched for the engine so it won't exceed the max.
BlackMax posted 09-29-2006 12:23 AM ET (US)
Engine is redlined at 5250, and those four cylinder Mercs don't like being over-revved. Based on your figures, you need a 19" Laser II to really make her run, engine in middle set of holes.
nanzpac posted 09-29-2006 11:31 AM ET (US)
The redline is 5250 on a 1991 Mariner/Merc 100hp? I thought it was 5700. I never run it over 5 anyway but the one time I did go over 6 gs and realized I really don't have the right prop. This summer was my first summer with the boat.
The Judge posted 09-29-2006 12:34 PM ET (US)
Yup 5250. I think a 19 or 20".
nanzpac posted 09-29-2006 01:13 PM ET (US)
Will I be able to pick up some top speed with the bigger pitch. I feel the 15 pitch is really slowing my top speed. I don't have a speedo, but a frind clocked me at only 33mph on a Sea Doo and I was kind of bummed. The engine runs perfectly and has full compression so I guess the prop is really the issue.
The Judge posted 09-29-2006 01:34 PM ET (US)
You don't know how props work do you? In "theory" for every revolution a prop turns it will move that far in inches. So "theoretically" a 15" prop will move 15" and a 19 will move 19" for every turn. So do you think a 19" will go faster than a 15"? Now the problem is what can you spin and what is your slip? What that means is can you swing a 19" to 5250 WOT nailed to the deck trimmed the hell out shooting a rooster tail, if so you have the perfect prop. If she will only turn 4900 with a 19" but will swing 5200 with a 17" then the 17" is the perfect prop. What you have to do is run the 17" and let us know RPMS. I would not howeber suggest running more than 5250 for more than a blip just to see how high. I am also amazed that your 100 does not have a rev limiter, at 6300 she should have grenaded.
nanzpac posted 09-29-2006 06:39 PM ET (US)
Yeah I admit I don't know anything about props. I will definately put the 17 and let you know. I am wondering if my tackometer is not reading correctly becasue I have not ever hit any rev limiter even though it was just for a few seconds. It is screaming though at that RPM.
BlackMax posted 09-29-2006 11:12 PM ET (US)
The 20" Mercury Laser II is what you want, and the hull lift will improve and smooth out the ride. Your rig should run around 46-47 mph with this set-up. All of this assumes your bottom is clean and engine putting out rated HP. You're wasting your time and fuel money on those hard riding aluminum props.
deepwater posted 10-01-2006 02:07 PM ET (US)
At times i wish i had insisted the dealer put the 100 hp motor on my montauk,,,HIS WORDS,,, Larry you don't need that much power on this lite whaler,,she is a bit squirrely withe the 88 as it is ,,,, He was right ,, If you nail it down to the right prop,, keep in mind that montauk will fly in more ways than one ,, you can catch a lot of air in that whales mouth,, just a thought
nanzpac posted 10-02-2006 06:23 PM ET (US)
Just once this summer I ran it up to 6300 RPMS with me alone and a few times I ran it to 5700 with 4 people in it and gear. I have only done this a couple times this entire summer and the 6300 RPM incident was a short blast only for 10 to 20 seconds. My question is...do you think I damaged the motor? It still runs perfect and it never hit a rev limiter. Do these motors have rev limiters? I would appreacite anyones opinion on this.
Thank you
Tom W Clark posted 10-03-2006 09:12 AM ET (US)
No. It is an old wive's tale that over revving a motor will instantly destroy it, but chronically exceeding the upper limits of the RPM range will not be good in the long term.
nanzpac posted 10-03-2006 12:25 PM ET (US)
Thanks for the comfort Tom. I questioned this over in the Repairs/Mod forum and got a couple responses to have the motor inspected now and to consider it probably damaged goods. All this for just one 6300 punch for a matter of seconds and maybe 2 other occasions at 5700 RPM's for maybe 1 min tops. I'll try not to lose sleep over it anymore.
jimh posted 10-03-2006 07:48 PM ET (US)
Throw in the question of how accurate your tachometer reading is, and you can really start to worry!
stant01 posted 10-13-2006 04:04 PM ET (US)
I've got a 1996 Merc 100 hp on a "Montauk", and with a LaserII 20-inch SS prop she runs 47 mph at 5200 rpm. Loaded a bit less, but not much. The 4-cyl Merc/Mariner 100 is a very high-torque engine that does not like to rev.
