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Author Topic:   MONTAUK 16, 75-HP

Fishmore posted 08-18-2008 03:01 PM ET (US)
I finally got to do a fishing trip with my new to me 75hp 1994 Mercury 2-stroke on my 73 re-built Montauk hull. Engine ran great, Jumped up on plane and cruised nicely at 3800rpm at about 28mph. WOT was 36mph at 5400 RPM. troll was 2.2 mph at 750 rpm and 3.5mph at 1000 rpm . Fuel econonmy was beyond my expectations. In general I did a combination of running and trolling covered about 32 miles in 5.5 hours and burned 4.26 gals of fuel. Running time was 32 minutes/14 miles the rest was spent trolling. Engine was off for about 30 minutes total but at random times during the day. It did load up once during trolling and I just shifted to neutral and reved it a bit to clear that up. People and gear weighed about 700 lbs. All speeds and distances by GPS. Fuel by refilling the tank.
I have not recieved my manuals yet (on order) but I think that WOT on this motor should be 5250 RPM and according to my research top speed should be closer to 40mph. I am currently using the original aluminum prop (no numbers yet), is it worth trying to get more out of this engine/boat combo by switching to a Stainless prop? Should I change pitch because the RPM is a tad higher than 5250 rpm? Or am I just wasting money to do these modifications.
Thanks Tim C.
Tohsgib posted 08-18-2008 03:07 PM ET (US)
Double check your redline and find out what prop you are running. 28mph @ 3800 amd then only getting 8 more mph out of the last 1800rpm does not make sense. Yes a SS prop is better for you performance wise.
Fishmore posted 08-18-2008 03:27 PM ET (US)
Thanks, I was just looking at the motor and thought about pulling the prop to check it out and found the numbers 4877344 A40 17P on the outside of the prop so it is a 17 pitch but not sure of the diameter. I agree that it should gain more than 7-8 mph in 1600 RPM maybe it is the flex of the old aluminum prop?
Fishmore posted 08-18-2008 06:07 PM ET (US)
Well I had some time this afternoon so I went to the Mercury site and found/ran thier prop selector inputing my performance settings and they reccomended 4 props for overall performance.
Black Max Aluminum 3-blade 13x19
LaserII Stainless 3-blade 13.25x19
Trophy+ Stainless 4-blade 13.75x19
Vengeance Stainless 3-blade 13x18
Interesting to note was that if I changed my criteria to improved acceleration the LaserII was dropeed from the reccomendation and all props were dropped to a 17p. If I changed criteria to improved top speed then the Black Max was dropped and the Trophy+ dropped pitch to 17.
So it sounds like I should go up in pitch as I run a 17p now. Does anyone have experience with the previously mentioned props or have recomendations? I am leaning towards the LaserII in 19p or the Vengeance in 18p. I am one-hole up and my cavitation plate sits 1.25 above the bottom of the transom.
Tohsgib posted 08-19-2008 11:40 AM ET (US)
Most run Lasers on their montauks with merc power. I believe keep the vent holes plugged as well.
cooper1958nc posted 08-20-2008 03:21 PM ET (US)
I will bet your boat will go about the same speed with the new prop.
The aluminum prop just does not "flex" that much with 75 hp going through it. Al props have been on outboards of that power for decades and they do fine if you don't bang them into someting.
This idea that Al props are flexing so much as to materially reduce boat speed is specious. If they flexed so much the blades would fatigue and fall off.
If you want a new prop, go up in pitch for quieter,more economical cruise, unless you have trouble getting on plane.
Otherwise forget it. Look for hull factors, engine trim or height, or tachometer inaccuracy.
cooper1958nc posted 08-20-2008 03:33 PM ET (US)
I would also note that Mercury's "prop selector" is not a scientific research tool. Although it may well have some scientific validation behind it (the algorithm is not available), its primary purpose is to sell propellers.
And everyone knows, you won't buy one if you don't think it will be better than what you already have.
Fishmore posted 08-21-2008 04:57 AM ET (US)
Thanks for the input Cooper. As a matter of fact my dealer said the same thing. Several other people told me the 75 can probably not turn a 19" prop effectivly or that I am wasting my time. I did confirm that WOT operating range is 4750 to 5250 and that I have a 2.33:1 gear ratio. I trim out to the point that the prop ventilates and then I trim in about 3 clicks to get the prop to bite again. It just seems strange that I can only gain 8 mph out of a 1600 rpm increase. That and the higher than optimum WOT RPM makes me think I should go up in pitch.
Besides the Merc prop selector I tried two other prop selectors and they also reccomended I go to a 19 pitch prop. But, I could not find a dealer that would let me test props so I ordered a 13.25 x 19 Aluminum prop for about $100 to see if the 75 can indeed turn a 19 pitch prop effectivly and to see what kind of performance changes happen. If the motor can not handle a 19 pitch then I am only out $100 and I can keep it for an emergency spare.
fishgutz posted 08-21-2008 09:11 AM ET (US)
Maybe I can help. I have a Dauntless 14 with a 75 Merc 2 stroke. I have 3 props. 17 and 19 Black Max aluminum props and an 18 Vengeance. I believe my boat weighs about the same as your's when loaded but is shorter. I usually run the 18 Vengeance SS prop. I get 5250 RPM and run right up to 37 MPH (gps) and then it inches up to 40. If I use the 17 Black Max it shoots up to about 34 MPH and then inches up to 36-37 MPH. The 19 works about the same as the 18 Vengeance but the top speed and hole shot performance seem to vary more. Hole shot seems a bit slower and the top speed seems to take longer to get to 40. I got the slightly used 18 Vengeance (with the hub kit) on Ebay for about $275.
I think you'd be best off with the 17 BlackMax and the 18 Vengeance. I don't know how a Lazer prop will work.
You're definitely in the ballpark.
Tohsgib posted 08-21-2008 02:16 PM ET (US)
I would try the 19 and if you like it start looking for a 18 Vengence which should smack you right about 5200.
Fishmore posted 08-21-2008 10:03 PM ET (US)
Thanks guys, I will report on my results when the new prop comes in.
jimh posted 08-21-2008 11:09 PM ET (US)
Your recollection that the maximum engine speed for your Mercury 75-HP motor is only 5,250-RPM seems to me to be too low. My recollection is that most Mercury two-cycle motors were rated to 5,500-RPM, except their four-cylinder in-line motors (of 115-HP or 125-HP), which were rated lower at 5,250-RPM. I believe the reason the four-cylinder motors were rated lower was due to their relatively large displacement, their four-cylinder in-line design, and their lack of any sort of balancing shafts or counterweights to suppress vibrations.
When you get the official literature for your 75-HP motor, check that engine speed rating to see if it isn't higher.
Fishmore posted 08-22-2008 01:11 AM ET (US)
Hi Jim, I got my manual today and it says 75hp / 4750 - 5250 max RPM WOT. The 90hp / 5000-5500. and you are right the 100/115/125 / 4750 - 5250.
Fishgutz, now that I reread your post I wish I would have waited to order a prop because that Vengeance 18 sounds like it performs exactly as I wanted it to.
Oh well I will still test the AL and see what I get before ordering a Vengeance.
Thanks again.
fishgutz posted 08-22-2008 09:28 AM ET (US)
Fishmore,
I'm sure in time you will be like everyone else on this forum. We all have at least 2 props. I'll bet there are guys out there with 10 props in their garage. Maybe more. You can always pick up slightly used props at substantial savings on ebay or even Craigslist.org. At one time I had 5 props. I don't even know how I accumulated that many. Sold 2 on ebay.
I think the Vengeance would work well for you, too. It has the right pitch for a good hole shot but is cupped more than many props, giving you more top end. I think that is how it works. Like I said they can be had for about $275 on ebay. You may have to wait for one to show up. It took me about one month to find one at the right price. It was absolutely like new. Just didn't have the correct box, big deal.