Acceleration is so good that we have to slowly push the throttle when picking up slalom skiers. A hard "shove" accelerates the boat so fast it yanks the rope away from the skier. If you get the Laser, you may want to experiment with vent hole size for best acceleration out of the hole. Mine came with approx 1/2 X 1/2 inch holes, and the engine was far too "loose" out of the hole: about 4500 rpm before the boat moved a few feet. I filled them with Marine Tex and re-drilled to 3/16 inch; that is near perfect for my rig, an ideal compromise between revs and bite. Once up on plane, the holes have no effect.
Your 17-inch prop is too little for a healthy 100 on a Montauk. The 15-inch is FAR too little pitch. I too am surprised that the rev limiter did not cut in on your test runs.
jimh posted 10-13-2006 11:50 PM ET (US)
Egad! There are plastic plugs which fill the vent holes! You generally never run them without a plastic plug of some size in there. The plugs come in several diameters, including completely blocked.
Check the Mercury website for information on the Performance Vent System (PVS) to find out more about how you tune their propellers.
stant01 posted 10-14-2006 10:19 AM ET (US)
I knew that, but the dealer was 20 miles away, and the Marine-Tex was at hand, so....
but you're right, I should not have expected a "prop newby" to do it my way. If you are buying a prop, buy the plugs at the same time.
Chuck Tribolet posted 10-14-2006 12:49 PM ET (US)
What rev limiter?
Modern cars have rev limiters because they are microprocessor
controlled and it's just a few lines of firmware. Old
fashioned engines (like carbed outboards) don't have one,
ESPECIALLY in a low-bucks line like Mariner.
For what it's worth, my '97ish Evinrude 90HP is well matched
to a 17"prop.

Chuck
The Judge posted 10-16-2006 02:21 PM ET (US)
Actually Mariner was a "higher" line than Mercury and your 17" prop on your 90 OMC has NOTHING to do with 100 Quicksilvers due to gear ratios. Yes even simple engines have rev limiters.
SS17 posted 10-16-2006 04:18 PM ET (US)
Coincidently, I was just going to post about rev limiters/props on the classic 2 stroke Mercury 90s. Do they have a limiter?
I just bought a 1997 Montauk with this motor and a 19" aluminum prop. The boat is a slug compared to my Supersport with a 90 Honda. The holeshot is slower and I could trim only slightly before the prop started to blow ventilate. 39+ mph GPS max.
My question relates to the way the motor felt as it hit around 5700 rpm. The motor would bog and go no faster. It felt like a limiter cutting in, but I would have guessed none existed on these motors either.
After reading here about what a great setup these motors on on Montauks, I was surprised by the poor performance which I relate to the prop.

I've read all the prop threads and think the consensus is a 21" stainless prop for this 2.33:1 motor, correct? The Merc prop calc comes up with a 13.5x20 Laser II.
The 19 aluminum is horrible. No bow lift whatsoever.
I'm hoping for 44 mph at 5500. Judging from my run yesterday of 39 gps mph at 5700+ bogging rpm, I would think this would be realistic.
Any recommendation with this combo appreciated.