Check out Powertech props http://www.ptprop.com/
They make a good prop and will give you some info on what prop to use. I had a 19 inch stainless steel Powertech prop that I sold on ebay. Nice prop but a little too much pitch.
cooper1958nc posted 08-23-2008 05:47 PM ET (US)
Just use a 19" Al prop if it will plane the boat.
Slow the engine for better fuel economy and less noise.
Hardly anyone runs WOT all the time anyway.
"Cupping" increases effective pitch, mostly at speed. It may make a little difference, may not. Probably will not.
Your tach may be off a little. Or your boat may develop a lot of resistance at high speed.
Designer props may make a difference of a couple of mph at top speed, but virtually no difference in fuel economy at cruise, or so I predict.
Unless, of course, you like to talk about how you have the "latest" in propeller fashion.
Tohsgib posted 08-25-2008 01:14 PM ET (US)
A double cup will drop you about 100-200 rpms.
Tom W Clark posted 08-25-2008 01:59 PM ET (US)
Fishmore,
You definitely want to use a good stainless steel propeller. Your boat will be both faster and get better fuel economy. As an added benefit, the propeller will last longer and give you less trouble.
For a 1973 Montauk with a 1994 Mercury 75 I would recommend the 13" x 18" Mercury Vengeance, part # 48-16988A46 or the 13-1/4" x 19" Mercury Laser II, part # 48-899004A46.
If you want to try an after market prop, try a 13-1/4" x 17" Stiletto Advantage 4.25, part # D 811317.
All of these propellers are Flo-Torq hubbed. I strongly recommend using the Flo-Torq III hub kit which will offer some cushioning to the gearcase used on the pre-1999 models which were a little less robust than current gearcases.
Fishmore posted 08-26-2008 02:01 AM ET (US)
Thanks everyone. Tom Clark good to see your are back in the fray! I am still waiting for the 19 pitch prop I ordered to come in so I can test it. But, according to further reading and a reccomendation from the prop guru Tom I will probably go for the 13 x 18 vengeance unless this 19 pitch I ordered ends up doing exactly what I want. Then I will probably hold off and get a SS for a xmas present.
(I buy my own xmas presents and then give them to the wife and she gives each kid something to wrap up and give me. Now I get exactly what I want and I do not have a bunch of cologne or ties hanging around).
Fishcop posted 08-28-2008 06:12 PM ET (US)
Tim,
I see you are in Alameda. Try The Outboard Motor Shop in Alameda and see if Craig or Barney has a prop you can try. If not, I would go with Tom W. Clark's prop numbers. If you are running around the Bay or offshore, a SS prop is fine. If you are running the delta or inland, use the Aluminum or at least bring a spare or hub kit.
For your old girl to be running around at 36mph @ 5400rpm with a 14 year old motor, I would count my blessings and stick with what works. More gear/beer/bait and buddies vs. top speed is what I look for in a fishing boat.
Feel free to contact me with any questions.
Andy
Fishmore posted 08-29-2008 01:20 AM ET (US)
Thanks for the advice and offer Andy. I already spoke with the guys at OBMS they told me to not waste my time with the prop thing. But anyway I am just trying to dial it in.
I did a test tonight with the new prop. I installed a 13.25 x 19 in place of the 17 pitch I had on my 94 Mercury 75hp 2-stroke.
Old 17p AL prop was running
3800rpm at 28mph. WOT was 36mph at 5400
New 19p AL prop was running
3800rpm at 29.5mph WOT was 38.5 at 5400
So I went up 2' in pitch and the WOT RPM stayed the same so there must be a rev limiter on this engine.
By the way even after going up in pitch my time to plane was the same. I mean you hit the throttle and you are on plane no waiting to get over the hump or anything it just goes.
I am not sure what I am going to do now. I am trying to get the motor to max out at the reccomended maximum RPM of 5250.
Either I buy a SS prop that is 13.25 x 19 or I buy a 21 pitch AL and try that.
Tom W Clark posted 08-29-2008 11:24 AM ET (US)
There is no rev limiter on a 1994 Mercury 75 HP two stroke. The reason the two props reach the same ultimate RPM is probably because they are not the same model of propeller or the old 17" was repitched or otherwise modified (which is what I suspect).
Already you are seeing a 2.5 mph (7 percent) increase in top speed at the same RPM with nothing more than a simple change of propeller. That's great. If you go to the stainless steel prop you will see even more improvement.
I still stand by my recommendations.
davej14 posted 08-29-2008 05:44 PM ET (US)
Fishmore,
I have a Merc Black Max 21 pitch that is like new with a Flo Torq II hub kit (48-77348-A45 21P). E.mail me if you are interested. ($60.00 plus actual freight)
Fishmore posted 08-30-2008 01:08 AM ET (US)
DaveJ thanks that is a generous offer. but, I think I will stick with Tom's suggestion and order the 13-1/4" x 17" Stiletto Advantage 4.25. Hopefully, that will get me to where I want to be.
davej14 posted 08-30-2008 10:23 AM ET (US)
Fishmore,
That should be a good choice for you. Hope it works out.
Tom Clarke,
I tried to find the Laser II small hub 19 pitch on the Mercury website but the lowest pitch they list is 21. Is the 19 pitch available?
Tom W Clark posted 08-31-2008 12:03 PM ET (US)
Dave,
I don't know. The 19" and 21" version of the small tube Laser II were recent additions to the line in 2006. I don't see the 19" on Mercury's web site either but given how messed up the Mercury web site has gotten in the last year, I would not put too much faith in what it is representing. Call a dealer.
L H G posted 09-02-2008 06:15 PM ET (US)
The small hub 19" Laser II is part # 899004A46
The small hub 21" Laser II is part # 899006A46
Either is $345 at jacosmarine.com (about the best pricing you'll find).
Fishmore posted 09-27-2008 04:28 PM ET (US)
Got to test the reworked Stiletto today. Tim at RTK repitched it to 19. Results are that the prop has my RPMs at the perfect setting now 5200 at WOT. Manufacturers specs call for optimum rpm at WOT of 4750 to 5250 so I would say you can not get much better than 5200!
Final results are:
4000 RPM 27.5 mph
5200 RPM 38.5 mph (WOT)
In addition, I still get to 2.0 mph at idle and if I trim the motor all the way in I can plane at 16 mph. By the way it also still hops the boat right up on plane.
I can highly recomend Tim at RTK in San Leandro CA for your prop needs. The prop does exactly what I asked for, the price was reasonable (much better than buying another prop) and the prop was ready on the day it was promised to me. Perfect!
scottfarm posted 10-06-2008 07:00 AM ET (US)
I had a 96 montauk with a 95 merc 75 and got 42mph with 30 gallons of fuel and two people. It had a 13.25 X 21 propco stainless steel prop. It would jump out of the hole quick too. Make sure your cavitation plate is 1 1/2 inches above the bottom of the boat. I you don't it's a drag.
Fishmore posted 10-07-2008 01:02 AM ET (US)
Scott, thanks for that info. I think if I went to a larger prop I could get more speed and my cav plate is 1.25 above the bottom of the boat. What I asked Tim at RTK to do is to give me a good all-around prop. I do a lot of fishing, and some tubing and some running around. But most important is I want the prop to keep the RPMs at the manufacturers specs at WOT. So Tim at RTK said he will make this prop so that it performs like a 17 at trolling speeds but give me 19 performance at the high end of my RPM range and it will top out at 5200. That seems to be what he has done so I am real happy with the way it turned out. I did think that it would top out at 40mph but considering everything else he only missed that mark by 1.5 mph and I spend a lot more time trolling at 2 mph than I do at WOT.