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Author	Topic: MONTAUK: 100-HP Mariner: 15-, 16- 17-inch Pitch Propellers
nanzpac	posted 09-28-2006 06:11 PM ET (US) Hello. I have a 1980 Montauk with a 1991 Mariner 100hp. I have 3 Merc 3 blade props for it. They are 15, 16 and a 17 pitch. I want the highest top speed out of the boat. Does anyone know which prop would be the best. Thank you.
brisboats	posted 09-28-2006 07:32 PM ET (US) Takes less than a minute to switch them why not try each one and see. Generally if your motor can spin it the greater the pitch the faster the boat will go at it's top end. Brian
nanzpac	posted 09-28-2006 07:55 PM ET (US) Thats what I will do. I have a 15 on there right now and floored with me alone the boat hits almost 6300 RPM's and the motor manual calls for 5700. The boat is crazy fast out of the hole, but I'm afraid to even see what the top speed is becasue of the high RPM's. I'll probably go up to the 17 pitch I have and see what I get with that. I want top speed to increase at the max RPM of 5700
galtsfan	posted 09-28-2006 09:12 PM ET (US) I'm no authority on props or pitch but I know if you're running an engine above the max recomended you are killing the engine. The prop has to be matched for the engine so it won't exceed the max.
BlackMax	posted 09-29-2006 12:23 AM ET (US) Engine is redlined at 5250, and those four cylinder Mercs don't like being over-revved. Based on your figures, you need a 19" Laser II to really make her run, engine in middle set of holes.
nanzpac	posted 09-29-2006 11:31 AM ET (US) The redline is 5250 on a 1991 Mariner/Merc 100hp? I thought it was 5700. I never run it over 5 anyway but the one time I did go over 6 gs and realized I really don't have the right prop. This summer was my first summer with the boat.
The Judge	posted 09-29-2006 12:34 PM ET (US) Yup 5250. I think a 19 or 20".
nanzpac	posted 09-29-2006 01:13 PM ET (US) Will I be able to pick up some top speed with the bigger pitch. I feel the 15 pitch is really slowing my top speed. I don't have a speedo, but a frind clocked me at only 33mph on a Sea Doo and I was kind of bummed. The engine runs perfectly and has full compression so I guess the prop is really the issue.
The Judge	posted 09-29-2006 01:34 PM ET (US) You don't know how props work do you? In "theory" for every revolution a prop turns it will move that far in inches. So "theoretically" a 15" prop will move 15" and a 19 will move 19" for every turn. So do you think a 19" will go faster than a 15"? Now the problem is what can you spin and what is your slip? What that means is can you swing a 19" to 5250 WOT nailed to the deck trimmed the hell out shooting a rooster tail, if so you have the perfect prop. If she will only turn 4900 with a 19" but will swing 5200 with a 17" then the 17" is the perfect prop. What you have to do is run the 17" and let us know RPMS. I would not howeber suggest running more than 5250 for more than a blip just to see how high. I am also amazed that your 100 does not have a rev limiter, at 6300 she should have grenaded.
nanzpac	posted 09-29-2006 06:39 PM ET (US) Yeah I admit I don't know anything about props. I will definately put the 17 and let you know. I am wondering if my tackometer is not reading correctly becasue I have not ever hit any rev limiter even though it was just for a few seconds. It is screaming though at that RPM.
BlackMax	posted 09-29-2006 11:12 PM ET (US) The 20" Mercury Laser II is what you want, and the hull lift will improve and smooth out the ride. Your rig should run around 46-47 mph with this set-up. All of this assumes your bottom is clean and engine putting out rated HP. You're wasting your time and fuel money on those hard riding aluminum props.
deepwater	posted 10-01-2006 02:07 PM ET (US) At times i wish i had insisted the dealer put the 100 hp motor on my montauk,,,HIS WORDS,,, Larry you don't need that much power on this lite whaler,,she is a bit squirrely withe the 88 as it is ,,,, He was right ,, If you nail it down to the right prop,, keep in mind that montauk will fly in more ways than one ,, you can catch a lot of air in that whales mouth,, just a thought
nanzpac	posted 10-02-2006 06:23 PM ET (US) Just once this summer I ran it up to 6300 RPMS with me alone and a few times I ran it to 5700 with 4 people in it and gear. I have only done this a couple times this entire summer and the 6300 RPM incident was a short blast only for 10 to 20 seconds. My question is...do you think I damaged the motor? It still runs perfect and it never hit a rev limiter. Do these motors have rev limiters? I would appreacite anyones opinion on this. Thank you
Tom W Clark	posted 10-03-2006 09:12 AM ET (US) No. It is an old wive's tale that over revving a motor will instantly destroy it, but chronically exceeding the upper limits of the RPM range will not be good in the long term.