Regards.

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Author	Topic: MONTAUK 16, 75-HP
Fishmore	posted 08-18-2008 03:01 PM ET (US) I finally got to do a fishing trip with my new to me 75hp 1994 Mercury 2-stroke on my 73 re-built Montauk hull. Engine ran great, Jumped up on plane and cruised nicely at 3800rpm at about 28mph. WOT was 36mph at 5400 RPM. troll was 2.2 mph at 750 rpm and 3.5mph at 1000 rpm . Fuel econonmy was beyond my expectations. In general I did a combination of running and trolling covered about 32 miles in 5.5 hours and burned 4.26 gals of fuel. Running time was 32 minutes/14 miles the rest was spent trolling. Engine was off for about 30 minutes total but at random times during the day. It did load up once during trolling and I just shifted to neutral and reved it a bit to clear that up. People and gear weighed about 700 lbs. All speeds and distances by GPS. Fuel by refilling the tank. I have not recieved my manuals yet (on order) but I think that WOT on this motor should be 5250 RPM and according to my research top speed should be closer to 40mph. I am currently using the original aluminum prop (no numbers yet), is it worth trying to get more out of this engine/boat combo by switching to a Stainless prop? Should I change pitch because the RPM is a tad higher than 5250 rpm? Or am I just wasting money to do these modifications. Thanks Tim C.
Tohsgib	posted 08-18-2008 03:07 PM ET (US) Double check your redline and find out what prop you are running. 28mph @ 3800 amd then only getting 8 more mph out of the last 1800rpm does not make sense. Yes a SS prop is better for you performance wise.
Fishmore	posted 08-18-2008 03:27 PM ET (US) Thanks, I was just looking at the motor and thought about pulling the prop to check it out and found the numbers 4877344 A40 17P on the outside of the prop so it is a 17 pitch but not sure of the diameter. I agree that it should gain more than 7-8 mph in 1600 RPM maybe it is the flex of the old aluminum prop?
Fishmore	posted 08-18-2008 06:07 PM ET (US) Well I had some time this afternoon so I went to the Mercury site and found/ran thier prop selector inputing my performance settings and they reccomended 4 props for overall performance. Black Max Aluminum 3-blade 13x19 LaserII Stainless 3-blade 13.25x19 Trophy+ Stainless 4-blade 13.75x19 Vengeance Stainless 3-blade 13x18 Interesting to note was that if I changed my criteria to improved acceleration the LaserII was dropeed from the reccomendation and all props were dropped to a 17p. If I changed criteria to improved top speed then the Black Max was dropped and the Trophy+ dropped pitch to 17. So it sounds like I should go up in pitch as I run a 17p now. Does anyone have experience with the previously mentioned props or have recomendations? I am leaning towards the LaserII in 19p or the Vengeance in 18p. I am one-hole up and my cavitation plate sits 1.25 above the bottom of the transom.
Tohsgib	posted 08-19-2008 11:40 AM ET (US) Most run Lasers on their montauks with merc power. I believe keep the vent holes plugged as well.
cooper1958nc	posted 08-20-2008 03:21 PM ET (US) I will bet your boat will go about the same speed with the new prop. The aluminum prop just does not "flex" that much with 75 hp going through it. Al props have been on outboards of that power for decades and they do fine if you don't bang them into someting. This idea that Al props are flexing so much as to materially reduce boat speed is specious. If they flexed so much the blades would fatigue and fall off. If you want a new prop, go up in pitch for quieter,more economical cruise, unless you have trouble getting on plane. Otherwise forget it. Look for hull factors, engine trim or height, or tachometer inaccuracy.
cooper1958nc	posted 08-20-2008 03:33 PM ET (US) I would also note that Mercury's "prop selector" is not a scientific research tool. Although it may well have some scientific validation behind it (the algorithm is not available), its primary purpose is to sell propellers. And everyone knows, you won't buy one if you don't think it will be better than what you already have.
Fishmore	posted 08-21-2008 04:57 AM ET (US) Thanks for the input Cooper. As a matter of fact my dealer said the same thing. Several other people told me the 75 can probably not turn a 19" prop effectivly or that I am wasting my time. I did confirm that WOT operating range is 4750 to 5250 and that I have a 2.33:1 gear ratio. I trim out to the point that the prop ventilates and then I trim in about 3 clicks to get the prop to bite again. It just seems strange that I can only gain 8 mph out of a 1600 rpm increase. That and the higher than optimum WOT RPM makes me think I should go up in pitch. Besides the Merc prop selector I tried two other prop selectors and they also reccomended I go to a 19 pitch prop. But, I could not find a dealer that would let me test props so I ordered a 13.25 x 19 Aluminum prop for about $100 to see if the 75 can indeed turn a 19 pitch prop effectivly and to see what kind of performance changes happen. If the motor can not handle a 19 pitch then I am only out $100 and I can keep it for an emergency spare.
fishgutz	posted 08-21-2008 09:11 AM ET (US) Maybe I can help. I have a Dauntless 14 with a 75 Merc 2 stroke. I have 3 props. 17 and 19 Black Max aluminum props and an 18 Vengeance. I believe my boat weighs about the same as your's when loaded but is shorter. I usually run the 18 Vengeance SS prop. I get 5250 RPM and run right up to 37 MPH (gps) and then it inches up to 40. If I use the 17 Black Max it shoots up to about 34 MPH and then inches up to 36-37 MPH. The 19 works about the same as the 18 Vengeance but the top speed and hole shot performance seem to vary more. Hole shot seems a bit slower and the top speed seems to take longer to get to 40. I got the slightly used 18 Vengeance (with the hub kit) on Ebay for about $275. I think you'd be best off with the 17 BlackMax and the 18 Vengeance. I don't know how a Lazer prop will work. You're definitely in the ballpark.
Tohsgib	posted 08-21-2008 02:16 PM ET (US) I would try the 19 and if you like it start looking for a 18 Vengence which should smack you right about 5200.
Fishmore	posted 08-21-2008 10:03 PM ET (US) Thanks guys, I will report on my results when the new prop comes in.
jimh	posted 08-21-2008 11:09 PM ET (US) Your recollection that the maximum engine speed for your Mercury 75-HP motor is only 5,250-RPM seems to me to be too low. My recollection is that most Mercury two-cycle motors were rated to 5,500-RPM, except their four-cylinder in-line motors (of 115-HP or 125-HP), which were rated lower at 5,250-RPM. I believe the reason the four-cylinder motors were rated lower was due to their relatively large displacement, their four-cylinder in-line design, and their lack of any sort of balancing shafts or counterweights to suppress vibrations. When you get the official literature for your 75-HP motor, check that engine speed rating to see if it isn't higher.
Fishmore	posted 08-22-2008 01:11 AM ET (US) Hi Jim, I got my manual today and it says 75hp / 4750 - 5250 max RPM WOT. The 90hp / 5000-5500. and you are right the 100/115/125 / 4750 - 5250. Fishgutz, now that I reread your post I wish I would have waited to order a prop because that Vengeance 18 sounds like it performs exactly as I wanted it to. Oh well I will still test the AL and see what I get before ordering a Vengeance. Thanks again.
fishgutz	posted 08-22-2008 09:28 AM ET (US) Fishmore, I'm sure in time you will be like everyone else on this forum. We all have at least 2 props. I'll bet there are guys out there with 10 props in their garage. Maybe more. You can always pick up slightly used props at substantial savings on ebay or even Craigslist.org. At one time I had 5 props. I don't even know how I accumulated that many. Sold 2 on ebay. I think the Vengeance would work well for you, too. It has the right pitch for a good hole shot but is cupped more than many props, giving you more top end. I think that is how it works. Like I said they can be had for about $275 on ebay. You may have to wait for one to show up. It took me about one month to find one at the right price. It was absolutely like new. Just didn't have the correct box, big deal. Check out Powertech props http://www.ptprop.com/ They make a good prop and will give you some info on what prop to use. I had a 19 inch stainless steel Powertech prop that I sold on ebay. Nice prop but a little too much pitch.