nanzpac	posted 10-03-2006 12:25 PM ET (US) Thanks for the comfort Tom. I questioned this over in the Repairs/Mod forum and got a couple responses to have the motor inspected now and to consider it probably damaged goods. All this for just one 6300 punch for a matter of seconds and maybe 2 other occasions at 5700 RPM's for maybe 1 min tops. I'll try not to lose sleep over it anymore.
jimh	posted 10-03-2006 07:48 PM ET (US) Throw in the question of how accurate your tachometer reading is, and you can really start to worry!
stant01	posted 10-13-2006 04:04 PM ET (US) I've got a 1996 Merc 100 hp on a "Montauk", and with a LaserII 20-inch SS prop she runs 47 mph at 5200 rpm. Loaded a bit less, but not much. The 4-cyl Merc/Mariner 100 is a very high-torque engine that does not like to rev. Acceleration is so good that we have to slowly push the throttle when picking up slalom skiers. A hard "shove" accelerates the boat so fast it yanks the rope away from the skier. If you get the Laser, you may want to experiment with vent hole size for best acceleration out of the hole. Mine came with approx 1/2 X 1/2 inch holes, and the engine was far too "loose" out of the hole: about 4500 rpm before the boat moved a few feet. I filled them with Marine Tex and re-drilled to 3/16 inch; that is near perfect for my rig, an ideal compromise between revs and bite. Once up on plane, the holes have no effect. Your 17-inch prop is too little for a healthy 100 on a Montauk. The 15-inch is FAR too little pitch. I too am surprised that the rev limiter did not cut in on your test runs.
jimh	posted 10-13-2006 11:50 PM ET (US) Egad! There are plastic plugs which fill the vent holes! You generally never run them without a plastic plug of some size in there. The plugs come in several diameters, including completely blocked. Check the Mercury website for information on the Performance Vent System (PVS) to find out more about how you tune their propellers.
stant01	posted 10-14-2006 10:19 AM ET (US) I knew that, but the dealer was 20 miles away, and the Marine-Tex was at hand, so.... but you're right, I should not have expected a "prop newby" to do it my way. If you are buying a prop, buy the plugs at the same time.
Chuck Tribolet	posted 10-14-2006 12:49 PM ET (US) What rev limiter? Modern cars have rev limiters because they are microprocessor controlled and it's just a few lines of firmware. Old fashioned engines (like carbed outboards) don't have one, ESPECIALLY in a low-bucks line like Mariner. For what it's worth, my '97ish Evinrude 90HP is well matched to a 17"prop. Chuck
The Judge	posted 10-16-2006 02:21 PM ET (US) Actually Mariner was a "higher" line than Mercury and your 17" prop on your 90 OMC has NOTHING to do with 100 Quicksilvers due to gear ratios. Yes even simple engines have rev limiters.
SS17	posted 10-16-2006 04:18 PM ET (US) Coincidently, I was just going to post about rev limiters/props on the classic 2 stroke Mercury 90s. Do they have a limiter? I just bought a 1997 Montauk with this motor and a 19" aluminum prop. The boat is a slug compared to my Supersport with a 90 Honda. The holeshot is slower and I could trim only slightly before the prop started to blow ventilate. 39+ mph GPS max. My question relates to the way the motor felt as it hit around 5700 rpm. The motor would bog and go no faster. It felt like a limiter cutting in, but I would have guessed none existed on these motors either. After reading here about what a great setup these motors on on Montauks, I was surprised by the poor performance which I relate to the prop. I've read all the prop threads and think the consensus is a 21" stainless prop for this 2.33:1 motor, correct? The Merc prop calc comes up with a 13.5x20 Laser II. The 19 aluminum is horrible. No bow lift whatsoever. I'm hoping for 44 mph at 5500. Judging from my run yesterday of 39 gps mph at 5700+ bogging rpm, I would think this would be realistic. Any recommendation with this combo appreciated.