cooper1958nc	posted 08-23-2008 05:47 PM ET (US) Just use a 19" Al prop if it will plane the boat. Slow the engine for better fuel economy and less noise. Hardly anyone runs WOT all the time anyway. "Cupping" increases effective pitch, mostly at speed. It may make a little difference, may not. Probably will not. Your tach may be off a little. Or your boat may develop a lot of resistance at high speed. Designer props may make a difference of a couple of mph at top speed, but virtually no difference in fuel economy at cruise, or so I predict. Unless, of course, you like to talk about how you have the "latest" in propeller fashion.
Tohsgib	posted 08-25-2008 01:14 PM ET (US) A double cup will drop you about 100-200 rpms.
Tom W Clark	posted 08-25-2008 01:59 PM ET (US) Fishmore, You definitely want to use a good stainless steel propeller. Your boat will be both faster and get better fuel economy. As an added benefit, the propeller will last longer and give you less trouble. For a 1973 Montauk with a 1994 Mercury 75 I would recommend the 13" x 18" Mercury Vengeance, part # 48-16988A46 or the 13-1/4" x 19" Mercury Laser II, part # 48-899004A46. If you want to try an after market prop, try a 13-1/4" x 17" Stiletto Advantage 4.25, part # D 811317. All of these propellers are Flo-Torq hubbed. I strongly recommend using the Flo-Torq III hub kit which will offer some cushioning to the gearcase used on the pre-1999 models which were a little less robust than current gearcases.
Fishmore	posted 08-26-2008 02:01 AM ET (US) Thanks everyone. Tom Clark good to see your are back in the fray! I am still waiting for the 19 pitch prop I ordered to come in so I can test it. But, according to further reading and a reccomendation from the prop guru Tom I will probably go for the 13 x 18 vengeance unless this 19 pitch I ordered ends up doing exactly what I want. Then I will probably hold off and get a SS for a xmas present. (I buy my own xmas presents and then give them to the wife and she gives each kid something to wrap up and give me. Now I get exactly what I want and I do not have a bunch of cologne or ties hanging around).
Fishcop	posted 08-28-2008 06:12 PM ET (US) Tim, I see you are in Alameda. Try The Outboard Motor Shop in Alameda and see if Craig or Barney has a prop you can try. If not, I would go with Tom W. Clark's prop numbers. If you are running around the Bay or offshore, a SS prop is fine. If you are running the delta or inland, use the Aluminum or at least bring a spare or hub kit. For your old girl to be running around at 36mph @ 5400rpm with a 14 year old motor, I would count my blessings and stick with what works. More gear/beer/bait and buddies vs. top speed is what I look for in a fishing boat. Feel free to contact me with any questions. Andy
Fishmore	posted 08-29-2008 01:20 AM ET (US) Thanks for the advice and offer Andy. I already spoke with the guys at OBMS they told me to not waste my time with the prop thing. But anyway I am just trying to dial it in. I did a test tonight with the new prop. I installed a 13.25 x 19 in place of the 17 pitch I had on my 94 Mercury 75hp 2-stroke. Old 17p AL prop was running 3800rpm at 28mph. WOT was 36mph at 5400 New 19p AL prop was running 3800rpm at 29.5mph WOT was 38.5 at 5400 So I went up 2' in pitch and the WOT RPM stayed the same so there must be a rev limiter on this engine. By the way even after going up in pitch my time to plane was the same. I mean you hit the throttle and you are on plane no waiting to get over the hump or anything it just goes. I am not sure what I am going to do now. I am trying to get the motor to max out at the reccomended maximum RPM of 5250. Either I buy a SS prop that is 13.25 x 19 or I buy a 21 pitch AL and try that.
Tom W Clark	posted 08-29-2008 11:24 AM ET (US) There is no rev limiter on a 1994 Mercury 75 HP two stroke. The reason the two props reach the same ultimate RPM is probably because they are not the same model of propeller or the old 17" was repitched or otherwise modified (which is what I suspect). Already you are seeing a 2.5 mph (7 percent) increase in top speed at the same RPM with nothing more than a simple change of propeller. That's great. If you go to the stainless steel prop you will see even more improvement. I still stand by my recommendations.
davej14	posted 08-29-2008 05:44 PM ET (US) Fishmore, I have a Merc Black Max 21 pitch that is like new with a Flo Torq II hub kit (48-77348-A45 21P). E.mail me if you are interested. ($60.00 plus actual freight)
Fishmore	posted 08-30-2008 01:08 AM ET (US) DaveJ thanks that is a generous offer. but, I think I will stick with Tom's suggestion and order the 13-1/4" x 17" Stiletto Advantage 4.25. Hopefully, that will get me to where I want to be.
davej14	posted 08-30-2008 10:23 AM ET (US) Fishmore, That should be a good choice for you. Hope it works out. Tom Clarke, I tried to find the Laser II small hub 19 pitch on the Mercury website but the lowest pitch they list is 21. Is the 19 pitch available?
Tom W Clark	posted 08-31-2008 12:03 PM ET (US) Dave, I don't know. The 19" and 21" version of the small tube Laser II were recent additions to the line in 2006. I don't see the 19" on Mercury's web site either but given how messed up the Mercury web site has gotten in the last year, I would not put too much faith in what it is representing. Call a dealer.
L H G	posted 09-02-2008 06:15 PM ET (US) The small hub 19" Laser II is part # 899004A46 The small hub 21" Laser II is part # 899006A46 Either is $345 at jacosmarine.com (about the best pricing you'll find).
Fishmore	posted 09-27-2008 04:28 PM ET (US) Got to test the reworked Stiletto today. Tim at RTK repitched it to 19. Results are that the prop has my RPMs at the perfect setting now 5200 at WOT. Manufacturers specs call for optimum rpm at WOT of 4750 to 5250 so I would say you can not get much better than 5200! Final results are: 4000 RPM 27.5 mph 5200 RPM 38.5 mph (WOT) In addition, I still get to 2.0 mph at idle and if I trim the motor all the way in I can plane at 16 mph. By the way it also still hops the boat right up on plane. I can highly recomend Tim at RTK in San Leandro CA for your prop needs. The prop does exactly what I asked for, the price was reasonable (much better than buying another prop) and the prop was ready on the day it was promised to me. Perfect!
scottfarm	posted 10-06-2008 07:00 AM ET (US) I had a 96 montauk with a 95 merc 75 and got 42mph with 30 gallons of fuel and two people. It had a 13.25 X 21 propco stainless steel prop. It would jump out of the hole quick too. Make sure your cavitation plate is 1 1/2 inches above the bottom of the boat. I you don't it's a drag.
Fishmore	posted 10-07-2008 01:02 AM ET (US) Scott, thanks for that info. I think if I went to a larger prop I could get more speed and my cav plate is 1.25 above the bottom of the boat. What I asked Tim at RTK to do is to give me a good all-around prop. I do a lot of fishing, and some tubing and some running around. But most important is I want the prop to keep the RPMs at the manufacturers specs at WOT. So Tim at RTK said he will make this prop so that it performs like a 17 at trolling speeds but give me 19 performance at the high end of my RPM range and it will top out at 5200. That seems to be what he has done so I am real happy with the way it turned out. I did think that it would top out at 40mph but considering everything else he only missed that mark by 1.5 mph and I spend a lot more time trolling at 2 mph than I do at WOT. Regards.